Tube Fitter’s

Manual

Swagelok Tube Fitter’s Manual

Swagelok
Tube
Fitter’s
Manual

Swagelok Company — Solon, Ohio U.S.A.

The electronic version of the Tube Fitter Manual supercedes the
printed version.

All trademarks shown are owned and registered by Swagelok Company,

unless otherwise noted.
Delrin­—TM E.I. du Pont de Nemours and Company
Dowtherm—TM The Dow Chemical Company
Therminol—TM Solutia Inc. Corporation
Tygon—TM Saint-Gobain Performance Plastics Corporation

Copyright © 1963-2025
Rev J
MS-13-03

Swagelok Company
Solon, Ohio

Printed in the United States of America

Published simultaneously in the Dominion of Canada

All rights reserved. This book or any parts thereof may not be reproduced in
any form without the express permission of Swagelok Company.

Tube fittings, valves, and other fluid system components illustrated in this
manual are the subject of pending or issued U.S. and foreign patents.

The contents of this manual are intended to provide reference information

to assist the user. However, it is important that total system design be
considered to ensure safe, trouble-free performance. Component function,
material compatibility, adequate ratings, proper installation, operation, and
maintenance are the responsibilities of the system designer and user.

iii
Preface
Wherever gases and liquids flow, Swagelok® tube fittings are preferred for their
robust performance, reliability and availability. Swagelok tube fittings have attained
leadership in industry because of outstanding design principles in combination
with superior metallurgy, close manufacturing tolerances and quality assurance
within each stage of the manufacturing process. In addition, our network of local
authorized sales and service centers helps you optimize your supply chain, offering
off-the-shelf delivery, inventory management, and support throughout the world.

These fittings have been used successfully on demanding applications in

such fields as semiconductor, alternative fuels, chemical and petrochemical,
oil and gas, fossil and nuclear power, pulp and paper, and aerospace. Our
Continuous Improvement efforts have allowed Swagelok tube fittings to set the
standard for excellence since 1947.

As industry requirements have grown and changed over the years, so too
has the content of this manual. We have expanded the manual to include in-
formation on selecting tube fittings for severe service requirements, metallurgy,
innovations in product design, and advanced manufacturing processes. Yet
the information you have always counted on, such as troubleshooting, tubing
specifications, and pressure ratings is still here.

To improve the accessibility of information in this manual, we have added a

QR code, as shown below. This code links you to important information, such as
supplemental publications or videos. Simply use your mobile device’s QR code
reader application or go to www.swagelok.com/TFM to access the content.

For more information, please refer to

this video of leak-tight performance.
www.swagelok.com/TFM

The success of your fluid system is dependent not only upon specifying
Swagelok tube fittings, but also upon proper installation and use of high-quality
tubing. We believe that the combination of these factors will go far to help en-
sure leak-tight connections.

The information contained in this manual is a result of extensive field r­ esearch

and laboratory studies conducted by our research and development engineers,
as well as by our customers. We would like to thank the many pipe fitters, sys-
tem design and instrument engineers, and shop floor personnel whose exten-
sive help, suggestions, contributions and comments made this book possible.

iv
Table of Contents

Chapter 1 The Swagelok Tube Fitting������������������ 1

Chapter 2 Tubing: Specification

and Ordering������������������������������� 17

Chapter 3 Tubing and Tube Fitting

Handling and Installation����������������� 33

Chapter 4 Severe Service��������������������������� 123

Chapter 5 Troubleshooting�������������������������� 149

Chapter 6 Special Purpose Fittings������������������ 157

Chapter 7 Testing and Evaluation

of Tube Fitting Performance�������������� 173

Chapter 8 Threads����������������������������������� 193

Chapter 9 Pressure Ratings������������������������� 209

Chapter 10 The Hidden Costs of Leakage������������ 223

Appendix A Flow/Pressure Charts

and Conversions������������������������� 233

Appendix B Miscellaneous Tables�������������������� 263

Appendix C Corrosion Charts������������������������� 283

Index �������������������������������������������� 299

v
C hap ter 11
h a pter
The Swagelok
Swagelok Tube
Tube Fitting
Fitting

Table of Contents
The Swagelok® Tube Fitting
Fitting Advantage
Advantage 2
Swagelok Tube
How the Swagelok Tube Fitting
FittingWorks
Works 3
Enhanced Factors of of Performance:
Performance:The The Big
BigThree
Three 4
Tube Grip 4
Gas Seal 5
Vibration Resistance 6
Materials 7
Material Standards 7
Additional Processing
Processing 8
Swagelok Tube
Bored-Through Swagelok Tube Fittings
Fittings 8
A Checklist for
for Excellence
Excellence inin Tube
Tube Fitting
Fitting Selection
Selection 10
Design 10
Performance 11
Installation 11
Quality Assurance 12
Why Close Tolerances Are Important 12
Gaugeability 14
Interchange and Intermix of TubeTube Fitting
Fitting Components
Components 14
15
2 Tube Fitter’s Manual

The Swagelok Tube Fitting Advantage

The Swagelok tube fitting is a flareless, mechanical grip-type ­fitting
consisting of a body, nut, front ferrule, and back ferrule. It is the
­industry-leading two-ferrule, mechanical grip-type tube fitting and
has set the standard for performance and reliability. All components
are manufactured to exacting tolerances from the highest quality
material, providing a tube fitting that will perform in a wide array of
markets and applications. The design has evolved over the years to
keep up with changing industry needs.

For more information, please refer to

this video of the design.
www.swagelok.com/TFM

Swagelok tube fittings are offered in a variety of configurations,

sizes, and materials that are designed to handle some of the most
severe field applications. Learn more about Swagelok’s leak-tight
performance.

For more information, please refer to

this video of leak-tight performance.
www.swagelok.com/TFM
Back ferrule

Hinge point

Nut

Tubing Front ferrule

Fitting body
■ Excellent gas-tight sealing and tube-gripping
action
■ Easily achieved proper installation
■ Consistent reassemblies
■ Excellent vibration fatigue resistance and
tube support

Figure 1-1 The Swagelok tube fitting advantage.

 The Swagelok Tube Fitting 3

How the Swagelok Tube Fitting Works

The Swagelok tube fitting is a sequential-phase, controlled-action
sealing and gripping device. Superior design, rigid manufacturing
­tolerances, and strict quality assurance programs produce an all-
metal sealing and holding device that performs leak-tight when
­properly installed.
For more information, please refer to
this video of how the pull-up works.
www.swagelok.com/TFM

Consisting of a nut, back ferrule, front ferrule, and body, the

­Swagelok tube fitting functions as follows:
1. Tubing is inserted into the completely assembled fitting until it
­bottoms against the shoulder of the fitting.
2. The nut is tightened 1 1/4 turns from finger-tight. During this
tightening, a number of different movements take place within
the ­fitting in a preplanned sequence.
For more information, please refer to
this video of How It Works.
www.swagelok.com/TFM

a) Through threaded mechanical advantage, the nut moves

­forward, driving the back ferrule forward.
b) The back ferrule drives the front ferrule forward.
c) The front ferrule is forced inward by the fitting body bevel.
d) The front ferrule takes up the tolerance between its inside
diameter and the outside diameter of the tube.
e) As the front ferrule moves forward and inward, its trailing edge
is lifted by the back ferrule to a sealing position with the fitting
body bevel.
f) As greater resistance is encountered because more tubing is
deformed and a greater area of body bevel and front ferrule is
in contact, the back ferrule is driven inward to form a grip, or
hold, on the tubing.
g) At 1 1/4 turns of wrench pull-up, the nut has moved 1/16 in.
forward. Within this 1/16 in. movement, the sequence of
­
sealing and holding has been accomplished.
h) One of the unique abilities of this proven design is the ability
to seal and hold on a wide variety of tubing materials, wall
4 Tube Fitter’s Manual

t­hicknesses, and hardnesses. Because the amount of back

ferrule grip is determined by the tube’s resistance to front
ferrule action, grip is much tighter when heavy wall tubing
is encountered. This is an important design feature because
heavy wall tubing is often used in service conditions such as
high pressure or other unusual stresses, vibration, pulsation,
or shock. Thus, the Swagelok tube fitting, by design, grips
much more securely on heavy wall tubing than it does on thin
wall tubing used for more moderate service (Figure 1-2).

Figure 1-2 Compensating action of the Swagelok tube fitting.

Enhanced Factors of Performance:

The Big Three
Tube Grip
The patented recessed and contoured geometry of the Swagelok
back ferrule creates the hinging and colleting™ action that grips the
tube. The hinging and colleting action allows for more material of
the back ferrule to be in close contact with the tube adjacent to
the tube grip. This material provides direct and axial support to the
tube-­gripping function.
 The Swagelok Tube Fitting 5

Nut

Body

Front ferrule
Back

Figure 1-3 The hinging and colleting™ action provides more material of the
back ferrule in close contact with the tube adjacent to the tube grip.

Gas Seal
A gas seal is achieved by the burnishing or polishing that occurs
­between the front ferrule and the tube fitting body and the front
ferrule and the tubing. This burnishing action accompanies
concentrated zones of contact, as shown in yellow.
The back ferrule drives the front ferrule a sufficient distance to
achieve the gas seal. Once this is accomplished, the back ferrule
will no longer progress against the front ferrule. By controlling the
­movement of the back ferrule just enough to ensure a leak-tight
seal, the Swagelok tube fitting limits the stroke and deformation on
the front ferrule.
We refer to this controlled movement of the ferrules as compensating
action. Compensating action allows the tube fitting to overcome
tubing variables such as materials, hardness, wall thickness, and
­dimensions, while achieving a leak-tight seal.

For more information, please refer to

this video of the tube fitting and gas
seal. www.swagelok.com/TFM
6 Tube Fitter’s Manual

Nut

Body

Back Front ferrule

Figure 1-4 Gas seal between front ferrule and the tube.
­Concentration of burnished zone shown in yellow.

Vibration Resistance
To reduce the effects of bending, deflection, and vibration, the
mid portion of the back ferrule adjacent to the tube-gripping nose
collets and applies a compressive stress against the tube that
isolates, dampens, and protects the stress riser at the nose of the
back ­ferrule.
The live-loading, spring action and residual elasticity of the front
and back ferrules compensate for thermal cycling and thermal and
mechanical transients (rapid changes). The elasticity of the ferrules
responds and maintains a seal through these transients. This design
has a protected stress riser through our patented back ferrule
geometry, which reduces the damaging effects of system dynamics.
 The Swagelok Tube Fitting 7

Materials
Material Standards

Material Bar Stock➀ Forgings➁ Designator

ASTM A276,
316 stainless ASTM A182, ASME
ASME SA479, SS
steel SA182, EN 1.4401
EN 1.4401/ 1.4404
ASTM B564,
Alloy 400 ASTM B164 M
ASME SB564
ASTM B166, ASTM B564,
Alloy 600 INC
ASME SB166 ASME SB564
ASTM B564,
Alloy 625 ASTM B446➂ 625
ASME SB564➃
ASTM B564,
Alloy 825 ASTM B425 825
ASME SB564
Alloy C-276 ASTM B574 ASTM B564 HC
6-Moly ASTM A479 ASTM A182 6MO
Aluminum ASTM B211 ASTM B247 A
ASTM B16,
Brass ASTM B283 B
ASTM B453
Carbon steel ASTM A108 — S
ASTM D3307
PFA➄ — PFA
Type I
PTFE ASTM D1710 ASTM D3294 T
Alloy 2507➅ ASTM A479 ASTM A182 2507
Titanium
ASTM B348 ASTM B381 TI
(grade 4)
➀ Straight fittings and tube adapters.
➁ Elbows, crosses, and tees.
➂A ll straight fittings and tube adapters and 1/4 and 3/8 in.; 6 and 10 mm elbows,
crosses, and tees.
➃ Elbows, crosses, and tees larger than 3/8 in. and 10 mm.
➄ See the Swagelok PFA Tube Fittings catalog, MS-01-05.
➅S ee the Swagelok Gaugeable Alloy 2507 Super Duplex Tube Fittings catalog,
MS-01-174.
8 Tube Fitter’s Manual

Additional Processing
Fitting bodies are processed for improved performance, as shown.
No additional processing is required for alloy 625, alloy 825, brass,
316 stainless steel, 6-Moly stainless steel, and PTFE ­materials.

Fitting Body Material Process

Aluminum Anodized, hydrocarbon film
Alloy 400, alloy C-276,
Hydrocarbon film
alloy 600
Carbon steel (except weld bodies) Zinc plating
Hydrocarbon film chemical
Carbon steel (weld bodies)
conversion coating
Titanium Anodized

■ Over 1 in./25 mm fittings are supplied with a package of fluorinated-

base with PTFE and tungsten disulfide lubricant for use in fitting
­assembly.
■ Over 1 in./25 mm stainless steel fittings use stainless steel
ferrules with PFA coating. Applications above 450°F (232°C)
require silver-plated front ferrules and uncoated back ferrules. To
order fittings with silver-plated front ferrules and uncoated back
ferrules, add BM to the fitting ordering number.
Example: SS-2400-6BM
■ All carbon steel Swagelok tube fittings are supplied with 316
stainless steel back ferrules.

Bored-Through Swagelok Tube Fittings

For many years, Swagelok tube fittings have been successfully
used for introducing thermocouples or other types of probes into
piping systems. There is one physical difference between a bored-
through fitting and a standard fitting. When a fitting body is bored-
through, the shoulder of the Swagelok tube fitting is removed and
the ferrules will not meet the same resistance as when the tubing
is properly bottomed.
 The Swagelok Tube Fitting 9

Swagelok bored-through male connectors accommodate

thermocouples or dip tubes. Most male connectors are available as
a bored-through fitting, but male connectors whose pipe thread end
is small relative to the tube fitting end—such as -600-1-2 or -8M0-1-
2RT—cannot be bored through.
Swagelok bored-through reducers and standard Swagelok tees can
be used to create a heat exchanger tee.
To order bored-through fittings, add BT to the ordering number.
Example: SS-400-1-4BT
Bored-through fittings have a reduced pressure rating.

Figure 1-5 Bored-through fittings for thermocouples, dip tubes, and heat
exchanger tees.

The most obvious effect is that pressure rating is reduced. In general,

we have multiplied the allowable working pressure of the tubing, as
found on the Tubing Data Sheet, by the following factors:

Size (in.) Size (mm) Factor

Up to 1/2 in. Up to 12 mm 0.75
Above 1/2 in. to 3/4 in. Above 12 mm to 18 mm 0.50
Above 3/4 in. Above 18 mm 0.25
10 Tube Fitter’s Manual

All other requirements for correct installation of Swagelok tube

­fittings need to be observed for bored-through fittings:
■ Correct tube material
■ Hardness and wall thickness
■ Correct pull-up
■ Temperature limitations
First, for sizes 1/16 and 1/8 in. (4 mm and below), always tighten the
nut until the tube will not turn by hand or move axially in the fitting,
then complete the required assembly procedure.
Because many bored-through fitting applications involve thermocouples
with different types of filler materials, the user should verify the suitability
of the thermocouple with the Swagelok fitting.
With over 1 in. and over 25 mm bored-through fittings, the tubing
is inserted through the fitting body, and pull-up must be done with
wrenches and inspected with the multihead hydraulic swaging unit
(MHSU) gap gauge.

A Checklist for Excellence in Tube

Fitting Selection
Design
■ The tube fitting will be a controlled-phased, sequential-gripping
device consisting of four machined components—the body,
­
front ferrule, back ferrule, and nut—that are produced by a single
manufacturer and engineered to work in a wide range of system
conditions.
■ The back ferrule will have a uniform surface hardening. This
surface hardening will be a low-temperature carburization,
avoiding carbide formation. It will follow a disclosed and auditable
process procedure.
■ There will be no machined ferrule stops. Assembly of parts will
provide for ferrule movement during tightening. The tube fitting
components will be engineered to provide appropriate controlled-
phased, sequential ferrule movement during tightening. Upon
proper installation, the tube fitting will be capable of disassembly
and reassembly, producing a leak-tight seal.
■ The back ferrule will hold the tube with a hinging colleting action.
This radial hinging colleting action of the back ferrule will grip the
tube adjacent to and outboard from the swaging point to enhance
the vibration endurance.
■ The hinging colleting action will cause the mid portion of the back
ferrule to press onto the tube while keeping the back end of the
 The Swagelok Tube Fitting 11

back ferrule away from the tube surface. The back ferrule will not
bow during assembly.
■ The sealing and gripping actions of the fitting will provide a
compensating action between ferrules that will accommodate
the ­allowed ranges of tube wall thickness, diameter, and material
hardness. For example, on thin wall tubing, the back ferrule will
grip the wall of the tube with less indentation than is necessary
on heavy wall tubing. The front ferrule will move farther down the
body ramp to burnish or polish a seal on the tube more than is
needed on a heavy wall tube.
■ The stainless steel material, from which tube fitting bodies
and components are made, will be restricted to a minimum
­chromium content of 17.0 % and a minimum nickel content of
12.0 % for improved corrosion resistance, and to a maximum
carbon content of 0.05 %, which provides better corrosion-­
resistant weldability.
■ The tube fitting nut will be internally plated with a high-purity silver
to eliminate galling during assembly.

Performance
■ The tube fitting will produce a leak-tight seal in pressure or
vacuum service.
■ The tube fitting manufacturer will specify the allowed ranges of
tube wall thickness, diameter, and material hardness.
■ The tube fitting will function on standard ASTM stainless steel
­tubing, fully annealed according to ASTM A269 or A213.
■ The tube fitting will contain pressure up to a minimum of four
times (4×) the working pressure of the tube without fitting material
­rupture when properly installed.

Installation
■ The manufacturer should offer a wide variety of tools for tube
fitting installation.
■ The manufacturer will provide clear instructions for proper tube
­fitting installation.
■ The tube fitting will not apply torque to or twist the tubing during
original or subsequent assembly of the connection.
■ The fitting should use geometry or defined axial movement of the
nut for assembly.
■ The tube fitting will not require fitting disassembly for inspection
after assembly.
12 Tube Fitter’s Manual

Quality Assurance
■ All tube fitting metal components will be stamped to identify
manufacturer and material.
■ All tube fittings will have a gaugeable shoulder to check for
­sufficient pull-up on initial installation. The gaugeable shoulder
will allow a gap inspection gauge to be inserted between the
hex of the nut and hex of the body shoulder. C ­ onsistently,
the gap inspection gauge will not fit between the nut and
shoulder ­hexes of a sufficiently tightened fitting on the initial
­installation.
■ The tube fitting manufacturer will be certified to produce fittings
under an N Stamp Program accredited by ASME.
■ The tube fitting manufacturer will have a Statistical Quality ­Control
program, which will have an acceptance quality limit (AQL) level of 1.5.
Note: Additional information may be referenced in Zero
Acceptance Number Sampling Plans, 5th Edition, written by
N.L. Squiglia, published by ASQ Press.
■ The tube fitting manufacturer will be committed to Statistical
­Control of Processes for manufacture of all critical dimensions.
■ The tube fittings will be procured from the tube fitting
manufacturer’s distribution network supported and trained by the
manufacturer.
■ No component of any other tube fitting manufacturer will be
interchanged or intermixed with the four components (body, nut,
front ferrule, and back ferrule) of the tube fitting.

Why Close Tolerances Are Important

The Swagelok tube fitting consists of four components, as shown
here. In actual practice, there is a fifth component, the tubing.
Various organizations publish tolerance data, notably ASTM in the
United States. In general, Swagelok has found that international
specifications follow the same approximate guidelines as shown in
ASTM standards.
The tolerances published for tubing partially control the tolerancing
of tube fittings. For example, a common tubing outer diameter (OD)
variable in ASTM A269 for 1/2 in. OD stainless steel is / 0.005
in. Therefore, the tube OD can vary from 0.495 in. to 0.505 in.
Obviously, the bore of the nut, ferrules, and body must be large
enough to accept this tubing. Beyond this, we must hold the closest
bore tolerance achievable. At the same time, however, the ferrule
system must allow for the fact that the tube OD could be as small as
 The Swagelok Tube Fitting 13

Front
Nut
ferrule

Back Body
ferrule
Figure 1-6 Swagelok tube fitting: four components.

0.495 in. Therefore, very stringent quality control is essential just to

overcome the sizeable variation in tube OD.
Besides OD tolerances, there are tolerances in tube wall thickness,
ovality, and hardness. All these variables must be overcome in only
1 1/4 turns of the nut.
Therefore, we must keep our tolerances within an extremely tight
range to ensure consistent performance. We have been told that
our quality is “too good” for some applications. We continue to say,
“It is never good enough,” and we are constantly looking for ways
to do it better.

Nut

Back Front Body

ferrule ferrule
Tube

Figure 1-7 SAT12 patented surface hardening process.

14 Tube Fitter’s Manual

Gaugeability
Swagelok’s tube fittings are developed with such stringent control
over all variables that a gap inspection gauge can be used to ensure
proper tightening when the fittings are first installed.
On initial installation, the Swagelok gap inspection gauge assures
the installer or inspector that a fitting has been sufficiently ­tightened.

Position the Swagelok gap inspection gauge next to the gap between
the nut and body.

Correct Incorrect

If the gauge will not enter the If the gauge will enter the
gap, the fitting is sufficiently gap, additional tightening is
tightened. required.

Figure 1-8 Ensure proper tightening with Swagelok gap inspection gauge.
 The Swagelok Tube Fitting 15

Interchange and Intermix of Tube

Fitting Components
Over the years, many manufacturers have stated that their products
are interchangeable and can be intermixed with Swagelok tube
­fittings.
Swagelok recommends no intermix/interchange of Swagelok tube
fitting components with other manufacturers’ components.
■ No industrial design standard exists for two ferrule tube fittings.
Each company makes components to its own design and not to
any recognized standards.
■ Interchanging and intermixing tube fitting components can result
in unpredictable performance, environmental releases, increased
costs, and can be dangerous in critical applications.
C hap ter 2
Tubing: Specification and
Ordering

Table of Contents
Tube Specification and Ordering
General Comments and Suggestions 18
Tubing for Gas Service 19
Metal Tube Selection and Specification 20
Specify Limits on Your Tubing Purchase Order 22
Suggested Ordering Information by Material 23
Plastic Tubing 25
Tubing Standards 28
18 Tube Fitter’s Manual

Tube Specification and Ordering

General Comments and Suggestions
Careful selection, specification, purchase, and handling of tubing
are essential to the successful use of Swagelok tube fittings.
Several general rules apply:
■ Metal tubing must always be softer than the fitting material. For
example, stainless steel tubing should never be used with brass
fittings.
■ When tubing and fitting are made of the same material, the tubing
must be fully annealed. Mechanical, structural, or ornamental
grade tubing should never be used for fluid systems.
■ Extremely soft or pliable tubing such as Tygon® or PVC tubing
should always use an insert. Seals on the outside diameter (OD) of
tubing require a certain amount of tube resistance for tight sealing.
■ Extremes of wall thickness should be checked against our
suggested minimum and maximum wall thickness limitations.
Swagelok tube fittings are not recommended for tube wall
thicknesses outside the ranges shown in the following tables for
each size. A wall too thin will collapse under ferrule action and
may not resist enough to allow the ferrules to coin out surface
defects. A wall thickness greater than the maximum suggested
does not increase the allowable working pressure.
■ Tubing surface finish is very important to proper sealing. Tubing
that is deeply embossed (such as copper water tube); has a
visible weld seam on its OD; or has flat spots, scratches, or draw
marks may not seal properly when used with a fitting sealing on
the tubing OD.
■ Oval tubing that will not easily fit into fitting nuts, ferrules, and
bodies should never be forced into the fitting. Such forced tube
entry will scrape the tube OD surface at the maximum diameter,
making sealing difficult.
■ Laminated or multiwall tubing, such as braided hose, should
generally not be used with Swagelok tube fittings. Because the
Swagelok fitting seals on the tube OD, system fluid may leak
between hose or tube layers, causing ballooning and possible
wall rupture.
 Tubing: Specification and Ordering 19

Tubing for Gas Service

Gases such as air, hydrogen, helium, and nitrogen have very small
molecules that can escape through even the smallest leak path.
Some surface defects on the tubing can provide such a leak path.
As the tube OD increases, the likelihood of scratches or other
surface defects also increases. The most successful connection
for gas service will occur if all installation instructions are carefully
followed and the heavier wall thicknesses of tubing are selected
from the tables shown below.
A heavy wall tube resists ferrule action more than a thin-wall tube
and allows the ferrules to coin out minor surface imperfections.
Thinner wall tubing offers less resistance to ferrule action during
pull-up and reduces the chance of coining out surface defects, such
as scratches.
For the greatest safety factor against surface defects in any gas
system, use a wall thickness no less than the ones listed in the
tables shown here.
Fractional Sizes, in inches
Minimum Nominal Minimum Nominal
Tube OD Wall Thickness Tube OD Wall Thickness
1/8 0.028 3/4 0.065
3/16 0.028 7/8 0.083
1/4 0.028 1 0.083
5/16 0.035 1 1/4 0.109
3/8 0.035 1 1/2 0.134
1/2 0.049 2 0.180
5/8 0.065 × ×
Metric Sizes, in millimeters
Minimum Nominal Minimum Nominal
Tube OD Wall Thickness Tube OD Wall Thickness
3 0.8 18 1.5
6 0.8 20 1.8
8 1.0 22 2.0
10 1.0 25 2.2
12 1.0 28 2.5
14 1.2 30 3.0
15 1.5 32 3.0
16 1.5 38 3.5
20 Tube Fitter’s Manual

Metal Tube Selection and Specification

Please refer to the Swagelok Tubing Data Sheet

(MS-01-107) for additional tubing information.
www.swagelok.com/TFM

When using a Swagelok tube fitting, it is important to remember

that the fitting performance can be greatly compromised by the use
of poor quality tubing. The Swagelok tube fitting consists of four
components as shown here. They come to you fully inspected and
assembled.

Nut Front ferrule

Back ferrule Body

Figure 2-1 Swagelok tube fitting: Four components.

Tubing is considered to be the fifth important component when

considering tube fittings and tubing selection for a fluid system.
Despite its importance, tubing selection is often treated as an
afterthought. It is counterproductive to use low quality tubing in the
design of a critical fluid system.
Purchasing tubing to ASTM, or equivalent specifications, is a start
toward tubing quality. However, most such specifications allow
rather wide latitudes when considering several important factors.
For example:
■ ASTM A269, a commonly used stainless steel tube specification,
refers one to ASTM A1016 General Requirements, which include:
13. Straightness and Finish
13.1 Finished tubes shall be reasonably straight and have
smooth ends free of burrs. They shall have a workmanlike finish.
Surface imperfections (Note 1) may be removed by grinding,
provided that a smooth curved surface is maintained, and the
wall thickness is not decreased to less than that permitted by
this or the product specification. The outside diameter at the
point of grinding may be reduced by the amount so removed.
Note 1–An imperfection is any discontinuity or irregularity found
in the tube.
 Tubing: Specification and Ordering 21

Figure 2-2 Fifth component: Quality tubing.

■ ASTM A269 allows ovality of the tube to be two times the OD

tolerance of ±0.005 in. or ±0.010 in. for thin-walled tube.
However, the specifications lack standards. What, or who, defines
a workmanlike finish? How deep or how flat must the grinding be?
In the second specification, if this ovality were to be ±0.010 in.
(0.510 in. by 0.490 in. for 1/2 in. OD tubing), the tube would not fit
into most tube fittings.
In conclusion, the mere use of ASTM specifications does not
actually indicate that you have a quality piece of tubing. Tubing
quality depends on the integrity and the quality consciousness of
the tubing supplier.
To be sure of selecting tubing with quality good enough to perform
properly when used with the precision-made Swagelok tube fitting,
we suggest that the following variables be considered:
■ Tubing material and method of manufacture
■ Tubing wall thickness and OD
■ Tubing surface finish
■ Tubing hardness
■ Tubing concentricity
■ Tubing ovality
22 Tube Fitter’s Manual

Seamless or Welded

Hardness
Concentricity

Wall Thickness

Outside & Inside Type of Material

Diameter

Surface Finish
Ovality
Figure 2-3 Tubing variables to be considered when selecting tubing.

Specify Limits on Your Tubing Purchase Order

Often, a user can specify certain limits on a tubing purchase order,
particularly on large purchases, at no extra cost. These limits
may well be considerably narrower than those permitted in ASTM
specifications. For example, Restricted OD Tolerances: Typical ASTM
tubing specifications shown here permit various plus and minus
tolerances. Some users will not accept tubing with a minus tolerance
because it is more difficult to seal undersize tubing. Also, for tubing
1/8 in. OD and smaller, we suggest restriction to ±0.003 in. Please
refer to Figure 2-5, ASTM Tolerance—Tube OD, on page 27.
Restricted Surface Finish Tolerances
As mentioned previously, ASTM specifications are ambiguous and
unclear on the subject of finishes. In particular, when stainless steel
welded and drawn tubing is specified, poor quality of weld or weld
bead removal can cause sealing problems when the tube and tube
fitting are assembled.
■ Poor welding usually results in a visible depression (concavity),
which ferrules cannot seal.
■ Poor weld bead removal results in a raised (slag) portion or in a
flat spot at the weld.
Any of these conditions may result in a leak when flareless tube
fittings are assembled.
A rule to consider that may be written in welded tube specifications is:
“Weld bead on the tube OD should not be visible to the naked
eye.” Locate the weld seam on the tube ID. Then inspect the OD
at that location. You should not be able to see the weld on the OD
if it is high quality tubing.
Please refer to Chapter 5, Troubleshooting, page 152, Trouble #5.
 Tubing: Specification and Ordering 23

Hardness Restrictions:
All flareless tube fittings require that the tubing be softer than the
fitting material. Various terms are used to describe tubing hardness.
In general, metal tubing should be fully annealed to work properly
with Swagelok tube fittings. Most stainless steel tubing is restricted
to a maximum Rockwell hardness of 90 HRB.

Suggested Ordering Information by Material

The following are suggested tubing specifications for specifying the
best quality tubing for leak-free tubing systems.
Aluminum Tubing: High quality drawn and seamless aluminum
alloy tubing, ASTM B210 or (Type 6061-T6) or equivalent.
Carbon Steel Tubing: High quality, soft, annealed, seamless carbon
steel hydraulic tubing, ASTM A179 or equivalent. Hardness not to
exceed 72 HRB or 130 HV. Tubing is to be free of scratches and
suitable for bending and flaring. Other acceptable specifications:
ASTM A161, ASTM A556 grade A2, ASME SA179, AMS 5050, and
SAE J524b.
Copper Tubing: High quality, soft, annealed, seamless copper
tubing to ASTM B75, EN 1057, or equivalent. Also soft annealed
(Temper O) copper water tube, type K or type L to ASTM B88.
If copper water tube to ASTM B88 is used, it should be ordered
without OD embossing. Such deep embossing interferes with ferrule
action. Even the areas where there is no embossing are sometimes
flattened by blank dies.
Stainless Steel Tubing: High quality, fully annealed (Type 304,
304/304L, 316, 316/316L, 317, 317/317L) (seamless or welded and
drawn) stainless steel hydraulic tubing, ASTM A269 or A213, A632,
EN ISO 1127, or equivalent. Hardness not to exceed 90 HRB or 200
HV. Tubing to be free of scratches, suitable for bending and flaring.
OD tolerances not to exceed ±0.003 in. for 1/16 in. and 1/8 in. OD
tubing and equivalent metric sizes. Dual-certified grades such as
304/304L, 316/316L, and 317/317L meet the minimum chemistry
and the mechanical properties of both alloy grades.
Note: Certain austenitic stainless tubing has an allowable ovality
tolerance double the OD tolerance and may not fit into Swagelok
tube fittings.
24 Tube Fitter’s Manual

Alloy 400 Tubing: High quality, fully annealed, seamless alloy

400 hydraulic tubing, ASTM B165 or equivalent. Hardness not to
exceed 75 HRB or 137 HV. Tubing to be free of scratches, suitable
for bending and flaring. OD tolerances not to exceed ±0.005
in.; for 1/16 and 1/8 in. tubing, OD tolerances are not to exceed
±0.003 in.
Alloy 600 Tubing: High quality, fully annealed, cold-drawn #1
temper alloy 600 seamless alloy tubing, ASTM B167 or equivalent.
Hardness not to exceed 92 HRB or 198 HV. Tubing to be free of
scratches, suitable for bending and flaring. Order to OD and wall
thickness only, not to inside diameter, average wall specification.
OD tolerances not to exceed ±0.005 in.
Alloy 625 Tubing: High quality, fully annealed, seamless alloy
625 tubing, ASTM B444, grade 1 or 2, or equivalent. Hardness not
to exceed 25 HRC or 266 HV. Tubing to be free of scratches, suitable
for bending and flaring.
Alloy C-276 Tubing: High quality, fully annealed alloy C-276 tubing,
ASTM B622 or equivalent. Hardness not to exceed 100 HRB or
248 HV. Tubing to be free of scratches, suitable for bending and
flaring. OD tolerances not to exceed ±0.005 in.
Titanium Tubing: High quality, fully annealed, seamless or welded
and drawn grade 2 titanium tubing, ASTM B338 or equivalent.
Tubing to be free of scratches, suitable for bending. OD tolerances
not to exceed ±0.005 in.
Alloy 2507 Super Duplex Tubing: High quality, fully annealed alloy
2507 super duplex tubing, ASTM A789 or equivalent. Hardness
not to exceed 32 HRC. Tubing to be free of scratches, suitable for
bending and flaring.
Alloy 825 Tubing: High quality, fully annealed, seamless alloy
825 tubing, ASTM B163, ASTM B423, or equivalent. Fully annealed
welded alloy 825 tubing, ASTM B704, class 1 or equivalent. Hardness
not to exceed HR15T90 or 201 HV. Tubing to be free of scratches,
suitable for bending and flaring. Wall thickness tolerances not to
exceed ±10 %.
Alloy 254 Tubing: High quality, fully annealed, seamless or welded
and drawn alloy 254 hydraulic tubing, ASTM A269 or ASTM A213,
or equivalent. Hardness not to exceed 96 HRB. Tubing to be free of
scratches, suitable for bending and flaring.
 Tubing: Specification and Ordering 25

Plastic Tubing
Many different types of plastic tubing are available for use in a wide
range of fluid applications. The most common types are listed below
with certain characteristics and limitations and suggested ordering
information.
Nylon Tubing: Nylon tubing is a tough tubing material that is readily
available for a wide variety of low-pressure tubing systems. Typical
uses are on low-pressure hydraulics or air fluid power systems and
in laboratory piping. Because of its good flexibility and abrasion
resistance, it is often used for instrument air, lubrication, beverage,
and fuel lines. Size ranges generally run from 1/8 in. OD to 1/2
in. OD. Nylon tubing is usually rated by short-time burst rating,
commonly from 1000 to 2500 psig (68 to 172 bar). Working pressure
is generally 250 to 625 psig (17 to 43 bar) using a 4:1 design factor.
Working temperature range is 75 to 165°F (24 to 74°C).
Swagelok metal tube fittings may be used up to the maximum
working pressure of nylon tubing.
Suggested ordering information: OD is not to exceed ±0.005 in.
from nominal OD for 3/16 to 1/2 in. tubing and is not to exceed
±.003 in. for 1/8 in. OD.
Polyethylene Tubing: This inexpensive, flexible tubing is widely
used in laboratories, instrument air lines, and other applications. It is
more flexible than nylon but not as abrasion resistant. It is generally
very corrosion resistant, so it is very good for air service in corrosive
environments.
It is rated by burst pressure from 250 to 500 psig (17 to 34 bar) and
working pressure from 60 to 125 psig (4 to 9 bar) with a 4:1 design
factor. It is generally rated to a maximum temperature of 140°F
(60°C).
Swagelok metal tube fittings may be used to the maximum working
pressure of such tubing. No insert is required unless the tubing OD
is larger than 1/2 in.
Suggested ordering information: OD is not to exceed ±0.005 in.
from nominal OD for 3/16 to 1/2 in. tubing and is not to exceed
±0.003 in. for 1/8 in. OD.
Polypropylene Tubing: An excellent flexible tubing that is much
stronger than polyethylene. It is rated by burst pressure from 1600
to 2400 psig (110 to 165 bar) and working pressure from 400 to
600 psig (28 to 41 bar) with a 4:1 design factor. It has unusually good
26 Tube Fitter’s Manual

temperature characteristics and is generally rated to a maximum

temperature of 250°F (121°C).
Swagelok metal tube fittings are satisfactory for use on polypropylene
tubing.
Suggested ordering information: OD is not to exceed ±0.005 in.
from nominal OD for 3/16 to 1/2 in. tubing and is not to exceed
±0.003 in. for 1/8 in. OD.
PFA and PTFE Tubing: This tough tubing is used in a wide variety
of fluid handling operations. It has excellent properties that resist
corrosion. It has good temperature capabilities to 400°F (204°C).
Standard metal Swagelok tube fittings may be used on PTFE or
PFA tubing. When PTFE fittings are used on PTFE tubing, there
is very little holding power because of the very low coefficient of
friction when a PTFE fitting tries to hold a length of PTFE tubing.
However, the PFA Swagelok tube fitting, when used with Swagelok
PFA tubing (and grooved with the Swagelok groove cutter), will hold
to the rated working pressure of the tubing. Consult your Swagelok
representative for pressure rating information on this combination.
Suggested ordering information: OD is not to exceed
±0.005 in. from nominal OD for 3/16 to 1/2 in. tubing
and is not to exceed ±0.003 in. for 1/8 in. OD.

■ PTFE fittings with PTFE tubing.

■ PTFE ferrules with SS or plastic tubing and SS body and nut.
■ Nylon ferrules with SS or plastic tubing and SS body and nut.
Suggested Allowable
Tube O.D. Working Pressure
in. (psig)
1/8 35
1/4 25
3/8 25
1/2 15
5/8 10
3/4 5
1 5
 Tubing: Specification and Ordering 27

Soft PVC Tubing: This tubing is used for flexibility and corrosion
resistance in many laboratory, medical, food, and pharmaceutical
applications. It is normally rated at approximately 165°F (74°C).
When used with Swagelok metal or plastic tube fittings, a serrated
insert must be used. The insert supports the tube wall from the
inside so that ferrules can grip and seal the tubing. Swagelok hose
connectors may also be used with this type of tubing (see Chapter
6 for details). Reinforced soft PVC tubing is also available. An inner
braid is imbedded in the tube wall to increase strength and working
pressure.

Figure 2-4 Tubing insert.

Swagelok tube fittings should NOT be used with reinforced soft

PVC tubing because of possible leakage from the end of the tube
around the braid, within the tube wall. An inside diameter seal, such
as a Swagelok hose connector, should be used.
Suggested ordering information: OD is not to exceed ±0.005
in. from nominal for 3/16 to 1/2 in. tubing and is not to exceed
±0.003 in. for 1/8 in. OD.
28 Tube Fitter’s Manual

Tubing Standards
The following list covers the commonly encountered metal tubing
specifications for tubing to be used with Swagelok tube fittings.
For OD tolerances, refer to the table shown here.

Stainless Steel
Carbon
Decimal ASTM Steel Copper Aluminum
Tube Swagelok Equivalents A213 and ASTM ASTM ASTM ASTM
OD (in.) Tube Size (in.) A249 A269 A179 B75 B210
1/16* 100 0.0625 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
1/8* 200 0.125 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
3/16 300 0.1875 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
1/4 400 0.250 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
5/16 500 0.3125 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
3/8 600 0.375 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
1/2 810 0.500 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.003 in.
5/8 1010 0.625 ±.004 in. ±.005 in. ±.004 in. ±.002 in. ±.004 in.
3/4 1210 0.750 ±.004 in. ±.005 in. ±.004 in. ±.0025 in. ±.004 in.
7/8 1410 0.875 ±.004 in. ±.005 in. ±.004 in. ±.0025 in. ±.004 in.
1 1610 1.000 ±.006 in. ±.005 in. ±.005 in. ±.0025 in. ±.004 in.
1 1/4 2000 1.250 ±.006 in. ±.005 in. ±.006 in.
1 1/2 2400 1.500 ±.006 in. ±.010 in. ±.006 in.
2 3200 2.000 ±.010 in. ±.010 in. ±.010 in.
Notes:
Certain austenitic stainless tubing has an allowable ovality tolerance double the OD tolerance. Such oval tubing
may not fit into Swagelok precision tube fittings.
* ±0.003 in. maximum recommended for 1/16 and 1/8 in. OD tubing when used with Swagelok tube fittings

Figure 2-5 ASTM Tolerance—Tube OD.

 Tubing: Specification and Ordering 29

Stainless Steel Tubing

ASTM A213 Standard to which seamless austenitic stainless
Seamless ferritic and steel tubing may be purchased for general service.
austenitic alloy steel Hardness 90 HRB maximum. OD tolerances are
boiler, superheater, and determined by ASTM A1016. Satisfactory for use
heat-exchanger tubes. with Swagelok stainless steel tube fittings.
ASTM A249 Standard to which welded austenitic stainless steel
Welded austenitic steel tubing may be purchased for general and high
boiler, superheater, temperature service. Hardness 90 HRB maximum.
heat-exchanger, and OD tolerances determined by ASTM A1016. A draw
condenser tubes. pass to blend the weld groove into a smooth tube
OD is necessary for satisfactory use with Swagelok
tube stainless steel fittings.
ASTM A269 Standard to which both welded and seamless
Seamless and welded austenitic stainless steel tubing may be purchased
austenitic stainless for general, corrosion-resisting, and low- and
steel tubing for general high-temperature service. Hardness 90 HRB
service. maximum. Should be purchased cold finished and
is satisfactory for use with Swagelok stainless steel
tube fittings in the cold finished condition.
ASTM A1016 Covers general requirements for steel and stainless
General requirements steel welded or seamless tubing. Many of its
for ferritic alloy steel, requirements are mandatory in such specifications
austenitic alloy steel, as A213 and A249. Except for A269, all these
and stainless steel specifications cover OD tolerances by reference to
tubes. A1016. Tubing is not purchased to ASTM A1016. It
is purchased to other specifications that get their
general requirements from A1016.
ASTM A632 Covers stainless steel tubing that may be
Seamless and welded purchased for small diameter work from 0.050 to
austenitic stainless 1/2 in. OD. Wall thicknesses are 0.005 to 0.065 in.
tubing (small diameter) Can be either seamless or welded and drawn. Often
for general service. used for small instrument tube requirements. Has
closer OD and inside diameter (ID) tolerances (plus
0.002 in. minus 0.000 in. OD, plus 0.000 in. minus
0.002 in. ID).

Carbon Steel Tubing

ASTM A161 Standard to which cold-drawn, seamless carbon
Seamless low- steel tubing may be purchased for elevated
carbon and carbon- pressure-temperature service. Carbon content is
molybdenum steel tubes 0.10 % to 0.20 %. Hardness 70 HRB maximum. OD
for refinery service. tolerances are determined by ASTM A450. Only the
cold-drawn, low-carbon variety is satisfactory for
use with Swagelok steel tube fittings.
30 Tube Fitter’s Manual

ASTM A179 Standard to which cold-drawn, seamless carbon

Seamless cold-drawn, steel tubing may be purchased for general service.
low-carbon steel Carbon content is 0.06 % to 0.18 %. Hardness 72
heat-exchanger and HRB maximum. OD tolerances are determined by
condenser tubes. ASTM A450. Satisfactory for use with Swagelok
steel tube fittings.
SAE J524b Similar to A179, maximum carbon content is 0.18
Seamless low-carbon %. Hardness 65 HRB maximum. However, in 3/8 in.
steel tubing, annealed OD and smaller sizes with a wall thickness less than
for bending and flaring. 0.065 in., no hardness test is required. Satisfactory
for use with Swagelok steel tube fittings.
Copper Tubing
ASTM B68 Covers annealed seamless copper tubing suitable
Seamless copper tube, for use in refrigerators, oil lines, gasoline lines,
bright annealed. etc., where tube absolutely free of scale and dirt is
required. Should be specified as “soft annealed,”
temper 060 for use with Swagelok brass fittings.
Wall thickness and diameter tolerances are
determined by ASTM B251.
ASTM B75 Covers seamless copper tube for general purposes.
Seamless copper tube. Should be specified as annealed temper 060 for
use with Swagelok brass fittings. Wall thickness and
diameter tolerances are determined by ASTM B251.
Covers seamless copper water tube suitable for
general plumbing. It comes in Type K, Type L, and
Type M. Sizes 3/8 to 12 1/8 in. OD (1/4 to 12 in.
nominal). Should always be specified as annealed
temper 0 for use with Swagelok brass fittings. OD
and wall thickness tolerances are specified in ASTM
B88, but OD tolerances generally follow ASTM
B251 guidelines. Type K is the heaviest wall, Type L
is medium wall, and Type M is very thin wall. Type
M is normally available only in hard temper straight
ASTM B88 lengths and has a wall too thin to be used with
Seamless copper water Swagelok brass fittings. Both Type K and Type L
tube. are available either in 20 ft. straight lengths or 60
ft. coils and soft annealed. Type K or L is usually
satisfactory for use with Swagelok brass fittings,
but wall thickness may not be sufficient for gas
service. NOTE: Beware of tubing that is marked by
embossing into the OD. Such depressed lettering
can interfere with proper ferrule sealing. Water tube
is normally sized by “nominal” OD, not actual OD,
so actual OD should be determined when using
with Swagelok tube fittings.
 Tubing: Specification and Ordering 31

ASTM B251 This is the general specification for copper tubing

General requirements that governs many requirements for ASTM B68
for wrought seamless and B75 copper tubing. It covers wall thickness
copper and copper alloy and OD tolerances applicable to ASTM B68 and
tube. B75 tubing.
Other Alloy Tubing
ASTM B210 Covers drawn seamless aluminum tubes in straight
Aluminum alloy lengths and coils. Alloy 6061 in T4 and T6 tempers
seamless tubes. is suggested and is indicated in our Tubing Data
Sheet. For Swagelok tube fitting use with other
aluminum alloy tubing, consult your Swagelok
representative.
Alloy 400 Covers alloy 400 seamless tubing. Should be
ASTM B165 specified “annealed” for use with Swagelok
Nickel-copper alloy alloy 400 fittings. Hardness 75 HRB maximum
(UNS N04400) seamless (annealed). OD tolerance is ±0.005 in. up to 5/8 in.
pipes and tubes. OD. Over 5/8 in. OD allows ±0.0075 in., so tubing
should be ordered to a special tolerance of ±0.005
in. for best results with Swagelok alloy 400/405
fittings.
Alloy 600 Covers alloy 600 tubing. Should always be
ASTM B167 specified “cold-drawn annealed” for use with
Nickel-chromium-iron Swagelok alloy 600 fittings. Hardness 92 HRB
alloy (UNS N06600) maximum. OD tolerance is ±0.005 in. up to 5/8 in.
seamless pipes and OD. Over 5/8 in. OD allows±0.0075 in., so tubing
tubes. should be ordered to a special tolerance of ±0.005
in. for best results with Swagelok alloy 600 fittings.
Titanium Covers titanium tubing that may be used with
ASTM B338 Swagelok titanium fittings. Swagelok tube fittings
Seamless and welded are manufactured from grade 4 titanium. Tubing
titanium and titanium should be ordered as grade 2 to perform properly
alloy tubes for with Swagelok titanium fittings. Grade 2 titanium is
condensers and heat approximately 98.75 % pure titanium.
exchangers.

Alloy C-276 Covers several nickel alloys, but in particular,

ASTM B622 it covers alloy C-276 tubing such as would be
Seamless nickel used with Swagelok alloy C-276 tube fittings. OD
alloy pipes and tubes tolerance is ±0.005 in. up to 5/8 in. OD. Over 5/8
(UNS N10276 or UNS in. OD allows ±0.0075 in., so tubing should be
N10665). ordered to a special tolerance of ±0.005 in. for
best results with Swagelok alloy C-276 fittings.
32 Tube Fitter’s Manual

Alloy 2507 Super Covers fully annealed alloy 2507 Super Duplex
Duplex tubing, such as would be used with Swagelok
ASTM A789 alloy 2507 Super Duplex tube fittings. Hardness
Seamless and welded not to exceed 32 HRC. Tubing to be free of
ferritic/austenitic scratches, suitable for bending and flaring.
stainless steel tubing for
general service.
Alloy 825
ASTM B163
Seamless nickel and
nickel alloy condenser
and heat-exchanger Covers fully annealed seamless alloy 825 tubing,
tubes. ASTM B163, ASTM B423, or equivalent, such
ASTM B423 as would be used with Swagelok alloy 825 tube
Nickel-iron-chromium- fittings. Fully annealed, welded alloy 825 tubing,
molybdenum-copper ASTM B704, class 1 or equivalent. Hardness not
alloy seamless pipes to exceed HR15T90 or 201 HV. Tubing to be free
and tubes. of scratches, suitable for bending and flaring. Wall
thickness tolerances not to exceed ±10 %.
ASTM B704
Welded UNS N06625,
UNS N06219, and UNS
N08825 alloy tubes.
Alloy 254
ASTM A269
Seamless and welded
austenitic stainless Covers fully annealed seamless or welded and
steel tubing for general drawn alloy 254 hydraulic tubing, ASTM A269 or
service. ASTM A213, or equivalent, such as would be used
ASTM A213 with Swagelok 6-Moly tube fittings. Hardness not
Seamless ferritic and to exceed 96 HRB. Tubing to be free of scratches,
austenitic alloy steel suitable for bending and flaring.
boiler, superheater, and
heat-exchanger tubes.

Alloy 625 Covers fully annealed seamless alloy 625 tubing,

ASTM B444 ASTM B444, grade 1 or 2, or equivalent, such
Nickel-chromium- as would be used with Swagelok alloy 625 tube
molybdenum-columbium fittings. Hardness not to exceed 25 HRC or 266
alloys (UNS N06625 HV. Tubing to be free of scratches, suitable for
and UNS N06852) bending and flaring.
and nickel-chromium-
molybdenum-silicon alloy
(UNS N06219) pipes and
tubes.
C hap ter 3
Tubing and Tube Fitting Handling
and Installation

Table of Contents

Tubing Handling 35
Tubing System Layout 36
Advantages of Tubing versus Pipe 42
Tube-Straightening Techniques 45
Stainless Steel Tubing: Coils 47
Tube Bending 47
Marks Used in Bend Layout 54
The Measure-Bend Method 56
Tube Bending Defects 60
Swagelok Tube Benders 61
Hand Tube Bender 62
Bench Top Tube Bender 63
Electric Tube Bender 64
Minimum Straight Tube Length 65
Tube Preparation 67
Tube Cutter 67
Hacksaw 69
Tube Deburring 70
Tube Facing Tool 72
Handling of Tube Fittings 74
Swagelok Tube Fitting Safety Considerations 75
Best Practice: Using the Depth Marking Tool (DMT) 78
Gaugeability: Manual Installation 81
Reassembly 83
Preswaging Tools 86
Hydraulic Swaging Using the Air-Actuated
Hydraulic Swaging Unit 88
Hydraulic Swaging Using the Multihead
Hydraulic Swaging Unit 89
Recommended Minimum Wall Thickness of
Tubing for Use with the MHSU 90
Intermix/Interchange of Swagelok Components 91
The Swagelok Limited Lifetime Warranty 91
System Configuration Tools 92
Installation of a Swagelok Tube Adapter
End Connection 92
Installation of a Swagelok Machined
Ferrule End Connection 95
Bulkhead Connections 101
SAE or MS Straight Thread Ports (Installation) 101
SAE/MS Straight Thread Positionable
Elbows and Tees (Installation) 103
O-Ring Seals 103
Medium-Pressure Tube Fittings, FK Series 103
Medium- and High-Pressure Products: IPT Series 104
Pipe End (Installation) 107
Thread Sealants 109
Assembly Using Liquid Thread Sealants 111
Assembly Using PTFE Tape 116
 Tubing and Tube Fitting Handling and Installation 35

Tubing Handling
Careful handling of tubing, from receiving to installation, will promote
leak-free systems.
Good handling practices will reduce scratches, gouges, and nicks,
which can interfere with proper sealing (particularly on gas service).

Never Drag Tubing Off Racks

■  he weight of the tube as it is dragged over the edge of a truck
T
bed or tube rack may be sufficient to score or scratch outside
diameter (OD) surfaces.
■ Scratches can occur if an OD burr is left on the tubing.
■ Tubing should never be dragged across rough surfaces such as
cement, dirt, asphalt, or sand.

Never Drop Tubing

■ Tubing can be damaged if dropped onto a hard surface.
■ This may create dents, making tubing out-of-round.
■ Forcing out-of-round tubing into the fitting may result in leakage.

Figure 3-1.
36 Tube Fitter’s Manual

Tubing System Layout

When installing a system, the first step is to draw a layout of the system
to determine the number of tube fittings and the length of tubing
required.
■ Measure all dimensions from the end of tubing and between
tubing centerlines.
■ Treat all bends as if they were square corners.
1/4" SS
STREAM 7
1/4" SS
STREAM 6
1/4" SS
STREAM 5
1/4" SS
STREAM 4
1/4" SS
STREAM 3
1/4" SS
STREAM 2
1/4" SS
STREAM 1

WR RELIEF
1/2" SS HDR

RV-AA-310-1 RV-AA-310-2 RV-AA-310-3 RV-AA-310-4 RV-AA-310-5

SET-50 PSIG SET-50 PSIG SET-50 PSIG SET-50 PSIG SET-50 PSIG
PI 30 PSIG PI 30 PSIG PI 30 PSIG PI 30 PSIG

0-60 0-60 0-60 0-60

PSIG  PSIG  PSIG  PSIG 
F

Figure 3-2.

Other considerations:

Provide Good Accessibility for Fittings

■ Easy installation
■ Easy maintenance

Figure 3-3.
 Tubing and Tube Fitting Handling and Installation 37

Proper Tubing Placement

■ Avoid placement directly in front of access doors, bolts, and
equipment.
■ Do not prevent access to controls.
■ Allow access for repair or maintenance.

Correct

Incorrect
Figure 3-4.

Avoid Locating Tubing in “Foot Rail” Positions

■ Low level runs of tubing may be inappropriately used as a foot
rest, which may lead to damaging the tube.
■ Low tubing may create a trip or safety hazard.

Correct

Incorrect
Figure 3-5.
38 Tube Fitter’s Manual

Avoid Locating Tubing in “Hand Rail” Positions

■ High runs of tubing may be inappropriately used like a hand rail,
which may lead to damaging the tube.
■ Tubing may be inappropriately used as a support for other objects,
which may lead to damaging the tube.

Correct

Incorrect

Figure 3-6.

Provide Proper Support

■ Proper support limits the effects of impulse and vibration on fluid
systems.
■ Use resilient supports on tubing.
■ Long runs of tubing should be supported to prevent sagging.
 Tubing and Tube Fitting Handling and Installation 39

Figure 3-7 Resilient supports.

■ Tubing should not support weight of valves, fittings, regulators,

etc. Components should be mounted.
■ Fluid density and tube size determine the frequency of supports.
■ All tubes should be clamped on both sides of a bend, as close to
the bend radius as possible.

Figure 3-8 Bent tubes clamped on

both sides.

For further information, refer to the Standard

Practice ANSI/MSS SP-58-2009, replacing
SP‑69. www.swagelok.com/TFM

Fluid systems may be subjected to repeated impulse and vibration.

Appropriate system design can limit the effects of impulse and
vibration by including a proper tube support system that limits the
movement of tubing and fluid components. The types and location
of tube supports will depend on the design of the fluid system in
40 Tube Fitter’s Manual

question. Supports are especially important around elbows, tees,

bends, and heavy in-line objects such as valves. There are several
published guidelines that outline support selection and spacing
of tubing in systems based on different industry practices and
experiences.

The Manufacturers Standardization Society (MSS)

of the Valve and Fittings Industry Suggested
Spacing for Supports

Tubing Tubing Distance Distance

Diameter Diameter between Clamps between Clamps
OD in OD mm ft. m
3/16 to 3/8 4 to 10 3 0.9
1/2 to 7/8 15 to 22 5 1.5
1 to 1 1/4 25 to 30 7 2.1

Maximum Horizontal Pipe Hanger and

Support Spacing

Nominal Standard Wt. Steel Pipe Copper Tube

Pipe or Nominal
Tube Pipe or Water Water Vapor Vapor Water Water Vapor Vapor
Size Tube Service Service Service Service Service Service Service Service
in. Size mm ft. m ft. m ft. m ft. m
1/4 6 7 2.1 8 2.4 5 1.5 5 1.5

3/8 10 7 2.1 8 2.4 5 1.5 6 1.8

1/2 15 7 2.1 8 2.4 5 1.5 6 1.8

3/4 20 7 2.1 9 2.7 5 1.5 7 2.1

1 25 7 2.1 9 2.7 6 1.8 8 2.4

1 1/4 32 7 2.1 9 2.7 7 2.1 9 2.7

1 1/2 40 9 2.7 12 3.6 8 2.4 10 3.0

2 50 10 3.0 13 3.9 8 2.4 11 3.3

 Tubing and Tube Fitting Handling and Installation 41

Stack Tubing Vertically

■ Avoids collection of dirt, corrosives, and contaminants.
■ If tubing must be ganged horizontally, the tubing should be
covered.

Figure 3-9.

Utilize Expansion Loops

■ Conserves space, allowing runs to be placed closer together
■ Allows for expansion or contraction due to temperature changes
■ Provides access for assembly or disassembly

Figure 3-10.
42 Tube Fitter’s Manual

Do Not Spring Tubing into Position

Avoiding springing results in these benefits:
■ Allows proper bottoming of tubing
■ Allows for system to be easily maintained
■ Prevents side-load stresses and allows for expansion

Correct Incorrect
Figure 3-11.

Additional tubing considerations:

■ Metal tubing material should be softer than fitting material. For
example, stainless steel tubing should not be used with brass
fittings.
■ When tubing and fitting are made of the same material, the tubing
must be fully annealed. Mechanical, structural, or ornamental
grade tubing should never be used for fluid systems.
■ Always use an insert with extremely soft or pliable plastic tubing.
■ Extremes of wall thickness should always be checked against the
suggested minimum and maximum wall thickness limitations.
■ Surface finish is very important to proper sealing. Tubing with
any kind of depression, scratch, raised portion, or other surface
defect will be difficult to seal, particularly in gas service.
■ Tubing that is oval and will not easily fit through fitting nuts,
ferrules, and bodies should never be forced into the fitting.

Advantages of Tubing versus Pipe

■ Tubing can be more cost effective than pipe for connecting fluid
system components.

Ease of Installation
■ Standard wrenches
■ No threading
■ No flaring
 Tubing and Tube Fitting Handling and Installation 43

■ No soldering or brazing
■ No welding

Figure 3-12.

Better Strength-to-Weight Ratio

■ Threading on pipe reduces the effective wall thickness.
■ Thinner-walled tubing may be used to similar pressure ratings as
pipe.
■ Tubing is typically lighter, making it less expensive to transport
and easier to assemble and fabricate.

Figure 3-13.
44 Tube Fitter’s Manual

Fewer Connections Required

■ Decreases the number of potential leak points
■ Can be bent around obstructions

Figure 3-14.

Lower Pressure Drop

■ Sharp right angle bends are reduced.
■ Smooth transitions reduce turbulence.

Figure 3-15.
 Tubing and Tube Fitting Handling and Installation 45

Tube-Straightening Techniques
Straightness of tubing is important from two standpoints.
■ Where the tube enters the fitting, it is necessary to have a
straight run long enough to allow the tube to bottom in the
fitting body.
■ Also, straight tubing is easier to support properly and makes
access for maintenance simpler. Straight tube runs are also more
attractive and reduce support installation time.
Softer tube materials such as copper and aluminum are often
furnished in coils, and some straightening must be done to make
the tubing ready for use.

How to Uncoil Tubing

Take the end of the tubing and, with one hand, hold it down on a flat
surface such as a table top, wooden plank, floor, or sidewalk. If the
flat surface is rough, put padding down to protect the end of the
tubing from scratches.

Figure 3-16.
46 Tube Fitter’s Manual

Begin rolling the coil away from the end of the tubing with the other
hand.

Figure 3-17.

Slide the first hand along the tubing, following the coil in such a
manner that the tubing lies flat on the flat surface. Unroll the coil
rather than pulling the tubing end out sideways from the coil.
Uncoiling from the side of the roll can twist or weaken the tubing
and will tend to throw the tubing out of round.

Figure 3-18.
 Tubing and Tube Fitting Handling and Installation 47

Do not uncoil more tubing than is necessary, because repeated

uncoiling and recoiling will distort, harden, and stiffen coiled
tubing.
Soft coiled copper tubing is sometimes unrolled and then stretched
to straighten it. Stretching can slightly harden the tube. Therefore, this
practice is not recommended, but if it is performed, tubing should
be stretched no more than 1 % or 6 in. per 50 ft. of coil. If tubing
is stretched beyond this, OD reduction takes place and can cause
sealing problems.
Another common field method to straighten copper tubing is to lay
the tubing on a smooth floor or bench and use a wooden board
flatwise to strike the high spots. Do not strike too hard or flat spots
will be formed. Soft tubing is easily dented and may collapse at a
dent when it is being bent.

Stainless Steel Tubing: Coils

Stainless steel tubing may also be ordered in coils. In this instance,
you may require mechanical assistance to straighten the tubing.
Swagelok offers the Five-Roll Straightener, which is designed either
for hand-held operation or to be mounted to a spool stand for more
automated tube straightening.

Please refer to the Swagelok Five-Roll Straightener

User’s Manual (MS-CRD-0147) for operating
instructions. www.swagelok.com/TFM

Tube Bending
Bend Terminology
Blueprints, engineering drawings, and bend templates typically
indicate the position of a tube bend as the point where the centerlines
of two straight sections of tube intersect.
The straight sections are referred to as “legs,” whereas the
intersection point of the two legs is called the vertex.
48 Tube Fitter’s Manual

There are three points commonly used to dimension bends:

■ Beginning end of the tube
■ Vertex of the bend
■ Finishing end of the tube

Figure 3-19.

In multiple bend layouts, distances between bends are usually

dimensioned vertex-to-vertex along the tube centerlines.

Figure 3-20.
 Tubing and Tube Fitting Handling and Installation 49

Sometimes bends are dimensioned using the theoretical beginning

and ending points of the bends.
Bends dimensioned in this manner will often require the operator to
calculate the actual vertex-to-vertex lengths.

Figure 3-21.

180° Bends
The legs of 180° bends are parallel and, as a result, do not have a
vertex. For layout purposes, the intersection of a line tangent to the
midpoint of the 180° bend (B) is treated as if it were the vertex of
the bend. The length of a leg containing a 180° bend is measured
from the beginning point of the leg (A), along the centerline, and then
extended to a point perpendicular to a line tangent to the midpoint
of the 180° bend (B). It is not measured directly from (A) to (B).

Midpoint
B
C B2

Incorrect! 180º

A B1
5 in.

Line tangent to
midpoint of bend

Figure 3-22.
50 Tube Fitter’s Manual

In the example below, the length of the leg from (A) to (B) is correctly
dimensioned at 5 in. along a straight line from (A) to (B1). In the same
way, a leg dimensioned from (B) to (C) would be measured parallel
to the leg from (B2) to (C), not at an angle from (B) to (C).

C B2

Correct 180º

A B1
5 in.

Line tangent to
midpoint of bend
Figure 3-23.

Bend Radius
The radius of tube bends is defined as the radius to the center of
the tube. This table shows commonly used bend radii on currently
available tube benders.
Tube material, wall thickness, and type of equipment used will
influence the smallest bend radius that can be attained.

TYPICAL TUBE BEND RADIUS

Tube OD Radius
1/8 in. 3/8 in.
1/4 in. 9/16 in.
3/8 in. 15/16 in.
1/2 in. 1 1/2 in.
5/8 in. 1 1/2 in.
3/4 in. 1 3/4 in.
7/8 in. 2 in.
1 in. 4 in.
1 1/4 in. 5 in.
1 1/2 in. 6 in.
2 in. 8 in.
 Tubing and Tube Fitting Handling and Installation 51

Offset Bends
The purpose of an offset bend is to change the centerline of the run,
usually to avoid an obstruction. In an offset bend, two bends of the
same angle (E) are placed back-to-back on opposite sides of the
tube.
In many applications, the length of the offset (O) may be provided
or known rather than the actual vertex-to-vertex length (L) between
the bends.

E
L

Figure 3-24.

It is important to be aware of offset dimensions, as it is easy to

mistake the length of the offset as the vertex-to-vertex length. This
may lead to the bends being placed too close together.
The vertex-to-vertex length (L) can be easily calculated by multiplying
the amount of offset (O) by the offset bend allowance, which is the
cosecant* of the bend angle (E).

Offset Bend Angle (E) Offset Bend Allowance

22 1/2° 2.613
30° 2.000
45° 1.414
60° 1.154
52 Tube Fitter’s Manual

Example:

Offset Bend Offset

Angle Dimension Offset Bend Length of Offset
(E) (O) × Allowance = (L)
22 1/2° 30 mm × 2.613 = 78 mm
30° 2.0 in. × 2.0 = 4 in.
45° 65 mm × 1.414 = 92 mm
10.96 in.
60° 9.5 in. × 1.154 = (approximately
11 in.)
* Cosecant is a trigonometric term describing the inverse of the sine of an angle. It is
a ratio of the length of the hypotenuse of an angle to the length of the opposite side.

Springback
Springback occurs when a material is bent from its original form.
The bent tube will elastically “spring back” slightly toward its original
pre-bent form as the pressure exerted on it during the bending
process is released.
As a tube is bent around a bend radius, it will conform to the radius
of the bend die; however, once the pressure is released, the tube
will spring away from the bend die. For example, a stainless steel
tube bent 180° using a bender with a 3/4 in. bend radius (1 1/2 in.
diameter) may spring open to as much as 1 5/8 in. diameter after
bending.
The amount of springback will vary depending on variables such as
the bend radius, tube material, diameter, and wall thickness.
Springback can also vary with the bend angle, with a larger bend
angle exhibiting more springback than a smaller angle. In extreme
cases, springback can be so great that large bend angles may not
be achievable using the hand bender.
There are two ways to compensate for springback:
■ The operator can anticipate the amount of springback by bending
the tube past the angle indicated on the bend die. As the bend
pressure is released, the tube will spring open slightly.
■ The bender can be manufactured with the angle marks on the
bend die offset to compensate for a predetermined amount
of springback. The Swagelok hand tube bender is designed in
this manner, with the angle marks offset approximately 3° to
compensate for the springback typically observed when bending
 Tubing and Tube Fitting Handling and Installation 53

stainless steel. When bending softer tube, such as copper and

aluminum, do not bend all the way to the angle mark!

3°

Figure 3-25.

Regardless of the method used to overcome springback, it is

recommended to use caution when bending and to verify the actual
bend angle using a protractor or angle indicator. It is much easier to
reload the tube into the bender and bend it a little more than it is to
try to unbend it!

Stretch
The term “stretch” is used to describe the difference between a
bend marked and bent using conventional trigonometry (theory)
against what is actually produced.
In practice, tubing often appears to lengthen slightly, or stretch, as
it is bent.
NOTE: In some cases the tubing may also appear to get shorter,
or shrink (usually the result of a mismarked bender die or bend
reference mark).
Regardless of the reason, whether the resulting piece is longer or
shorter than desired, without accounting for stretch, the location of
the bend is likely to be wrong.
54 Tube Fitter’s Manual

Bend data provided by Swagelok accounts for the stretch typically

observed while using Swagelok benders.

Figure 3-26.

Marks Used in Bend Layout

The biggest challenge for the tube bender operator is to make sure
the bend is made in the right location and in the right direction.
Three marks are commonly used:
■ Reference mark
■ Bend marks
■ Directional marks

Reference Mark
The reference mark is placed at one end of the tube and is used to
indicate the end of the tubing from where all measurements were
made.

Bend Marks
Bend marks are used to indicate the location of the bend on the
tube. Use of bend marks will vary depending on the layout method
used.
Always make bend marks neatly all the way around the tube to
make sure they will be visible when changing direction.
 Tubing and Tube Fitting Handling and Installation 55

Reference
Mark

Bend
Mark

Figure 3-27.

Directional Marks
When making multiple bends on a single piece of tube, it is important
to make sure that each bend is made in the correct direction.
Directional marks help ensure that the bend is made in the intended
direction.
The directional mark is placed across the bend mark on the outside
surface, or heel, of the intended bend.
Directional marks provide two visual reminders for the operator:
■ The directional mark will be visible when the tube is correctly
positioned in the bender.
■ As the rollers are placed against the tube, they will contact the
directional mark.

Directional mark

Outside surface
(heel) of bend

Figure 3-28.
56 Tube Fitter’s Manual

The Measure-Bend Method

The measure-bend method of tube bending is a popular method.
Accuracy is largely dependent on the operator’s ability to position
the tube in the tube bender.

Directions
1. Estimate the overall length of tubing required by adding the
length of each of the sections together.
For example, the estimated length of tube needed to complete the
elbow pictured below is 5 in. or 125 mm.
However, there are two special circumstances that will require
additional calculations:
■ Offsets
■ 180° bends

Figure 3-29.

Offsets
As explained earlier, offsets require the length of tube (L) to be
calculated.

E
L

Figure 3-30.
 Tubing and Tube Fitting Handling and Installation 57

180° Bends
Unlike other bends where the legs intersect at the vertex, the legs of
180° bends are parallel.
As a result, consideration must also be made for the tube
consumed by the bend. This can be done by multiplying the bend
radius by a factor of 1.25 and then adding this amount to the sum
of the legs.

Figure 3-31.

2. Make a reference mark at the end of the tube from which your
measurements will begin.

Figure 3-32.

3. Measure from the reference mark and make a bend mark

neatly all around the tube at a distance equal to the length of
the first leg.
58 Tube Fitter’s Manual

This indicates the vertex of the 90° bend.

Example: The bend mark is placed 3 in. or 75 mm from the
reference end of the tube.
4. Bend the tube 90°.

Figure 3-33.

5. Measure 2 in. or 50 mm from the vertex of the first bend and

make a mark equal to the length of the second leg. This indicates
the cut length.
6. Cut the tube to length.

Figure 3-34.

Note: If a 5 in. or 125 mm long piece of tube is used to make

this layout, the tube will be too long by a little more than the tube
diameter.
 Tubing and Tube Fitting Handling and Installation 59

Bent Tube Is Stronger Than Straight Tube

Once the tube material has been bent beyond its elastic limit,
the thickness of the tube wall on the inside of the bend will be
compressed, while the tube wall on the outside of the bend will be
stretched, or thinned. This results in work hardening of the bent
material. Work hardening increases the strength of the material.
If a length of tube containing a bend is capped with a Swagelok tube
fitting and then pressurized to the bursting point of the tube, the
tube will visibly expand along the straight lengths much more than it
will at a bend, and when it eventually bursts, it will burst in a straight
length (typically along the longest straight length).
The work hardening that occurs during bending increases the
strength of this stretched material more than enough to offset the
loss of strength resulting from the thinning of the wall.
However, if a bend is made in the wrong location or in the wrong
direction, it cannot be unbent. This makes it critical to learn how to
correctly bend tube.
In this figure, tubing bursts on the straight portion showing an
increased tensile strength of material at the bend.

Figure 3-35.

Contact your local authorized Swagelok Sales and Service Center

for tube bending training.
60 Tube Fitter’s Manual

Tube Bending Defects

Defect Causes Solutions

Undersized bend radius Increase bend radius

Tube wall thickness Increase wall thickness

too thin

Wrinkled Bend
Bender is intended for Use the correct size
use with a larger tubing bender for the tubing
diameter being bent

Tubing is collapsing Increase wall thickness

during bending
Pressure die is Use a bender equipped
flattening the tubing with rollers instead of a
during the bending pressure die
operation
Flattened Bend
Bender is intended for Use the correct size
use with a larger tubing bender for the tubing
diameter being bent

Premature bending Make sure the link is

caused by link not vertical before placing
remaining vertical prior rollers on tubing
to bending

Kinked Bend
continued
 Tubing and Tube Fitting Handling and Installation 61

Defect Causes Solutions

Bender is intended Use the correct size
for use with a smaller bender for the tubing
tubing diameter being bent

Damaged bender die Repair bender die or

replace bender
Dirt or foreign matter Clean bender die/shoe
in bender die/shoe or or roller
roller

Frozen roller Replace damaged roller

Scored Bend
or bender
Improper alignment Make sure that the
bender die and bend
shoe are aligned

Excessive pressure on Reduce latch pressure

the tube latch (generally
visible on softer tubing
only)

Excessive Tube
Deformation

Swagelok Tube Benders

Swagelok offers three styles of tube benders: the hand tube bender,
the bench top tube bender (manual and electric), and the electric
tube bender. Together, the three styles of tube benders cover tubing
sizes from 1/8 to 2 in. and 3 to 50 mm.
62 Tube Fitter’s Manual

Hand Tube Bender

The Swagelok hand tube bender (HTB) is a compression type tube
bender. Each bender is designed to bend a particular tubing size in
a variety of wall thicknesses.

Figure 3-36.

Vise Clamp Block

The vise clamp block allows you to clamp the bender in a vise. This
feature is especially helpful when bending tubing of a hard material
or heavy wall thickness or long pieces of tubing that need to be
supported.

Vise clamp block

Figure 3-37.
 Tubing and Tube Fitting Handling and Installation 63

Straight Tube Length Mark

On Swagelok hand tube benders, the straight tube length mark
indicates the minimum length of straight tube required to allow the
tube to be bottomed in the Swagelok tube fitting.

Straight tube
Length Mark

Roll Support

Nameplate

Figure 3-38.

Please refer to the Swagelok Hand Tube Bender

(HTB) User’s Manual (MS-13-43) for more information
and operating instructions. www.swagelok.com/TFM

Bench Top Tube Bender

The Swagelok bench top tube bender (BTTB) is a rotary draw type
tube bender. Swagelok offers bench top tube benders in both
electric and manual units.
Each bender comes equipped with either aluminum or steel bend
shoes and roller sets. Each shoe/roller set is designed to bend a
particular tubing size in a variety of wall thicknesses. Steel bend
shoes should be used to bend heavy-walled tubing and for high-
production applications.
64 Tube Fitter’s Manual

Figure 3-39.

Please refer to the Swagelok Bench Top Tube Bender

(BTTB) User’s Manual (MS-13-145) for set-up, calibration,
and operating instructions. www.swagelok.com/TFM

Electric Tube Bender

Control
Pendant

Tube
Bend
Clamp
Shoe

Tail
Roller

Roller
Tower

Figure 3-40.

Please refer to the Swagelok Electric Tube Bender

(ETB) User’s Manual (MS-13-138) for operating
instructions. www.swagelok.com/TFM
TUBE FITTERS MANUAL C-ELD-103
Tubing and Tube Fitting Handling and Installation 65

Minimum Straight Tube Length

When installing fittings near tube bends, a minimum length of
straight tube is required to allow the tube to be bottomed in the
Swagelok tube fitting.

R
T Tube OD
R Radius of Bend
SWAG
L Straight Tube Length
L (See table)

T Tube outside diameter Fig.51

R Radius of tubing bend as required or minimum allowed
for specified wall thickness and tube size as recommended
by bender manufacturer
L Straight tube length required from end of tube to
beginning of bend
Figure 3-41.

Bends Near Tube Fittings

Tube bends that are too close to a fitting installation may be a source
of leaks, and care must be used on such installations. Several
precautions should be taken:
■ Leave a length of straight tube so that the deformed section at a
bend does not enter the fitting.
■ Inspect, for proper roundness, the length of tube that will be
inserted into a fitting. Out-of-round tubing could scratch when
entering the fitting and result in leaks.
■ Long runs of tubing should be supported, as should all other
components.
■ When a section of bent tubing is being connected, be certain that
the tube is in proper alignment with the fitting before doing any
66 Tube Fitter’s Manual

tightening. Springing the tube into position with the fitting can
result in excessive stress on the tubing and the connection.
■ Proper bends in the tubing and proper alignment will ensure a
good, trouble-free connection.

Swagelok Tube Fitting Minimum Straight Tube Length Requirements

(by Tube OD)
Tube OD
1/4 5/16 3/8 1/2 5/8 3/4 7/8 1 1 1/4 1 1/2 2
in.
Min.
13/16 7/8 15/16 1 3/16 1 1/4 1 1/4 1 5/16 1 1/2 2 2 7/16 3 1/4
Length
Tube OD
6 8 10 12 14 15 16 18
mm
Min.
21 22 25 29 31 32 32 32
Length
Tube OD
20 22 25 28 30 32 38 50
mm
Min.
33 33 40 40 52 51 60 83
Length

Please refer to the Bench Top Tube Bender (BTTB) User’s

Manual (MS-13-145) to determine the appropriate bend
radius for your application. www.swagelok.com/TFM

For example, to determine the minimum vertex-to-vertex distance

between two 90° bends using a 1/4 in. hand tube bender:

Bend deduction for bend at beginning of leg 9/16 in.

Bend deduction for bend at end of leg + 9/16 in.
Tube clamp requirement + 1 1/8 in.
Minimum vertex-to-vertex distance 2 1/4 in.

Or, to determine the minimum vertex-to-vertex distance between

a 45° bend and a 135° bend using 25 mm tubing and a steel bend
shoe (bend shoe radius = 82 mm)

Bend deduction for 45° bend 36 mm

Bend deduction for 135° bend + 201 mm
Tube clamp requirement + 108 mm
Minimum vertex-to-vertex distance 345 mm
 Tubing and Tube Fitting Handling and Installation 67

It is important to understand that although the tube clamp

requirement will remain constant for the bender or bend shoe, the
minimum vertex-to-vertex distance will change depending on the
bend angles at the beginning and end of the configuration.

Training and Education

At Swagelok, training is more than an academic exercise; it is an
action that focuses on results. The purpose of the Swagelok Tube
Bending Qualification Program is to learn how to bend tube within
the limitations of the Swagelok tube benders, as well as provide
several tips and shortcuts that will help to take some of the mystery
out of tube bending.
There are multiple options to learn more about tube bending:
1. Attend the Basic Tube Bending course at your local Swagelok
sales center—complete with hands-on exercises.
2. Take the online tube bending course at Swagelok University.
3. Attend an advanced tube bending class taught by Swagelok
experts.
Contact your Swagelok Authorized Sales and Service representative
or visit the Swagelok.com website for details about the Tube
Bending Qualification Programs available.

Please refer to www.swagelok.com/TFM

for details.

Tube Preparation
Proper tube preparation is critical when making up tube fitting
assemblies. Most assemblies will be constructed of short lengths
of tube that have been carefully measured, marked, and cut from
longer lengths of tube. Prior to learning how to install a Swagelok
tube fitting, it is important to learn how to prepare the tube being
used in an assembly. Two common tools are used to cut tube. These
are (1) the tube cutter and (2) the hacksaw. Once cut, burrs created
during the cutting process must be removed.

Tube Cutter
Tube cutters do not remove material, but rather “push” material
aside and down.
68 Tube Fitter’s Manual

The Swagelok tube cutter is designed to cut tubing materials from

3/16 to 1 in. and 6 to 25 mm OD.
Always use a sharp wheel, since this is the best way to minimize
burring. Using a dull wheel will also expand and work harden the
tube end. Replace wheel when cutting becomes difficult or end of
tube begins to expand.

Figure 3-42 Swagelok tube cutter.

Tube Cutter Instructions

1. Position tubing between rollers and cutting wheel.
2. Turn handle until wheel touches tube.
3. Advance handle an additional 1/16 turn. (The handle knobs are
spaced in 1/8-turn increments. Use them as reference points.)

Figure 3-43 Align the cutter wheel with the measurement

mark.
 Tubing and Tube Fitting Handling and Installation 69

4. Rotate cutter around tube. After every second rotation, advance

handle 1/16 turn. (For softer materials, advance the handle after
each rotation.)

Figure 3-44 Turn the tube cutter completely around the tubing.

5. Continue until tubing is cut through.

Figure 3-45 Tighten the handle 1/16 turn every second

rotation.

Hacksaw
If a tube cutter of the proper size is not available, a hacksaw may
be used. Tube should always be cut to length with a square cut.
When using a hacksaw to cut tube, a Swagelok tube sawing guide
should be used to facilitate a square cut and to keep the tube from
flattening out. Hacksaw blades should have at least 24 teeth per
inch.
70 Tube Fitter’s Manual

Figure 3-46 Swagelok tube sawing guide and hacksaw.

Tube Deburring
During the cutting process, tube cutters push burrs into the inside
diameter (ID) of the tube, and hacksaws will burr both the ID and the
OD of the tube. Regardless of which method is used to cut the tube,
these burrs must be removed.
Deburring is important for proper fitting function as well as for clean,
leak-free systems. If burrs are not removed from the OD of the tube,
they could prevent the tube from being fully inserted through the nut
and ferrules or against the shoulder of the fitting body. ID burrs could
also break off and cause damage to components in other parts of
the system by lodging in small holes or vents or by scratching valve
seats or soft seals such as O-rings.

Figure 3-47 Hacksaw and tube

cutter burrs.
 Tubing and Tube Fitting Handling and Installation 71

Deburring Tools
Outside deburring can be accomplished with a smooth file. Inside
and outside deburring can be accomplished using Swagelok
deburring tools.

Figure 3-48 OD deburring with a Swagelok deburring tool.

Figure 3-49 OD deburring with a file.

The Swagelok tube deburring tool (part ordering number MS‑TDT-24)

is used to deburr steel and stainless steel (or other softer tubing)
from both the inside and outside diameters. The tool is used for
deburring the inside and outside diameters of 3/16 to 1 1/2 in.
(4 to 38 mm) tubing.
72 Tube Fitter’s Manual

Figure 3-50 ID deburring with a Swagelok deburring tool.

Inside deburring can easily be accomplished using the Swagelok

deburring tool with rugged, heavy-duty, die-cast housing and steel
blades for long life (part ordering number MS-44CT-27). This tool
is used for deburring the inside diameter of 1/4, 3/8, and 9/16 in.
stainless steel tubing.

Figure 3-51 ID deburring with a Swagelok deburring tool.

Tube Facing Tool

The Swagelok tube facing tools are designed to machine flat,
smooth, square, burr-free, and chamfer-free tube ends and Micro-
Fit® miniature tube butt weld fittings. The tools can be used on 316
stainless steel, carbon steel, titanium, and most nickel-based alloys.
Collets are available to ensure precise mounting of tubes and quick
change without the use of tools. Micro-Fit collets require a Micro-Fit
insert holder, which is included with each tube facing tool.
 Tubing and Tube Fitting Handling and Installation 73

Figure 3-52.

For more information, please refer to:

■ Tube Facing Tools Catalog (MS-02-426) and
■ Tube Facing Tool User’s Manual (MS-13-215).
www.swagelok.com/TFM

Swagelok offers four tools to fit most needs: the TF16, TF24, TF40,
and TF72 series.
Some of the features include:
■ Tube sizes of 1/8 to 4 1/2 in. and 3 to 114.3 mm
■ Maximum wall thickness of 0.118 in. or 3 mm
■ Portable and lightweight design for mobility and easy operation
■ Corded and cordless tools
■ Graduated microfeed advancement for controlled material
removal
■ High-performance coated tool bit with two cutting edges
■ Heavy-duty industrial motor with easy speed adjustment and
control
■ No tools required to change the collet sets to different sizes
■ Removable bench mount bracket included with corded tools
■ Clear safety shield or guards to protect operator from the cutting
area
■ Optional holder to enable bevel cutting
■ Storage and shipping case included
■ CE marked cordless tools also feature:
■ Robust lithium ion battery packs with capacity display
■ Electronic overload protection with integrated temperature
monitoring
■ Air-cooled technology for quick charging and long service life
74 Tube Fitter’s Manual

Handling of Tube Fittings

Swagelok tube fittings come to you completely assembled, finger-
tight, and ready for immediate use. Avoid disassembling the tube
fittings prior to installation. Doing so can result in dirt or foreign
material getting into the fitting, which can interfere with sealing.
This illustration shows a cutaway of the ferrules inside the tube
fitting contacting the tube and a cross-sectioned view at the nose
portion of the back ferrule that has gone through the carburization
process.

Nut

Back Front Body

ferrule ferrule
Tube

Figure 3-53.

The diffusion has gone into the surface of the ferrule and is not a
layer applied on top of the ferrule. That white ribbon is the consistent
effect of carbon diffused into the surface providing incredible
hardness and corrosion resistance, without dimension change,
while retaining ductility.
Prior to installation:
■ Make sure the proper-sized fitting for the tubing you are using has
been selected.
■ Never mix metric components with fractional components.
 Tubing and Tube Fitting Handling and Installation 75

Figure 3-54.
Swagelok Tube Fitting Safety Considerations
■ Do not bleed system pressure by loosening fitting nut or fitting
plug.
■ Do not assemble or tighten fittings when system is pressurized.
■ Make sure that the tubing rests firmly on the shoulder of the tube
fitting body before tightening the nut.
■ Use the correct Swagelok gap inspection gauge to ensure
sufficient pull-up upon initial installation.
■ Do not mix fitting components (ferrules, nuts, and fitting bodies)
with those of other manufacturers.
■ Do not mix materials unless defined by Tubing Data - Engineered
Combinations MS-06-117.
■ Never turn fitting body. Instead, hold fitting body and turn nut.
■ Avoid unnecessary disassembly of unused fittings.
■ Use only long reducers in female Swagelok end connections.

Manual Installation of Swagelok Tube Fittings up to

1 in. or 25 mm
Safe practices and proper installation are imperative to the
performance of the Swagelok tube fitting, especially in critical
applications.
For 5/8, 3/4, 7/8 and 1 in.; 16, 18, 20, 22 and 25 mm tube fittings,
in all materials except for aluminum and brass, it is a best practice
to preswage the ferrules onto the tube adapter using a Swagelok
multihead hydraulic swaging unit (MHSU) to lower installation time
and increase ease of installation (see Multihead Hydraulic Swaging
Unit (MHSU), Setup and Operating Instructions, MS-12-37).
76 Tube Fitter’s Manual

1. Fully insert the tube into the fitting and against the shoulder;
rotate the nut finger-tight.

Figure 3-55 Insert tubing into tube fitting.

2. Mark the nut at the 6 o’clock position.

This will be your reference starting position..

Figure 3-56 Mark the nut at 6 o’clock.

 Tubing and Tube Fitting Handling and Installation 77

3. While holding the fitting body steady, tighten the nut 1 1/4 turns
to the 9 o’clock position.
For 1/16, 1/8, and 3/16 in. or 2, 3, and 4 mm tube fittings, tighten
the nut 3/4 turn to the 3 o’clock position.

Figure 3-57 Tighten the nut 1 1/4 turns.

For Assembly in High-Pressure Applications and High Safety Factor

Systems for Tubing Diameters 1 in. (25 mm) and Smaller, please
refer to Chapter 4.
78 Tube Fitter’s Manual

Best Practice: Using the Depth Marking Tool

(DMT)
The Swagelok DMT is designed to provide safe installation of tubing
into Swagelok tube fittings. Following is a procedure using the DMT
to ensure proper bottoming of the tubing on the shoulder inside the
Swagelok tube fitting body.
The DMT should only be used on tubing intended for use with
Swagelok tube fittings. Intermix or interchange of Swagelok tube
fitting parts with parts made by other manufacturers should never
occur.
Tubing should be cut cleanly and fully deburred on both the outside
diameter (OD) and inside diameter (ID) prior to using the DMT.
1. Insert the tube into the DMT until it has fully bottomed in the tool.

Figure 3-58 Tubing fully bottomed in DMT.

 Tubing and Tube Fitting Handling and Installation 79

2. Mark the tube at the top of the DMT with a pen, pencil, or
adequate marking device. Use marking pens with low-chloride
ink when marking any stainless steel component, particularly
those to be used in nuclear and high-safety applications. Many
marking pens are manufactured with permanent ink that contains
chlorides, which cause stress corrosion cracking in austenitic
stainless steel.

Figure 3-59 Marking the tube.

3. Remove the tube from the DMT and insert into the Swagelok
fitting until it is fully bottomed inside the fitting body. Inspect the
mark on the tube prior to fitting assembly. If any portion of the
mark on the tube can be seen above the fitting nut, the tube has
not fully inserted into the fitting.
80 Tube Fitter’s Manual

Figure 3-60 Removing the tube. Figure 3-61 Visual inspection of mark.

Figure 3-62 Mark the nut at the 6 o’clock position.

4. While holding the fitting body steady, install the fitting by using
the installation instructions, including using the gap inspection
gauge as shown beginning on p. 81.
 Tubing and Tube Fitting Handling and Installation 81

Best Practice: Low-Chloride Markers

Many marking pens are manufactured with permanent ink that
contains chlorides. Chlorides are a cause of stress corrosion
cracking in austenitic stainless steel.
Many manufacturers of marking pens offer products with low-
chloride ink. Their use is advised when marking any stainless steel
component, particularly those to be used in nuclear and high-safety
applications.

No Disassembly Inspection
There is no need to disassemble a Swagelok fitting to inspect
the connection after assembly. Exhaustive tests and on-the-job
performance have proven that disassembly is not needed as long
as the fitting has been assembled in accordance with the installation
instructions.

Gaugeability: Manual Installation

On initial installation, or when using a gaugeable preswage tool, the
Swagelok gap inspection gauge assures the installer or inspector
that a fitting has been sufficiently tightened.
Gap inspection gauges should not be used on reassembled
connections.
Gap gauges manufactured for individual sizes can be used to
inspect fittings installed using either installation method.
■ The thicker end of the gauge is used for fittings installed using
finger-tight method.
■ The thinner end of the gauge is used for fittings installed when
using the installation methods in high-pressure applications and
high safety factor systems to assure the installer or inspector that
the fitting has been sufficiently tightened on initial installation.
82 Tube Fitter’s Manual

Figure 3-63 Two-sided gap inspection gauge for manually

installed fittings.

Multisided gauges are also available, providing the convenience of

three gauges in one (fractional sizes 1/4, 3/8, and 1/2 in.), or four
gauges in one (metric sizes 6, 8, 10, and 12 mm).
These gauges can be used to inspect initial makeup on fittings
installed using the finger-tight method.

Figure 3-64 Multisided gap inspection gauges.

 Tubing and Tube Fitting Handling and Installation 83

How the Gap Inspection Gauge Is Used

For more information, please refer to this video

of the procedure. www.swagelok.com/TFM

Position the Swagelok gap inspection gauge next to the gap

between the nut and body and gently attempt to push it into the
gap.
Be sure to choose the correct Swagelok gap inspection gauge for
the size of the fitting being inspected, as well as the method of
assembly.

Always depressurize a system before

CAUTION: adjusting the tightness of a tube fitting
connection.

Sufficiently Tightened Additional Tightening Required

Figure 3-65 Gap inspection gauge procedure.

■ If the gauge will not enter the gap, the fitting is sufficiently
tightened.
■ If the gauge will enter the gap, additional tightening is required.

Reassembly
You may disassemble and reassemble Swagelok tube fittings many
times.
Always depressurize the system before
CAUTION:
disassembling a Swagelok tube fitting.
Do not use the Swagelok gap inspection gauge with reassembled
fittings.
84 Tube Fitter’s Manual

Reassembly Procedure

For more information, please refer to this video

of the procedure. www.swagelok.com/TFM

1. Prior to disassembly, mark the tubing at the back of the nut; mark
a line along the nut and body flats.
Use these marks to ensure that you return the nut to the previously
pulled-up position.

Figure 3-66 Prior to disassembly, mark the tubing and flats.

2. Insert the tubing or tube adapter end connection with preswaged

ferrules into the fitting until the front ferrule seats against the
fitting body.
Over 1 in./25 mm sizes: If needed, reapply factory-supplied
lubricant lightly to the body threads and the rear surface of the
back ferrule.
 Tubing and Tube Fitting Handling and Installation 85

Figure 3-67 Insert tube with preswaged ferrules into the fitting body.

3. While holding the fitting body steady, rotate the nut with a wrench
to the previously pulled-up position, as indicated by the marks
on the tubing and flats. At this point, you will feel a significant
increase in resistance. Tighten the nut slightly.

Figure 3-68 Rotate nut to pulled-up position; tighten slightly.

86 Tube Fitter’s Manual

Preswaging Tools
For Swagelok tube fitting installations in close quarters, the
Swagelok preswaging tool is a convenient accessory allowing the
preswaging of ferrules onto the tube when working in a more open
or safe area. After using the tool, follow the retightening instructions
discussed earlier in the manual.
■ Preswaging tools have a finite life. After frequent use, ask your
Swagelok representative to have them checked.
■ Dirt, chips, and other metal inclusions can interfere with proper
swaging action. The tool should be thoroughly cleaned after each
use.

Preswaging Operation
This illustrates tubing with a union connected high above ground. If
a run of tubing were to be connected, it would be difficult to pull up
the second end of the union.

Figure 3-69.

Assemble the Swagelok nut and ferrules onto the preswaging tool.
Insert tubing through the ferrules into the preswaging tool until it
rests firmly on the shoulder of the preswaging tool body. Tighten the
nut 1 1/4 turns from finger-tight (sizes 1/16, 1/8, and 3/16 in.; 2, 3,
and 4 mm require only 3/4 turn).
 Tubing and Tube Fitting Handling and Installation 87

Figure 3-70.

The nut is loosened, and the tubing with preswaged ferrules is

removed from the preswaging tool.
The connection can now be made by following the retightening
instructions.

Figure 3-71.

Completed installation.

Figure 3-72.
88 Tube Fitter’s Manual

NOTE: Oversized or very soft tubing may occasionally stick in the

tool after pull-up. If this happens, remove the tube by gently rocking
it back and forth. Do not turn or twist the tube with pliers or other
tools because this may damage sealing surfaces.

Hydraulic Swaging Using the Air-Actuated

Hydraulic Swaging Unit
The Swagelok Air-Actuated Hydraulic Swaging Unit (AHSU) requires
only one unit with interchangeable tooling to swage 1/4 to 1/2 in.
and 6 to 12 mm Swagelok tube fitting end connections; it is not
intended for use with tube adapter or machined ferrule connections.

Please refer to the AHSU Operations Manual (MS-12-38)

for more information. www.swagelok.com/TFM

When properly used, the AHSU provides Swagelok tube fittings that
are 100 % gaugeable when installed. In addition, use of the AHSU:
■ Places no initial strain on the nut or fitting body threads or on
body seal surfaces
■ Requires no threading of the nut on or off the tooling
■ Reduces assembly and installation time and operator error

Hydraulic housing
Nut retainer Indicator knob
Air pump

Air input
decal
Base
Air input

Air inlet
Operating Indicator knob valve
instructions set lever
Figure 3-73.
 Tubing and Tube Fitting Handling and Installation 89

Hydraulic Swaging Using the Multihead

Hydraulic Swaging Unit
The Multihead Hydraulic Swaging Unit (MHSU) provides Swagelok
tube fitting installations that are 100 % gaugeable upon initial
installation.
The Swagelok MHSU is available with interchangeable die heads to
install 1/2 to 2 in. and 12 to 50 mm Swagelok tube fittings to tubing.
It MUST be used to install 1 1/4, 1 1/2, and 2 in. and 28, 30, 32,
38, and 50 mm Swagelok tube fitting end connections to tubing.
In addition, the MHSU can also be used to pull up Swagelok tube
fittings to tube adapter end connections from 1/2 in. or 12 mm up
to 1 in. or 25 mm.

Please refer to MHSU Operations Manual

MS-12-37. www.swagelok.com/TFM

The MHSU also:

■ Places no initial strain body threads or body seal surfaces.
■ Is available with a tube marking feature to indicate when tubing is
properly bottomed.
■ Reduces assembly and installation time.

Pump bypass Hydraulic

valve hand pump

Indicator knob

Retaining ring &

locating pin
Chamfer
blocks
Gap
inspection
gauges

Base
MHSU hydraulic
housing
Safety glasses Die heads
Retaining ring pliers

Figure 3-74.
90 Tube Fitter’s Manual

Recommended Minimum Wall Thickness of Tubing

for Use with the MHSU
Use of tubing below the recommended minimum wall thickness
may result in the tube sticking in the die head.

Swagelok Tube Fittings

Stainless Steel,
Steel, Alloy 400, Alloy (600, 6-moly, 825,
Grade 2 Titanium and 625)
Tooling Size Tubing Wall
Dimensions, in.
1/2 0.049
5/8
0.065
3/4
0.065
7/8
1 0.083
1 1/4
0.083 0.095
1 1/2
2 0.095 0.109

Swagelok Tube Fittings

Stainless Steel,
Steel, Alloy 400, Alloy (600, 6-moly, 825,
Grade 2 Titanium and 625)
Tooling Size Tubing Wall
Dimensions, mm
12
14 1.5
15 1.5
16
1.8
18
20
22 2.0 2.0
25
28
30 2.2
32 2.2
38
2.5
50

For other materials, contact your local Swagelok Authorized Sales

and Service Center.
 Tubing and Tube Fitting Handling and Installation 91

Intermix/Interchange of Swagelok Components

Leak-tight seals that will withstand high pressure, vibration,
vacuum, and temperature changes depend on close tolerances and
consistent, exacting quality control in conjunction with good design
principles. The critical interaction of precision parts is essential
for reliability and safety. Components of other manufacturers may
look like Swagelok tube fitting components, but they cannot be
manufactured in accordance with Swagelok engineering standards,
and they do not benefit from innovations in design and manufacture
defined by more than 100 active Swagelok tube fitting patents
issued worldwide.
■ Interchange
A tube fitting manufactured from one company that has been
installed on a piece of tubing and that is then disassembled, and the
tubing, nut, and ferrules from that installed fitting are reassembled
into the body of another manufacturer.
■ Intermix
Tube fitting components, which include the nuts, ferrules, and bodies,
from two or more fitting manufacturers that are mixed together and
then assembled to make a complete fitting component.
■ Swagelok recommends NO intermix/interchange of Swagelok tube
fitting components with other manufacturers’ components.
■ No industrial design standard exists for two ferrule tube fittings.
Each company makes components to its own design and not
to any recognized standards.
■ Interchanging and intermixing tube fitting components can
result in unpredictable performance, environmental releases,
increased costs, and can be dangerous in critical applications.

The Swagelok Limited Lifetime Warranty

Swagelok products are backed by The Swagelok Limited
Lifetime Warranty. For a copy, contact your authorized Swagelok
representative.
92 Tube Fitter’s Manual

System Configuration Tools

Installation of a Swagelok Tube Adapter End
Connection
The Swagelok tube adapter end connection is designed to connect to a
Swagelok tube fitting end connection in much the same manner as tube.
Tube adapter end connections come to you in one of two ways,
depending on their size:

Figure 3-75 Swagelok tube adapter end connection

(diameters up to and including 1 in./25mm).

■ Tube adapters up to and including 1 in./25 mm are grooved.

The groove is positioned to receive the ferrules during installation.
It simulates the action of the ferrules as they would perform on
annealed tube.
■ Tube adapters over 1 in./25 mm are furnished with nut and
preswaged ferrules.

Figure 3-76 Swagelok tube adapter end connection

(diameters larger than 1 in./25 mm).
 Tubing and Tube Fitting Handling and Installation 93

Tube Adapters up to 1 in./25 mm

Safe practices and proper installation are imperative to the
performance of the Swagelok tube fitting, especially in critical
applications.
For 5/8, 3/4, 7/8 and 1 in.; 16, 18, 20, 22 and 25 mm tube fittings,
in all materials except for aluminum and brass, it is a best practice
to preswage the ferrules onto the tube adapter using a Swagelok
multihead hydraulic swaging unit (MHSU) to lower installation time
and increase ease of installation (see Multihead Hydraulic Swaging
Unit (MHSU), Setup and Operating Instructions, MS-12-37).

1. Install the end opposite the tube adapter end.

Install this end

Tube adapter end

Figure 3-77 Install the end opposite the tube adapter end first.

2. Insert the tube adapter into the Swagelok tube fitting. Make sure
that the tube adapter rests firmly on the shoulder of the tube
fitting body and that the nut is finger-tight.
3. Mark the nut at the 6 o’clock position.
4. While holding the fitting body steady, tighten the nut 1 1/4 turns
to the 9 o’clock position.

Figure 3-78 Insert the tube adapter end connection into the Swagelok tube fitting end
connection.

For 1/16, 1/8, and 3/16 in. or 2, 3, and 4 mm tube fittings, tighten the
nut 3/4 turn to the 3 o’clock position.
94 Tube Fitter’s Manual

Tube Adapters over 1 in./25 mm

Install the end opposite the tube adapter end.

Figure 3-79 Install the end opposite the tube

adapter first.

1. Tube adapters over 1 in./25 mm are furnished with nut and

preswaged ferrules. Remove the nut and ferrules from the
Swagelok tube fitting end connection.
2. Apply the lubricant packaged with the fitting lightly to the
Swagelok tube fitting body threads.

Figure 3-80 Remove the nut and ferrules from the tube
fitting end connection.
 Tubing and Tube Fitting Handling and Installation 95

3. Insert the tube adapter with preswaged ferrules into the fitting
until the front ferrule seats against the fitting body; rotate the nut
finger-tight.

Figure 3-81 Make sure the tube adapter rests firmly on the
shoulder of the tube fitting body.

4. Mark the nut at the 6 o’clock position.

5. While holding the fitting body steady, tighten the nut 1/2 turn to
the 12 o’clock position.
Do not use the Swagelok gap inspection gauge with
preswaged tube adapter connections over 1 in./25 mm.

Installation of a Swagelok Machined Ferrule End

Connection
During installation the nut pushes the machined ferrule securely
against the seat in the tube fitting end connection. This provides a
leak-tight seal.

Figure 3-82 Swagelok

Machined Ferrule.
96 Tube Fitter’s Manual

The machined ferrule end connection is most commonly found on

two components:
■ Plug
■ Port connector
Each requires a slightly different preparation for installation:

Plug
1. Remove and discard the nut and ferrules from the Swagelok tube
fitting end connection.

Figure 3-83 Remove the nut and ferrules from the

tube fitting end connection.

2. Turn the nut onto the fitting so that it is finger-tight.

Figure 3-84 Install the nut onto

the fitting to finger-tight.
 Tubing and Tube Fitting Handling and Installation 97

3. While holding the fitting body steady, tighten the nut 1/4 turn.
For 1/16, 1/8, and 3/16 in. or 2, 3, and 4 mm tube fittings, tighten
the nut 1/8 turn.
For over 1 in./25 mm installation, see page 63 in MS-01-140.
Do not use the Swagelok gap inspection gauge with plug
assembly.

Figure 3-85 Tighten the nut.

Port Connector
Machined Ferrule End
1. Remove the nut and ferrules from the Swagelok tube fitting end
connection. Discard the ferrules.
SWAGELOK

SWAGELOK

SWAGELOK

Figure 3-86 Remove the nut and ferrules from the tube fitting end
connection.
98 Tube Fitter’s Manual

2. Slip the nut over the machined ferrule end of the port connector.
Over 1 in./25 mm sizes:
The nut is preassembled on the port connector.

Figure 3-87 1 in./25 mm and under.

Figure 3-88 Over 1 in./25 mm.

3. Insert the port connector into the end connection and finger-
tighten the nut.
SWAGELOK

Figure 3-89 Insert the port connector.

 Tubing and Tube Fitting Handling and Installation 99

4. While holding the fitting body steady, tighten the nut 1/4 turn.
For 1/16, 1/8, and 3/16 in. or 2, 3, and 4 mm tube fittings, tighten
the nut 1/8 turn.
Do not use the Swagelok gap inspection gauge with machined
ferrule ends.

Figure 3-90 Tighten the nut.

Tube Adapter End

1. Insert the tube adapter until it rests firmly on the shoulder of the
Swagelok tube fitting body. Finger-tighten the nut.
Over 1 in./25 mm sizes:
Remove and discard the nut and ferrules from the end connection,
and then insert the tube adapter.
100 Tube Fitter’s Manual

2. Mark the nut at the 6 o’clock position. While holding fitting body
steady, tighten the nut 1 1/4 turns to the 9 o’clock position.

12

3
6

Figure 3-91.

For 1/16, 1/8, and 3/16 in. or 2, 3, and 4 mm tube fittings, tighten the
nut 3/4 turn to the 3 o’clock position.
For preswaged over 1 in./25 mm tube fittings, tighten the nut 1/2
turn to the 12 o’clock position.
Do not use the Swagelok gap inspection gauge with preswaged
tube adapter connections over 1 in./25 mm.
 Tubing and Tube Fitting Handling and Installation 101

Bulkhead Connections

Unions

Figure 3-92.

Bulkhead connections are used when fluid is to be transferred

through a panel wall.

“U” Drive Screw

Panel wall Bulkhead retainer

Bulkhead fitting installation

SWAGELOK
SWAGELOK

utilizing bulkhead retainer

Side A Body Side B

Jam
nut hex

Figure 3-93.

Please refer to the Gaugeable Tube Fittings and Adapter

Fittings catalog MS-01-140 for more information.
www.swagelok.com/TFM

SAE or MS Straight Thread Ports (Installation)

Hydraulic equipment often uses SAE/MS straight thread ports
instead of pipe threads. Such ports require a Swagelok tube fitting
using an O-ring seal. A wide variety of Swagelok tube fittings,
adapters, reducers, and plugs are readily available in steel, stainless
steel, and other alloy materials with SAE/MS straight threads.

Please refer to the Gaugeable Tube Fittings and Adapter

Fittings catalog MS-01-140 for more information.
www.swagelok.com/TFM
102 Tube Fitter’s Manual

Straight fittings have an O-ring, which is directly driven into the

tapered port to make a seal.

SWAGELOK
Figure 3-94 Male SAE/MS
Connector.

Positionable elbows and tees have an elongated male thread, a jam

nut, metal washer, and elastomer O-ring.
SWAGELOK

Figure 3-95 90° SAE/MS

Positionable Male Elbow.

1. Lubricate the O-ring with a lubricant that is compatible with the

system fluid, environment, and O-ring material. (Standard O-ring
material is fluorocarbon FKM. Other O-ring materials are available
on request.)
2. Turn the fitting into the straight thread boss until the metal back-
up washer contacts the face of the boss and forces the O-ring
into the tapered port.
3. Position the fitting by backing it out (not more than 1 turn
counterclockwise) until the Swagelok end is oriented in the
proper direction.
4. Hold the wrench pad with a back-up wrench and tighten the
locknut until the washer is against the face of the boss, forcing
the O-ring into the tapered port.
Contact your Swagelok Authorized Sales and Service Center for
assembly torque specifications.
 Tubing and Tube Fitting Handling and Installation 103

SAE/MS Straight Thread Positionable Elbows

and Tees (Installation)
Positionable elbows and tees are compatible with SAE J1926 or
MS16142 female straight thread O-ring bosses.
NOTE: Although O-ring sealed ports are excellent for tight sealing,
remember that O-rings do have some inherent disadvantages:
■ Some elastomer compounds are attacked by certain system
fluids.
■ Elastomer compounds sometimes harden and crack under
certain field conditions. Both system fluid and environment must
be considered.
■ Elastomer compounds are easily damaged by sharp surfaces,
burrs, or chips.
■ Special tools are required to make SAE/MS ports.

O-Ring Seals
O-ring seal fittings include a 70 durometer Buna N O-ring. Other
straight-thread fittings with O-rings include a 90 durometer
fluorocarbon FKM O-ring. Other O-ring materials are available
upon request. O-rings are coated with a thin film of silicone-
based lubricant. Removal of factory-applied lubricants may alter
performance.

Medium-Pressure Tube Fittings, FK Series

The simple two-piece design of the Swagelok medium-pressure
tube fittings and adapters consists of a female fitting body and
preassembled cartridge containing the male nut and color-
coded front and back ferrules on a disposable plastic arbor. The
preassembled cartridge ensures installers correct ferrule orientation,
visual confirmation of ferrule presence, and proper installation into
the female body. Components are released only after the nut is
threaded finger-tight on the fitting body. The Swagelok medium-
pressure tube fitting offers a leak-tight gas seal and vibration
resistance in applications up to 20 000 psig (1 378 bar).
104 Tube Fitter’s Manual

Arbor
Preassembled
cartridge

Female body
Male nut

Front and back

ferrules

Figure 3-96.

Please refer to the Swagelok Medium- and High-Pressure

Fittings, Tubing, and Valves Catalog MS-02-472 for more
information. www.swagelok.com/TFM

Medium- and High-Pressure Products:

IPT Series
The IPT series is a wide product line of medium- to high-pressure
fittings, valves, and other fluid control devices.

Figure 3-97.
 Tubing and Tube Fitting Handling and Installation 105

Training and Education

Contact your authorized Swagelok representative for details about
the IPT Series Medium- and High-Pressure Products.
Coned and Threaded Fittings, IPT Series
Swagelok IPT series coned and threaded fittings are available in
both medium- and high-pressure designs. The medium-pressure
fittings are designed to withstand pressures up to 20 000 psig
(1378 bar) and are available in a variety of sizes from 1/4 to 1 1/2 in.
The high-pressure fittings can accommodate pressures up to
60 000 psig and are available in sizes from 1/8 to 1 in.
For both fittings the standard material of construction is 316 cold-
worked stainless steel. This material is required for higher yields in
tensile strength for higher pressure applications.

Figure 3-98.
106 Tube Fitter’s Manual

Coned and threaded fittings have three basic components. These

components are a gland, collar, and body. These components work
together with coned and threaded tubing to create a leak-tight seal.
Coned and threaded fittings seal at the interface between the angle
of the coned tubing and the angle of the seat within the fitting body.

Medium pressure cone High-pressure cone and

and thread end connection thread end connection
shown on left side of fitting shown right side of fitting

Primary seal surface Weep hole enables leak

detection and verification of a
proper installation.

Fitting body

Cone and thread tubing is required

Gland creates a load on
for cone and thread fitting installation.
the collar to ensure a seal
High-pressure tubing has a thicker
on the tubing and body
wall than medium-pressure tubing.
angle area.

Collar threads onto the cone and

thread tubing with left-hand threads
to prevent accidental disassembly of
collar during installation.

Figure 3-99.

Assembly
Safe, leak-tight operation of any medium- or high-pressure system
depends on preparing and installing the coned and threaded
connections correctly.
These instructions apply to 1/4, 3/8, 9/16, 3/4, and 1 in. medium-
pressure cone and thread fitting sizes and 1/4, 3/8, and 9/16 in.
high-pressure cone and thread fitting sizes.
1. Lubricate all male threads with an anti-seize lubricant, such as a
Swagelok GoopTM product. Lubricate the cone end of the tubing
with a system-compatible lubricant.
 Tubing and Tube Fitting Handling and Installation 107

2. Slide the coned and threaded (C&T) tubing into the gland.
3. Thread the collar counterclockwise (left-hand thread) onto the
C&T tubing.
4. Continue threading until one to two full threads are exposed at
the cone end of the tubing. This will indicate proper position of
the collar.
5. Insert the C&T tubing with collar into the fitting body.
6. Make sure the cone end of tubing rests firmly on the angled seat
of the fitting body.
7. Thread the gland into the fitting body until finger-tight. Hold the
fitting body steady and tighten the gland to the required torque
shown.

Fitting Size Required Torque

in. ft∙lb (N∙m)
1/4 20 (27.2)
3/8 30 (40.7)
9/16 55 (74.6)
3/4 90 (123)
1 150 (204)
Medium-Pressure C&T Fitting

Fitting Size Required Torque

in. ft∙lb (N∙m)
1/4 25 (33.9)
3/8 50 (67.8)
9/16 110 (150)
High-Pressure C&T Fitting

Please refer to the Swagelok Medium- and High-Pressure

Fittings, Tubing, and Valves Catalog MS-02-472 for more
information. www.swagelok.com/TFM

Pipe End (Installation)

Pipe threads are the most common end connections found in
industry. Pipe threads always need a sealant because the design
creates gaps between male and female threads.
108 Tube Fitter’s Manual

Swagelok End Connections with Tapered Threads

Swagelok manufactures end connections with two types of tapered
pipe threads.
■ Swagelok NPT end connections are manufactured with NPT
tapered threads.
■ Swagelok RT end connections are manufactured with ISO 7/1
tapered threads.
NPT (National Pipe Tapered)
■ Thread taper 5 1°47’
■ Truncation of roots and crests are flat
■ Pitch measured in threads per inch
■ 60° thread angle

ISO 7/1
■ Thread taper 5 1°47’
■ Truncation of roots and crests are rounded
■ Pitch measured in threads per inch
■ 55° thread angle

FPO
Figure 3-100.
 Tubing and Tube Fitting Handling and Installation 109

1°47’

Figure 3-101.

Product Marking: RT and NPT End Connections

RT
All products containing a Swagelok RT end connection are marked
ISO7.
Fittings with an RT end connection and either a Swagelok tube
fitting or tube adapter end connection are also marked RT on the
hex or wrench flat.
NPT
NPT end connections on Swagelok components are generally not
marked.
However, Swagelok fitting components with both NPT and RT end
connections will be marked NPT and ISO7, with arrows pointing to
the corresponding end to which each mark refers.

Thread Sealants
Threaded Fitting Installation
Proper sealing depends on many variables, including quality and
cleanliness of threads, temperature, component material, installation
torque, specific gravity of system media, and system operating
pressures.
110 Tube Fitter’s Manual

When assembling a Swagelok product containing a threaded

connection, the threaded connection should always be assembled
prior to the other connection because of the rotation required to
assemble the threaded connection.

Figure 3-102.

Thread Sealant
Tapered threads always need a sealant to seal system fluids and
prevent galling of the threads during installation.
Swagelok PTFE tape and liquid products such as SWAK™
anaerobic pipe thread sealant and PTFE-Free pipe thread sealant
help to achieve both the sealing and lubricating functions required
of tapered threads.

Figure 3-103.
 Tubing and Tube Fitting Handling and Installation 111

Swagelok PTFE Tape

For service up to 450°F (232°C), Swagelok PTFE tape helps to
achieve leak-free connections. PTFE tape is wrapped around male
pipe threads. As the threads are tightened, the PTFE tape fills voids
at the flank, crest, and root of the threads to provide a seal.
Swagelok PTFE tape conforms to Commercial Item Description
A-A-58092, a U.S. standard specifying the chemical, density,
and elongation properties of PTFE tape permitted for use by U.S.
government agencies.

Swagelok SWAK
Swagelok SWAK anaerobic thread sealant provides reliable sealing
on metal pipe threads for service in applications between 65 and
350°F (53 and 176°C). It also acts as a lubricant during assembly,
resisting galling or seizing of threads. SWAK sealant is applied as
a paste to the male threads. Once the threaded components are
assembled it hardens or cures to form a reliable seal. SWAK pipe
thread sealant with PTFE is a semi-liquid, packaged in a squeezable
plastic tube with a ribbon applicator.
Some fluids and materials are NOT compatible with SWAK
sealant. Please contact your Swagelok Authorized Sales and
Service Center for more information.
Swagelok PTFE-Free
For some applications, Swagelok PTFE-Free pipe thread sealant
may provide an alternative liquid thread sealant. For service in
applications between – 65 and 300°F (–53 and 148°C), it seals metal
pipe threads upon assembly while providing lubrication to resist
galling or seizing of threads.
Do not use Swagelok PTFE-Free pipe thread
sealant in systems containing a strong
WARNING:
oxidizer. A chemical reaction, including
spontaneous combustion, can occur.

Assembly Using Liquid Thread Sealants

Following are instructions on how to use two types of liquid sealant:
■ Swagelok SWAK anaerobic pipe thread sealant
■ Swagelok PTFE-Free pipe thread sealant
1. Remove the thread protector from the male threads. Remove the
bits of plastic that may have been scraped onto the threads from
the inside of the thread protector using a clean, dry, soft-bristled
brush.
112 Tube Fitter’s Manual

Figure 3-104.

2. Where possible, place the component containing the female

threads into a vise.

Figure 3-105.

NOTE:
■ Tighten the jaws ONLY on the flats.
■ Tighten just enough to securely hold the component because
overtightening could result in damage to the component.
 Tubing and Tube Fitting Handling and Installation 113

Use a back-up wrench in applications where a vise cannot be used.

3. Knead the tube of sealant (with the cap in place) to blend the
contents prior to use.
4. Remove the cap from the ribbon applicator.

Figure 3-106.

5. While viewing the male threads from the open end, or face, of
the threaded connection, locate the point where the root of the
thread (dashed line) blends into the thread chamfer near the face
of the fitting. This point is referred to as the scratch mark.

Figure 3-107.
114 Tube Fitter’s Manual

6. Place the tip of the ribbon applicator on the crest immediately

behind this point.
Do not apply sealant prior to this point
CAUTION: because excess sealant could get into
the fluid system!

Figure 3-108.

7. Apply sealant to fill the next three threads.

Figure 3-109.

8. Use a solvent such as acetone to remove any excess sealant.

9. Replace the cap before storing the tube.
 Tubing and Tube Fitting Handling and Installation 115

Figure 3-110.

10.Tighten the male end connection into the female end connection
until finger-tight.
Use an appropriately sized wrench.
An oversized wrench will permit
CAUTION:
overtightening and might lead to galling
of the threads.
11. Tighten the male end connection until wrench-tight.
There is no standard for torque or number of turns. ANSI/ASME
B1.20.1–1983 states, “NPT taper pipe threads are intended to be
made up wrench-tight and with a sealant whenever a pressure-tight
joint is required.” Do not overtighten so much as to strip the threads!

Figure 3-111.
116 Tube Fitter’s Manual

If the tapered end connection is on an elbow, tee, cross, valve, or

pressure gauge, assembly may not result in the desired alignment of
the component. Use a tube adapter to get proper alignment.
Once tight, do not loosen the connection!
CAUTION: Doing so could mean leakage at the pipe
thread.

Assemblies made up using SWAK sealant must be allowed to cure

for at least 24 hours at room temperature before pressurizing the
connection.
Assemblies made up using PTFE-Free sealant may be pressurized
immediately.

Assembly Using PTFE Tape

1. Remove the thread protector from the male threads.

Figure 3-112.

2. Where possible, place the component containing the female

threads into a vise.
 Tubing and Tube Fitting Handling and Installation 117

NOTE:
■ Tighten the jaws ONLY on the flats.
■ Tighten just enough to securely hold the component because
overtightening could result in damage to the component.
Use a back-up wrench in applications where a vise cannot be used.

Figure 3-113.

3. While viewing the male threads from the open end, or face, of
the threaded connection, locate the point where the root of the
thread (dashed line) blends into the thread chamfer near the face
of the fitting. This point is referred to as the scratch mark.

Figure 3-114.
118 Tube Fitter’s Manual

4. Place the edge of the tape on the crest immediately behind this
point.
■ Use 1/4 in. wide tape on 1/8, 1/4, and 3/8 in. male tapered pipe
threads.
■ Use 1/2 in. wide tape on larger male pipe threads.

Figure 3-115.

5. While keeping the edge of the tape parallel to the face of the fitting,
wrap the tape in the direction of the thread spiral (clockwise for
right-hand threads) two to three revolutions.

Figure 3-116.
 Tubing and Tube Fitting Handling and Installation 119

NOTE:
If the tape is applied in the opposite direction of the thread spiral, it
is likely to fall off as the male component is tightened into the female
component.

Figure 3-117.

6. Draw the free end of the tape around the threads tautly so that it
conforms to the threads. Cut or tear off excess tape.
Do not cut across the threads.

Figure 3-118.
120 Tube Fitter’s Manual

Firmly press the tape into the threads. Properly applied PTFE tape
will exhibit the following:
The tape must not overhang the first
CAUTION: thread because the tape could shred and
get into the fluid system.
■ The space between the face of the connection and the edge of
the tape closest to it will be even, with the edge intersecting the
thread immediately behind the scratch mark.
■ The number of wraps will be consistent, with no gaps, folds, or
creases in the tape.

Figure 3-119.

■ All crests will be covered. There will be no slices or gouges in the

tape.

Figure 3-120.
 Tubing and Tube Fitting Handling and Installation 121

Figure 3-121.

■ Tape must be clear of dirt and debris.

7. Tighten the male end connection into the female end connection
until finger-tight.
Use an appropriately sized wrench. An
CAUTION: oversized wrench will permit overtightening
and might lead to galling of the threads!
8. Tighten the male end connection until wrench-tight.
There is no standard for torque or number of turns. ANSI/ASME
B1.20.1–1983 states, “NPT taper pipe threads are intended to be
made up wrench-tight and with a sealant whenever a pressure-tight
joint is required.” Do not overtighten so much as to strip the threads!
If the tapered end connection is on an elbow, tee, cross, valve, or
pressure gauge, assembly may not result in the desired alignment
of the component.
Once tight, do not loosen the connection! Doing so could mean
leakage at the pipe thread.
C hap ter 4
Severe Service

Table of Contents
Severe Service 125
Safety Considerations for Severe Service Systems 125
Severe Service Requirements 126
Assembly in High-Pressure Applications and
High Safety Factor Systems for Tubing Diameters
1 in. (25 mm) and Smaller 126
Five Categories of Compressed Gases 129
Oxygen Systems 130
Toxic, Flammable, Explosive Gases 130
Tracing 131
Tracer Installation on Process Lines 132
Tracer Installation on Vertical Lines 132
Tracer Installation on Horizontal Lines 133
Tracer Attachment to Process Lines 134
Multiple Tracers 134
Before Selecting a Tracing Method 135
System Start-Up Instructions 137
Leak Test 137
Tube Fittings 138
Tracer Installation on Process Equipment 138
Heat Transfer Fluids 140
Ultra-Clean Systems 141
Vacuum Systems 141
Vibration 143
Disassembly/Reassembly 144
Impulse/Shock 144
Elevated Temperature Service 145
Materials 145
Tensile Strength 145
Wall Thickness 146
Cryogenic Service 146
Plastic Materials 146
Elastomer Materials 147
Metal Materials 147
 Severe Service 125

Severe Service
Fittings connect some of a plant’s most essential and costly
equipment. Because fluid mobility is an integral part of a plant’s most
critical systems, these applications are often custom-designed and
highly engineered, making them significant financial investments.
Years of successful performance in the field and rigorous testing
have validated the performance of Swagelok tube fittings. These
tube fittings have been engineered to perform reliably in a wide range
of critical applications, from ambient conditions to the extreme,
high-pressure, high-temperature, or highly-corrosive environments.
Swagelok tube fittings are used in severe service applications
across many industries.

Safety Considerations for Severe Service

Systems
■ Do not bleed the system by loosening the tube fitting nut or the
fitting plug.
■ Do not assemble or tighten fittings when the system is pressurized.
■ Make sure that the tubing rests firmly on the shoulder of the tube
fitting body before tightening the nut.
■ Use the correct Swagelok gap inspection gauge to ensure
sufficient tightening upon initial installation.
■ Never allow problems to go unreported.
■ Always use proper thread sealants on tapered pipe threads.
■ Do not mix materials or fitting components from various
manufacturers—tubing, ferrules, nuts, and fitting bodies.
■ Never turn the fitting body. Instead, hold the fitting body and turn
the nut.
■ Avoid unnecessary disassembling of unused fittings.
■ Use only long reducers in female Swagelok end connections.
■ Metal tubing material should be softer than fitting material. For
example, stainless steel tubing should not be used with brass
fittings.
■ Use fully annealed tubing when tubing and fittings are made of
the same material.
■ Always use an insert with extremely soft or pliable plastic tubing.
■ Check extremes of wall thickness against fitting manufacturer’s
suggested minimum and maximum wall thickness limitations.
■ Check the surface finish of the tubing. Surface finish is very
important to proper sealing. Tubing with any kind of depression,
126 Tube Fitter’s Manual

scratch, raised portion, or other surface defect will be difficult to

seal, particularly in gas service.
■ Check tubing for ovality. Tubing that is oval and will not easily fit
through fitting nuts, ferrules, and bodies should never be forced
into the fitting.

Refer to the Swagelok Tubing Data Sheet

(MS-01-107) for more information about tubing
selection. www.swagelok.com/TFM

Severe Service Requirements

For severe service requirements, there are tools and methods to
ensure that installation is correct.
■ Depth marking tool (DMT)
■ Specific high-pressure and high safety factor instructions
■ Gap inspection gauge
Please refer to Depth Marking Tool instructions in Chapter 3 starting
on page 78.

Assembly in High-Pressure Applications

and High Safety Factor Systems for Tubing
Diameters 1 in. (25 mm) and Smaller
This procedure is specific to tubing diameters 1 in. (25 mm) and
smaller, and it varies only slightly from the standard procedure.
1. First, fully insert the tubing into the fitting and against the
shoulder. Rotate the nut finger-tight.
2. Next, due to variations of tubing diameters, a common starting
point is desirable. Therefore, further tighten the nut until the
tubing will not turn by hand or move axially within the fitting.
3. Next, mark the nut at the 6 o’clock position. Finally, while holding
the body steady, tighten the nut 1 1/4 turns to the 9 o’clock
position.
As was mentioned previously, 1/16, 1/8, and 3/16 in. or 2, 3, and
4 mm tube fittings require only a 3/4 turn of the nut for sufficient
tightening.
 Severe Service 127

Gap Gauge
Swagelok gap inspection gauges assure the installer or inspector
that the fitting has been sufficiently tightened on initial installation.

Figure 4-1 Gap inspection gauge.

Correct Incorrect

If the gauge will not enter the If the gauge will enter the
gap, the fitting is sufficiently gap, additional tightening is
tightened. required.

Figure 4-2 Position the Swagelok gap inspection gauge next to the gap
between the nut and body.
128 Tube Fitter’s Manual

High-Pressure Gas Systems

What is high pressure? It depends on the consequences of failure.
Pressurized gas systems contain a large amount of stored energy.
Because light gas can leak through the most minute leak path, the
sealing of high-pressure, relatively light gases becomes difficult.
Small scratches, gouges, nicks, or weld seams on the tubing OD
may easily create a leak path. These deformities can sometimes
cause problems even when the very best Swagelok tube fittings are
used.
The general suggestions for this severe service all apply to high-
pressure gas systems. In particular, tubing wall thickness should
be carefully considered, and no less than the minimum wall for
gas service, as shown here, should be used.
Tubing for Gas Service

Fractional Sizes, in inches

Minimum Nominal Minimum Nominal

Tube OD Wall Thickness Tube OD Wall Thickness
1/8 0.028 3/4 0.065
3/16 0.028 7/8 0.083
1/4 0.028 1 0.083
5/16 0.035 1 1/4 0.109
3/8 0.035 1 1/2 0.134
1/2 0.049 2 0.180
5/8 0.065

Metric Sizes, in millimeters

Minimum
Nominal Wall Minimum Nominal
Tube OD Thickness Tube OD Wall Thickness
3 0.8 18 1.5
6 0.8 20 1.8
8 1.0 22 2.0
10 1.0 25 2.2
12 1.0 28 2.5
14 1.2 30 3.0
15 1.5 32 3.0
16 1.5 38 3.5

Minimum wall for gas service

 Severe Service 129

To achieve the best results in achieving an absolutely leak-tight seal

on high-pressure gas systems, consider these recommendations:
■ Order good-quality hydraulic tubing with proper hardness and
a surface finish free of scratches or other defects. Be sure that
minimum wall thickness for gas service is used.
■ Cut tubing cleanly, deburring both the ID and OD.
■ Insert tubing fully into the Swagelok tube fitting. Make sure that
the end of the tube rests firmly on the internal shoulder of the
fitting.
■ Follow the assembly instructions starting on page 75.
■ Check each connection with the Swagelok gap inspection gauge.
■ Never bend the tube after it has been inserted into the fitting.
■ If special cleaning treatments are required, consider the use of
specially cleaned Swagelok stainless steel or alloy fittings with
silver-plated ferrules.
■ Consider use of VCO® or VCR® fittings if you are unable to get
proper surface finish on tubing. Because tube is welded to the
fitting, the tube surface finish and hardness do not affect the seal.

Five Categories of Compressed Gases

Compressed gases are generally classified in the five categories
listed here.
■ Corrosive: Gases that attack and damage materials and actually
remove some of the material by chemical attack. Such chemical
attack is usually more severe with the presence of water. Care in
material selection is vital.
■ Examples: Hydrogen chloride, hydrogen sulfide
■ Flammable: Gases that form a flammable mixture in air at 12 %
or more concentration. Changes in temperature, pressure, and
concentration may cause wide changes in flammability.
■ Examples: Hydrogen, methane
■ Inert: Gases that generally do not react with ordinary materials
at commonly used temperatures and pressures. Generally
noncorrosive, nontoxic. Not hazardous except when used in
confined spaces. Air can be displaced, making life support difficult.
Adequate air supply and ventilation should be considered.
■ Examples: Helium, argon
■ Oxidant: Gases that do not themselves burn but that support
combustion.
■ Example: Oxygen
130 Tube Fitter’s Manual

■ Toxic: Gases that produce deadly or harmful effects on humans

by chemical attack.
■ Examples: Arsine, phosphine

Oxygen Systems
Oxygen has unique and hazardous properties. Handling it, either in
the liquid or gaseous state, is a specialized field. Design and safety
are the responsibility of oxygen system users, who should obtain
qualified professional assistance to establish design specifications
and operating practices for the safe use of oxygen.

Please refer to the Swagelok Oxygen System Safety

technical bulletin (MS-06-13) for additional information.
www.swagelok.com/TFM

Toxic, Flammable, Explosive Gases

Industries such as chemical, semiconductor, and analytical
instruments regularly handle gases that are particularly hazardous.
The care listed for high pressure gases above should be exercised
for such system fluids.
In addition to the items listed in the “High-Pressure Gas Systems”
section earlier, you should also consider the following:
■ Tube surface finish and careful deburring are essential. In
assembly, extra care should be used in fully bottoming the tube in
the fitting body before pull-up.
■ If gas bottles or cylinders are used, they should always be fully
secured in use, storage, and transit. The tremendous stored
energy in such containers has caused severe damage and injuries
in many recorded accidents, usually caused by dropping or
tipping the container and breaking off the cylinder valve.
Steam Piping
Steam is one of the most erosive of system fluids. High-velocity
steam can erode metals as hard as stainless steel in a very short
time. Dry, superheated steam is less erosive than wet steam.
Unless water chemistry is carefully controlled, corrosive inclusions
add to the erosive properties and make steam a difficult fluid to
handle.
 Severe Service 131

When installing Swagelok tube fittings for steam service, the

following precautions should be taken:
■ Material selection should be based on pressure, temperature,
and environmental conditions. Both fitting and tubing must have
compatible thermal properties.
■ Steam should be considered a gas for purposes of wall thickness
determination.
■ Deep scratches or gouges of tube OD must be avoided. A very
slight steam leak through such a defect will become a larger leak
as erosive steam etches a deeper valley in the tubing.
■ If steam temperatures are above 400°F (204°C), consider the use of
Silver Goop high-temperature thread lubricant on fitting nut threads.

Tracing
Tracing is a method of providing heat or cold input to raise, lower,
or maintain temperature in process piping systems and equipment.
Swagelok tube fittings are commonly used to connect steam tracing
tubing to prevent freeze-up in cold weather. Some heat transfer
fluids other than steam, such as Therminol® or Dowtherm®, are
also used. Tracing can also be applied to piping and equipment that
contain materials that could solidify or become extremely viscous,
even in summer months.
This method is not covered in depth since the amount of tracing
required will vary with the application. An engineering analysis is
recommended on viscous fluid tracing requirements. The severity of
winters in a particular locale usually determines the need and methods
of tracing. Individual plant practices and preferences also influence
requirements. The methods suggested in this manual are for guidance
only.
Process lines and equipment can be protected from freezing by
using tubing as the tracing lines. Common steam tracing line sizes
of copper tubing are:
■ 1/4 in. OD × 0.035 in. wall
■ 3/8 in. OD × 0.049 in. wall
■ 1/2 in. OD × 0.065 in. wall
The heavier wall tubing is preferred because the thicker wall gives
improved performance during a cool-down period from full steam
temperature and increases temperature cycling ability. It is during
that time that thin wall tubing tries to shrink away from the fitting.
Once this occurs, any slight scratch becomes a potential leak path.
The tubing should be a fully annealed quality.
132 Tube Fitter’s Manual

Tracer Installation on Process Lines

Locating Horizontal Tracers: Several techniques have been
developed for positioning the tracing lines in the best manner for
suitable heat transfer. Always supply steam to tracers on the high
end of a sloping process line to prevent back-up of condensate. As
a general guide, small tracers should not exceed 60 ft. in length, and
the limit for all other sizes should be about 150 ft.

Jacketed Two Channel Single External Multiple External

Tracing Pipe Tracing Tube Tracer Tube Tracer

Liquid Products Insulation

Figure 4-3 Tracer location on horizontal or sloping lines.

Tracer Installation on Vertical Lines

Locating Vertical Tracers: A single tracer on a vertical, or nearly
vertical, process line can be spiral wrapped. Multiple tracers on
vertical lines should be equally spaced for the most efficient heat

Steam In
Steam In

Figure 4-4 Left: Single tracer, spiral wrapped.

Right: Multiple tracers, equally spaced.

Vertical lines with spiral-wrapped tracers do not require additional

attachment.
 Severe Service 133

transfer.

Fastener Correct
too Close
Unequal to Flange
Condensate
Trapped
Incorrect

Figure 4-5 Left: Side view. Right: Top view.

Tracer Installation on Horizontal Lines

Horizontal lines with:
■ 1/4 in. (6 mm) OD tracers should be fastened every 1 1/2 ft. (45 cm)
■ 1/2 in. (12 mm) OD tracer lines should be fastened every 2 ft. (60 cm)
Fasteners should be equally spaced on each side of flanges. Always
use a large radius bend around the flange on a flat plane so that the
loop is not below or above the level of the horizontal tube run.
The table below provides suggested information on the size and
number of tracers for process lines of various sizes:

Max. Max. Tracer

Process Pipe No. of Tracer Length
Size Tracer Size2 Tracers2 Length Between Traps1
1½ in. and ¼  0.035 in. or 1 60 ft. 60 ft.
smaller 3⁄8  0.049 in. wall

copper tubing
2 in. and 0.065 in. wall, ½ in. 1 150 ft. 150 ft.
2½ in. OD copper tubing
3 in. to 4 in. 0.065 in. wall, ½ in. 2 150 ft. 150 ft.
OD copper tubing
6 in. and 8 in. 0.065 in. wall, ½ in. 3 150 ft. 150 ft.
OD copper tubing
10 in. and 0.065 in. wall, ½ in. 4 150 ft. 150 ft.
12 in. OD copper tubing
134 Tube Fitter’s Manual

Max. Max. Tracer

Process No. of Tracer Length
Pipe Size Tracer Size2 Tracers2 Length Between Traps1
40 mm and 6 × 0.80 mm, 1 18 m 18 m
smaller 8 × 0.90 mm, or
10 × 0.90 mm wall
copper tubing
50 mm and 12 × 1.20 mm wall 1 45 m 45 m
65 mm copper tubing
80 mm to 12 × 1.20 mm wall 2 45 m 45 m
100 mm copper tubing
150 mm and 12 × 1.20 mm wall 3 45 m 45 m
200 mm copper tubing
250 mm and 12 × 1.20 mm wall 4 45 m 45 m
300 mm copper tubing

1. Use individual traps for each tracer line. Never attach tracer lines
to one trap via a manifold.
2. Or as required by individual needs.

Tracer Attachment to Process Lines

Single tracer lines may be fastened to the pipe with wire, bands, or
tape. Care should be taken to use wires or bands that are galvanically
compatible with the pipe or tracer tubes. Tapes for stainless steel
tubes and pipes should not contain chlorides or halides, since these
can cause corrosive failures of the tracer or pipe. There are several
manufacturers of glass fiber tapes that are free of such corrosives
and good for temperatures up to 500°F (260°C).
Care must be taken with some process fluids in stainless steel
pipe to make sure that local spot overheating does not cause very
rapid pipe corrosion on the inside of the pipe at the point the tracer
contacts the outside. Such action can be prevented by a layer of
insulation between the pipe and the tracer tube. Consult process
data for details.

Multiple Tracers
When attaching multiple tracer lines to a process line, fasten each
tracer individually to the process line. This will prevent the tracer
lines from sliding to the bottom of the process line.
 Severe Service 135

Incorrect Correct

Figure 4-6 Attachment of multiple tracers to a process line.

Expansion: Tracer tubing will expand as the temperature increases.
The process piping will also expand when heat is transferred. The
rates of expansion of the tracer tubing and the process line will
usually differ because of unlike coefficients of expansion of the two
materials and the temperature differential between the tracer and
the process line. Sufficient slack in the tracer lines and expansion
bends is required to prevent the tracer tubing from stretching or
kinking.

Before Selecting a Tracing Method

Consider the following:
The capability of any given tracing installation must be matched
carefully with the requirements of the system to be traced. Here are
some important factors to consider:
■ Extreme care should be used on installations where difficult bends
and complicated valve manifolds are encountered.
■ The choice of tracing techniques can be narrowed by temperature
requirements, particularly where high temperatures are needed or
where temperatures must be held within precise limits.
■ The length and diameter of the process piping to be traced provide
an indication of the liquid volume to be maintained at a specified
temperature. Therefore, these dimensions should be measured
accurately to help estimate tracing system heat requirements.
■ Heat loss depends, to a large degree, on the location of the piping
to be traced. For example, different tracing methods would be
needed for two identical installations if one were outdoors in a
cold environment and the other were indoors. Another pertinent
factor in estimated heat loss is the type and thickness of the
136 Tube Fitter’s Manual

insulation that covers the pipe and tracing.

■ The choice of tracing techniques is limited if the installation is an
existing process pipe that may not be moved or disconnected.
New installations seldom present this problem.
■ Some tracing methods will be ruled out if hot spots on a pipe
would be incompatible with the process to be traced (causing
unsafe conditions, for instance). Special installation may be
needed.
■ Heat source for the tracing system must be constant. Steam, for
example, must be available even during shutdown.

Insulation

Swagelok Shut-Off Valve Steam Trap

Swaglok
Swagelok Union Tee Strainer Male Connector

1/2 in. Tubing Discharge

6 in. Long Dirt Trap Line
Swagelok Blow Down
Valve with Swagelok Ends Strainer Blow Down Valve

Figure 4-7 Proper installation of steam trap system.

Steam Trap Installation

The efficiency of tracer systems depends on the proper installation
of steam traps. It is suggested that the following guide rules be used:
■ Insulate the steam tracer line to within 2 lineal ft. of the trap inlet.
■ Always install a strainer in front of the steam trap to protect the
seating surfaces of the trap.
■ Install a 6 in. long section of 1/2 in. OD tubing to provide a dirt trap
in front of the steam trap. Large pieces of dirt or contamination
accumulate in the dirt trap, thus increasing the service life of the
steam trap.
■ Install the steam trap, control valves, and strainer as close to the
ground as practical.
■ Use 1/2 in. OD tubing for the discharge line. This line should be as
short as possible and should discharge into a condensate recycle
collection header. Make sure the discharge line is not a safety
hazard.
 Severe Service 137

■ Provide proper support for wiring the horizontal discharge line

and accessories.
■ Suggested arrangement of components is shown in the steam
trap installation graphic.

System Start-Up Instructions

Leak Test
All new tracer lines should be pressurized with air and checked for
leaks with SNOOP® or REAL COOL SNOOP® leak detectors. After
performing any needed repairs, the system is ready for start-up with
steam.

Please refer to the Leak Detectors, Lubricants, and

Sealants catalog (MS-01-91) for additional sealant
information. www.swagelok.com/TFM

Figure 4-8 Snoop liquid leak detectors.

138 Tube Fitter’s Manual

Tube Fittings
Swagelok brass tube fittings are suggested for use on copper
tracer lines (trace steam temperature up to 400°F [204°C]), since
they provide easy, reliable, leak-tight connections. In many cases,
stainless steel tracing systems may be required due to the external
environment.
For ease of maintenance, insulation should not be placed over the
Swagelok tube fittings because each Swagelok tube fitting is a union
joint. Access to the fittings allows easy replacement of corroded or
damaged tube sections.
Wherever possible, locate the Swagelok tube fittings at the process
pipe flanges or other uninsulated areas.
When a Swagelok tube fitting must be used in an insulated area,
provide a small window in the insulation for accessibility as
shown here.

Process Line Insulation

Window

Swagelok Union

Swagelok Union 3/8 in. OD x 0.049 in. Copper Tubing

Figure 4-9 Fitting window in an insulated area.

Tracer Installation on Process Equipment

Two methods are available for installing tracers on irregularly
shaped equipment such as valves, pumps, and instruments. The
two methods are:
1. Spiral wrapped
2. Flat grid
 Severe Service 139

1. Spiral Wrapping Method

Approximately 6 in. should be maintained between coils when
the spiral wrapping method is used. Use Swagelok unions to
permit removal of the equipment without uncoiling the tracer line.

Steam In

6 in. 1/2 x 0.065 in.

Copper tubing

Swagelok Union

Figure 4-10 Spiral wrapping of irregular shaped process equipment.

When equipment must be frequently removed for servicing, the loop

method of spiral wrapping is recommended, as illustrated here.

Steam In

1/2 x 0.065 in.

6 in. Copper tubing

Swagelok Union

Figure 4-11 Spiral loop wrapping of process equipment for easy removal.
140 Tube Fitter’s Manual

2. Flat Grid Method

For flat or irregular surfaces, 1/4 in. OD tracer tubing should be
used. The tubing should be bent to form a grid and shaped to the
surface. A 6 in. spacing should be maintained between coils, as
illustrated here.

Swagelok Union Steam In

3 in. Radius
6 in.

6 in.

6 in.

Swagelok Union

Figure 4-12. Flat grid method.

Heat Transfer Fluids

Commercial heat transfer fluids are readily available. Liquid phase
and vapor phase fluids cover a wide range of operating temperatures
up to about 750°F (399°C).
One of the chief advantages of such fluids is that high-pressure
equipment, steam traps, and water conditioning equipment are
not necessary. Thus a high-temperature system does not need to
operate at high pressures like a steam trace system.
Heat transfer fluids are generally difficult to seal. Care should be
exercised when fittings are used for such systems. In particular,
wall thickness of tubing should be selected in line with gas pressure
suggestions provided earlier in this chapter.
When selecting materials for heat transfer fluid systems, follow the
suggestion of the fluid manufacturer.
 Severe Service 141

Ultra-Clean Systems
Today’s high-technology demands call for ever-more-stringent
cleanliness requirements. Standard production Swagelok tube
fittings are carefully degreased, but for certain electronic, aerospace,
and ultra-pure gas systems, special cleaning may be required.
A number of different methods may be used, depending on system
requirements and fitting materials. Swagelok specially cleaned
fittings are packaged individually in sealed plastic bags. Consult
your Swagelok representative for details. If Swagelok tube fittings
are specially cleaned in the field, we suggest the following:
■ Cleaning of the nut or back ferrule should be avoided because
only the body and front ferrule are wetted parts.
■ Galling and possible leakage may occur when absolutely dry
parts are brought together under the high loads necessary to seal.
Therefore, use specially cleaned, silver-plated Swagelok front
ferrules, or apply a system-compatible anti-gall material.

Vacuum Systems
Swagelok tube fittings are widely used on industrial vacuum
applications. The importance of keeping all action moving in an axial
direction with absolutely no torque or rotary motion in making a seal
is demonstrated in applying Swagelok tube fittings to vacuum work.
Any scoring of the sealing surfaces could prevent a helium leak-
tight seal. The axial motion, when making and remaking joints with
Swagelok tube fittings, results in pressing the sealing surfaces
together so that there is no scoring of any surfaces and, therefore,
helium leak-tight joints can be made over and over again. Extreme
care should be used in the handling of tubing for vacuum service to
ensure successful use in your system. Scratches on tube surfaces
can cause problems.
In vacuum work, cleanliness is absolutely essential. All tubing used
should be degreased and then dried thoroughly. If this is not done,
oils and moisture may vaporize as pressure is reduced and the
system will appear to leak even though it is tight. Tube fittings for
vacuum work should also be specially cleaned.
When using stainless steel or other special alloys that have
tendencies to gall, we suggest that only the body and front ferrule
be degreased as these are the only items that are within the system.
The nut and back ferrule are outside the sealed system, and special
lubricants that have been applied to prevent galling should not be
removed.
142 Tube Fitter’s Manual

Swagelok can supply specially cleaned Swagelok tube fittings.

Stainless steel and other special alloys use specially cleaned, silver-
plated front ferrules to prevent galling of specially cleaned parts.
Swagelok metal tube fittings with PTFE ferrules can also be used for
quick, easy industrial vacuum connections. Consideration must be
given to the cold-flow and outgassing properties of PTFE and the
greatly reduced holding power of PTFE ferrules.
Because of partial dependence on tube OD surface finish, when
using “OD seal” fittings such as Swagelok tube fittings, we find that
when systems are operating in the ranges of very-high or ultra-high
vacuum range (below 10‒6 torr), all-welded systems are the most
reliable. Swagelok tube or weld fittings (see Chapter 6) have been
used in many such systems. Where systems require breakdown for
cleaning or maintenance, VCO® or VCR® fittings are suggested (see
Chapter 6).
Swagelok Ultra-Torr Vacuum Fittings are ideal for making quick,
easily removed vacuum seals, such as connecting to helium leak
detectors or connecting metal to glass tubing. So, both Swagelok
tube fittings and other style fittings, such as Swagelok VCO, VCR,
etc., can be used on vacuum systems. Caution should be used if
fitting components contain elastomers or plastics, especially if
the vacuum system will see temperatures in the bakeout range.
In bakeout applications, one should not mix metals when system
temperatures will be increased unless coefficients of expansion are
considered.
For example:
Assume a 316 stainless steel fitting (coefficient of expansion 11 ×
10‒6/in./in./°F) was installed on alloy 400 tubing (coefficient of
expansion 7.8 × 10‒6/in./in./°F).
When the temperature is raised, the stainless steel would
increase in size at a greater rate than the tubing. The fitting
would become loose on the tubing because of a property of the
material (coefficient of expansion) coupled with the temperature
change.
On the other hand, if alloy 400 is put on stainless and raised
to a high temperature, the joint becomes tighter. However, the
stainless steel tubing increases in size at a greater rate than
the alloy 400 fitting and may yield the fitting, and a leak could
result upon returning to lower temperatures. Mixing materials is
not recommended (i.e., using different materials for fittings and
tubing) unless an engineering analysis is made of temperature
variation.
 Severe Service 143

For your convenience, coefficients of expansion for materials

commonly employed in tube fitting applications are shown here.

Coefficient of Expansion
Material in./in./°F
Stainless Steel (304 and 316) 8.5 × 10–6
Alloy 400 7.7 × 10–6
Brass 9.3 × 10–6
Aluminum 12.1 × 10–6
Carbon Steel 7.0× 10–6
Copper 9.3 × 10–6

Temperature Rating: Operating temperature ratings are dependent

on application and installation methods, cycle life required, and
other variables. Consult your Swagelok representative for additional
information. Use Swagelok PTFE tape on pipe threads in a vacuum
system to create a seal. VAC-GOOP lubricant is suggested for use
in the vacuum system on bolts and surfaces where it is desired to
prevent galling.

Vibration
Systems such as compressor or pump piping often have stringent
requirements regarding the fittings’ resistance to vibration. Well-
designed fittings such as Swagelok tube fittings have built-in vibration
protection.
In applications where severe vibration is present, the best protection
is to properly support the tubing near the fitting. Limiting the
amplitude of the vibration increases fitting and tube connection
life. It is particularly important in vibration applications to install
fittings exactly according to suggested installation instructions. The
bottoming of the tube against the shoulder of the fitting body should
receive careful attention. If the tube is fully bottomed, the tube OD
ahead of the ferrules is increased during pull-up, creating a more rigid
assembly. We have conducted extensive tests on vibration service,
particularly on stainless steel fittings. The results are summarized in
Product Test Reports.
Refer to Tube Fitting Performance Product Test Reports
(MS-06-108) and search for the following test results:
PTR-976 and PTR-3222. www.swagelok.com/TFM
See Chapter 3 for tubing support information details.
144 Tube Fitter’s Manual

Disassembly/Reassembly
One of the key qualities that distinguishes a well-designed tube
fitting from the ordinary is the ability to take frequent disassembly
and reassembly service without losing sealing integrity. In instrument
systems or temporary laboratory experiments, where constant
cleaning or maintenance is required, a tube fitting with good
disassembly/reassembly abilities may often save its price many times
over.
Swagelok tube fittings have earned their reputation since 1947 by
their ability to seal difficult fluids repeatedly, after many disassembly
and reassembly cycles. Swagelok test programs are described in
Chapter 7.
As in any application, the original installation will often determine
just how many disassembly/reassembly cycles a connection
can take while remaining leak free. Swagelok’s tests indicate that
25 disassembly/reassembly cycles are not unusual with proper
care, although customers routinely report far more than just
25 disassembly/reassembly cycles.
The compensating action of the two Swagelok ferrules promotes
longtime service under disassembly/reassembly conditions.

Impulse/Shock
Impulse or pressure cycling is caused by many factors, but
primarily by quick-opening valves in hydraulic systems. It causes
considerable stress on a tubing system. The Swagelok two-ferrule
design absorbs such stress and allows the use of off-the-shelf tube
fittings for such service. Proper support of tube runs, as close as
possible to the fitting, will prolong the life of tubing connections.
Proper assembly of tubing and fitting is essential. Tube wall (within
the limits shown in Chapter 9) should be carefully considered, and
an additional design factor should be considered where severe
impulses are present. Swagelok’s impulse testing is described in
Chapter 7.
One example is a quick-closing valve that causes very rapid
pressure changes.
Shock may take many forms in tubing systems. It normally is
considered as any type of a sudden, violent stress that may affect a
tubing system.
An example would be the shock that must be absorbed if an
ambient temperature component is quickly immersed in liquid
nitrogen. Another type of shock is a sudden jolt near a forging
 Severe Service 145

hammer or other heavy equipment that causes a sudden, but

short-lived, shock condition.
Temperature cycling, particularly very rapid cycling, is another
form of shock.

Elevated Temperature Service

For purposes of definition, high temperature is considered to be
above 100°F (40°C). A number of different factors must be considered
when tubing and fittings are used at elevated temperatures.

Materials
The first consideration is the material required to resist high
temperatures and temperature excursions over a long period of
service. Temperature limits of most fitting and tubing materials are
listed in ANSI piping codes, including specific conditions regarding
tubing materials and methods of manufacture.
This table shows the general range of maximum temperatures for
the given materials.

Aluminum 400°F 204°C

Copper 400°F 204°C
Steel 375°F 191°C
304SS/316SS 1000°F 538°C
316SS * 1200°F 649°C
Alloy 400 800°F 427°C
Maximum temperatures by material
* The 316-ELT material meets the ASME B31.1 requirements for service up to 1200°F.

Tensile Strength
The second consideration is that as temperature increases, the
tensile strength of metal decreases. Thus the allowable working
pressure of tubing is lower at elevated temperatures than at room
temperature.
146 Tube Fitter’s Manual

This table lists the factors used to determine tubing pressure ratings
at elevated temperatures. Multiply working pressure rating by the
factors shown for temperature indicated.

°F Aluminum Copper Steel 304SS 316SS Alloy 400

200 1.00 0.80 0.95 1.00 1.00 0.88
400 0.40 0.50 0.86* 0.93 0.96 0.79
600 0.82 0.85 0.79
800 0.76 0.79 0.76
1000 0.69 0.76
1200 0.30 0.37
1400
* Based on 375°F max.
Factors to determine tubing pressure ratings

Wall Thickness
Finally, as temperatures increase, some fluids that are normally
liquids can become gases. It is important to use the minimum wall
thickness recommended for gas service as listed on pp. 19 and 213
for these applications.

Cryogenic Service
For purposes of definition, cryogenic temperatures will be
considered as temperatures substantially below room temperature.
The primary consideration is similar to the primary consideration for
elevated temperatures: material characteristics.

Plastic Materials
In general, plastic and elastomer materials are not satisfactory
for cryogenic applications. Plastics have much higher thermal
coefficients of expansion than metals. Therefore, plastic components
used as sealing members at room temperature will shrink markedly
when temperatures are lowered, causing leakage. Many plastics
also have some porosity, which allows water absorption. Water will
solidify when temperatures are lowered and make the tube or fitting
material brittle. Plastic manufacturers should be consulted before
using plastics in cryogenic service.
 Severe Service 147

Elastomer Materials
Most elastomers harden at low temperatures and may crack. Care
should be exercised in selecting elastomer seals when cryogenic
temperatures are required. Elastomers also have much higher
thermal coefficients of expansion than metals. Used as sealing
members at room temperature, they will shrink markedly when
temperatures are lowered. This shrinkage may result in leakage.

Metal Materials
The most commonly used materials in cryogenic piping systems are
aluminum and austenitic stainless steel. Alloy 600, alloy 400, and
titanium are also selected for some applications. It is particularly
important to use the same alloy for both tube fitting and tubing so
that thermal coefficients are the same. Tube wall thicknesses should
be selected from the minimum wall for gas service as shown in
tables earlier in this chapter. It should be remembered that minimum
walls for gas service should be considered even if cryogenic liquids
are the system fluid. If at some time the system is brought up to
ambient temperatures, the liquid will become a gas.
C hap ter 5
Troubleshooting

Table of Contents
Introduction 150
Troubleshooting 150
150 Tube Fitter’s Manual

Introduction
This section is designed to guide you through the installation of
trouble-free fittings. The information is not exhaustive. Should you
encounter a problem that is not covered in this section, please
contact the local Swagelok Authorized Sales and Service Center for
assistance.

To locate your local Swagelok Authorized Sales

and Service Center www.swagelok.com/TFM

Troubleshooting
Recommended
Trouble Possible Cause Corrective Measures
1. Tubing will not Burrs on tubing from Deburr tubing. Use outside
fit into fitting. tube cutting operation. diameter (OD) deburring tool.
Flattened tubing from Use caution in cutting soft
bearing too hard with tubing with hacksaw.
hacksaw in cutting or
using dull hacksaw.
Tubing out of round from Swagelok tube fittings are
bending. manufactured to tolerances
to accept the upper limit of
allowed tubing diameters used
in tubing manufacture. If tubing
is bent too far out of round by
improper bend, the tubing will
not fit into the tube fitting. Use
caution with bends when near
the end of tubing.
Tubing is the wrong size Make sure you use the proper
for fitting. This seldom size fitting for each diameter
occurs, but infrequently tubing.
a piece of 3/8 in. tubing Check OD of tubing.
may be used with a 5/16
in. fitting by mistake. Determine if it is fractional or
millimeter size tubing.
Tubing is oversize. Poor-
quality tubing may exceed Buy good quality tubing. For
the allowed tolerances for 1/16 or 1/8 in. fittings, tubing
tubing. should be ±0.003 in. on the OD
Tubing end raised due to tolerance.
dull tube cutter wheel. Replace with good sharp wheel
or use good-quality hacksaw for
cutting. Use OD deburring tool.
 Troubleshooting 151

Recommended
Trouble Possible Cause Corrective Measures
2. Fitting cannot This could happen with Buy fully annealed, hydraulic
be pulled up steel or stainless steel or pressure type steel and
proper amount tubing that is very hard stainless steel tubing of
of turns. and not intended for fluid recommended hardness.
system applications.
Interchange of other
manufacturers Use only Swagelok tube fittings.
components. DO NOT INTERCHANGE.
Components have been
cleaned, removing Never remove lubricants from
proprietary lubricants. nut. If special cleaning is
required, clean body and front
ferrule only. In stainless steel
Dirt or other and special alloys, use specially
contaminants on cleaned, silver-plated front
threads. ferrules.

Tube wall is too heavy. Protect all thread and seal

surfaces from contamination.

Galled threads on nut or

body. Use tubing within suggested
wall thickness.
Replace complete fitting.
3. Leakage at pipe Fittings not sufficiently Tighten fittings.
thread. tightened with mating
thread.
Pipe threads require Swagelok PTFE tape should
a sealant to make a be used on all pipe threads
leak‑free connection. to provide leak-tight sealing.
SWAK anaerobic pipe thread
sealant with PTFE is also an
excellent pipe thread sealant.
Pipe threads damaged Good pipe thread sealants
from galling of materials such as Swagelok PTFE tape or
during installation. SWAK also help prevent galling
of pipe threads. Discard galled
components.

Poor-quality pipe thread Use high quality pipe threads,

either on female or male such as on Swagelok fittings.
end. These pipe threads are
precision-manufactured, but
this is not sufficient to make
a leak-tight connection with a
pipe thread on other equipment.
Use a good sealant.
152 Tube Fitter’s Manual

Recommended
Trouble Possible Cause Corrective Measures
4. Leakage at Poor flares. Cracked Use Swagelok tube fittings.
flare joint. or split flare.
5. Tubing leaks Not using Swagelok Use Swagelok tube fittings.
at fitting tube fittings. Fittings not Follow installation instructions.
after initial pulled up properly. Check for hard tubing or galling.
installation. Use good-quality annealed
tubing. Check for sufficient
pull-up with a Swagelok gap
inspection gage.
Tubing not bottomed in Cut off ferrules and replace.
fitting body. Insert tube until it fully bottoms
against shoulder of fitting body.
Tubing has deep Handle tubing with care.
longitudinal scratches Replace tubing or cut off
or is nicked or otherwise damaged section and
damaged. reconnect.

Fitting body was rotated, Always connect fittings by

instead of nut, galling rotating the nut while holding
seat and/or front ferrule. body stationary.

Fitting not tightened Preswage or use the Multihead

according to installation Hydraulic Swaging Unit
instructions because of (MHSU), then snug 1/2 turn.
inaccessible location. See preswaging and hydraulic
swaging instructions in
Chapter 3.

Fitting was used as Replace tubing. Never use the

vise or anchor to bend fitting as a holding device for
tubing by hand. bending. This will deform the
tubing inside of the fitting and
pull the tube away from the
seal.

Interchange of other Use only Swagelok tube fittings.

manufacturers’ DO NOT INTERCHANGE.
components.
Poor weld bead removal Use high-quality, annealed,
on welded and drawn welded and drawn hydraulic
tubing. Raised bead or stainless steel tubing. If OD
flat spots interfere with weld is easily seen with the
proper sealing. naked eye, leakage may result.
 Troubleshooting 153

Recommended
Trouble Possible Cause Corrective Measures
6. Tubing leaks Damage caused by Replace tubing and fitting.
at fitting mechanical means Relocate where damage is less
after system outside the system. likely to be a problem. Check
installation. tubing supports.
Corrosion is eating Inspect connection for
away fitting or tubing. corrosion. If present, check
corrosion compatibility of fluid,
tubing, and fitting materials and
ambient atmosphere. Consider
galvanic action as a possible
cause or microbial influenced
corrosion (MIC) in marine
applications.
Cracking of tubing due Swagelok tube fittings should
to overstressing while be used to replace such fittings
making flare for a flare and avoid this difficulty.
fitting.
Interchange of other Use only Swagelok tube fittings.
manufacturers’ DO NOT INTERCHANGE.
components.
7. Copper tubing Copper tubing becomes Heavier wall copper tubing will
leaks at fitting very weak above 400°F help in some cases in which
after operation (204°C). This is an the temperature is close to
above 400°F inherent characteristic 400°F for temperature cycling,
(204°C). of the function of fitting but copper tubing should not
performance. Codes limit be used above 400°F (204°C).
copper tubing to 400°F Stainless steel tubing and
(204°C). fittings can be used.
8. Tubing is Excessive pressure. Use stronger material or heavier
deformed Tubing of insufficient wall tubing. Use Swagelok FK
after system tensile strength or wall or IPT fittings
has been in thickness was used.
operation.
Freeze-up of water or Prevention through proper
condensate in steam installation, operation, and
tracing. maintenance.
9. Polyethylene Check ferrule material— Use metal Swagelok tube
tubing slips PTFE ferrules not fittings with polyethylene tubing
from fitting. satisfactory or possible whenever possible. If tubing is
undersized tubing. very soft, use an insert.
154 Tube Fitter’s Manual

Recommended
Trouble Possible Cause Corrective Measures
10. PTFE tubing Slippery characteristic of Use all metal fittings whenever
slips from PTFE material. possible. PTFE fittings have
fitting. very low pressure ratings.*
NOTE: * The Swagelok PFA
tube fitting, when used with
Swagelok PFA tubing (which
has been grooved with the
Swagelok groove cutter), will
hold to the rated working
pressure of the tubing. Consult
your Swagelok representative
for pressure rating information
on this combination.
11. Glass tubing Metal ferrule used Use Swagelok Ultra-Torr
breaks when improperly. vacuum fittings. With Swagelok
connecting tube fittings, use a plastic front
fitting. and back ferrule.
12. Tubing Fitting not properly Follow instructions.
leaks at retightened.
reconnection Dirt got into fitting Observe cleanliness practices
following or on ferrules while whenever disconnecting and
maintenance. disconnected. reconnecting. Clean out foreign
material and inspect fitting for
damage. If ferrules or seat are
damaged, replace the damaged
parts.
Interchange of other Use only Swagelok tube fittings.
manufacturers’ DO NOT INTERCHANGE.
components.
13. Flows are too Obstruction in system. When assembling a system,
low in system. be cautious so that gravel, dirt,
sand, or other foreign materials
do not get in tubing or fitting.
Single-ferrule fitting has Use only Swagelok tube
overswaged, restricting fittings.
tube inside diameter (lD).

System sized too small. Check to determine if system

should be constructed of a
larger diameter tubing.
 Troubleshooting 155

Recommended
Trouble Possible Cause Corrective Measures
14. Fittings cannot Pipe threads have SILVER GOOP lubricant may
be taken apart welded together. Nut be used on high-temperature
after high threads have welded to alloys for operation at high
temperature threads on tube fitting temperatures to 1200°F (649°C).
operation. body. While SILVER GOOP may
prevent galling, it will not be a
sealant. We know of no good
thread sealant for use above
450°F (204°C).
15. Fittings Proprietary lubricants There are a number of different
gall or leak have been removed. special cleaning options
after special available. Contact your local
cleaning by Swagelok Sales and Service
customer. Center to determine which is
best for you.
C hap ter 6
Special Purpose Fittings

Table of Contents
Special Purpose Fittings 158
Weld Fittings 158
Tube Socket Weld Fittings (TSW) 159
Automatic Tube Socket Weld Fittings (ASW) 159
Pipe Socket Weld Fittings (PSW) 159
Adapters 160
Pipe to Tube Weld (MPW) 160
Tube to Tube Weld (MTW) 160
Tube Butt Weld Fittings (TBW) 161
Automatic Tube Butt Weld Fittings (ABW) 161
Subsea Weld Fittings 162
Micro-Fit Fittings 162
Welding System 163
Face Seal Fittings 164
VCR Metal Gasket Face Seal Fitting 164
VCO O-Ring Face Seal Fittings 164
Ultra-Torr Vacuum Fittings and Tubing 165
Fittings for Very Soft Plastic Tubing 166
Fittings for Harder Plastic Tubing 167
Cone and Thread Fittings 167
JTC Tube Fittings 168
Snubber Fittings (Gauge Protectors) 169
Gaugeable Chromatograph and Column End Fittings 170
Orifice Plate and Wire Drilled Fittings 171
Flange Adapters and Lap Joint Connectors 172
158 Tube Fitter’s Manual

Special Purpose Fittings

In previous chapters, we discussed the Swagelok general purpose,
flareless, mechanical grip-type tube fitting. Swagelok also offers
special purpose fittings that have certain characteristics, making
them desirable for specific applications.

Weld Fittings
Swagelok produces a complete range of tube and pipe weld fittings.
Swagelok weld fittings provide permanent welded connections for
critical applications involving corrosive fluids, shock from pressure
surges, temperature cycling, system vibration, and ultra-pure
applications.
Swagelok offers a variety of weld connections. They include:
■ Tube socket weld (TSW)
■ Pipe socket weld (PSW)
■ Male pipe weld (MPW) pipe to tube weld
■ Male tube weld (MTW) tube to tube weld
■ Automatic socket weld (ASW)
■ Automatic tube butt weld (ATW)
■ Tube butt weld (TBW)
Standard material of construction is dual Cert 316/316L stainless
steel. 316L is also available, as well as other alloy materials.

Figure 6-1 Weld fittings.

Refer to the Swagelok Weld Fittings catalog

(MS-01-149) for additional information.
www.swagelok.com/TFM
 Special Purpose Fittings 159

Tube Socket Weld Fittings (TSW)

Tapered socket speeds layout, assembly, and alignment.
Accurate socket depth ensures proper tube support and consistent
assembly.

Figure 6-2 Tube socket weld

fitting.

Precise machining of socket

ensures proper tube fit.

Automatic Tube Socket Weld Fittings (ASW)

Thin wall reduces
weld heat input.

Figure 6-3 Automatic

tube socket weld fitting.

Precise machining of socket

ensures proper tube fit.

Figure 6-4 Union tee.

Pipe Socket Weld Fittings (PSW)

Weld end can be butt or socket welded.
Precision machining of all
surfaces ensures consistent
welding to pipe.

Figure 6-5 Pipe socket

weld fitting.
Heavy wall, plus strength
of material, ensures long
life in severe service
applications.
Socket depth equals or
exceeds requirements of
ASME B16.11 and ensures
proper pipe support.
160 Tube Fitter’s Manual

Adapters
37 1/2° chamfer ensures
proper weld
(not included on 1/4 in. size).

Figure 6-6 Adapter.

Male weld end can be

butt or socket welded.

Pipe to Tube Weld (MPW)

Used to reduce from a pipe butt weld or pipe socket weld to a
smaller tube size.

Figure 6-7 Pipe to tube weld.

Tube to Tube Weld (MTW)

Used to reduce from a tube butt weld or tube socket weld to a
smaller tube size.
Swagelok tube butt weld (TBW), automatic tube weld (ATW),
automatic socket weld (ASW), and Micro-Fit® weld fittings are
designed for systems welded manually or with automatic welding
equipment, like the Swagelok® Welding system.
Standard material for Micro-Fit fittings is 316L VAR (vacuum arc
re-melt). Other grades of stainless steel and other alloy materials
can also be offered.

Figure 6-8 Tube to tube weld.

 Special Purpose Fittings 161

Tube Butt Weld Fittings (TBW)

Tube ends are machined with

a square face and corners
to enhance alignments and
maintain tube wall uniformly.

Standard surface
finish is average
10in. (0.25 m) Ra.
Controlled surface
finish is available Precisely finished diameter
Figure 6-9 Union elbow. for ultrahigh-purity matches tubes diameter.
systems.
Figure 6-10 Tube butt weld fitting.

Automatic Tube Butt Weld Fittings (ABW)

Precisely finished diameter

Standard surface matches tubes diameter.
finish is average
10m (0.25 m) Ra.
Controlled surface
finish is available
for ultrahigh-purity
systems.
Integral filler ring aids in alignment.

Figure 6-11 Union tee. Figure 6-12 Automatic tube butt weld fitting.
162 Tube Fitter’s Manual

Subsea Weld Fittings

Subsea applications have extreme environmental conditions in
settings where space is at a premium. Swagelok subsea weld
fittings are available in 316L stainless steel, alloy 2507, and alloy
625 to withstand those harsh conditions. Tees and elbows are made
from forgings, giving them a lower profile than those made from
extrusions. Weld tangent lengths of up to 2 inches are standard
to facilitate on-site repairs, reducing system downtime and scrap
costs.
Our subsea weld fittings are designed to meet the requirements of
demanding applications such as:
■ Subsea Christmas tree
■ Umbilical termination assembly
■ Steel flying lead
■ Hydraulic distribution manifold
■ Subsea ROV control panels
■ Subsea control modules
■ Wellhead control panels
■ Hydraulic control panels
Refer to the Swagelok Subsea
Weld Fitting catalog (MS-02-481)
for additional information.

Micro-Fit Fittings
(Miniature Tube Butt Weld)
Swagelok Micro-Fit weld fittings are designed for tubing systems
requiring light weight, close component spacing, and cleanliness.
These miniature fittings equal the flow rate and service ratings of
larger fittings designed for the same size tubing. They are available
in standard fractional and metric sizes.
Rounded body block helps prevent
damage to other components during
system fabrication or maintenance.

Marking identifies
manufacturer, material,
and, when applicable,
Material heat code ultrahigh-purity
is roll stamped to cleaning.
ensure raw material
traceability.
 Special Purpose Fittings 163

Micro-Fit Fittings
Ultrahigh-purity cleaning with
average 5 in. (0.13 m) Ra surface
finish is available. Standard surface
finish is average 10 in. (0.25 m) Ra.

Square, sharp, burr- Radiused junction

free tube weld ends allows for a smooth
enhance alignment, flow transition and
maintain tube wall eliminates pockets
uniformly, and promote and entrapment
weld repeatability. zones.

Figure 6-13 Micro-Fit fittings.

Welding System
The Swagelok welding system M200 power supply offers precision
and control combined with easy-to-use touch-screen operation for
orbital welding.
It can be used to weld a variety of tubing and valves and fittings with
weld end connections. The Swagelok welding system uses the gas
tungsten arc welding (GTAW) process, which is commonly referred
to as TIG (tungsten inert gas) welding. During the welding process,
the components to be welded are held stationary in a fixture while
an electric arc is mechanically rotated around the weld joint. Various
weld heads are available that allow the Swagelok welding system to
accommodate outside diameter sizes ranging from 1/16 in. to 4 in.
and from 2 mm to 114.3 mm.

Figure 6-14 Swagelok welding system: M200 power supply.

Refer to the Swagelok Welding System

catalog (MS-02-342) for additional
information.
www.swagelok.com/TFM
 164 Tube Fitter’s Manual

Face Seal Fittings

VCR Metal Gasket Face Seal Fitting
Swagelok VCR metal gasket face seal fittings offer the high purity
of a metal-to-metal seal, providing leak-free service from critical
vacuum to positive pressure. The seal on a VCR assembly is made
when the gasket is compressed by two highly polished beads during
the engagement of a male nut or body hex and a female nut.

Side-load retainer gasket for Test port at two locations for Markings identify manufacturer,
easy installation and minimal easy leak testing material, and when applicable,
clearance for removal the appropriate process
designator, in accordance with
Standard surface finish Swagelok Ultrahigh-Purity
on glands and bodies is Process Specification (SC-01),
a roughness average of MS-06-61
10 m (0.25 m) Ra

No “virtual leak” zones

Material heat code is
Precision manufactured Female threads are silver plated stamped on glands and
gasket for maximum to prevent galling, ensure easy, all shapes to ensure raw
performance consistent assembly material traceability

Figure 6-15 VCR metal gasket face seal fitting.

Reference the Swagelok VCR Metal Gasket Face

Seal Fittings catalog (MS-01-24) for additional
information. www.swagelok.com/TFM

VCO O-Ring Face Seal Fittings

Swagelok VCO O-ring face seal fittings are designed for rapid
assembly and disassembly in pipe, tube, and welded systems.
Because of their unique design, zero clearance installation and
removal is possible where space is limited. Sealing is accomplished
with a captive O-ring in the body component. Assemblies can be
used from high pressure to critical vacuum, within a wide range of
temperatures.

Refer to the Swagelok VCO O-Ring Face Seal

catalog (MS-01-28) for additional information.
www.swagelok.com/TFM
 Special Purpose Fittings 165

Test ports at two

O-ring contained locations for easy Female nut threads
completely for leak testing silver plated for
maximum efficiency easy assembly

VCO Body

VCO Gland
Smooth finish on VCO Nut
gland face ensures
positive seal

Figure 6-16 VCO O-ring face seal fitting.

Ultra-Torr Vacuum Fittings and Tubing

Swagelok Ultra-Torr fittings are designed to provide a vacuum-tight
seal with quick, finger-tight assembly on glass, metal, or plastic
tubing. The Ultra-Torr fitting design has been helium leak tested to
a maximum leak rate of 4 × 10–9 std cm3/s at ambient temperature.
The leak rate increases as temperature increases due to permeation
through the O-ring.

Refer to the Swagelok Vacuum Fittings catalog

(MS-01-32). www.swagelok.com/TFM

Seal performance is maintained O-ring seals to

through repeated disconnects. glass, metal,
or plastic tubing.

Knurled nut for easy, finger-tight assembly.

Figure 6-17 Vacuum fitting.

166 Tube Fitter’s Manual

Fittings for Very Soft Plastic Tubing

Many types of soft plastic tubing are used in laboratory or low-
pressure air systems because of their purity, transparency, flexibility,
and smooth interior surface.
Swagelok metal or plastic tube fittings are suitable for use on this
tubing. The only additional requirement for use on plastic tubing is
an insert. The insert is used to support the tubing so that it will not
collapse when the ferrules deform the tube.
Another connection for such service is the Swagelok hose connector
(HC). This hose-type fitting has a specially designed serrated shank
that properly stretches the tube for optimum sealing. An optional
sleeve may be used when the system pressure is more than 50 % of
the maximum working pressure of the tube.

Figure 6-18 Insert.

Figure 6-19 Insert used in Tygon® tubing with Swagelok male connector.

Figure 6-20 Male hose connector for soft PVC tubing with sleeve.

Refer to the Swagelok Hose and Flexible Tubing

catalog (MS-01-180). www.swagelok.com/TFM
 Special Purpose Fittings 167

Fittings for Harder Plastic Tubing

Fittings for polyethylene, polypropylene, PTFE, and PFA tubing
are available in a wide range of Swagelok tube fitting sizes and
materials. Metal fittings can be used on these types of tubing. PFA
Swagelok tube fitting, when used with Swagelok PFA tubing (and
grooved with the Swagelok groove cutter), will hold to the rated
working pressure of the tubing. Metal Swagelok tube fittings will
also hold the rated working pressure of the PFA tubing. Consult
your Swagelok representative for pressure rating information on this
combination.

Cone and Thread Fittings

Swagelok IPT Series cone and thread fittings are available in
medium pressure (MP), with a maximum working pressure of
20 000 psig (1378 bar), and high pressure (HP), with a maximum
working pressure of 60 000 psig (4136 bar). All fittings are supplied
complete with gland and collars. Antivibration assemblies are also
available. Swagelok offers safety heads in a flat or angled design for
our cone and thread fittings. The rupture discs must be purchased
separately. They are available in 316SS and other alloy materials.
Line filters are another available option. They come standard with
two mesh filters. Filter elements available are 0.5, 2, 5, 10, 20, 40,
and 100 μm sizes.

Figure 6-21 Swagelok medium-

pressure cone and thread Figure 6-22 Swagelok high-pressure
fittings. cone and thread fittings.

Refer to the Medium- and High-Pressure Fittings,

Tubing, Valves, and Accessories catalog (MS-02-472).
www.swagelok.com/TFM
168 Tube Fitter’s Manual

JTC Tube Fittings

The Swagelok jacketed tube connector (JTC) is a fitting designed
to provide a leak-tight connection on the end of single-jacketed
tubing, eliminating the need for sleeves and sealing tape. The JTC
is a patent-pending design that combines Swagelok’s proven tube
fitting technology with an innovative environmental seal on the
tubing jacket.
This integral connector consists of a Swagelok tube fitting that
provides a leak-tight seal on the stainless steel core of the jacketed
tubing and the JTC seal O-ring and jacket seal nut, which provide a
watertight seal on the outside diameter (OD) of the jacketed tubing.
Additional features of the Swagelok JTC include:
■ Ease of assembly: Knurled jacket seal nut allows for easy, hand-
tight assembly.
■ Repeated reassembly: Seal performance is maintained through
repeated reassemblies of the connector.
■ Visual confirmation: Jacket seal nut covers vent O-ring when
leak-tight assembly is achieved.
■ Vent port: Prevents accidental pressurization of jacket cavity.

Figure 6-23 Swagelok jacketed tube connector (JTC).

 Special Purpose Fittings 169

Snubber Fittings (Gauge Protectors)

Swagelok snubber fittings protect gauges and instruments from
system pressure surges and shocks. Pressure damping (snubbing)
is accomplished through the use of a porous sintered 316 stainless
steel element. When a Swagelok snubber is installed upstream from
a pressure-sensitive instrument, the response rate of the instrument
is reduced and generally varies with the initial pressure drop across
the porous metal element, and the snubber allows the instrument to
smoothly come to line pressure.

Figure 6-24 Swagelok gauge protector.

Elements
With five basic elements available, snubber fittings can meet the
requirements of fluid applications ranging from light gases to liquids
with viscosities above 1000 SUS (Saybolt universal seconds)
170 Tube Fitter’s Manual

(220 cSt [mm2/s]). Element designators are stamped on all fittings

for proper identification.

Refer to the Swagelok Pressure Gauges Catalog

(MS-02-170). www.swagelok.com/TFM

Sintered 316
stainless
steel element
(Magnified 13×)

Press-fit sleeve holds

element in one place

Figure 6-25 Five basic elements available.

Gaugeable Chromatograph and

Column End Fittings
Swagelok chromatograph and column end fittings are suitable for
liquid or gas chromatography. They are offered in sizes from 1/16 to
1/2 in. Swagelok chromatograph and column end fittings are rated
to the working pressure of tubing as listed in Swagelok Tubing Data,
MS-01-107.

Refer to the Swagelok Gaugeable Chromatograph

and Column End Fittings catalog (MS-02-173).
www.swagelok.com/TFM

Figure 6-26 Swagelok chromatograph and column end fittings.

 Special Purpose Fittings 171

Orifice Plates
Swagelok orifice plate fittings allow for pressure adjustments by
reducing the orifice size with a plate predrilled to the specified
dimensions.

MINIMUM OPENING
AS SPECIFIED
BY CUSTOMER

TUBE O.D.

NUT NEX
BODY HEX
ORIFICE PLATE

Figure 6-27 Orifice plate.

Wire Drilled Fittings

Swagelok offers wire drilled fittings. These fittings are typically used
in safety applications where the wire is tied to the nut and the body
to prevent the fitting from being disassembled.
Contact your local Swagelok Authorized Sales and Service
representative for more information.

Figure 6-28 Wire drilled elbow.

172 Tube Fitter’s Manual

Flange Adapters and Lap Joint Connectors

Swagelok offers flanges that meet the design standards of ASME,
DIN, EN, and JIS. They are one-piece, integrally machined forged
bodies and are available in a full range of flange sizes and pressure
classes as well as sealing options (flat face, raised face, ring type
joint [RTJ], and tongue and groove).

Wrench flats

Sealing face

One-piece forged body

Figure 6-29 Flange adapter.

Swagelok tube fitting lap joint connectors provide easy connections

between process and instrumentation lines. They are designed to
be used with lap joint pipe flanges. They are available with either
smooth or serrated surface finish for sealing. Lap joint connectors
are compatible with ANSI B16.5 lap joint flanges.

Figure 6-30 Lap joint connector.

Refer to the Swagelok Flange Adapters catalog

(MS-02-200). www.swagelok.com/TFM
C hap ter 7
Testing and Evaluation of Tube
Fitting Performance

Table of Contents
Testing and Evaluation of Tube Fitting Performance 174
Reasons for a Tube Fitting Performance
Test Program 174
Overview 174
Test Program Planning 174
Planning the Test Program 176
Quality Control 179
Implementing the Test Program 179
Gas Leak Tests 179
Vacuum Tests 181
Disassemble/Reassemble Tests 182
The Importance of Disassemble/Reassemble
Testing 183
Rotary Flex Vibration Tests 184
Tensile Pull Tests 186
Rotation Tests 186
Hydraulic Impulse Tests 187
Hydraulic Burst Tests 187
Thermal Cycling Tests 189
Factors Affecting Seals 190
Effects of Steam 190
Evaluating Product Test Reports (PTR) 190
Intermix/Interchange 191
Summary 191
174 Tube Fitter’s Manual

Testing and Evaluation of Tube Fitting

Performance
In this chapter, we discuss the basic principles of establishing a
tube fitting performance test program as an important and ongoing
process for all fluid systems.

Reasons for a Tube Fitting Performance Test

Program
Testing is performed for four basic reasons.
■ Prevent material leakage loss.
■ Prevent environmental contamination.
■ Maintain a pressure differential
■ Ensure operational reliability of the system.

Overview
Over the years, tubing systems have become more complex, creating
the need for more thorough testing in addition to a wider and deeper
evaluation of tube fitting performance. The goal of leak testing is
to eliminate safety hazards and the high costs of leakage in fluid
systems.
When reviewing leak test results or establishing a leak test program, it
is important to select tests that fairly represent actual usage. We begin
our discussion on how to conduct effective tests and then continue
with an overview of common tests performed. Because Swagelok
Company has been in the fluid systems industry since 1947, the
observations, data, and recommendations offered here are the results
of that experience. Leak testing at Swagelok includes in-house testing,
customer-specific tests, industry standard testing, and external or
independent tests.

Test Program Planning

Consider the following prior to requesting a test or planning your
own testing program.
1. Are you trying to prove a predetermined outcome?
Assumption testing is when a certain result is assumed and then
tests are designed to find the data to support the assumption.
 Testing and Evaluation of Tube Fitting Performance 175

For example, a department has been directed to cut the cost of

tube fittings. Cost reductions are to be accomplished by proving,
through testing, that a less expensive fitting is capable of replacing
a more expensive fitting. The result of the finding is assumed,
therefore negating any test results.
2. Do test results trump long-term experience?
Controlled laboratory test conditions may return better, or worse,
results compared to what is actually found in the field.
For example, a new fitting is tested in the laboratory with specific
results. However, the history of hundreds or even thousands of
fittings in the field contradicts the limited laboratory test results.
3. Will an independent test laboratory be used?
Independent test laboratories may be enlisted to perform tests;
however, the samples should always be purchased through the
normal supply chain without mention that they are to be used in a
testing environment.
For example, the customer is considering replacing a current fitting
and has asked for two other manufacturers’ fittings to be tested.
The samples should always be purchased through the normal
supply chain in order to maintain an objective and fair testing
procedure.
4. Will valid statistical sampling be employed?
An organization may have over 100 000 tube connections in use
each year but test only a small sample of 5 to 10 connections in one
or two sizes.
For example, the laboratory testing arrives at one conclusion but
doesn’t substantiate the test results with the performance in the
field. It is possible that the testing parameters thought to reflect
the usage of the 100 000 tube connections in the field were not
properly documented or conveyed to the test laboratory, causing
erroneous conclusions to be drawn.
5. Will extrapolation be used to minimize test costs?
Specific fitting sizes and materials are successfully in service.
When the organization expands their fluid system, new materials
are ordered but in different fitting sizes and different materials,
assuming that the new materials will perform as well as the tried and
tested fittings have performed in the past. This assumption can be
dangerous.
For example, brass fittings have been tested on copper tubing in
176 Tube Fitter’s Manual

1/4 and 3/8 in. sizes. However, the new fluid system mandates
that steel or stainless steel is to be used in sizes from 1/4 to 1 in.
Instead of testing the new materials and sizes, an assumption is
made that because the current fittings perform so well, the new
fittings will work equally as well.
6. Will field-use conditions be simulated?
Laboratory tests may lack validity simply because of the focus
and training of the technicians performing the tests. Whereas
a laboratory technician is careful to set up the test to the
manufacturer’s specifications, field technicians of various levels
of training and experience can introduce improper installation at
any time.
For example, field conditions involve varying pressures,
temperatures, impulsing, vibration, and disassemble/reassemble
conditions, in addition to tube material, wall thickness,
concentricity, condition, and hardness variations that can affect
a fitting’s performance.
Careful consideration of these six questions may help avoid errors
in new test programs or will reveal errors in tests that have been
completed and published.
The best test of any component, such as a tube fitting, is repeated
use in large numbers under various installation and operating
conditions in the field.

Planning the Test Program

When planning the test, be sure to factor in careful selection of
fittings, tubing, sizes, materials, and configurations to be tested.
Remember, the same considerations can apply to the evaluation of
completed and published tests.
1. Obtain fittings.
The fittings to be used for testing should always be purchased through
the normal supply chain without mention that they are to be used in a
testing environment. This ensures that the sampling is taken from the
average supply that will be available for the final solution.
2. Obtain tubing.
The tubing to be used for testing should either be tubing used in the
plant or purchased through the normal supply chain without mention
that it is to be used in a testing environment. When stainless steel
tubing is required, both welded-and-drawn and seamless should be
tested, unless only one or the other is used exclusively in actual plant
 Testing and Evaluation of Tube Fitting Performance 177

service. When a manufacturer recommends only seamless tubing,

all tests should be conducted on seamless tubing. Additionally,
testing only seamless tubing when the plant requirement is actually
welded-and-drawn tubing can skew test results.
It is important to test more than one wall thickness.
For example, if fittings are to be used on 0.035, 0.049, 0.065, and
0.083 in. wall thickness, at least 0.035 and 0.083 in. should be
tested (minimum and maximum wall).
All tubing tests should use an identical method each time. When
competitive tests are conducted, the two sides of each tube cut
should also be put into the competitive fittings to ensure all variables
are equal for each manufacturer fitting used in the test.

Figure 7-1 Thick- and thin-wall tubing.

3. Select sizes.
When establishing your test pattern, remember that the larger
the seal, the larger the potential leak. Test the largest fitting you
anticipate installing more times than testing the smallest fitting you
plan to install. If the test succeeds on the larger 1 in. fitting, it is likely
that it will work on the smaller 1/8 in. fitting. The reverse is not true.
4. Select materials.
Test fittings in all materials you expect to install. A brass fitting may
work well, but the same fitting in steel or stainless steel may fail. The
fact that it works in stainless steel does not necessarily indicate that
it will work in other alloys such as alloy 400 or alloy 2507.
178 Tube Fitter’s Manual

5. Select fitting configurations.

Test several configurations. Elbows, tees, and crosses are made
from forgings, which normally are softer than the bar stock used in
straight fittings. Therefore, different factors may affect sealing and
holding ability, as well as thread life. Testing several configurations
negates the possibility of all test fittings being made on the same
machine on the same day with the same tools. For example, testing
for quality control of four different configurations is a more valid
testing pattern than testing four fittings of one configuration. Nuts
and ferrules are more likely to come from different manufacturing
lots.
The components shown here in each size, material, and wall thickness
should give you a representative test for quality and consistency.
This assortment will make six connections: four bar stock fitting
connections and two forged body fitting connections. This approach
ensures a valid test of consistency because the fittings would be
made on various machines at various times.
Testing different configurations also provides an excellent quality
control check on a manufacturer in terms of holding critical tolerances
throughout the product line. Such tolerances are discussed under
disassemble/reassemble testing.
Another test of quality control and consistency is to take apart all
the fitting components and measure the components as listed here.

Cap

Union Elbow

Union

Male Connector

Figure 7-2 Typical test set-up.

 Testing and Evaluation of Tube Fitting Performance 179

Front Back
Body Ferrule Ferrule Nut
Inside bore
X X X X
diameter
Skirt diameter X
Outside diameter X X
Length X X X

Quality Control
■ Measure the total spread of measurements of each manufacturer
to check consistency and quality control.
■ Never average the variations in any critical dimension. Maximum
deviation from highest to lowest measurement of such dimensions
will reveal a great deal about a manufacturer’s quality control.
■ Thorough planning in the above areas is time well spent in
ensuring a comprehensive, objective, and valid test program,
and information gained may determine that further tests are not
needed.
The best test of any component, such as a tube fitting, is repeated
use in large numbers under various installation and operating
conditions in the field.

Implementing the Test Program

Next, we discuss nine types of tube fitting tests. Some can be
performed by the user without major expense, whereas others are
more practically performed by manufacturers due to the time and
expense involved.

Gas Leak Tests

Gas leak tests evaluate seal integrity. Inert gas, such as nitrogen or
helium, should be used. Air is acceptable. Test pressures should
be at least equal to the working pressures recommended by tubing
manufacturers. Various test methods can be used depending on
cost, equipment availability, and sensitivity desired. These include
180 Tube Fitter’s Manual

bubble checking (underwater); using a leak detector fluid such

as Snoop at all connections; or more sensitive methods such
as ultrasonic, halogen torch, or mass spectrometer helium leak
detectors using a probe, as shown below.

Figure 7-3 Snoop leak test.

Figure 7-4 Sniffer test of helium pressurized system.

 Testing and Evaluation of Tube Fitting Performance 181

A very important facet of gas leak testing is to determine in advance

what will be considered a leak. The test pressure and a realistic leak
rate should be decided based on the maximum plant requirements
and the limitations of the fittings and tubing. The test pressure may
be determined by multiplying the plant pressure times an appropriate
safety factor, for example:
1000 psig (68 bar) × 2 (2:1) = 2000 psig (138 bar)
A common error is to not report a leak if it can be stopped by
additional tightening. If a fitting is assembled and reassembled
according to instructions, it should not leak. The necessity of this
approach is to simulate field conditions where leaks are expensive.
For example, a system with 100 connections is tested as a system.
Leaks are located and isolated, and repairs or replacements are
made. All these steps are costs, and the cost of failures is high,
even if leaks can be stopped by additional tightening.
If you can stop a leak by further tightening, you still need to consider
it a leak.

Refer to Tube Fitting Performance Product Test Reports

(MS-06-108) and search for the following test result:
■PTR-1388
■PTR-3221
www.swagelok.com/TFM

Tube fitting performance can be evaluated using three specific

types of test criteria. These tests allow a tube fitting to be evaluated
under varying dynamic conditions. Product Test Reports (PTRs) for
Swagelok tube fittings are available upon request.

Vacuum Tests
Vacuum tests are excellent tests of seal integrity. Any fitting that
must rely on internal system pressure to help effect a seal will
usually fail vacuum tests.
Vacuum tests are advisable where vacuum is in regular use,
particularly ultra-high vacuum in sophisticated instruments. The
equipment is expensive, but so is the cost of failures. Usually,
helium leak detectors of the mass spectrometer type are used.
182 Tube Fitter’s Manual

A fitting-tube assembly is attached to the test port, vacuum is

pulled internally, and a helium gun is used to squirt helium at all
seal points.

Refer to Tube Fitting Performance Product Test Reports

(MS-06-108) and search for the following test result:
PTR-1369. www.swagelok.com/TFM

Disassemble/Reassemble Tests
A tube fitting’s ability to stand many make/break cycles is perhaps
the best measure of comparison among competitive products.
These tests can be extremely important in instrumentation fitting
applications where periodic maintenance requires making, breaking,
and remaking tube connections. Therefore, disassemble/reassemble
tests should be performed very carefully. When equated to field
usage, disassemble/reassemble test results can greatly reduce
in-service tube fitting costs. But such tests will not relate to field
usage unless they incorporate the following two vital procedures:
1. Use a variety of configurations (elbows, tees, crosses, unions,
bulkhead unions, male and female connectors) to ensure a fair
representation of quality parts has been tested, as discussed
earlier.
2. Randomly reassemble nut-ferrule-tubing assemblies with
different bodies to simulate field conditions.

Figure 7-5 Typical disassemble/reassemble test.

 Testing and Evaluation of Tube Fitting Performance 183

Let’s examine the second procedure in more detail and consider

what really happens in the field.

For example, analytical instruments such as chromatographs have

column changes, where the nut-ferrule-tubing assemblies are
removed with columns. The fitting stays attached to the instrument.
Another column with nut-ferrule-tubing assembly is connected to
the same body.
In another example, process or measuring instruments, such as
controllers or transmitters, are dropped from a system with fitting
bodies attached, while the nut-ferrule-tubing assemblies stay on
the same tubing. Other instruments with different fitting bodies
are installed as replacements. Here the bodies are changed, but
the nut and ferrule systems stay. You can see that in these realistic
disassemble/reassemble situations, the same nut-ferrule-tubing
combination seldom sees the same body twice. Therefore,
disassemble/reassemble testing with the same nut-ferrule-tubing
assembly repeatedly into the same body does not simulate field
disassemble/reassemble conditions.

The Importance of Disassemble/Reassemble

Testing
There are several reasons why disassemble/reassemble testing
is one of the best ways to check the quality control of any fitting
manufacturer.
■ Due to sealing ferrule design, galling takes place at the body seal
area (particularly in stainless and other corrosion-resistant alloys),
and another ferrule trying to seat in the damaged body seal area
often causes a leak—another simulation of what happens in the
field.
■ Regarding the sealing mechanism, several different nut-ferrule-
tube combinations must seal at different points on the body seal
area (because it is necessary to coin or groove the body seal at a
slightly different spot each time), and leakage often results.
■ Thread integrity during repeated disassemble/reassemble cycles
is an important indication of sound quality control, as well as good
design.
■ Uniform unblemished sealing surfaces indicate good surface
quality control. In any metal-to-metal sealing device, good
surface finish is a necessity. But a smooth surface finish is only
184 Tube Fitter’s Manual

a beginning. If that surface is greatly degraded during original

or subsequent disassemble/reassemble cycles, especially with
several different bodies, there is a good chance of field failure.
Tests and calculated data show that leakage varies by a cube
function as seal smoothness degrades. A 50 % improvement
in the sealing surface provides an 800 % improvement in seal
integrity.

Refer to Tube Fitting Performance Product Test Reports

(MS-06-108) and search for the following test results:
■PTR-383
■PTR-395
www.swagelok.com/TFM

Rotary Flex Vibration Tests

The specialized equipment costs of such tests usually make them
impractical for the user to design. Swagelok’s tests use a minimum
of a 1750 rpm motor with a deflection block that adjusts the center
line deviation of the tube assembly under test.

Figure 7-6 Vibration test stand.

 Testing and Evaluation of Tube Fitting Performance 185

Figure 7-7 Adjustable tube deflection for vibration tests.

An internal tube pressure is selected (maximum working pressure

of the tubing).
Motor rotation causes the motor end of the capped tube to move in
a circle whose radius is the tube deflection from center line.
The test sample should be flexed until one of the following occurs:
■ The fitting leaks.
■ The tube fractures.
■ Ten million cycles are achieved.
An in-line pressure transducer stops the test if fitting leakage or tube
fatigue fracture occurs.
We have seen other tests where a 90° bend in the tubing is placed
between the test fitting and the adjustable block. This causes
indeterminate test results; the applied stress cannot be measured or
estimated. Best practice is to follow the guidelines of ASME B31J,
Standard Test Method for Determining Stress Intensification Factors
(i -Factors) for Metallic Piping Components.

Refer to Tube Fitting Performance Product Test

Reports (MS-06-108) and search for the following
test result: PTR-3222. www.swagelok.com/TFM
186 Tube Fitter’s Manual

Tensile Pull Tests

These tests usually are performed only by fitting manufacturers
because of costs and equipment requirements. Tensile pull tests are
used to check the holding ability of fitting connections rather than
sealing ability.
Results allow calculation of the internal pressure needed to cause
separation, where the tube actually could blow out of the fitting.
Most quality tube fittings will hold tubing to hydraulic pressures
approaching yield or burst of the tubing. Hydraulic burst testing is
discussed later in this chapter.

Refer to Tube Fitting Performance Product Test Reports

(MS-06-108) where you can search for the following test
result:PTR-4060. www.swagelok.com/TFM

Figure 7-8 Tensile pull test.

Rotation Tests
These tests sometimes are performed to determine what torque
would be required to twist a piece of tubing so severely as to break
the ferrule-tubing seal and cause leakage. Although we can test
fittings this way, the test rarely would be equated to a field type of
malfunction.
 Testing and Evaluation of Tube Fitting Performance 187

Hydraulic Impulse Tests

Hydraulic impulse tests commonly are run by fitting manufacturers
to determine the ability of the tube and fitting assembly to resist
severe and sudden pressure impulses without failure.
Swagelok’s impulse method is to shock the assembly under test
with an impulse of 1.5 × tubing maximum working pressure. A
quick-opening valve is used to achieve the shock at a frequency of
35 to 40 cycles per minute for 100 000 pressure cycles.
Hydraulic impulse tests provide valuable bits of test information but
not as valuable as actual field use.

Refer to Tube Fitting Performance Product Test

Reports (MS-06-108) and search for the following
test result: PTR-2849. www.swagelok.com/TFM

Figure 7-9 Hydraulic impulse test.

Hydraulic Burst Tests

Hydraulic burst tests are an excellent test of tube grip performance
but a poor test of sealing ability.
Burst tests can be significant when designed properly to test the
fitting. In Swagelok’s own general program tests, the tubing is
restricted from burst by clamping blocks, thereby forcing a failure at
the fitting-to-tubing engagement.
188 Tube Fitter’s Manual

Figure 7-10 Hydraulic burst test.

The pressure is gradually increased, and pressure is recorded when

one of the following occurs that prevents applying higher pressure:
■ Loss of tube grip
■ Material rupture
■ Leakage
Results are then compared to the tubing working pressure.

Reference Tube Fitting Performance Product Test

Reports (MS-06-108) and search for the following
test result: PTR-3220. www.swagelok.com/TFM

Figure 7-11 Tubing yield before burst. Figure 7-12 Tube burst.
 Testing and Evaluation of Tube Fitting Performance 189

Thermal Cycling Tests

Temperature cycling is one of the toughest services a tube fitting
must experience.
Examples:
■ Steam
■ Cryogenics
■ Arctic or tropical environments
■ Heat transfer fluids such as liquid metals
■ Space simulation
■ Analytical instrument ovens, chambers, columns
The cost of setting up a test facility is usually prohibitive, except for a
major fitting manufacturer or a government-funded research program.
As mentioned previously, most large users of tube fittings have
their own testing laboratories in the form of their existing in-plant
applications. In the case of thermal cycling, most process plants
have some or all of the services listed earlier.

Reference Tube Fitting Performance Product Test Reports

(MS-06-108) and search for the following test results:
■ PTR-386
■ PTR-392
■ PTR-2835 (high temperature)
■ PTR-2836 (low temperature)
www.swagelok.com/TFM

Figure 7-13 1000 psig (68 bar) gas test at 1000°F (538°C).
190 Tube Fitter’s Manual

Factors Affecting Seals

In general, seal integrity between fitting components is severely
affected by temperature excursions. Factors directly affecting seals
include:
■ Relative wall thicknesses (thin tube wall versus relatively heavy
fitting wall thickness)
■ Differential thermal coefficients of expansion (copper tube versus
brass fitting)
■ Length of tube support within the fitting (affecting heat transfer as
tube cools faster than fitting)
■ Rate of temperature change (Thermal shock or very rapid
temperature change is a much more severe test than temperature
excursion made slowly.)

Effects of Steam
Among all temperature cycling applications, steam is perhaps the
most common fluid and, in many ways, the most difficult. Its erosive
properties are well known, and these properties often preclude the
luxury of retightening if a leak does occur. A high-velocity, erosive
steam leak passing through a very small orifice usually increases
the original leak rate greatly and, therefore, the cost of leaks. Extra
tightening seldom stops that first steam leak (particularly on copper
steam-trace tubing) because the high-velocity steam etches a deeper
and deeper path in the soft tubing under the sealing ferrule.

Evaluating Product Test Reports (PTR)

It is important to understand the testing parameters when evaluating
Product Test Reports. The first question to ask is whether all fittings
used the same parameters. It would not be considered a comparable
test if the test duration was shorter or if water or hydraulic oil was
used instead of the lighter gases such as nitrogen, air, or helium.
Also, as stated earlier, laboratory installations tend to be more
focused and cautious than field installations.
The best test of any component, such as a tube fitting, is repeated
use in large numbers under various installation and operating
conditions in the field.
 Testing and Evaluation of Tube Fitting Performance 191

Intermix/Interchange
Many manufacturers claim that their fitting components are
interchangeable and/or intermixable with Swagelok tube fittings.
These claims are sometimes accompanied by some test data.
However, these tests are often subject to many of the pitfalls
mentioned earlier in the chapter (lack of objectivity, governed by
predetermined results, lack of statistical validity, extrapolation, etc.).
It should be noted that many users of tube fittings have developed
their own tests of tube fitting component interchangeability. It is
generally agreed that component interchange is not a recommended
or accepted practice.
Behind this is the fact that there is no third-party commercial
design standard that governs component design and dimension
for Swagelok and other ferrule-type tube fittings. The lack of a
third-party design standard means that test results would not be
repeatable.
See Chapter 1, page 15, for more information on tube fitting intermix/
interchange.

Summary
Plan test programs with fittings, tubing, materials, and configurations
that will ensure objectivity and statistical validity, while avoiding
predetermined results and extrapolation. Pay close attention to
the same considerations when evaluating test results from outside
sources.
Recognize the fact that existing plants represent the most reliable
test labs possible. Those who ignore field operating results and rely
on limited lab test programs are overlooking their most valuable input.
C hap ter 8
Threads

Table of Contents
Introduction 194
Screw Thread Terminology 194
Pipe Threads 196
Tapered Threads 196
National Pipe Tapered (NPT) 197
National Pipe Tapered Dryseal (NPTF) 198
ISO 7/1 (British Standard Pipe Taper) 198
Parallel Threads 200
Unified Screw Thread 200
ISO 228/1 Parallel Pipe Thread
(British Standard Pipe Parallel) 201
Metric (ISO 261) 202
Unified Screw Threads 204
SAE/MS Internal Straight Thread Boss 205
Metric Screw Threads (ISO 261) 207
Additional Items to Consider 208
194 Tube Fitter’s Manual

Introduction
Proper sealing of threads depends on many variables: quality and
cleanliness of threads, temperature, component material, installation
torque, specific gravity of system media, and system operating
pressures.
The type of thread used for a connection can enhance the quality
of the seal. This chapter lists the most common threads and their
typical use. It is important to note that even experienced workers
sometimes have difficulty identifying threads, regardless of their
thread identification procedure and the quality of their gauges.

Screw Thread Terminology

Threads have peaks and valleys, referred to as crests and roots,
respectively. The surface between the crest and root is called the
flank.

Figure 8-1 Thread terminology.

Threads also have a pitch and an angle as shown here.

Figure 8-2 The pitch of a thread.

 Threads 195

Screw threads are the workhorse of the threaded product industry.

Almost all tube fittings and valves use these for nut and fitting end
threads, valve stems, lock nuts, jam nuts, etc.

Figure 8-3 Typical designation.

Whether a thread is:

■ UNC (coarse), or
■ UNF (fine), or
■ UNEF (extra fine),
is the relationship of threads per inch to thread diameter.
For example:
■ 5/16–18 is a UNC thread
■ 5/16–24 is a UNF thread
■ 5/16–32 is a UNEF thread
But the determination of coarse, fine, or extra fine is not merely
threads per inch, but the relationship of threads per inch to thread
diameter.
For example:
■ 1/4–20 is a UNC (coarse) thread
■ 7/16–20 is a UNF (fine) thread
■ 3/4–20 is a UNEF (extra fine) thread
Screw threads are straight (not tapered). They are described in
terms of thread OD and threads per inch. An example is a nominal
3/8 in. SAE port using a 9/16–18 UNF-2A thread.
All Swagelok tube fittings use American National screw threads in
which a nut and threaded body work together to advance the nut
and swage the ferrules onto the tube.
196 Tube Fitter’s Manual

Pipe Threads
There are two general categories of threads, tapered and parallel.
This refers to how the threads are applied to the end connection in
relation to the center of rotation of the thread form.

Tapered Threads
Tapered threads are applied at an angle, most commonly 1°47’
(which reflects a taper of 1/16 in. per foot). Tapered pipe threads
are designed to seal between the flanks of the threads. However,
manufacturing tolerances and truncation limits for crests and roots
will rarely create a leak-tight seal.
■ Tapered pipe threads work by interference fit. The tolerances for
angles, lengths, heights, etc., cannot be held closely enough to
make a seal.
■ Male pipe threads cannot be manufactured to tolerances that will
seal on a taper with female pipe threads without a sealant.

Figure 8-4 Tapered (dynamic).

For this reason, a good thread sealant is always needed to fill in the
gaps between the crests and roots and to prevent system fluids from
penetrating the connection. The sealant, such as Swagelok PTFE
tape, will fill the voids between the threads. The thread sealant will
also act as an anti-galling lubricant between the sealing surfaces.
Leakage due to thread galling is prevalent with threads made of
stainless steel and other nickel alloys that are more prone to seizing.
 Threads 197

Swagelok manufactures end connections with two types of tapered

pipe threads.
These are NPT and ISO 7/1.

National Pipe Tapered (NPT)

■ Thread taper = 1°47’
■ The truncated areas of roots and crests are flat
■ Pitch measured in threads per inch
■ 60 thread angle
Standards:
■ ANSI/ASME B1.20.1
■ SAE AS71051
National Pipe Tapered (NPT) is made to specifications outlined in
ANSI B1.20.1. This is the pipe thread used on the pipe end of all
Swagelok tube fittings when the abbreviation NPT is used in the
Swagelok Product Binder.
Swagelok manufactures NPT pipe ends that exceed the standards
of ANSI B1.20.1 (Pipe Threads, except Dryseal). Some type of pipe
thread sealant is always required. Swagelok PTFE tape is made
specifically for pipe thread sealing. Swagelok SWAK is an anaerobic
pipe thread sealant with PTFE. For further information, consult your
authorized Swagelok representative.

Figure 8-5 NPT.

198 Tube Fitter’s Manual

National Pipe Tapered Dryseal (NPTF)

NPTF is made to specifications outlined in ANSI B1.20.3. This
pipe end is used on some hydraulic equipment and is sometimes
specified on military hardware.
In “Dryseal” threads, the roots of the threads are more truncated than
the crests so that an interference fit causes the roots to crush the
crests of the mating threads, leading to galling. Supposedly, when
made up, the crests, roots, and flanks are always in full contact, but
this can cause galling, particularly without lubrication or a sealing
compound on stainless steel or nickel alloys.
Swagelok tube fittings are not manufactured with Dryseal Pipe
Threads.

ISO 7/1 (British Standard Pipe Taper)

■ Swagelok RT
■ Thread taper = 1°47’
■ The truncated areas of roots and crests are rounded
■ Pitch measured in threads per inch
■ 55° thread angle

Figure 8-6 ISO 7/1 (British Standard Pipe Taper).

 Threads 199

Standards:
■ BS EN 10226-1
■ JIS B0203
■ BS 21
■ DIN 2999
ISO tapered threads are equivalent to DIN 2999, BSPT, and JIS
B0203.
In applications, ISO threads are used similarly to NPT threads.
However, care should be used that ISO and NPT threads are not
mixed. ISO threads have a 55° angle versus 60° for NPT. Thread
pitch is usually measured in millimeters but may be expressed in
inches. In many sizes, the number of threads per inch is different,
and the root and crest configurations are different from NPT.

Comparison Chart: Tapered Pipe Threads

Pipe Outside Included
Nominal Diameter Thread
Size Threads per Inch (OD) Angle Pitch
NPT/NPTF 27 0.313 in. 60° 0.037 in.
1/16 in.
ISO 28 0.312 in. 55° 0.036 in.
NPT/NPTF 27 0.405 in. 60° 0.037 in.
1/8 in.
ISO 28 0.398 in. 55° 0.036 in.
NPT/NPTF 18 0.540 in. 60° 0.056 in.
1/4 in.
ISO 19 0.535 in. 55° 0.053 in.
NPT/NPTF 18 0.675 in. 60° 0.056 in.
3/8 in.
ISO 19 0.672 in. 55° 0.053 in.
NPT/NPTF 14 0.840 in. 60° 0.071 in.
1/2 in.
ISO 14 0.843 in. 55° 0.071 in.
NPT/NPTF 14 1.050 in. 60° 0.071 in.
3/4 in.
ISO 14 1.060 in. 55° 0.071 in.
NPT/NPTF 11-1/2 1.315 in. 60° 0.087 in.
1 in.
ISO 11 1.331 in. 55° 0.091 in.
NPT/NPTF 11-1/2 1.660 in. 60° 0.087 in.
1 1/4 in.
ISO 11 1.669 in. 55° 0.091 in.
NPT/NPTF 11-1/2 1.900 in. 60° 0.087 in.
1 1/2 in.
ISO 11 1.900 in. 55° 0.091 in.
NPT/NPTF 11-1/2 2.375 in. 60° 0.087 in.
2 in.
ISO 11 2.374 in. 55° 0.091 in.
200 Tube Fitter’s Manual

Parallel Threads
Parallel (sometimes referred to as straight) threads are applied
parallel to the centerline.
■ Unlike tapered threads, which seal as the flanks of the threads
are drawn together, there is no interference between the flanks,
crests, and roots of parallel threads.
■ Almost all tube fittings and valves use parallel threads for nut and
fitting end threads, valve stems, lock nuts, jam nuts, etc.

Figure 8-7 Parallel (mechanical).

Swagelok manufactures products using a variety of fractional and

metric parallel threads. While the two most common parallel thread
series are unified screw threads and ISO 228/1, metric (ISO 261)
screw threads are also a common option on some Swagelok
components.

Unified Screw Thread

■ Swagelok ST, O-Seal
■ 60° thread angle
■ Pitch measured in threads per inch
■ The truncated areas of roots and crests are flat
Standard:
■ ANSI/ASME B1.1
■ SAE/MS straight thread
 Threads 201

Figure 8-8 Unified screw thread with 60° thread angle.

ISO 228/1 Parallel Pipe Thread (British Standard

Pipe Parallel)
■ Swagelok RP, RS, RG, RJ
■ 55° thread angle
■ Pitch measured in threads per inch
■ The truncated areas of roots and crests are rounded
Standard:
■ JIS B0202
■ BSPP

Figure 8-9 ISO 228 with 55° thread angle.

202 Tube Fitter’s Manual

ISO parallel threads are equivalent to DIN ISO 228/1, BSPP, and
JIS B0202. These pipe threads are similar in configuration to
7/1 threads except there is no taper. Therefore, they do not work by
thread interference like the tapered pipe threads of ISO 7/1 or NPT.
A gasket or O-ring is normally used to seal into the parallel female
threaded component. In some cases, the body is tightened until a
face on the hex is imbedded into the female threaded component.
Surface flatness perpendicular to the axis of the threads is essential.

Metric (ISO 261)

■ 60° thread angle
■ Pitch measured in millimeters
■ The truncated areas of roots and crests are flat and of different
width
Standard:
■ ISO 68-1
■ JIS B0205
■ ANSI/ASME B1.13M

Figure 8-10 Metric (ISO 261) with 60° thread angle.

Unlike tapered threads, parallel threads are not sealing threads.

Even the use of good-quality thread sealants will not provide reliable
seals for these threads. Four methods of sealing ISO 228/1 male
threads to female ports are as follows.
1. A metal-to-metal seal is made between the face of the body hex
and the face of the female threaded component (Swagelok “RP”
thread).
 Threads 203

Figure 8-11 Metal-to-metal seal.

2. A metal gasket (usually copper) makes the seal between the

face of the body and the face of the female threaded component
(Swagelok “RP” thread).

Figure 8-12 Metal gasket seal.

3. A self-centering taper is used at the hex, which centers a

composite washer (usually metal and elastomer) to seal to the
surface surrounding the female thread (Swagelok “RS” thread).

Figure 8-13 Composite washer seal.

204 Tube Fitter’s Manual

4. A gasket is dropped into the flat bottom of the female thread.

The face of the male thread exerts a load on the gasket to seal
(Swagelok “RG” thread).

Figure 8-14 Gasket to seal.

Unified Screw Threads

■ 60° thread angle
■ Pitch measured in inches
■ The truncated areas of root and crest are flat
■ Diameter measured in inches

Figure 8-15 American Standard Unified Screw Thread.

 Threads 205

Figure 8-16 Straight threads.

Unified screw threads are commonly used in the hydraulics industry

and in military hardware. Swagelok SAE/MS Straight Thread Fittings
are used to seal to SAE/MS ports by means of elastomer O-rings.
Thread sizes and other dimensions of SAE ports per SAE J1926
Standard are shown below:

SAE/MS Internal Straight Thread Boss

Figure 8-17 SAE/MS Internal Straight Thread Boss.

SAE J1926/1 Port Dimensions

B Straight Thread J Full K U* Dia

Nom Thread +0.015 +0.005 Z
Tube Thread Pitch Dia Minor Dia D Dia Depth –0.00 0 Dia P§ S·† –0.000 ±1
OD Size Min Max Min Max Min Min Min Min Max Max Y† Dia Deg
1/8 5/16–24 0.2854 0.2902 0.267 0.277 0.062 0.390 0.074 0.438 0.468 0.062 0.358 0.674 12
3/16 3/8–24 0.3479 0.3528 0.330 0.340 0.125 0.390 0.074 0.500 0.468 0.062 0.421 0.753 12
1/4 7/16–20 0.4050 0.4104 0.383 0.395 0.172 0.454 0.093 0.563 0.547 0.062 0.487 0.832 12
206 Tube Fitter’s Manual

5/16 1/2–20 0.4675 0.4731 0.446 0.457 0.234 0.454 0.093 0.625 0.547 0.062 0.550 0.911 12
3/8 9/16–18 0.5264 0.5323 0.502 0.515 0.297 0.500 0.097 0.688 0.609 0.062 0.616 0.989 12
1/2 3/4–16 0.7094 0.7159 0.682 0.696 0.391 0.562 0.100 0.875 0.688 0.094 0.811 1.186 15
5/8 7/8–14 0.8286 0.8356 0.798 0.814 0.484 0.656 0.100 1.000 0.781 0.094 0.942 1.344 15
3/4 1 1/16–12 1.0084 1.0158 0.972 0.990 0.609 0.750 0.130 1.250 0.906 0.094 1.148 1.619 15
7/8 1 3/16–12 1.1334 1.1409 1.097 1.115 0.719 0.750 0.130 1.375 0.906 0.094 1.273 1.777 15
1 1 5/16–12 1.2584 1.2659 1.222 1.240 0.844 0.750 0.130 1.500 0.906 0.125 1.398 1.934 15
1 1/4 1 5/8–12 1.5709 1.5785 1.535 1.553 1.078 0.750 0.132 1.875 0.906 0.125 1.713 2.288 15
1 1/2 1 7/8–12 1.8209 1.8287 1.785 1.803 1.312 0.750 0.132 2.125 0.906 0.125 1.962 2.564 15
2 2 1/2–12 2.4459 2.4540 2.410 2.428 1.781 0.750 0.132 2.750 0.906 0.125 2.587 3.470 15
All dimensions in inches.
* Diameter U shall be concentric with thread pitch diameter within 0.005 full indicator reading (FIR) and shall be free from longitudinal and spiral tool
marks. Annular tool marks up to 100 𝛍in. maximum shall be permissible.
• Maximum recommended spotface depth to permit sufficient wrench grip for proper tightening of the fitting or locknut.
† If face of boss is on a machined surface, dimensions Y and S need not apply.
§ Tap drill depths given require use of bottoming taps to produce the specified full thread lengths. Where standard taps are used, the tap drill depths
must be increased accordingly.
Note: MS16142 ports are almost identical to SAE ports except for spotface dimensions.
 Threads 207

Metric Screw Threads (ISO 261)

■ 60° thread angle
■ Pitch measured in millimeters
■ The truncated areas of root and crest are flat and of different width
■ Diameter measured in millimeters
Metric screw threads are straight (not tapered) and are often used
to connect to metric threaded equipment. The system is similar
to the unified screw thread system mentioned previously, but it is
specified as follows. A 10 mm OD × 1.5 mm pitch thread would be
designated as shown in the following figure:

Figure 8-18 International Organization for Standardization (ISO) metric.

208 Tube Fitter’s Manual

Figure 8-19 Typical designation.

Either a gasket or O-ring is used to seal male metric screw threaded

components to female threaded components.

Additional Items to Consider

■ When assembling a Swagelok product containing a threaded
connection, the threaded connection should always be assembled
prior to the Swagelok tube fitting end because of the rotation
required to assemble the threaded connection.
■ Tapered threads always need a sealant to seal system fluids and
prevent galling of the threads during installation. Refer to Chapter
3 section on thread sealants to learn more about how to apply
sealants.

Refer to the Swagelok Thread and End Connection

Identification Guide (MS-13-77) for additional information.
www.swagelok.com/TFM
C hap ter 9
Pressure Ratings

Table of Contents
Tubing Calculations and Pressure Ratings 210
Gas Service 212
Tubing for Gas Service Tables 213
Suggested Allowable Working Pressures for
Stainless Steel and Copper 214
Table 1—Fractional Stainless Steel
Seamless Tubing 214
For Welded Tubing 214
Suggested Ordering Information 215
Table 2—Metric Stainless Steel Seamless Tubing 216
For Welded Tubing 216
Suggested Ordering Information 217
Table 3—Fractional Copper Tubing 218
Suggested Ordering Information 218
Table 4—Metric Copper Tubing 219
Suggested Ordering Information 219
Factors Used to Determine Tubing Pressure
Ratings at Elevated Temperatures 220
Pipe End Pressure Ratings 221
210 Tube Fitter’s Manual

Tubing Calculations and Pressure Ratings

Tubing outside diameter (OD) and inside diameter (ID) are related by
the following formulas:
■ Tube OD = 2t + Tube ID
■ Tube ID = Tube OD – 2t
■ Where t = Tube wall thickness
Proper wall thickness of tubing to contain internal pressure may be
found by using one of the Allowable Pressure Tables in the Tubing
Data Sheet (MS-01-107). All tubing pressure ratings are based on
ASME Code for Pressure Piping, B31.3-2012.

Refer to the Swagelok Tubing Data Sheet (MS-01-107)

for pressure rating of various materials and tubing wall
thicknesses. www.swagelok.com/TFM

Figure 9-1 Definitions of tube OD and ID.

 Pressure Ratings 211

All pressure ratings are based on minimum wall and maximum OD

within the applicable ASTM tubing specifications. A conservative
rating is thus established based on worst-case conditions.
Because various ASTM specifications have different OD and
wall thickness tolerances, use of tubing purchased to ASTM
specifications other than those specified in the Tubing Data Sheet
(MS-01-107) may cause some changes from the pressure ratings
shown in the tables.
As an example, we will use 3/8 in. OD × 0.049 in. wall seamless
stainless steel tubing purchased to ASTM A269 specification.

Nominal OD 0.375
Actual OD 0.370 to 0.380 in. (±0.005 in.)
Nominal wall 0.049 in.
Actual wall 0.042 to 0.056 in. (±15 %)

Pressure rating based on nominal wall OD = 5820 psi (401 bar)

Pressure rating based on minimum actual wall (0.042 in.) and
maximum actual OD (0.380 in.) = 4860 psi (335 bar)
(Truncated in table to lower 100 psi = 4800 psi [331 bar])
No allowance is taken for corrosion or erosion in the Tubing Data
Sheet. As used in this chapter, the term maximum allowable pressure
is defined as the maximum pressure a system will encounter. The
allowable system pressure should be based on the maximum
pressure that one can reasonably expect the system will see. Then
the system designer, with knowledge of other system variables,
can assign an adequate design factor based on familiarity with the
system.
212 Tube Fitter’s Manual

Gas Service
Gases (air, hydrogen, helium, nitrogen, etc.) have very small molecules
that can escape through even the most minute leak path. Some
surface defects on the tubing can provide such a leak path. As tube
OD increases, so does the likelihood of a scratch or other surface
defects interfering with proper sealing.
The most successful connection for gas service will occur if all
installation instructions are carefully followed and the heavier wall
thicknesses of tubing shown with no shading in the Tubing Data
Sheet are selected.
A heavy wall tube resists ferrule action more than a thin-wall
tube and, therefore, allows the ferrules to coin out minor surface
imperfections. A thin-wall tube will collapse, thus offering little
resistance to ferrule action during pull-up. This reduces the chance
of coining out surface defects, such as scratches. For performance
reliability against surface defects in any gas system, use a wall
thickness no less than the following:
 Pressure Ratings 213

Tubing for Gas Service Tables

Fractional sizes in inches

Minimum Thickness Minimum Thickness

Tube OD Nominal Wall Tube OD Nominal Wall
1/8 0.028 3/4 0.065
3/16 0.028 7/8 0.083
1/4 0.028 1 0.083
5/16 0.035 1 1/4 0.109
3/8 0.035 1 1/2 0.134
1/2 0.049 2 0.180
5/8 0.065

Metric sizes in millimeters

Minimum Thickness Minimum Thickness

Tube OD Nominal Wall Tube OD Nominal Wall
3 0.8 18 1.5
6 0.8 20 1.8
8 1.0 22 2.0
10 1.0 25 2.2
12 1.0 28 2.5
14 1.2 30 3.0
15 1.5 32 3.0
16 1.5 38 3.5
Suggested Allowable Working Pressures for Stainless Steel and Copper
Table 1—Fractional Stainless Steel Seamless Tubing
Allowable working pressures are calculated from an S value of 20 000 psi (137.8 MPa) for ASTM A269 tubing at –20 to
100°F (–28 to 37°C), as listed in ASME B31.3, and ASTM A213 tubing at –20 to 100°F (–28 to 37°C), as listed in ASME
B31.1, except as noted.

For Welded Tubing

214 Tube Fitter’s Manual

For welded and drawn tubing, a derating factor must be applied for weld integrity:
■ For double-welded tubing, multiply working pressure by 0.85
■ For single-welded tubing, multiply working pressure by 0.80

Tube Wall Thickness, in.

0.010 0.012 0.014 0.016 0.020 0.028 0.035 0.049 0.065 0.083 0.095 0.109 0.120 0.134 0.156 0.188
Tube Working Pressure, psig Swagelok
OD Note: For gas service, select a tube wall thickness outside of the shaded area. Fitting
in. (See Gas Service, page 212.) Series
1/16 5600 6800 8100 9400 12 000 100
1/8 8500 10 900 200
3/16 5400 7 000 10 200 300
1/4 4000 5 100 7 500 10 200➀ 400
 5/16 4 000 5 800 8 000 500
3/8 3 300 4 800 6 500 7500➀➁ 600
1/2 2 600 3 700 5 100 6700 810
5/8 2 900 4 000 5200 6000 1010
3/4 2 400 3 300 4200 4900 5800 1210
7/8 2 000 2 800 3600 4200 4800 1410
1 2 400 3100 3600 4200 4700 1610
1 1/4 2400 2800 3300 3600 4100 4900 2000
1 1/2 2300 2700 3000 3400 4000 4900 2400
2 2000 2200 2500 2900 3600 3200
➀ For higher pressures, see the Swagelok Medium- and High-Pressure Fittings, Tubing, Valves, and Accessories catalog, MS-02-472.
➁ Rating based on repeated pressure testing of the Swagelok tube fitting with a 4:1 design factor based upon hydraulic fluid leakage.

For other tubing materials and the latest information, refer to the Swagelok Tubing Data Sheet (MS-01-107).

Suggested Ordering Information

High-quality, fully annealed (Type 304, 304/304L, 316, 316/316L, 317, 317/317L, 321, 347) (seamless or welded and drawn)
stainless steel hydraulic tubing, ASTM A269 and A213, or equivalent. Hardness not to exceed 90 HRB or 200 HV. Tubing
to be free of scratches, suitable for bending and flaring. OD tolerances not to exceed ±0.003 in. for 1/16 in. OD tubing.
Note: Certain austenitic stainless tubing has an allowable ovality tolerance double the OD tolerance and may not fit into
Swagelok precision tube fittings. Dual-certified grades such as 304/304L, 316/316L, and 317/317L meet the minimum
Pressure Ratings 215

chemistry and the mechanical properties of both alloy grades.

Table 2—Metric Stainless Steel Seamless Tubing
Allowable working pressures are calculated from an S value of 137.8 MPa (20 000 psi) for EN ISO 1127 tubing (D4, T4
tolerance for 3 to 12 mm; D4, T3 tolerance for 14 to 50 mm) at –28 to 37°C (–20 to 100°F), as listed in ASME B31.3, and
ASTM A213 tubing at –28 to 37°C (–20 to 100°F), as listed in ASME B31.1, except as noted.

For Welded Tubing

For welded and drawn tubing, a derating factor must be applied for weld integrity:
216 Tube Fitter’s Manual

■ For double-welded tubing, multiply working pressure by 0.85

■ For single-welded tubing, multiply working pressure by 0.80

Tube Wall Thickness, mm

0.8 1.0 1.2 1.5 1.8 2.0 2.2 2.5 2.8 3.0 3.5 4.0 4.5 5.0
Working Pressure, bar Swagelok
Tube Note: For gas service, select a tube wall thickness outside of the shaded area. Fitting
OD mm (See Gas Service, page 212.) Series
3 670 3M0
6 310 420 540 710 6M0
8 310 390 520 8M0
10 240 300 400 510 580 10M0
12 200 250 330 410 470 12M0
14 160 200 270 340 380 430 14M0
 15 150 190 250 310 360 400 15M0
16 170 230 290 330 370 400➀ 16M0
18 150 200 260 290 320 370 18M0
20 140 180 230 260 290 330 380 20M0
22 140 160 200 230 260 300 340 22M0
25 180 200 230 260 290 320 25M0
28 180 200 230 260 280 330 28M0
30 170 180 210 240 260 310 30M0
32 160 170 200 220 240 290 330 32M0
38 140 160 190 200 240 270 310 38M0
50 150 180 210 240 270 50M0
➀ Rating based on repeated pressure testing of the Swagelok tube fitting with a 4:1 design factor based upon hydraulic fluid leakage.

Suggested Ordering Information

High-quality, fully annealed (Type 304, 304/304L, 316, 316/316L, 317, 317/317L, 321, 347) stainless steel tubing, EN
ISO 1127 or equivalent. Hardness not to exceed 90 HRB or 200 HV. Tubing to be free of scratches, suitable for bending
or flaring. OD tolerances not to exceed ±0.076 mm for 3 mm OD tubing.
Note: Dual-certified grades such as 304/304L, 316/316L, and 317/317L meet the minimum chemistry and the
mechanical properties of both alloy grades.
Pressure Ratings 217
Table 3—Fractional Copper Tubing
Allowable working pressures are calculated from an S value of 6000 psi (41.3 MPa) for ASTM B75 and ASTM B88
tubing at –20 to 100°F (–28 to 37°C), as listed in ASME B31.3 and ASME B31.1.

Tube Wall Thickness, in.

0.028 0.030 0.035 0.049 0.065 0.083 0.095 0.109 0.1 20 0.134
Tube Working Pressure, psig Swagelok
OD Note: For gas service, select a tube wall thickness outside of the shaded area. Fitting
218 Tube Fitter’s Manual

in. (See Gas Service, page 212.) Series

1/8 2700 3000 3600 200
3/16 1800 1900 2300 3400 300
1/4 1300 1400 1600 2500 3500 400
5/16 1300 1900 2700 500
3/8 1000 1600 2200 600
1/2 800 1100 1600 2100 810
5/8 900 1200 1600 1900 1010
3/4 700 1000 1300 1500 1800 1210
7/8 600 800 1100 1300 1500 1410
1 500 700 900 1100 1300 1500 1610
1 1/8 600 800 1000 1100 1300 1400 1810

Suggested Ordering Information

High-quality, soft annealed seamless copper tubing, ASTM B75 or equivalent. Also soft annealed (Temper O) copper
water tube, type K or type L to ASTM B88.
 Pressure Ratings 219

Table 4—Metric Copper Tubing

Allowable working pressures are calculated from an S value of
41.3 MPa (6000 psi) for ASTM B75, ASTM B88, and EN 1057
tubing at –28 to 37°C (–20 to 100°F), as listed in ASME B31.3 and
ASME B31.1.

Tube Wall Thickness, mm

0.8 1.0 1.21.5 1.8 2.0 2.2 2.5 2.8 3.0
Working Pressure, bar
Tube Note: For gas service, select a tube wall thickness Swagelok
OD outside of the shaded area. Fitting
mm (see Gas Service, page 212.) Series
6 110 140 170 220 6M0
8 100 120 160 8M0
10 80 100 130 10M0
12 60 80 100 130 140 12M0
14 50 60 90 110 120 14M0
15 60 80 100 110 120 15M0
16 70 90 100 110 120 16M0
18 60 80 90 100 110 18M0
20 60 70 80 90 100 110 20M0
22 50 60 70 80 90 100 22M0
25 40 50 60 70 80 90 100 25M0
28 40 50 60 70 80 90 28M0

Suggested Ordering Information

High-quality, soft annealed seamless copper tubing, ASTM B75 and
EN 1057 or equivalent. Also soft annealed (Temper O) copper water
tube, type K or type L to ASTM B88.
For other tubing materials and the latest information, refer to the
Swagelok Tubing Data Sheet (MS-01-107).
Factors Used to Determine Tubing Pressure Ratings at Elevated Temperatures

Temperature Tubing Materials

220 Tube Fitter’s Manual

Carbon 304, 316, 317,

°F °C Aluminum Copper Steel➀ 304/304L➁ 316/316L➁ 317/317L➁ 321③ 347➂
200 93 1.00 0.80 0.95 1.00 1.00 1.00 1.00 1.00
400 204 0.40 0.50 0.87➀ 0.93 0.96 0.96 0.96 0.96
600 315 0.82 0.85 0.85 0.85 0.85
800 426 0.76 0.79 0.79 0.79 0.79
1000 537 0.69 0.76 0.76 0.76 0.76
➀ Based on 375°F (190°C) max.
➁ Dual-certified grades such as 304/304L, 316/316L, and 317/317L meet the requirements for the lower maximum carbon content of the L grades and
for the higher minimum yield and tensile strength of the non-L grades.
➂ Based on the lower derating factor for stainless steel, in accordance with ASME B31.3.
 Pressure Ratings 221

For temperature factors for other tubing materials, refer

to the Swagelok Tubing Data Sheet (MS-01-107) factors.
www.swagelok.com/TFM

To determine allowable pressure at elevated temperatures, multiply

allowable working pressure for a specific material and size by the
factor from the Elevated Temperature Factors table. Both values are
found in the Tubing Data Sheet.
Example:
Type 316 stainless steel 1/2 in. OD × 0.049 in. wall at 1000°F (538°C)
3700 psig × 0.76 = 2812 psig (255 bar × 0.76 = 193 bar).
Allowable working pressure for 1/2 in. OD × 0.049 in. wall type
316 stainless steel tubing is therefore 2812 psig (193 bar) at 1000°F
(538°C).

Pipe End Pressure Ratings

Many Swagelok tube fittings have a male or female pipe end. As
described below, these ends often have a lower pressure rating
than the maximum pressure rating of the tube fitting end.
The ratings shown in the Gaugeable Tube Fittings and Adapter
Fittings catalog (MS-01-140) are based on ANSI B31.3. Female pipe
ends generally have ratings lower than male pipe in a given size
because the inner and outer diameters of female threads are larger
than those of male pipe ends. To have the same pressure ratings for
male and female pipe threads of the same nominal size, a female
threaded fitting would need a heavier wall and would thus be too
bulky and heavy to be practical. To keep material and manufacturing
costs down, most of the tube fitting industry has adopted wall
thicknesses on female pipe threads that result in lower pressure
ratings on the female ends than on the male ends.

Refer to the Gaugeable Tube Fittings and Adapter

Fittings catalog (MS-01-140) for the ratings.
www.swagelok.com/TFM
222 Tube Fitter’s Manual

Note: Sealing Tapered Pipe Threads

A good-quality sealant is always required when sealing NPT or ISO
tapered pipe threads. A good sealant will also act as a lubricant,
reducing the galling tendency of many materials when subjected
to the high loads of the interference fit between a male and female
pipe thread.
Swagelok PTFE tape is an excellent thread sealant for temperatures
up to 450°F (232°C.) SWAK anaerobic pipe thread sealant is also an
excellent thread sealant for use to 350°F (180°C.)
Refer to the section on thread sealants in Chapter 3 to learn more
about how to apply sealants.
C hap ter 10
The Hidden Costs of Leakage

Table of Contents
Introduction 224
What Is Leakage? 224
Causes of Leakage 224
Leak Testing Terminology and Principles 224
Leakage Formula 228
What Is Energy Management? 230
224 Tube Fitter’s Manual

Introduction
This chapter discusses why leakage is a serious consideration in
the design, construction, and operation of fluid control systems.
Components must be leak-tight to ensure the reliable performance
of fluid systems.

What Is Leakage?
The uncontrolled flow into or out of a pipe or tube system, such as
leakage to the atmosphere

Causes of Leakage
■ Unreliable metal-to-metal seals
■ Improperly installed tube fittings
■ Poor tubing selection and preparation

Figure 10-1 Leakage.

Leak Testing Terminology and Principles

Leak rate: The rate of fluid leakage flow per unit of time under
known conditions. Properly expressed in units of volume per unit of
time (L/min, std cm3/s).
Leakage: Leaks can be referred to as real or virtual.
 The Hidden Costs of Leakage 225

Figure 10-2 Leakage.

Real leak (also referred to as true, mechanical, orifice, or capillary

leak): Occurs when a pressure barrier fails to contain or isolate a
system fluid from the surrounding environment. Real leaks can be
the result of cracks or gaps between sealing surfaces or permeation
through seal materials. There are three types of real leaks:
1. Inboard: Flow into a fluid system from outside containment,
such as dirt getting into a fluid system.
2. Outboard: Flow out of containment into the environment.
3. Internal: Flow across an internal pressure barrier within
containment. This type of leak is commonly associated with
valve seats.

Figure 10-3 Real leak.

226 Tube Fitter’s Manual

Virtual leak: A release of internally trapped fluid into a fluid

system due to material outgassing, absorbed or adsorbed fluids,
entrapment in cracks, or dead legs.
Outgassing: The escape of gas from a material in a vacuum.

Figure 10-4 Virtual leak.

Permeation: The passage of fluid into, through, and out of a

pressure barrier having no holes large enough to permit more than
a small fraction of the molecules to pass through any one hole. This
leakage is typically associated with PTFE hoses.

Figure 10-5 Permeation leak.

 The Hidden Costs of Leakage 227

Be aware that a leak detector using a gas such as helium cannot

tell the difference between the helium that gets detected from a real
leak and that from a virtual leak, permeation, or outgassing.
One way of detecting system leaks is to use SNOOP liquid leak
detector, as shown in the following illustrations.

NOTE: Numerous small bubbles can be

observed at the back of the nut.
NOTE: Numerous small bubbles can be
observed at the back of the nut.

Figure 10-6 Small leak being identified by Snoop liquid leak detector.

Figure 10-7 Medium-sized leak.

Snoop liquid leak detection fluid illustrates a leak in the medium range;
larger, more frequent bubbles are escaping from the back of the nut. The
important thing to remember with Snoop versus detecting leaks with simple
soap and water is that the Snoop will continue producing bubbles for a short
period of time after being applied, whereas the soap and water may only give
you one set of bubbles to observe before dissolving.
228 Tube Fitter’s Manual

Figure 10-8 Larger leak displays large bubbles.

A large leak identified with Snoop may display large bubbles, similar to the
photograph above, or Snoop may be completely blown off the nut by the
escaping media. If a large leak is suspected, use caution when checking for
leakage.

Leakage Formula
The leakage formula was created in an effort to determine how
much leakage may exist throughout a system.
Q = Leak rate, ft3/s
∆P = Pressure drop, (P1 – P2), psi
H = Height of gap between sealing surfaces, in.
W = Circumference of seal, in.
96 = Mathematical constant
𝛍 = Absolute viscosity, lb·s/ft2
L = Length of leakage path, in.

Figure 10-9 Leakage formula.

 The Hidden Costs of Leakage 229

Figure 10-10 Previously assembled Swagelok tube fitting (shown disassembled).

Swagelok tube fittings and valves are designed and manufactured

to create a long, smooth seal that performs properly in a variety
of customer applications. The gap (H) and length (L) are the only
factors in the formula Swagelok can control. Gap can be a problem
if tubing surface finish is poor. Because we cannot control operating
pressure, seal diameter, or fluid viscosity, we must work within
the parameters of gap and length of seal to make good, reliable,
repeatable seals.
The sealing material, surface finish, and load as a result of installation
impact the leak rate regardless of the system conditions involved in
valve and fitting installations.
Seals are designed to prevent leaks from occurring, and there are
two basic types of seals: static and dynamic.
Static seals are not intended to be broken or penetrated during
service. Tube fittings generally use static seals. Leaks from static
seals are commonly associated with vibration, overpressurization,
or degradation of the seal material due to chemical attack.
Dynamic seals must seal effectively where motion is involved,
which is more common in valve operation.
Leakage costs industry billions of dollars each year. These losses
are in many forms:
1. Lost fluid: It is estimated that millions of gallons of hydraulic oil
are lost each year from oil circulating and hydraulic systems just
through leakage.
230 Tube Fitter’s Manual

2. Equipment damage: Loss of lubrication due to leakage can

damage equipment.
3. Lost production: Loss of lubrication or hydraulic line leakage can
shut down machines and stop production.
4. Energy conservation: Power is used to pressurize hydraulic
systems and to compress air.
5. Unsafe work places: Oil drippage can cause accidents.
6. Degraded environment: Fugitive emissions (leakage) can be
expensive, illegal, and dangerous and can lead to a lowering of
the quality of life for workers and the surrounding population.
7. Product contamination: Food, beverage, pharmaceutical, or
other plants making products for human consumption cannot
have hydraulic or other contaminates in their system.
When process gases, analyzer gases, nitrogen, helium, and hydrogen
are considered, the cost of leakage alone can make the difference
between profit and loss. This is in addition to the fire or explosion
danger and the damage to the quality of life. As well, improperly
calibrated or operating instruments can result in off-specification
product.

What Is Energy Management?

Energy management is the process by which energy costs and
system leakage are controlled.
This can be accomplished by:
■ Identifying and reducing energy loss from system leakage
■ Efficiently and cost-effectively reducing the potential for loss of
energy
■ Improving overall fluid system component efficiency and
performance
Managing energy means energy savings.
Energy management impacts you by:
■ Establishing an efficient leak detection and repair program
■ Documenting energy savings
■ Reducing downtime
■ Lowering overall system costs, which translates into increased
profitability
■ Decreasing maintenance costs
 The Hidden Costs of Leakage 231

Figure 10-11 Detect and identify leaks.

Reducing downtime, lowering overall system costs, and decreasing

maintenance costs can all be achieved by effectively documenting
energy savings. The Swagelok Energy Emission Survey program is
designed to identify the presence of leakage in gas systems at a
facility. A Swagelok Authorized Sales and Service representative
can assist in performing a Swagelok Energy Emission Survey. The
following are conditions to consider prior to conducting a survey.
1. Preparation is essential. In creating an effective survey, it is
necessary to:
a. Plan
b. Document
c. Verify
2. Documentation is a requirement. Using appropriate data
collection forms will improve the accuracy in recording results.
3. Validation of survey results by a site representative is mandatory.
4. Site representatives will be made aware of visual identification of
fittings from other manufacturers to more accurately authenticate
the results.
5. Survey site selection is to be determined by the site representative.
6. All tube fitting and instrumentation or small process valve end
connections and packing, regardless of the brand, should be
surveyed.
7. Results of survey data collection will be presented, in person, to
site representatives.
Request the results of energy surveys from your local Swagelok
Authorized Sales and Service Center.
A p p en d i x A
Flow/Pressure Charts and
Conversions

Table of Contents

Determining Inside Diameter of Tubing 234

Equivalent Feet of Straight Tube 234
Calculations for Liquid Flow (Charts 1 through 10) 234
Calculations for Gas Systems (Charts 11 through 20) 235
Heads and Equivalent Pressure Conversions 259
Pressure Conversions 260
Flow Rate Conversions 261
234 Tube Fitter’s Manual

Determining Inside Diameter of Tubing

The ID of tubing is set by flow requirements, permissible pressure
drop, and maximum allowable velocity.
■ Charts 1 through 10 are provided on the following pages.
■ Charts 11 through 20 are provided for sizing tubing for gas flow.
These charts give pressure drop for 100 ft. of tubing for both water
and air flow. By using the formula provided, it is also possible to
obtain the pressure drop of fluids other than water and gas.
To allow for pressure drops in bends and fittings, the equivalent
lengths in Table A can be used when obtaining equivalent length of
tubing for pressure drop calculations. To obtain equivalent length of
tubing, total all straight lengths and then add lengths for each bend,
elbow, or tee from Table A.

Equivalent Feet of Straight Tube

Tubing OD 90° Elbow 90° Bend 180° Bend 45° Bend Tee Branch
(in.) (ft.) (ft.) (ft.) (ft.) (ft.)
1/4 1 1/2 1 1/2 1
3/8 1 1/2 1/2 1 1/2 1 1/2
1/2 2 1/2 1 1/2 2
5/8 2 1/2 1 2 1/2 2 1/2
3/4 3 1 2 1/2 3
1 4 1/2 1 2 1/2 4 1/2
1 1/4 5 2 4 1 5
1 1/2 6 2 4 1 6
2 9 2 4 1 9
Table A

Calculations for Liquid Flow (Charts 1 through 10)

Example 1
Water is to flow through 50 ft. of tubing at 4 gallons per minute (GPM).
Water velocity is not to exceed 5 ft. per second. The maximum
allowable pressure drop is 5 psig. What diameter of tubing can be
used?
■ Pressure drop for 100 ft. would be two times the allowable
pressure drop for 50 ft., that is, 10 psi.
■ By looking at Charts 1 through 9, it can be determined that only
3/4 in. or 1 in. OD tubing can be used because the pressure drop
 Appendix A 235

would be over 10 psi for a 4 GPM flow in smaller tubing. From

Chart 5, for 4 GPM flow rate, the pressure drop per 100 ft. of any
of the 3/4 in. OD tubes would be satisfactory.
■ The smallest ID on Chart 5 is 0.560 in. An ID of 0.560 in. on Chart
10 shows velocity of 5 ft. per second for 4 GPM. Therefore, any of
the 3/4 in. tubing can be used, and wall thickness selection would
be determined by pressure requirements.
Example 2
Suppose the maximum pressure drop of Example 1 was 1 psig. Find
the proper size tubing.
■ For 100 ft., maximum pressure drop would be 2 psi.
■ The 3/4 in. tubing is now too small as determined by Chart 5.
Looking at Chart 6, it can be seen that 1 in. OD tubing of wall
thickness less than 0.100 in. can be used because it will have less
than a 2 psi pressure drop.
For liquids with specific gravity near water, the equivalent water
flow rate can be calculated and then used to find pressure drop. An
example follows:
Example 3
Acetone at 1/10 GPM is to flow through 100 ft. of tubing with a
pressure drop not to exceed 5 psi.
equivalent flow rate of water = flow rate of other liquid multiplied
by √S.G. other liquid
■ Qw = Qacetone √specific gravity of acetone
= (1/10 GPM) √0.792
= 0.089 GPM water
■ Chart 2 shows that 1/4 in. OD tubing of wall thickness 0.049 or
less will be of sufficient ID to produce less than a 5 psi drop with
a water flow of 0.089 GPM.

Calculations for Gas Systems

(Charts 11 through 20)
Pressure drop is directly proportional to length, inversely propor­
tional to absolute pressure, and directly proportional to absolute
236 Tube Fitter’s Manual

temperature. Using this information, the pressure drop formula for use
with Charts 11 through 20 is:

∆PL =
∆P L
∙
114.7
100 100 14.7 + P ∙ ∙ 460530+ t ∙
where ∆PL — refers to pressure drop (in psi) of air per L feet of tubing at
conditions of pressure (P in psig) and temperature (t in °F)
∆P
— refers to pressure drop at 100 psig, 70°F for 100 ft. of tubing
100
In order to use Charts 11 through 20, it is necessary to obtain equivalent
conditions at 100 psig. This is most easily explained by example
problems shown here.
Example 1
What is the pressure drop for 6 CFM of 100 psig air at 70°F for 100 ft.
of 3/4 in. 0.095 wall tubing?
Solution: From Chart 15, read 7.5 psi pressure drop
Example 2
Same problem as Example 1 but for 200 ft. of tubing
Solution: Pressure drop is directly proportional to length. Therefore,
if 7.5 psi is the pressure drop for 100 ft., 2 × 7.5 = 15 psi is drop for
200 ft.
Example 3
Same problem as Example 1 but for 50 ft. of tubing
Solution: Pressure drop is directly proportional to length. Therefore,
if 7.5 psi is the pressure drop for 100 ft., 1/2 × 7.5 = 3.75 psi is the
drop for 50 ft. of tubing.
Example 4
10 CFM free air is to pass through 75 ft. of tubing at 80 psig inlet
pressure and 75°F. The diameter of the proper tubing is to be found
knowing the maximum allowable pressure drop is 6 psi.
Solution:
1. Find the pressure drop for 100 ft. of tubing at 70°F and 100 psig so
that the charts may be used.

∆P = 6 =
∆P 75
∙ ∙∙ 114.7
100 100 14.7 + 80 ∙∙
460 + 75
530 ∙
∆PL
100 = 6.55 psi drop per 100 ft. at 100 psig at 70°F
 Appendix A 237

2. Change flow rate at 80 psig and 75°F to the flow rate at 100 psig
and 70°F.
Qair at 100 psig, 70ºF = Qair at 80, 75 ∙
14.7 + 80
114.7 ∙∙
530
460 + 75 ∙
= 8.18 CFM
3. On Chart 16, note that all 1 in. tubing will give a pressure drop of
less than 6.55 psi at 8.18 CFM flow at 100 psig.
Example 5
Helium is to pass through 100 ft. of tubing at 25 psig inlet pressure
and 70°F. The flow rate of free helium is 8 CFM. What is the pressure
drop in 3/8 in. 0.035 in. wall tubing?
Solution:
1. Find the equivalent air flow so that air flow charts may be used.
flow rate of air = flow rate of helium √specific gravity of helium
Qair = QHe √(S.G.) He
Qair = 8 CFM √0.138 = 3 CFM
2. Change flow rate at 25 psig to the flow rate of air at 100 psig.

Qair at 100 = Qair at 25 ∙14.7114.7

+ 25
∙ = 1.0 CFM
3. See Chart 13 and find that the pressure drop of 100 psig air at
1.0 CFM is 6 psi for 100 ft. of tubing.
4. Solve for pressure drop in the problem by using the pressure
drop formula.

∆P =
P
∙ ∙∙
L 114.7
100 100 14.7 + P
460 + t
530 ∙∙ ∙
=6 ∙ ∙∙
100 114.7 530
100 14.7 + 25 530 ∙∙ ∙
= 6 (2.9) = 17.3 psi pressure drop
Example 6
8 CFM of 15 psig, 70°F air is to pass through 10 ft. of 1/2 in. OD,
0.049 wall tubing. What is the pressure drop?
Solution:
1. Change flow rate at 15 psig to flow rate at 100 psig.

Qair at 100 = Qair at 15 ∙

14.7 + 15
114.7 ∙ ∙
=8
29.7
114.7 ∙
= 2.07
238 Tube Fitter’s Manual

2. From Chart 14, pressure drop at 100 psig is found to be 6 psi for
100 ft. of tubing.
3. Change this pressure drop to the condition of the problem.

∆P = ∙ ∙ ∙14.7
∆P L
100 100 + P∙ ∙ 530 ∙
114.7 460 + t

=6∙
100∙ ∙14.7 + 15∙ ∙530∙
10 114.7 530

= 6 × 1/10 × 3.86 = 2.3 psi drop

 Appendix A 239
Chart 1: 1/8 in. OD Tubing
240 Tube Fitter’s Manual
Chart 2: 1/4 in. OD Tubing
 Appendix A 241
Chart 3: 3/8 in. OD Tubing
242 Tube Fitter’s Manual
Chart 4: 1/2 in. OD Tubing
 Appendix A 243
Chart 5: 3/4 in. OD Tubing
244 Tube Fitter’s Manual
Chart 6: 1 in. OD Tubing
 Appendix A 245
Chart 7: 1 1/4 in. OD Tubing
246 Tube Fitter’s Manual
Chart 8: 1 1/2 in. OD Tubing
 Appendix A 247
Chart 9: 2 in. OD Tubing
248 Tube Fitter’s Manual
Chart 10:
Mean Velocity versus Tube Inside Diameter for Various Water Flows

INSIDE DIAMETER (INCHES)

 Appendix A 249
Chart 11:
1/8 in. OD Tubing
250 Tube Fitter’s Manual
Chart 12: 1/4 in. OD Tubing
 Appendix A 251
Chart 13: 3/8 in. OD Tubing
252 Tube Fitter’s Manual
Chart 14: 1/2 in. OD Tubing
 Appendix A 253
Chart 15: 3/4 in. OD Tubing
254 Tube Fitter’s Manual
Chart 16: 1 in. OD Tubing
 Appendix A 255
Chart 17: 1 1/4 in. OD Tubing
256 Tube Fitter’s Manual
Chart 18: 1 1/2 in. OD Tubing
 Appendix A 257
Chart 19: 2 in. OD Tubing
258 Tube Fitter’s Manual
Chart 20:
Mean Air Velocity versus Tubing ID for 100 PSIG Air and 14.7 PSIA Air
 Appendix A 259

HEADS AND EQUIVALENT PRESSURE

CONVERSIONS
To Convert Into Multiply By
atmospheres pounds per sq in. 14.70
atmospheres pounds per sq ft. 2116.22
atmospheres in. of water at 60°F 407.17
atmospheres ft. of water at 60°F 33.931
atmospheres in. of mercury at 32°F 29.921
atmospheres mm of mercury at 32°F 760
ft. of water at 60°F pounds per sq in. 0.4335
ft. of water at 60°F pounds per sq ft. 62.43
ft. of water at 60°F in. of water at 60°F 12
ft. of water at 60°F in. of mercury at 32°F 0.8826
ft. of water at 60°F mm of mercury at 32°F 22.418
ft. of water at 60°F atmospheres 0.029481
in. of water at 60°F pounds per sq in. 0.03613
in. of water at 60°F pounds per sq ft. 5.204
in. of water at 60°F ft. of water at 60°F 0.08333
in. of water at 60°F in. of mercury at 32°F 0.073483
in. of water at 60°F mm of mercury at 32°F 1.8665
in. of water at 60°F atmospheres 2.458 × 10‒3
in. of mercury at 32°F pounds per sq in. 0.49116
in. of mercury at 32°F pounds per sq ft. 70.7266
in. of mercury at 32°F in. of water at 60°F 13.608
in. of mercury at 32°F ft. of water at 60°F 1.1340
in. of mercury at 32°F mm of mercury at 32°F 25.40005
in. of mercury at 32°F atmospheres 0.033421
mm of mercury at 32°F pounds per sq in. 0.019337
mm of mercury at 32°F pounds per sq ft 2.78450
mm of mercury at 32°F in. of water at 60°F 0.53576
mm of mercury at 32°F ft. of water at 60°F 0.04461
mm of mercury at 32°F in. of mercury at 32°F 0.03937
mm of mercury at 32°F atmospheres 1.3158 × 10‒3
pounds per sq ft. pounds per sq in. 6.9445 × 10‒3
pounds per sq ft. in. of water at 60°F 0.19224
pounds per sq ft. ft. of water at 60°F 0.01603
pounds per sq ft. in. of mercury at 32°F 0.01414
pounds per sq ft. mm of mercury at 32°F 0.35916
pounds per sq ft. atmospheres 4.725 × 10‒4
pounds per sq in. pounds per sq ft. 144.0
pounds per sq in. in. of water at 60°F 27.684
pounds per sq in. ft. of water at 60°F 2.307
pounds per sq in. in. of mercury at 32°F 2.03601
pounds per sq in. mm of mercury at 32°F 51.7148
pounds per sq in. atmospheres 0.06804
PRESSURE CONVERSIONS
To
260 Tube Fitter’s Manual

From mmHg in.Hg in.H2O ft.H2O atm lb/in.2 kg/cm2 kPa bar
mmHg 1 0.03937 0.5353 0.04461 0.00132 0.01934 0.00136 0.1333 0.0013
in.Hg 25.40 1 13.60 1.133 0.03342 0.4912 0.03453 30.387 0.0339
in.H2O 1.868 0.07355 1 0.08333 0.00246 0.03612 0.00254 0.2490 0.0025
ft.H2O 22.42 0.8826 12 1 0.02950 0.4334 0.03048 2.988 0.0299
atm 760 29.92 406.8 33.90 1 14.70 1.033 101.3 1.013
lb/in.2 51.71 2.036 27.69 2.307 0.06805 1 0.07031 6.894 0.0689
kg/ 735.6 28.96 393.7 32.81 0.9678 14.22 1 98.05 0.981
cm2
kPa 7.500 0.2953 4.016 0.3347 0.00987 0.1451 0.0102 1 0.01
bar 750 29.53 401.6 33.47 0.987 14.51 1.02 100 1
FLOW RATE CONVERSIONS
To
From L/s gal/min ft.3/s ft.3/min bbl/hr bbl/day
L/s 1 15.85 0.03532 2.119 22.66 543.8
gal/ 0.06309 1 0.00223 0.1337 1.429 34.30
min
ft.3/s 28.32 448.8 1 60 641.1 1.54 × 104
ft.3/min 0.4719 7.481 0.01667 1 10.69 256.5
bbl/hr 0.04415 0.6997 0.00156 0.09359 1 24
bbl/ 0.00184 0.02917 6.50 × 105 0.00390 0.04167 1
day
Appendix A 261
A p p en d i x B

Table of Contents

Birmingham Wire Gauge Table 264

O-Ring Dimensional Table 265
Properties of Saturated Steam 266
Specific Gravity of Water 268
Specific Gravity of Liquids 269
Specific Gravity of Gases 270
Table of Elements 271
Volume Conversions 274
Area Conversions 275
Decimal Equivalents 276
Temperature Conversion Formulas 277
Temperature Conversion Table 277
Pipe Wall Thickness 278
Fractional Tubing OD,
Wall, ID Cross-Sectional Area 278
Metric Tubing OD,
Wall, ID Cross-Sectional Area 280
264 Tube Fitter’s Manual

Birmingham Wire Gauge Table

Wall Thickness Decimal Wall Thickness Decimal
BWG Equivalent (in.) Equivalent (mm)
30 0.012 0.30
29 0.013 0.33
28 0.014 0.36
27 0.016 0.41
26 0.018 0.46
25 0.020 0.51
24 0.022 0.56
23 0.025 0.64
22 0.028 0.71
21 0.032 0.81
20 0.035 0.89
19 0.042 1.07
18 0.049 1.24
17 0.058 1.47
16 0.065 1.65
15 0.072 1.83
14 0.083 2.11
13 0.095 2.41
12 0.109 2.77
11 0.120 3.05
10 0.134 3.40
9 0.148 3.76
8 0.165 4.19
7 0.180 4.57
6 0.203 5.16
5 0.220 5.59
4 0.238 6.05
3 0.259 6.58
2 0.284 7.21
1 0.300 7.62
 Appendix B 265

O-Ring Dimensional Table

Uniform Size Actual Dimensions
Number ID (in.) Cross-Section (in.) OD (in.)
006 0.114 0.070 0.254
007 0.145 0.070 0.285
008 0.176 0.070 0.316
009 0.208 0.070 0.348
010 0.239 0.070 0.379
011 0.301 0.070 0.441
012 0.364 0.070 0.504
013 0.426 0.070 0.566
014 0.489 0.070 0.629
111 0.424 0.103 0.630
112 0.487 0.103 0.693
113 0.549 0.103 0.755
114 0.612 0.103 0.818
115 0.674 0.103 0.880
116 0.737 0.103 0.943
117 0.799 0.103 1.005
118 0.862 0.103 1.068
119 0.924 0.103 1.130
120 0.987 0.103 1.193
121 1.049 0.103 1.255
122 1.112 0.103 1.318
123 1.174 0.103 1.380
125 1.299 0.103 1.505
126 1.362 0.103 1.568
128 1.487 0.103 1.693
130 1.612 0.103 1.818
132 1.737 0.103 1.943
133 1.799 0.103 2.005
134 1.862 0.103 2.068
136 1.987 0.103 2.193
212 0.859 0.139 1.137
215 1.046 0.139 1.324
219 1.296 0.139 1.574
223 1.609 0.139 1.887
902 0.239 0.064 0.367
903 0.301 0.064 0.429
904 0.351 0.072 0.495
905 0.414 0.072 0.558
906 0.468 0.078 0.624
908 0.644 0.087 0.818
910 0.755 0.097 0.949
912 0.924 0.116 1.156
916 1.171 0.116 1.403
920 1.475 0.118 1.711
924 1.720 0.118 1.956
932 2.337 0.118 2.573
Properties of Saturated Steam
Abs press. Abs press. Abs press. Abs press. Abs press.
(psia) Temp. (°F) (psia) Temp. (°F) (psia) Temp. (°F) (psia) Temp. (°F) (psia) Temp. (°F)
1.0 101.74 38 264.16 84 315.42 160 363.53 520 471.07
1.2 107.92 39 265.72 85 316.25 162 364.53 540 475.01
1.4 113.26 40 267.25 86 317.07 164 365.51 560 478.85
1.6 117.99 41 268.74 87 317.88 166 366.48 580 482.58
1.8 122.23 42 270.21 88 318.68 168 367.45 600 486.21
2.0 126.08 43 271.64 89 319.48 170 368.41 620 489.75
266 Tube Fitter’s Manual

2.2 129.62 44 273.05 90 320.27 172 369.35 640 493.21

2.4 132.89 45 274.44 91 321.06 174 370.29 660 496.58
2.6 135.94 46 275.80 92 321.83 176 371.22 680 499.88
2.8 138.79 47 277.13 93 322.60 178 372.14 700 503.10
3.0 141.48 48 278.45 94 323.36 180 373.06 720 506.25
4.0 152.97 49 279.74 95 324.12 182 373.96 740 509.34
5.0 162.24 50 281.01 96 324.87 184 374.86 760 512.36
6.0 170.06 51 282.26 97 325.61 186 375.75 780 515.33
7.0 176.85 52 283.49 98 326.25 188 376.64 800 518.23
8.0 182.86 53 284.70 99 327.08 190 377.51 820 521.08
9.0 188.28 54 285.90 100 327.81 192 378.38 840 523.88
10 193.21 55 287.07 102 329.25 194 379.24 860 526.63
11 197.75 56 288.23 104 330.66 196 380.10 880 529.33
12 201.96 57 289.37 106 332.05 198 380.95 900 531.98
13 205.88 58 290.50 108 333.42 200 381.79 920 534.59
 14 209.56 59 291.61 110 334.77 205 383.86 940 537.16
14.70 212.00 60 292.71 112 336.11 210 385.90 960 539.68
15 213.03 61 293.79 114 337.42 215 387.89 980 542.17
16 216.32 62 294.85 116 338.72 220 389.86 1,000 544.61
17 219.44 63 295.90 118 339.99 225 391.79 1,050 550.57
18 222.41 64 296.94 120 341.25 230 393.68 1,100 556.31
19 225.24 65 297.97 122 342.50 235 395.54 1,150 561.86
20 227.96 66 298.99 124 343.72 240 397.37 1,200 567.22
21 230.57 67 299.99 126 344.94 245 399.18 1,250 572.42
22 233.07 68 300.98 128 346.13 250 400.95 1,300 577.46
23 235.49 69 301.96 130 347.32 260 404.42 1,350 582.35
24 237.82 70 302.92 132 348.48 270 407.78 1,400 587.10
25 240.07 71 303.88 134 349.64 280 411.05 1,450 591.71
26 242.25 72 304.83 136 350.78 290 414.23 1,500 596.23
27 244.36 73 305.76 138 351.91 300 417.33 1,600 604.90
28 246.41 74 306.68 140 353.02 320 423.29 1,700 613.15
29 248.40 75 307.60 142 354.12 340 428.97 1,800 621.03
30 250.33 76 308.50 144 355.21 360 434.40 1,900 628.58
31 252.22 77 309.40 146 356.29 380 439.60 2,000 635.82
32 254.05 78 310.29 148 357.36 400 444.59 2,200 649.46
33 255.84 79 311.16 150 358.42 420 449.39 2,400 662.12
34 257.08 80 312.03 152 359.46 440 454.02 2,600 673.94
35 259.29 81 312.89 154 360.49 460 458.50 2,800 684.99
36 260.95 82 313.74 156 361.52 480 462.82 3,000 695.36
37 262.57 83 314.59 158 362.03 500 467.01 3,200 705.11
Note: To convert psia into psig, subtract 14.7 (approx.)
Appendix B 267
268 Tube Fitter’s Manual

Specific Gravity of Water versus Temperature

Water Temperature Specific Gravity
(°F)
32 1.0013
40 1.0013
50 1.0006
60 1.0000
70 0.9989
80 0.9976
90 0.9963
100 0.9945
110 0.9920
120 0.9902
130 0.9872
140 0.9848
150 0.9817
160 0.9787
170 0.9751
180 0.9716
190 0.9681
200 0.9645
210 0.9605
212 0.9594
220 0.9565
240 0.9480
260 0.9386
280 0.9294
300 0.9193
350 0.8917
400 0.8606
450 0.8269
500 0.7863
550 0.7358
600 0.6797
 Appendix B 269

Specific Gravity of Liquids

Specific Gravity Relative to Water at
Liquid 60°F
Acetone 0.792
Alcohol, Ethyl (100 %) 0.789
Alcohol, Methyl (100 %) 0.796
Acid, Muriatic (40 %) 1.20
Acid, Nitric (91 %) 1.50
Acid, Sulfuric (87 %) 1.80
Bunkers C Fuel Max. 1.014
Distillate 0.850
Fuel 3 Max. 0.898
Fuel 5 Min. 0.966
Fuel 5 Max. 0.993
Fuel 6 Min. 0.993
Gasoline 0.751
Gasoline, Natural 0.680
Hydrochloric Acid 1.256
Kerosene 0.815
M. C. Residuum 0.935
Mercury 13.570
Olive Oil 0.919
Pentane 0.624
SAE 10 Lube* 0.876
SAE 30 Lube* 0.898
SAE 70 Lube* 0.916
Salt Creek Crude 0.843
Seawater 1.025
32.6° API Crude 0.862
35.6° API Crude 0.847
40° API Crude 0.825
48° API Crude 0.788
Water 1.000
*100 viscosity index.
Specific Gravity of Gases Relative to Air @ 68°F
(20°C) at 1 atm
Chemical Specific Gravity
Name of Gas Formula Relative to Air
Acetylene C2H2 0.90
Air — 1.000
Ammonia NH3 0.59
Anthracite Producer Gas — 0.85
Argon Ar 1.377
Benzene C6H6 2.696
Bituminous Producer — 0.86
Gas
Blast Furnace Gas — 1.000
Blue Water Gas — 0.53
Butane C4H10 2.0061
Butylene C4H8 1.94
Carbon Dioxide CO2 1.5189
Carbon Monoxide CO 0.9672
Carbureted Water Gas — 0.63
Chlorine Cl2 2.486
Coke Oven Gas — 0.44
Ethane C2H6 1.0378
Ethyl Chloride C2H5Cl 2.23
Ethylene C2H4 0.968
Freon (F-12) CCl2F2 4.520
Helium He 0.138
Hydrogen H2 0.06959
Hydrogen Chloride HCl 1.261
Hydrogen Sulfide H2S 1.176
Methane CH4 0.5537
Methyl Chloride CH3Cl 1.738
Natural Gas* — 0.667
Neon Ne 0.696
Nitrogen N2 0.9718
Nitric Oxide NO 1.037
Nitrous Oxide N2O 1.530
Oxygen O2 1.1044
Pentane C5H12 2.4872
Propane C3H8 1.5219
Propylene C3H6 1.4504
Sulfur Dioxide SO2 2.264
Toluene C7H8 3.1082
Xylene C8H10 3.6618
*Representative value.
Table of Elements
Name Symbol Atomic number Atomic weight Name Symbol Atomic number Atomic weight
Actinium Ac 89 227 Copernicium Cn 112 285
Aluminum Al 13 26.982 Copper Cu 29 63.54
Americium Am 95 243 Curium Cm 96 247
Antimony Sb 51 121.76 Darmstadtium Ds 110 281
Argon Ar 18 39.948 Dubnium Db 105 262
Arsenic As 33 74.922 Dysprosium Dy 66 162.50
Astatine At 85 210 Einsteinium Es 99 254
Barium Ba 56 137.33 Erbium Er 68 167.26
Berkelium Bk 97 247 Europium Eu 63 151.96
Beryllium Be 4 9.0122 Fermium Fm 100 253
Bismuth Bi 83 208.98 Flerovium Fl 114 289
Boron B 5 10.811 Fluorine F   9 18.9984
Bromine Br 35 79.907 Francium Fr 87 223
Cadmium Cd 48 112.41 Gadolinium Gd 64 157.25
Calcium Ca 20 40.078 Gallium Ga 31 69.723
Californium Cf 98 249 Germanium Ge 32 72.630
Carbon C 6 12.012 Gold Au 79 196.97
Cerium Ce 58 140.12 Hafnium Hf 72 178.49
Cesium Cs 55 132.91 Helium He   2 4.0026
Chlorine Cl 17 35.453 Holmium Ho 67 164.93
Chromium Cr 24 51.996 Hydrogen H   1 1.00797
Cobalt Co 27 58.933 Indium In 49 114.82
Iodine I 53 126.90 Rhenium Re 75 186.2
Appendix B 271

continued
Table of Elements (Continued)
Name Symbol Atomic number Atomic weight Name Symbol Atomic number Atomic weight
Iridium Ir 77 192.22 Rhodium Rh 45 102.905
Iron Fe 26 55.845 Roentgenium Rg 111 272
272 Tube Fitter’s Manual

Krypton Kr 36 83.798 Rubidium Rb 37 85.47

Lanthanum La 57 138.91 Ruthenium Ru 44 101.07
Lawrencium Lr 103 262 Rutherfordium Rf 104 261
Lead Pb 82 207.2 Samarium Sm 62 150.36
Lithium Li   3 6.939 Scandium Sc 21 44.956
Lutetium Lu 71 174.97 Seaborgium Sg 106 266
Magnesium Mg 12 24.307 Selenium Se 34 78.971
Manganese Mn 25 54.938 Silicon Si 14 28.086
Meitnerium Mt 109 268 Silver Ag 47 107.87
Mendelevium Md 101 256 Sodium Na 11 22.990
Mercury Hg 80 200.59 Strontium Sr 38 87.62
Molybdenum Mo 42 95.95 Sulfur S 16 32.064
Neodymium Nd 60 144.24 Tantalum Ta 73 180.95
Neon Ne 10 20.180 Technetium Tc 43 99
Neptunium Np 93 237 Tellurium Te 52 127.60
Nickel Ni 28 58.693 Terbium Tb 65 158.93
Niobium Nb 41 92.906 Thallium Tl 81 204.38
Nitrogen N   7 14.0067 Thorium Th 90 232.04
Nobelium No 102 254 Thulium Tm 69 168.93
Osmium Os 76 190.23 Tin Sn 50 118.71
Oxygen O   8 15.999 Titanium Ti 22 47.867
Palladium Pd 46 106.42 Tungsten W 74 183.85
Phosphorous P 15 30.974 Ununoctium Uuo 118 294
Platinum Pt 78 195.08 Ununpentium Uup 115 288
Plutonium Pu 94 242 Ununseptium Uus 117 294
Polonium Po 84 210 Ununtrium Uut 113 286
Potassium K 19 39.098 Uranium U 92 238.03
Praseodymium Pr 59 140.91 Vanadium V 23 50.942
Promethium Pm 61 147 Xenon Xe 54 131.29
Protactinium Pa 91 231.04 Ytterbium Yb 70 173.05
Radium Ra 88 226 Yttrium Y 38 88.906
Radon Rn 86 222 Zinc Zn 30 65.38
Zirconium Zr 40 91.224
Appendix B 273
274 Tube Fitter’s Manual

Volume Conversions
To Convert Into Multiply By
Cubic feet Cubic 2.83 × 104
centimeters
Cubic feet Cubic meters 0.02832
Cubic feet Cubic yards 0.03704
Cubic feet Cubic in. 1728
Cubic feet Gallons (Br.) 6.229
Cubic feet Liters 28.32
Cubic feet BBL (oil) 0.1781
Cubic feet BBL (liq.) 0.2375
Gallons Cubic 3785
centimeters
Gallons Cubic millimeters 0.00379
Gallons Cubic feet 0.1337
Gallons Cubic in. 231
Gallons Gallons (Br.) 0.8327
Gallons Liters 3.785
Gallons Pounds of water 8.35
Gallons BBL (oil) 0.02381
Gallons BBL (liq.) 0.03175
Liters Cubic 1000
centimeters
Liters Cubic millimeters 0.001
Liters Cubic yards 0.00131
Liters Cubic feet 0.0353
Liters Cubic in. 61.02
Liters Gallons (Br.) 0.2200
Liters Gallons 0.2642
Liters BBL (oil) 0.00629
Liters BBL (liq.) 0.00839
Cubic Cubic meters 1 × 10‒6
centimeters
Cubic Cubic feet 3.531 × 10‒5
centimeters
Cubic Cubic in. 0.06102
centimeters
Cubic Gallons (Br.) 2.20 × 10‒4
centimeters
Cubic Gallons 2.642 × 10‒4
centimeters
Cubic Liters 0.001
centimeters
Cubic BBL (oil) 6.29 × 10‒6
centimeters
Cubic BBL (liq.) 8.39 × 10‒6
centimeters
Cubic in. Cubic 16.387
centimeters
Area Conversions
To
From cm2 m2 km2 in.2 ft.2 mile2
cm2 1 0.0001 1 × 1010 0.1550 0.00108 3.86 × 1011
m2 1 × 104 1 1 × 106 1550 10.76 3.86 × 107
km2 1 × 1010 1 × 106 1 1.55 × 109 1.08 × 107 0.3861
in.2 6.452 6.45 × 104 6.45 × 1010 1 0.00694 2.49 × 1010
ft.2 929.0 0.09290 9.29 × 108 144 1 3.59 × 108
mile2 2.59 × 1010 2.59 × 106 2.590 4.01 × 109 2.79 × 107 1
Appendix B 275
276 Tube Fitter’s Manual

Decimal Equivalents
8ths 32nds 64ths
1/8 = 0.125 1/32 = 0.03125 1/64 = 0.015625 33/64 = 0.515625
1/4 = 0.250 3/32 = 0.09375 3/64 = 0.046875 35/64 = 0.546875
3/8 = 0.375 5/32 = 0.15625 5/64 = 0.078125 37/64 = 0.578125
1/2 = 0.500 7/32 = 0.21875 7/64 = 0.109375 39/64 = 0.609375
5/8 = 0.625 9/32 = 0.28125 9/64 = 0.140625 41/64 = 0.640625
3/4 = 0.750 11/32 = 0.34375 11/64 = 0.171875 43/64 = 0.671875
7/8 = 0.875 13/32 = 0.40625 13/64 = 0.203125 45/64 = 0.703125
16ths 15/32 = 0.46875 15/64 = 0.234375 47/64 = 0.734375
1/16 = 0.0625 17/32 = 0.53125 17/64 = 0.265625 49/64 = 0.765625
3/16 = 0.1875 19/32 = 0.59375 19/64 = 0.296875 51/64 = 0.796875
5/16 = 0.3125 21/32 = 0.65625 21/64 = 0.328125 53/64 = 0.828125
7/16 = 0.4375 23/32 = 0.71875 23/64 = 0.359375 55/64 = 0.859375
9/16 = 0.5625 25/32 = 0.78125 25/64 = 0.390625 57/64 = 0.890625
11/16 = 0.6875 27/32 = 0.84375 27/64 = 0.421875 59/64 = 0.921875
13/16 = 0.8125 29/32 = 0.90625 29/64 = 0.453125 61/64 = 0.953125
15/16 = 0.9375 31/32 = 0.96875 31/64 = 0.484375 63/64 = 0.984375

Inches to Millimeters Millimeters to Inch Equivalent

1/16 in. = 1.59 mm 1 mm = 0.039 in. 15 mm = 0.590 in.
1/8 in. = 3.17 mm 2 mm = 0.079 in. 16 mm = 0.630 in.
3/16 in. = 4.76 mm 3 mm = 0.118 in. 17 mm = 0.669 in.
1/4 in. = 6.35 mm 4 mm = 0.157 in. 18 mm = 0.709 in.
5/16 in. = 7.94 mm 5 mm = 0.197 in. 19 mm = 0.748 in.
3/8 in. = 9.52 mm 6 mm = 0.236 in. 20 mm = 0.787 in.
7/16 in. = 11.11 mm 7 mm = 0.276 in. 21 mm = 0.827 in.
1/2 in. = 12.70 mm 8 mm = 0.315 in. 22 mm = 0.866 in.
9/16 in. = 14.29 mm 9 mm = 0.354 in. 23 mm = 0.905 in.
5/8 in. = 15.87 mm 10 mm = 0.394 in. 24 mm = 0.944 in.
11/16 in. = 17.46 mm 11 mm = 0.433 in. 25 mm = 0.984 in.
3/4 in. = 19.05 mm 12 mm = 0.472 in. 25.4 mm = 1 in.
13/16 in. = 20.64 mm 13 mm = 0.512 in.
7/8 in. = 22.22 mm 14 mm = 0.551 in.
15/16 in. = 23.81 mm
1 in. = 25.40 mm
1 1/4 in. = 31.75 mm
1 1/2 in. = 38.10 mm
2 in. = 50.80 mm
 Appendix B 277

Temperature Conversion Formulas

Degrees Degrees Celsius Absolute Degrees Rankine (°R)
Fahrenheit (°F) (Centigrade) (°C) Degrees Kelvin (°K)
°F – 32 0°R = 0°K
°F = 1.8 (°C) + 32 °C = 1.8 °R = °F + 459.69
°F = °R – 459.69 °C = °K – 273.16 °K = °C + 273.16
Celsius (°C) Fahrenheit (°F) Temperature
Conversion Table
°C °F °C °F °C °F °C °F
–200 –328 65 149 410 770 790 1454
–180 –292 70 158 420 788 800 1472
–160 –256 75 167 430 806 810 1490
–140 –220 80 176 440 824 820 1508
–120 –184 85 185 450 842 830 1526
–100 –148 90 194 460 860 850 1562
–95 –139 95 203 470 878 900 1652
–90 –130 100 212 480 896 950 1742
–85 –121 110 230 490 914 1000 1832
–80 –112 120 248 500 932 1050 1922
–75 –103 130 266 510 950 1100 2012
–70 –94 140 284 520 968 1150 2102
–65 –85 150 302 530 986 1200 2192
–60 –76 160 320 540 1004 1250 2282
–55 –67 170 338 550 1022 1300 2372
–50 –58 180 356 560 1040 1350 2462
–45 –49 190 374 570 1058 1400 2552
–40 –40 200 392 580 1076 1450 2642
–35 –31 210 410 590 1094 1500 2732
–30 –22 220 428 600 1112 1550 2822
–25 –13 230 446 610 1130 1600 2912
–20 –4 240 464 620 1148 1650 3002
–15 5 250 482 630 1166 1700 3092
–10 14 260 500 640 1184 1750 3182
–5 23 270 518 650 1202 1800 3272
0 32 280 536 660 1220 1850 3362
5 41 290 554 670 1238 1900 3452
10 50 300 572 680 1256 1950 3542
15 59 310 590 690 1274 2000 3632
20 68 320 608 700 1292 2050 3722
25 77 330 626 710 1310 2100 3812
30 86 340 644 720 1328 2150 3902
35 95 350 662 730 1346 2200 3992
40 104 360 680 740 1364 2250 4082
45 113 370 698 750 1382 2300 4172
50 122 380 716 760 1400 2350 4262
55 131 390 734 770 1418 2400 4352
60 140 400 752 780 1436 2450 4442
278 Tube Fitter’s Manual

Pipe Wall Thickness

Nominal Wall Thickness Inside Diameter
Size OD Sch 10 Sch 40 Sch 80 Sch 10 Sch 40 Sch 80
1/8 0.405 0.049 0.068 0.095 0.307 0.269 0.215
1/4 0.540 0.065 0.088 0.119 0.410 0.364 0.302
3/8 0.675 0.065 0.091 0.126 0.545 0.493 0.381
1/2 0.840 0.083 0.109 0.147 0.674 0.622 0.546
3/4 1.050 0.083 0.113 0.154 0.884 0.824 0.742
1 1.315 0.109 0.133 0.179 1.097 1.049 0.957
1 1/4 1.660 0.109 0.140 0.191 1.442 1.380 1.278
1 1/2 1.900 0.109 0.145 0.200 1.682 1.610 1.500
2 2.375 0.109 0.154 0.218 2.157 2.067 1.939
All dimensions in inches.

Fractional Tubing OD, Wall,

ID Cross-Sectional Area
Tube ID ID Cross-Sectional
Tube (in.) OD (in.) Wall Thickness (in.) (in.) Area (in.2)
0.010 0.042 0.0014
1/16 0.062 0.015 0.032 0.0008
0.020 0.022 0.0004
0.028 0.069 0.0037
1/8 0.125
0.035 0.055 0.0024
0.028 0.131 0.0135
3/16 0.187 0.035 0.117 0.0108
0.049 0.089 0.0062
0.028 0.194 0.030
0.035 0.180 0.025
1/4 0.250
0.049 0.152 0.018
0.065 0.120 0.011
0.035 0.242 0.046
5/16 0.312 0.049 0.214 0.036
0.065 0.182 0.026
0.035 0.305 0.073
3/8 0.375 0.049 0.277 0.060
0.065 0.245 0.047
0.035 0.430 0.145
0.049 0.402 0.127
1/2 0.500
0.065 0.370 0.108
0.083 0.334 0.088
 Appendix B 279

Fractional Tubing OD, Wall,

ID Cross-Sectional Area (Continued)
Tube ID ID Cross-Sectional
Tube (in.) OD (in.) Wall Thickness (in.) (in.) Area (in.2)
0.049 0.527 0.218
0.065 0.495 0.192
5/8 0.625
0.083 0.459 0.166
0.095 0.435 0.149
0.049 0.652 0.334
0.065 0.620 0.302
3/4 0.750 0.083 0.584 0.268
0.095 0.560 0.246
0.109 0.532 0.222
0.049 0.777 0.474
0.065 0.745 0.436
7/8 0.875 0.083 0.709 0.395
0.095 0.685 0.369
0.109 0.657 0.339
0.065 0.870 0.595
0.083 0.834 0.546
1 1.000 0.095 0.810 0.515
0.109 0.782 0.480
0.120 0.760 0.454
0.083 1.084 0.923
0.095 1.060 0.883
0.109 1.032 0.837
1 1/4 1.250
0.120 1.010 0.801
0.134 0.982 0.757
0.156 0.938 0.691
0.095 1.310 1.348
0.109 1.282 1.291
0.120 1.260 1.247
1 1/2 1.500
0.134 1.232 1.192
0.156 1.188 1.109
0.188 1.124 0.992
0.109 1.782 2.494
0.120 1.760 2.433
2 2.000 0.134 1.732 2.356
0.156 1.688 2.238
0.188 1.624 2.071
280 Tube Fitter’s Manual

Metric Tubing OD, Wall, ID Cross-Sectional Area

Wall Thickness ID Cross-Sectional
Tube OD (mm) (mm) Tube ID (mm) Area (mm2)
0.2 0.6 0.2827
1 0.3 0.4 0.1257
0.4 0.2 0.0031
0.5 2.0 3.14
3 0.6 1.8 2.54
0.8 1.4 1.54
0.6 4.8 18.10
0.8 4.4 15.21
1.0 4.0 12.57
6
1.25 3.5 9.62
1.5 3.0 7.07
1.6 2.8 6.16
0.8 6.4 32.17
1.0 6.0 28.27
8 1.25 5.5 23.76
1.5 5.0 19.64
1.6 4.8 18.10
0.8 8.4 55.42
1.0 8.0 50.27
10 1.25 7.5 44.18
1.5 7.0 38.48
1.6 6.8 36.32
1.0 10.0 78.54
1.25 9.5 70.88
12 1.5 9.0 63.62
1.6 8.8 60.82
2.0 8.0 50.27
1.0 12.0 113.10
1.2 11.6 105.68
1.5 11.0 95.03
14
1.8 10.4 84.95
2.0 10.0 78.54
2.2 9.6 72.38
1.2 12.6 124.69
1.5 12.0 113.10
15 1.6 11.8 109.36
2.0 11.0 95.03
2.3 10.4 84.95
 Appendix B 281

Metric Tubing OD, Wall, ID Cross-Sectional Area

(Continued)
Wall Thickness ID Cross-Sectional
Tube OD (mm) (mm) Tube ID (mm) Area (mm2)
1.2 13.6 145.27
1.5 13.0 132.73
16 1.6 12.8 128.68
2.0 12.0 113.10
2.3 11.4 102.07
1.2 15.6 191.13
1.5 15.0 176.72
1.6 14.8 172.03
18 2.0 14.0 153.94
2.3 13.4 141.03
2.5 13.0 132.73
2.6 12.8 128.68
1.5 17.0 226.98
1.6 16.8 221.67
2.0 16.0 201.06
20
2.3 15.4 186.27
2.5 15.0 176.71
2.6 14.8 172.03
1.5 19.0 283.53
1.6 18.8 277.59
2.0 18.0 254.47
22
2.3 17.4 237.79
2.5 17.0 226.98
2.6 16.8 221.67
1.5 22.0 380.13
1.6 21.8 373.25
2.0 21.0 346.36
25 2.3 20.4 326.85
2.5 20.0 314.16
2.6 19.8 307.91
3.0 19.0 283.53
2.0 24.0 452.38
2.2 23.6 437.43
2.5 23.0 415.47
28
2.8 22.4 394.08
3.0 22.0 380.13
3.5 21.0 346.36

continued
282 Tube Fitter’s Manual

Metric Tubing OD, Wall, ID Cross-Sectional Area

(Continued)
Wall Thickness ID Cross-Sectional
Tube OD (mm) (mm) Tube ID (mm) Area (mm2)
2.0 26.0 530.92
2.2 25.6 514.71
2.5 25.0 490.87
30
2.8 24.4 467.59
3.0 24.0 452.38
3.5 23.0 415.47
2.0 28.0 615.75
2.2 27.6 598.28
2.5 27.0 572.55
32 2.8 26.4 547.39
3.0 26.0 530.92
3.5 25.0 490.87
4.0 24.0 452.38
2.2 33.6 886.68
2.5 33.0 855.29
2.8 32.4 824.47
38 3.0 32.0 804.24
3.5 31.0 754.76
4.0 30.0 706.85
4.5 29.0 660.51
A p p en d i x C

Corrosion Charts
The data presented is believed reliable, but a chart of this sort cannot
cover all conditions of concentration, temperature, impurities, and
aeration. It is suggested that this chart be used only to select possible
materials for use and then a more extensive investigation be made of
published corrosion results under the specific conditions expected.
Where such information cannot be found, corrosion testing should
be conducted under actual usage conditions to determine which
materials can be utilized.
1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Acetaldehyde 1 1 3 2 1 1 4 3 4 2 2 1
Acetic Acid 2 4 4 3 1 1 3 3 4 3 4 2 1 1
Acetic Anhydride 1 4 4 1 2 4 3 4 3 4 1
284 Tube Fitter’s Manual

Acetone 2 1 2 1 1 1 3 4 4 3 1 1
Acetylene 1 2 1 1 1 1 1 1 1 1 1 1
Acrylonitrile 2 1 1 1 1 1 4 3 4 4 1 1 1
Alcohols 2 2 2 1 1 1 1 1 1 1 1 1
Aluminum Chloride 4 4 4 2 4 1 2 2 1 2 1 4 1
Aluminum Fluoride 1 4 4 2 3 1 2 2 2
Aluminum Hydroxide 2 2 2 2 2 1 2 1
Aluminum Sulfate 3 4 4 2 3 1 2 1 1 1 1 4 1 1
Amines 2 2 2 1 1 1 4 4 1 2 1 1
Ammonia, Anhydrous 2 4 1 1 1 1 2 2 3 2 1 1
Ammonium Bicarbonate 2 4 2 4 2 1 1 2 1 1 1 4 1
Ammonium Carbonate 2 3 2 2 2 1 2 2 1 1 2 2
Ammonium Chloride 4 4 3 2 2 1 2 2 1 1 1 2 1 1
Ammonium Hydroxide 2 4 2 4 1 1 2 3 1 1 1 1 1 1
Amm. Monophosphate 2 4 4 2 2 1 1 1 1 1 2
Ammonium Nitrate 2 4 1 3 1 1 2 1 1 1 1 2 3
Ammonium Phosphate 1 1 1 1 1 1 1 1 1
Ammonium Sulfate 4 4 3 2 2 1 1 1 1 1 2 2 1
Ammonium Sulfite 4 4 4 3 2 1 4
Amyl Acetate 1 2 1 1 1 1 4 4 4 2 1 1 1
Aniline 2 4 1 2 1 1 4 3 3 1 2 2 1
Apple Juice 2 3 4 2 1 1 1 1 1
Arsenic Acid 4 4 4 2 2 1 1 1 1 1 1 2
Asphalt 1 2 1 1 1 1 3 1 3 1
Barium Carbonate 4 1 2 2 2 1 1 1 1 1 1 2 1
Barium Chloride 2 2 2 2 2 1 2 1 1 1 1 1 2 2
Barium Hydroxide 4 4 2 2 1 1 2 1 1 1 1 2 2 1
Barium Nitrate 2 4 2 3 2 1 2 2
Barium Sulfate 2 2 2 2 1 2 1 1 1 1 2 2
Barium Sulfide 4 4 1 4 1 1 2 1 1 1 1 1
Beer 1 2 3 1 1 1 1 1 1 1
Beet Sugar Liquor 1 3 2 1 1 1 1 1 1 1
Benzene 2 2 2 1 2 1 4 2 4 1 1 2 1
Borax 3 3 2 1 1 1 2 1 1 1 1
Blk. Sulfate Liquor 4 2 1 1 1 2 1
Boric Acid 2 2 4 2 2 1 1 1 1 1 2 1 1
Brine 3 1 2 1 1 1 1 1 1 1 1
Bromine—Dry 2 4 4 3 4 1 2 4 2 4 4 4 4
Bromine—Wet 4 4 4 2 4 1 4 4 2 4 4 4 4
Bunker Oil 1 2 2 1 1 1 1 2 1
Buttermilk 1 4 4 1 1 1 1 1 1 1 1
Butyric Acid 2 4 4 2 2 1 2 2 3 3 1 3 1 1
Calcium Bisulfite 4 4 4 4 1 1 4 1 1
Calcium Carbonate 3 2 1 2 1 1 1 1 1 1 1 2 2 1
Calcium Chloride 2 2 2 1 2 1 1 1 1 1 1 1 1
(continued)
Appendix C 285

Calcium Hydroxide 3 4 2 2 2 1 1 1 1 1 2 1 1
1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Calcium Hypochlorite 4 4 3 3 3 1 2 1 2 1 4 2 1
Calcium Sulfate 2 2 2 2 1 1 1 1 1 1 4 1
Carbolic Acid 2 3 3 2 1 1 4 2 4 4 2 1 1
286 Tube Fitter’s Manual

Carbon Bisulfide 1 3 2 2 2 1 4 1 4 1 1
Carbon Dioxide 1 1 1 1 1 1 2 3 1 2 1 1 1
Carbonic Acid 1 1 4 1 1 1 2 1 1 1 1 1 1
Carbon Tet—Wet 4 2 4 1 1 1 3 4 2 4 1 1 1 1
Carbon Tet—Dry 1 3 4 1 2 1 4 2 4 1 1 1 1
Carbonated Water 1 2 2 1 1 1 1 1 1 1 1
Castor Oil 1 1 2 1 1 1 1 2 1
Chlorinated Solvent 1 1 1 1 1 1 4 3 4 1 1 1 1
Chloric Acid 4 4 4 3 3 1 1 1
Chlorinated Water 4 4 4 1 3 1 1 1
Chlorine Gas—Dry 4 4 2 1 2 1 3 3 2 3 1 4 1 4
Chlorine Gas—Wet 4 4 4 2 3 1 3 4 4 2 4 1
Chloroform—Dry 1 1 1 1 1 1 4 2 4 1 1 2 1
Chlorosulfonic—Dry 1 4 1 3 2 1 4 4 3 1 4
Chlorosulfonic—Wet 4 4 4 4 4 1 4 4 3 1
Chrome Alum 3 3 2 1 1 2 2
Chromic Acid 4 4 2 4 4 1 2 4 3 4 4 2 2 1
Citric Acid 2 4 4 2 3 1 4 1 1 1 1 1
Coconut Oil 1 3 3 2 1 1 1 1 2 1 1 1 1
Coke Oven Gas 1 3 2 1 1 2 2 3 1
Copper Acetate 4 4 3 1 2 1 1 2 1
Copper Chloride 4 4 4 2 4 1 1 1 1 1
Copper Nitrate 4 4 4 4 2 1 2 1 1 1 1 4 2 1
Copper Sulfate 4 2 4 2 2 1 2 1 2
Corn Oil 4 4 4 4 1 1 2 1 1 1 2
Cottonseed Oil 2 2 3 2 1 1 1 2 1
Creosote 2 2 2 1 2 1 4 4 1 4 4 1 2
Crude Oil, Sweet 1 2 2 1 1 1 1 2
Diesel Fuel 1 1 1 1 1 1 1 3 1 1 1 1
Diethylamine 2 4 1 2 1 1 2 3 1 1 1
Dowtherm 1 1 2 1 1 4 1 4 1
Drying Oil 3 3 3 2 1 1 2 1
Epsom Salt 1 2 3 2 1 1 1 1 1 1 1 1
Ethane 1 1 1 1 1 1 1 1 2 1 1 1 1
Ethers 1 2 1 1 1 3 3 3 3
Ethyl Acetate 1 2 1 1 1 1 4 4 4 1 1 1 1
Ethyl Alcohol 2 1 1 1 2 1 1 1 1 1 1 1 1
Ethyl Chloride—Dry 2 2 1 2 1 1 4 3 3 1 1 2 1
Ethyl Chloride—Wet 2 2 4 2 1 1 3 3 1 1 2 1
Ethylene Glycol 1 2 1 1 1 1 2 1 2 1 3 1 1 1
Ethylene Oxide 4 4 2 2 2 1 3 4 4 4 2 1 1
Fatty Acid 1 3 2 2 1 1 2 1 2 1 1 1 1
Ferric Chloride 4 4 4 4 4 1 2 1 1 1 1 4 2 1
Ferric Nitrate 4 4 4 4 2 1 2 1 1 1 1 4 2
Ferric Sulfate 4 4 4 4 2 1 2 1 1 1 1 1 1 1
(continued)
Appendix C 287
1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Ferrous Chloride 4 4 4 4 4 1 1 1 1 1 4 2 1
Ferrous Sulfate 3 4 4 2 2 1 2 1 1 1 1 2 2 1
Fish Oils 2 2 2 1 1 1 1 2 1
288 Tube Fitter’s Manual

Fluorine—Dry 2 3 1 1 2 1 2 1 2 4
Fluorine—Wet 4 4 4 1 4 1 2 3 1 2 4
Fluoroboric Acid 4 1 1 1 1 4
Fluorosilicic Acid 4 1 4 1 1 1 3 1 2 4
Formaldehyde—Cold 1 1 1 1 1 1 2 2 1 2 2 1
Formaldehyde—Hot 2 2 4 2 2 1 2 2 1 2 2 1
Formic Acid—Cold 1 2 4 3 2 1 4 1 1 4 3 1 4
Formic Acid—Hot 4 2 4 4 2 1 4 1 1 4 4 2 4
Freon 2 2 3 1 3 1 2 3 3 3 2 2 3
Fuel Oil 1 1 1 1 1 1 1 1 2 1
Furfural 2 2 2 2 2 1 4 4 1 3 1 2 2 2
Gasoline 1 1 1 1 1 1 4 3 1 4 1 1 1 1
Gas, Manufactured 2 2 2 2 1 1 1 1 1 1 1 1
Gas, Natural 1 1 1 1 1 1 1 1 1 1 1 1
Gas Odorizers 1 1 2 2 1 1 1 1 1
Gelatin 1 1 4 1 1 1 1 1 1 1
Glucose 1 1 2 1 1 1 1 1 1 1 1 1
Glue 1 2 1 2 1 1 1 1 1 1 1
Glycerine 1 1 1 1 1 1 4 1 1 1 3 1 1 1
Glycols 1 1 1 1 1 1 1 1 3 1 1 1
Grease 1 1 1 1 1 1 1 1 2 1 1 1
Heptane 1 1 1 1 1 1 1 1 2 1 1 1
Hexane 1 1 1 1 1 1 1 1 3 1 1 1 1
Hydraulic Oil 1 1 1 1 1 1 1 1 2 1 1 1 1
Hydrobromic Acid 4 4 4 4 4 1 3 3 1
Hydrochloric Acid 4 4 4 2 4 1 2 2 3 4 4 4
Hydrocyanic Acid 1 4 1 2 1 1 2 4 1 2 1
Hydrofluoric Acid 4 4 4 2 4 1 3 3 4 4 2 3
Hydrogen Gas—Cold 1 1 1 1 1 1 2 1 1 1
Hydrogen Cl—Dry 4 3 2 1 2 1 2 1 1
Hydrogen Cl—Wet 4 4 4 3 4 1 4
Hydrogen Perox—Dil 1 4 4 2 2 1 2 1 1 1 2 1 1
Hydrogen Perox—Con 1 4 4 4 1 1 4 4 1 1 1
Hydrogen Sulfide—Dry 2 2 2 2 1 1 2 3 4 4 4 2 2 1
Hydrogen Sulfide—Wet 2 4 3 1 1 1 2 3 4 4 4 2 2 1
Hydrofluosilicic 4 4 4 1 3 1 2 1 1
Illuminating Gas 1 1 1 1 1 1 1 2 1 1 1
Ink 3 3 4 1 1 1 1 1 1
Iodine 4 4 4 2 2 1 3 2 1 2 1 4 2 4
Iodoform 1 1 1 2 1 1 1 1 2 2 1
Isooctane 1 1 1 1 1 1 1 1 3 1 1
Isopropyl Alcohol 2 2 1 1 1 1 3 1 3 1 1 1 1
Isopropyl Ether 1 1 1 1 1 3 3 1
JP-4 Fuel 1 1 1 1 1 1 1 3 1 1
JP-5 Fuel 1 1 1 1 1 1 1 3 1 1
Appendix C 289

JP-6 Fuel 1 1 1 1 1 1 1 3 1 1 (continued)

1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Kerosene 1 1 1 1 1 1 2 1 1 3 1 1
Ketchup 1 1 1 1 1 1 1 1 1 1
Ketones 1 1 1 1 1 4 4 4 1 1
290 Tube Fitter’s Manual

Lactic Acid 1 4 4 2 2 1 2 3 3 4 1 2 1
Lard Oil 1 1 3 2 1 1 1 2 1
Magnesium Bisulfate 2 2 3 2 1
Magnesium Chloride 2 2 2 1 2 1 2 1 1 1 1 1 1 1
Mag. Hydroxide—Cold 4 2 2 1 1 1 2 1 1 1 1
Mag. Hydroxide—Hot 4 4 2 1 1 1 2 1 1 1
Magnesium Sulfate 1 1 1 1 1 1 2 1 1 1 1 1 1 1
Maleic Acid 2 3 2 2 2 1 1 1 1 2 2 1
Malic Acid 2 2 4 2 1 1 1 1 1 1 1 1
Mayonnaise 4 4 4 1 1 1 1 1 1
Melamine Resin 2 2 1
Mercuric Cyanide 4 4 2 2 1 2 1
Mercury 4 4 2 2 1 1 2 1 1 1 1 1 1 4
Methane 1 1 1 1 1 1 1 1 2 1 1 1 1
Methyl Acetate 2 2 2 1 1 1 4 4 4 1 1 1
Methyl Acetone 2 1 1 1 1 1 4 4 4 1
Methyl Alcohol 2 2 2 1 2 1 1 4 1 1 1 1 1
Methyl Chloride 4 1 1 2 1 1 2 3 3 1 2
Methylamine 2 4 2 3 2 1 2 3 3 1 1 2 2
Methyl Ethyl Ketone 1 1 1 1 1 1 4 4 4 1 2 2 1
Methylene Chloride 1 2 2 2 2 1 3 4 3 4 1 2 1
Milk 1 4 4 2 1 1 3 1 1 1 1 1
Mineral Oil 1 1 1 1 1 1 1 1 1 2 1
Molasses 1 1 1 1 1 1 2 1 1 1 1 1
Mustard 2 1 2 1 1 1 1 1 1
Naphtha 1 1 1 1 1 1 3 1 4 1 1 1 1
Naphthalene 2 2 1 2 1 1 3 1 4 1 2 1
Nickel Chloride 4 4 4 2 2 1 2 1 1 1 1 4 1
Nickel Nitrate 3 4 2 2 2 1 1 1 1 1 2 2 1
Nickel Sulfate 4 3 4 1 2 1 2 1 1 1 1 2 2
Nitric Acid—10 % 4 4 4 4 1 1 3 1 2 4 4 1 1
Nitric Acid—30 % 4 4 4 4 1 1 3 1 3 4 3 1 1
Nitric Acid—80 % 4 4 4 4 1 1 4 2 4 4 1 4 2
Nitric Acid—100 % 4 4 4 4 1 1 4 2 4 4 1 4 2
Nitric Acid—Anhyd. 4 4 1 4 1 1 4 1 2 4
Nitrobenzene 1 1 1 1 1 1 4 3 4 1
Nitrogen 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Nitrous Acid—10 % 4 4 4 4 2 1 3 1 1
Nitrous Oxide 3 2 2 4 2 1 2 2 1 4 2
Oils, Animal 1 1 1 1 1 1 1 2
Oleic Acid 2 2 3 1 2 1 1 1 3 1 1 1 1
Oleum 2 2 2 2 1 3 3 3 4 2 2
Olive Oil 1 2 2 1 1 1 1 2 1
Oxalic Acid 3 2 4 2 2 1 3 1 1 3 2 2 4
Oxygen 1 1 2 1 1 1 1 1 1 1 1 1 1
(continued)
Appendix C 291

Ozone—Dry 1 4 1 1 1 1 1 1
1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Ozone—Wet 1 4 3 1 1 1
Palmitic Acid 2 2 2 2 1 1 2 1 2 1 1
Paraffin 1 1 2 1 1 1 1 2 1
292 Tube Fitter’s Manual

Paraformaldehyde 2 1 3 1 1 1 2 2 2 1 1 2
Pentane 1 2 2 2 2 1 1 1 2 1 2 1
Parez 607 4 4 1
Phenol 2 1 1 2 2 1 4 2 4 4 2 1 1
Phosphoric, 10 %—Cold 1 2 4 1 2 1 2 1 1 4 1 1
Phosphoric, 10 %—Hot 1 2 4 1 4 1 2 1 1 4 4 4
Phosphoric, 50 %—Cold 4 2 4 1 2 1 2 1 2 4 1 4
Phosphoric, 50 %—Hot 4 2 4 1 4 1 2 1 2 4 4 4 4
Phosphoric, 85 %—Cold 4 2 2 1 1 1 3 2 4 1 4
Phosphoric, 85 %—Hot 4 2 3 1 1 1 3 2 4 4 4
Phthalic Acid 2 2 3 2 1 1 3 1 3 1 2 2 1
Phthalic Anhydride 1 2 1 1 1 1 3 1 3 1 1 1
Picric Acid 3 4 4 4 2 1 3 1 2
Pine Oil 1 2 2 1 1 1 1 3 1
Pineapple Juice 1 3 3 1 1 1 1 1 1
Potassium Bisulfite 2 2 4 4 2 1 1 1 1 1 4 3
Potassium Bromide 4 2 4 2 2 1 1 1 1 1 2 2 1
Potassium Carbonate 4 3 2 2 2 1 2 1 1 1 1 2 1 1
Potassium Chlorate 4 2 3 3 1 1 2 1 1 1 1 3 2 1
Potassium Chloride 4 3 3 2 1 1 2 1 1 1 1 2 2 1
Potassium Cyanide 4 4 2 1 2 1 2 1 1 1 1 2 2
Potassium Dichromate 1 2 2 2 1 1 1 1 1 1 2 2 1
Potassium Diphosphate 2 2 1 1 1 1 1 1 1
Potassium Ferricyanide 2 2 3 2 2 1 2 1 1 1 1 2 2 1
Potassium Ferrocyanide 1 2 1 2 2 1 2 1 1 1 1 2 2 1
Potassium Hydroxide 4 4 3 1 1 1 2 1 2 4
Pot. Hypochlorite 4 4 3 4 2 1 4 2 1
Pot. Permanganate 1 2 2 2 2 1 2 2 2
Potassium Sulfate 1 3 2 1 1 1 2 1 1 1 1 2 1 1
Potassium Sulfide 4 4 4 4 2 1 2 1 2 2 1
Propane 1 1 1 1 1 1 1 1 2 1 1 1
Propyl Alcohol 1 1 1 1 1 1 1 3 1 1 1
Pyrogallic Acid 2 2 3 2 2 1 1 1 1 1 2 2
Salad Oil 4 4 4 2 1 1 1 1 1 1
Salicylic Acid 2 2 4 1 2 1 1 1 1 1 2 2
Salt 1 2 3 1 3 1 2 1 1 1 1 1 1 1
Seawater 2 2 3 1 1 1 2 1 1 1 1 1 1 1
Silver Bromide 4 4 4 2 4 1 1 1 1
Silver Chloride 4 4 4 2 4 1 2 1
Silver Nitrate 4 4 4 4 1 1 2 3 1 3 1 2 1 1
Sodium Acetate 1 1 1 1 2 1 2 2 1 2 1 1 1 1
Sodium Aluminate 4 2 1 1 1 1 1 1 1 1 2 2 1
Sodium Bicarbonate 2 2 2 1 1 1 1 1 1 1 1 1 1 1
Sodium Bisulfate 2 3 4 2 2 1 1 1 1 1 1 2 2 1
Sodium Bisulfite 4 4 2 2 1 1 2 1 1 1 1 2 2 2
(continued)
Appendix C 293

Sodium Borate 1
1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Sodium Bromide 4 3 2 2 2 1 2 1 1 1 1 2 2
Sodium Carbonate 4 4 1 1 1 1 1 1 1 1 1 1 1 1
Sodium Chlorate 2 2 2 1 2 1 1 1 1 1 1 2 1
294 Tube Fitter’s Manual

Sodium Chloride 1 2 3 1 3 1 2 1 1 1 1 1 1 1
Sodium Chromate 1 1 1 1 1 1 1 1 1 1 1 1 1
Sodium Cyanide 4 4 1 4 1 1 2 1 1 1 1 1 1 1
Sodium Fluoride 2 4 4 1 2 1 2 1 1 1 1 2 2
Sodium Hydroxide 4 4 2 1 1 1 2 2 3 2 1 2
Sodium Nitrate 1 3 1 1 1 1 2 3 1 1 1 1 1 1
Sodium Perborate 4 4 2 2 1 1 3 1 1 1 2 2
Sodium Peroxide 4 4 1 2 2 1 3 1 1 1 2 2
Sodium Phosphate 4 1 4 1 2 1 2 1 2 1 1 1 1
Sodium Silicate 1 1 1 1 1 1 1 1 1 1 1 2 1
Sodium Sulfate 2 2 2 2 1 1 2 1 1 1 1 2 2 2
Sodium Sulfide 1 3 3 2 2 1 2 1 1 1 1 2 2
Sodium Sulfite 1 4 4 2 1 1 2 2 2 1
Sodium Thiosulfate 2 4 4 1 1 1 1 1 1 1 2 2
Soybean Oil 2 2 3 1 1 1 1 2 1
Stannic Chloride 4 4 4 3 4 1 1 1 1 1 4 2 2
Starch 1 2 3 2 1 1 1 1 1
Steam—212°F 2 1 1 1 1 1 4 3 4 4 1 1 1
Stearic Acid 4 3 3 1 1 1 1 1 3 1 2 2 2
Styrene 1 1 1 1 1 1 4 4 2 1 1
Sulfate—Blk. Liq. 1 4 2 2 2 1 3 3 1 1 1
Sulfate—Grn. Liq. 4 4 2 2 2 1 3 3 1 1 2 2
Sulfate—Whi. Liq. 2 3 3 2 1 3 3 1 1
Sulfur 1 4 2 1 1 1 4 4 2 1
Sulfur Chloride 4 4 4 3 3 1 1 1
Sulfur Dioxide—Dry 1 3 2 2 1 1 3 1 3 1 2 4
Sulfur Dioxide—Wet 4 4 4 4 1 1 2 1
Sulfur—Molten 1 4 2 1 1 1 4 3 4 1
Sulfur Trioxide 2 2 2 2 2 1 2 2
Sulfuric Acid—0–7 % 1 3 4 1 2 1 2 1 1 3 2 2
Sulfuric Acid—20 % 4 3 4 1 4 1 3 1 2 1 4 3
Sulfuric Acid—50 % 4 3 4 4 4 1 3 1 3 4 4 4
Sulfuric Acid—100 % 4 3 2 4 1 1 4 2 4 4 4 4
Sulfurous Acid 2 4 4 4 2 1 3 1 3 3 4 2 1
Tannic Acid 1 1 1 1 1 1 2 1 1 2 1 1 2 1
Tartaric Acid 1 4 4 1 1 1 4 3 1 1 1 1 1 2
Tetraethyl Lead 2 2 3 2 1 1
Toluene 1 1 1 1 1 1 4 4 2 4 1 1 1 1
Tomato Juice 1 3 3 1 1 1 1 1 1
Transformer Oil 1 2 1 1 1 1 1 2 1
Tributyl Phosphate 1 1 1 1 1 1 3 3
Trichloroethylene 1 3 1 1 2 1 4 4 2 4 1 1 2 1
Turpentine 2 1 1 1 1 1 3 1 4 1 1 1 1
Urea 2 2 3 2 2 1 1 2
Varnish 1 1 3 1 1 3 1 1
Appendix C 295

Vegetable Oil 1 4 2 2 1 1 1 1 2 1 1 (continued)

 1. Excellent.

FKM

Steel
2. Good, most conditions.

Brass
316 SS
Delrin®
Titanium
3. Fair, limited life, and

Alloy 400
Alloy 600

Neoprene

PTFE/PFA

Aluminum
Alloy C276
restricted conditions.

Polyethylene
4. Unsatisfactory.

Buna-N (Nitrile)
Vinegar 3 4 4 1 1 1 2 4 4 4 2 1
Water, Boiler Feed 3 3 2 1 1 1
Water, Fresh 1 1 3 1 1 1 1 1 1
296 Tube Fitter’s Manual

Water, Salt 3 3 4 1 2 1 2
Whiskey 3 3 4 3 1 1 2 1 1 1 1
Wine 3 2 4 2 1 1 2 1 1 1 1
Xylene—Dry 1 1 2 1 2 1 4 2 4 1
Zinc Chloride 4 4 4 2 4 1 2 2 1 1 1 2 1 1
Zinc Hydrosulfite 1 2 1 1 1 1 1 1 2
Zinc Sulfate 3 4 4 2 2 1 2 1 1 1 1 2 2 1
NOTE: USE THIS CORROSION CHART WITH CAUTION! See p. 283.
Appendix C 297
Index

A ASTM B163 for, 24, 32

absolute viscosity, 228 ASTM B423 for, 24
ABW. See automatic tube butt standards for, 7
weld fittings alloy 2507, 7, 24, 32, 177
acceptance quality limit (AQL), 12 alloy C-276
Air-Actuated Hydraulic Swaging additional processing for, 8
Unit (AHSU), 88 ASTM B622 for, 24, 31
air flow curves, 249–257 corrosion of, 284–297
air velocity, ID and, 258 standards for, 7
alloy 254, 24, 32 alloy R-405
alloy 400 ASTM B165 for, 31
additional processing for, 8 corrosion of, 284–297
ASTM B165 for, 23–24, 31 aluminum
coefficient of expansion for, additional processing for, 8
143 ASTM B210 for, 23, 27, 30
corrosion of, 284–297 coefficient of expansion for,
for cryogenic service, 147 143
for elevated temperature corrosion of, 284–297
service, 145 for cryogenic service, 147
hardness of, 23–24, 31 for elevated temperature
pressure rating factors, 146 service, 145
standards for, 7 pressure rating factors, 146,
in vacuum systems, 142 220
alloy 600 standards for, 7
additional processing for, 8 tube bending, 53
ASTM B167 for, 24, 31 tube straightening, 45
corrosion of, 284–297 angle, of threads, 194
for cryogenic service, 147 ISO 7/1 and, 198
standards for, 7 for ISO 228/1, 201
alloy 625 for metric parallel threads,
ASTM B444 for, 24, 32 202
standards for, 7 for metric screw threads, 207
alloy 825 for tapered pipe threads, 198
300 Index

for unified screw thread, 200, ASTM B167, 24, 31

204 ASTM B210, 23, 30
ANSI/ASME B1.13M, 202 ASTM B251, 29–30
ANSI B1.20.1, 197 ASTM B338, 24, 31
ANSI B1.20.3, 198 ASTM B423
ANSI B16.5, 172 for alloy 825, 24
ANSI B31.3, 221 for nickel alloy, 32
AQL. See acceptance quality ASTM B444, 24, 32
limit ASTM B468, 24, 31
area conversions, 275 ASTM B622, 24, 31
argon, 129 ASTM B704, 24, 32
arsine, 130 ASTM B729, 24
ASME, N Stamp Program of, 12 ASW. See automatic tube
ASME B16.11, 160 socket weld fittings
ASME B31.1, 219 austenitic stainless steel
ASME B31.3, 219 ASTM A213 for, 28, 32
ASME B31.3-2012, 210 ASTM A249 for, 28
ASTM ASTM A269 for, 28
OD and, 27, 211 ASTM A632 for, 28
surface finish and, 22 ASTM A1016 for, 28
tolerances, 12, 27 chlorides and, 79
wall thickness and, 211 for cryogenic, 147
ASTM A161, 29 ovality tolerance for, 23, 215
ASTM A179, 23, 29 standards for, 28
ASTM A213, 24, 28, 32 stress corrosion cracking of,
ASTM A249, 28 79
ASTM A269, 211, 214 automatic tube butt weld
for alloy 254, 24, 32 fittings (ABW), 162
for austenitic stainless steel, automatic tube socket weld
28 fittings (ASW), 159
for ovality, 21
for stainless steel, 20 B
ASTM A450, 29 back ferrule
ASTM A632, 28 of 316 stainless steel, 8
ASTM A789, 24, 32 colleting action of, 4, 10–11
ASTM A1016, 28 compensating action of, 6
ASTM B68, 29 front ferrule and, 2, 3, 4
ASTM B75, 23, 29–30, 218, 219 gas seal and, 6
ASTM B88, 23, 30, 218, 219 gripping actions of, 11
ASTM B163, 24, 32 radial hinging colleting action
ASTM B165 of, 4, 10–11
for alloy 400, 23–24 sealing actions of, 11
for alloy 400/R-405, 31 silver-plating for, 8
 Index 301

uniform surface hardening for, for polyethylene, 25

10, 74 for polypropylene, 25
for ultra-clean systems, 141
vibration resistance and, 5 C
bakeout, 142 capillary leak. See real leak
bench top tube bender (BTTB), carbide, 10
63–64, 66 carbon-molybdenum steel, 29
bend marks, 54, 55 carbon steel
bend radius, 50 additional processing for, 8
BTTB and, 66 ASTM A179 for, 23
for Micro-Fit, 162 coefficient of expansion for,
minimum straight tube length 143
for, 65 standards for, 7, 29
springback and, 52 tube facing tool for, 72
bleed system, 75, 125 carburization, 10
BM, in ordering number, 8 Celsius temperature conversion
body bevel, 3 table, 277
bored-through fittings, 8–10 chlorides
braided hose, 18 corrosion from, 79, 81, 134
brass in marking pens, 79, 81
coefficient of expansion for, in tapes, 134
143 chromatographs, 170, 183
with copper, 29–30 chromium, in stainless steel, 11
corrosion of, 284–297 cleaning, 141
with stainless steel, 18 for severe service, 129
standards for, 7 tightening and, 154
on tracers, 138 troubleshooting and, 151, 155
British Standard Pipe Parallel. coefficient of expansion
See ISO 228/1 for elastomers, 147
British Standard Pipe Taper. seal integrity, 190
See ISO 7/1 in vacuum systems, 142, 143
BS 21, 199 coefficient of friction, 26
BS EN 10226-1, 199 colleting action, 4, 5, 10
BSPP, 201 compensating action, 4, 6, 144
BT, in ordering number, 9 composite washer seal, 203
BTTB. See bench top tube compressed gases, 129–130
bender concentricity of tubing, 21–22
bulkhead connections, 101–102 coned and threaded fittings
Buna N (C&T), 105–107, 167
corrosion of, 284–297 copper
O-ring, 103 annealing for, 29
burst pressure ASTM B68 for, 29
hydraulic tests for, 187–188 ASTM B75 for, 23, 29
302 Index

ASTM B88 for, 30 OD and, 70, 129

ASTM B251 for, 29–30 troubleshooting and, 150
coefficient of expansion for, decimal equivalents, 276
143 depth marking tool (DMT),
for elevated temperature 78–79, 126
service, 145 DIN 2999, 198
fractional sizes for, 218 dip tubes, 9
metric sizes for, 219 directional marks, 55
ordering of, 23, 218, 219 disassembly/reassembly, 83–85
pressure rating of, 146 expansion loops for, 41
standards for, 29–30 gas leak tests and, 181
tracers for, 131, 138 leak-tight seal with, 10
troubleshooting for, 153 orifice plate fittings and, 171
working pressure for, 219 performance testing, 182–184
corrosion for severe service, 144
of austenitic stainless steel, VCO O-ring face seal fittings
79, 81 for, 164
charts for, 283–297 DMT. See depth marking tool
from chlorides, 79, 123, 134 Dowtherm, 131
microbial influenced, 153 dynamic seals, 229–230
resistance to, 25, 26, 74
from steam, 130, 190 E
corrosive gases, 129 elastomers
crest, of threads, 194 in cryogenic service, 147
ISO 7/1 and, 198 O-rings and, 103
for ISO 228/1, 201 in vacuum systems, 142
for metric parallel threads, elbows, 7, 103, 177, 182
202 Electric tube bender (ETB), 64
for metric screw threads, 207 elements, table of, 271–273
in parallel threads, 200 elevated temperature service,
for unified screw thread, 200, 145–146, 155, 220–221
204 EN 1057, 219
crosses, 7, 178, 182 end connections with tapered
cryogenic service, 146–147, 189 ends, 108–109
energy management, 230–231
C&T. See coned and threaded environmental contamination
fittings from outboard real leaks, 225
performance testing for, 174
D erosion from steam, 130, 190
deburring, 70–72 ETB. See Electric tube bender
in high-pressure gas systems, expansion bends for tracer
129, 130 tubing, 135
ID and, 70, 72, 129 explosive gases, 130
 Index 303

extrapolation, for performance for pipe wall thickness,

testing, 175–176 278–279
for welded stainless steel,
F 214–215
face seal fittings, 164–165 front ferrule, 3, 4, 5, 6
Fahrenheit temperature sealing actions of, 11
conversion table, 277 silver-plating for, 8
ferritic alloy steel, 28, 32 for ultra-clean systems, 141
ferrules. See also back ferrule; for vacuum systems, 141
front ferrule
disassembly/reassembly and, G
144 galling, 141–143
testing of, 183 disassembly/reassembly
gas service and, 19 testing and, 183
machined ferrule end in NPTF, 198
connection, 95–96 Silver Goop and, 155
preswaging tools for, 86–88 silver plated tube fitting nut
silver-plated, 8, 129, 141, and, 11
142 SWAK and, 111
wall thickness and, 18 of tapered pipe threads, 196
Five-Roll Straightener, 47 troubleshooting and, 151,
FKM O-ring, 102, 103 155
FK Series, 103–104 gap inspection gauge, 12–14,
flammable gases, 129, 130 81–83
flange adapters, 172 for high-pressure gas service,
flank, of threads, 194 129
in parallel threads, 200 positioning of, 127
flare joint, leakage at, 152 quality assurance and, 12
flat grid method, 140 safety with, 75
flow rate conversions, 261 tightening and, 14, 125
fluorinated-base, with PTFE, 8 gases, specific gravity of, 270
forced tube entry into fittings, gasket to seal, 204
18 gas leak tests, 179–181
fractional sizes, 213 gas seal, 5–6
conversion of, 276
for copper, 218 gas service
for gas service, 19, 128 pressure ratings for, 212–221
for ID cross-sectional area, tubing for, 19, 128, 213
278–279 wall thickness for, 19, 129,
metric sizes and, 276 212, 213
for parallel threads, 200 gas systems, calculations for,
for seamless stainless steel, 235–258
214 gas tungsten arc welding
304 Index

(GTAW), 163 heat transfer fluids, 140, 189

gaugeable chromatograph and helium, 19, 129, 182
column end fittings, 170 helium leak detectors, 142,
gaugeable preswage tool. 179, 181, 227
See gap inspection gauge high pressure (HP)
gaugeable shoulder, 12 assembly in, 77
gauge protectors. See snubber C&T for, 167
fittings DMT and, 126
glass tubing, 154 gas systems, 128–131
Goop, 106 heat transfer fluids for, 140
gripping actions, of ferrules, 11 IPT Series and, 104–109
groove cutter, 167 for 1 in. and smaller tubing,
GTAW. See gas tungsten arc 126–129
welding high safety factor systems,
126–129
H horizontal tracers, 132, 133–134
hacksaw, 69–70, 150 hose connector (HC), 166
halides, 134 HP. See high pressure
halogen torch, 180 HTB. See hand tube bender
hand tube bender (HTB), hydraulic burst tests, 187–188
62–63 hydraulic impulse tests, 187
hardness, 11 hydraulic swaging, 88–90
of alloy 254, 24 hydrogen, 19, 129
of alloy 400, 23–24, 31
of alloy 600, 24 I
of alloy 825, 24 ID. See inside diameter
of alloy R-405, 31 impulse, proper support of, 38
annealing for, 23 impulse, 144, 187
of bored-through fittings, 10 inboard real leaks, 225
compensating action and, 6 independent test laboratories,
in high-pressure gas systems, 175
129 inert gases, 129
maximum, 23 inserts
in purchase orders, 22 flare joints and, 152
for alloy 2507, 24, 32 for polyethylene, 153
in selecting quality tubing, with PVC, 18, 166
21–22 safety with, 125
for stainless steel, 22 serrated, 26, 166
tolerances with, 13 with Tygon, 18
troubleshooting and, 151–154 inside diameter (ID), 22, 154
HC. See hose connector air velocity and, 258
heat exchanger tee, 9 for austenitic stainless steel,
heat loss, 135–136 28
 Index 305

deburring and, 70, 72, 129 energy management and,

determination of, 234 230–232
fractional sizes for, 278–279 formula for, 228
mean velocity and, 248 from loosening, 116
metric sizes for, 280–282 PVC and, 27
pressure ratings and, from seals, 229
210–211 in ultra-clean systems, 141
wall thickness and, 278 leak detectors
insulation, 134, 135, 136, 138 helium, 142, 179, 181, 227
intermix/interchange, 15, 91 Snoop, 137, 180, 227–228
leak-tight seal and, 91 soap and water as, 227
performance testing for, 191 leak rate, 224, 228–229
safety with, 75, 125 for Ultra-Torr, 165
troubleshooting and, leak tests, 137, 165, 174,
151–154 224–228
internal real leaks, 225 gas, 180–181
IPT Series, 104–109 leak-tight seal, 2, 4, 95
ISO 7/1 (British Standard Pipe with front ferrule, 6
Taper), 108–109, 198–199 with disassembly/reassembly,
ISO 68-1, 202 10
ISO 228/1 (British Standard on high-pressure gas
Pipe Parallel), 201–202 systems, 129
ISO 261. See metric screw intermix/interchange and, 91
threads with JTC, 168
with medium-pressure tube
J fittings, 103
jacketed tracers, 132 in vacuum systems, 141
Jacketed tube connector (JTC), liquid flow, calculations for,
168 234–235
JIS B0202, 201, 202 liquid metals, 189
JIS B0203, 199 liquids, specific gravity of, 269
JIS B0205, 202 live-loading, 5
JTC. See Jacketed tube loop method, for spiral-
connector wrapped tracers, 139

L loosening
laminar flow, 249 bleed system and, 75, 125
laminated tubing, 18 leakage from, 116, 125
lap joint connectors, 172 low-carbon steel, 29
leakage low-chloride marking pens, 79
causes of, 224 lubricants
costs of, 223–232 galling and, 155
from damaged tubing, 35 Goop as, 106
306 Index

Silver Goop as, 131, 155 for copper, 219

SWAK as, 110, 151, 197, 222 fractional sizes and, 276
troubleshooting and, 151 gas service tables, 213
tungsten disulfide, 8 for OD, wall, ID cross-
for vacuum systems, 141, 143 sectional area, 280–282
for parallel threads, 200
M for seamless stainless steel,
M200 power supply, for welding 216–217
system, 163 for wall thickness, 280–282
machined ferrule end MHSU. See multihead hydraulic
connection, 95–96 swaging unit
marking pens, 79 microbial influenced corrosion
mass spectrometer, helium leak (MIC), 153
detectors and, 180, 181 Micro-Fit (miniature tube butt
materials, 7, 21–27. weld), 72, 161, 162
See also specific materials MP. See medium pressure
for bored-through fittings, 10 MPW. See pipe to tube weld
compensating action and, 6 MS straight thread ports,
with corrosive gases, 129 101–102
for elevated temperature MS straight thread positionable
service, 145 elbows, 103
heat transfer fluids and, 140 MS straight thread positionable
for performance testing, 177 tees, 103
safety with, 125 MTW. See tube to tube weld
springback and, 52 multihead hydraulic swaging
for steam, 131 unit (MHSU), 10, 89–90, 152
maximum allowable pressure, multiple external tube tracer,
211 132
mean velocity, ID and, 248 multiwall tubing, 18
measure-bend method, 56–58
mechanical leak. See real leak N
medium pressure (MP) National Pipe Tapered (NPT),
C&T for, 167 108–109, 196
FK Series, 103–104 National Pipe Tapered Dryseal
IPT Series, 104–109 (NPTF), 198
metal gasket seal, 203 neoprene, corrosion of, 284–297
metal-to-metal seal, 202–203, nickel alloys, 11, 31, 32
224 NPTF and, 198
methane, 129 tube facing tool for, 72
metric screw threads (ISO 261), nitrogen, 19
202–204, 207–208 NPT. See National Pipe Tapered
metric sizes, 74–75 NPTF. See National Pipe
conversion of, 276 Tapered Dryseal
 Index 307

N Stamp Program, of ASME, 12 deburring and, 70, 129

for flat grid tracers, 140
O fractional sizes for, 278–279
OD. See outer diameter gas service and, 19
offset bends, 51–52, 56 in high-pressure gas systems,
180° bends, 49–50, 57–58 128
ordering, 23–27 for horizontal tracers, 133
of copper, 218, 219 JTC of, 168
of plastic, 24–27 tolerances for low-carbon
purchase order limits and, steel, 29
22–23 metric sizes for, 280–282
specifications and, 18–32 minimum straight tube length
of stainless steel, 215, 217 for, 65, 66
orifice leak. See real leak tolerances for polyethylene, 25
orifice plate fittings, 171 tolerances for polypropylene, 26
O-rings pressure drop and, 235–247
Buna N, 103 pressure ratings and, 210–211
deburring and, 70 seals on, 18
dimensional table for, 265 tolerances for stainless steel,
disadvantages, 103 23
ISO 228/1 and, 202 for steam, 131
in JTC, 168 steam traps and, 136
metric screw threads and, 208 tolerances for titanium, 24
seal fittings for, 103 tolerances with, 12–13
for straight fittings, 103 troubleshooting and, 150
in Ultra-Torr Vacuum Fittings, for vacuum systems, 142
165 vibration resistance and, 143
unified screw thread and, 205 wall thickness and, 278
VCO O-ring face seal fittings, welds on, 22
164–165 outgassing, 226
outboard real leaks, 225
outer diameter (OD), 21–22, 217 ovality
tolerances for alloy 400, 24, ASTM A269 for, 21
31 safety with, 126
tolerances for alloy 600, 24 in selecting quality tubing,
tolerances for alloy C-276, 21–22
24, 31 tolerances for, 13
tolerances for alloy R-405, 31 for austenitic stainless steel,
tolerances ASTM and, 27, 211 23, 215
tolerances for austenitic oxidant gases, 129
stainless steel, 28 oxidizers, 111
bend radius for, 50
tolerances for copper, 30 P
308 Index

parallel threads, 200–208 PFA, 7, 26, 154, 167

fractional sizes for, 200 corrosion of, 284–297
ISO 228/1, 201–202 phosphine, 130
metric sizes with, 200, pipe end pressure ratings,
202–204 221–222
thread sealants for, 202 pipe socket weld fittings (PSW),
performance testing, 173–191 160
configurations for, 177–178 pipe threads, 196–208.
crosses for, 178 See also tapered pipe threads
disassembly/reassembly, parallel, 200–208
182–184 sealants for, 107
elbows for, 178 troubleshooting and, 151
for environmental pipe to tube weld (MPW), 160
contamination, 174 pitch, of threads, 194
extrapolation for, 175–176 ISO 7/1 and, 198
gas leak tests, 179–181 for metric screw threads, 207
hydraulic burst tests, 187–189 for tapered pipe threads, 198
hydraulic impulse tests, 187 for unified screw thread, 200
implementation of, 179–191 plastics, 25–27, 166–167.
independent test laboratories See also specific plastics
for, 175 in cryogenic service, 146
for intermix/interchange, 191 in vacuum systems, 142
for leak testing, 174 polyethylene, 25, 153, 167
materials for, 177 corrosion of, 284–297
for operational reliability, 174 polypropylene, 25–26, 167
planning for, 174–179 port connector, 97–99
for pressure differential, 174 pressure conversions, 259, 260
quality control in, 179 pressure cycling, 144
rotary flex vibration tests, pressure damping, 169.
184–185 See also snubber fittings
rotation tests, 186
of seamless stainless steel, pressure differential,
176–177 performance testing for, 174
simulated field-use conditions pressure drop, 235–247
for, 176 for 1/8 in. OD tubing, 239, 249
statistical sampling for, 175 for 1/4 in. OD tubing, 240, 250
tees for, 178 for 3/8 in. OD tubing, 241, 251
tensile pull tests, 186 for 1/2 in. OD tubing, 242, 252
thermal cycling tests, 189 for 3/4 in. OD tubing, 243,
vacuum tests, 181–182 253
of welded stainless steel, for 1 in. OD tubing, 244, 254
176 for 1 1/4 in. OD tubing, 245,
permeation, 226 255
 Index 309

for 1 1/2 in. OD tubing, 246, for NPT, 197

256 for tapered pipe threads, 196,
for 2 in. OD tubing, 247, 257 222
pressure rating, 209–222. troubleshooting and, 151
See also working pressure for vacuum systems, 143
with bored-through fittings, 9 PTRs. See Product Test Reports
for elevated temperature purchase orders, 22–23
service, 145–146, 220–221 PVC, 18, 26–27, 166
for gas service, 212–221
heat transfer fluids and, 140 Q
ID and, 210–211 quality assurance, 12, 179
OD and, 210–211
for PFA, 154 R
pipe end pressure rating, radial hinging colleting action,
221–222 10–11
for seamless stainless steel, radius. See bend radius
211 REAL COOL SNOOP leak
wall thickness and, 210–211 detector, 137
preswaging tools, 86–88, 152 real leak, 225
process equipment, tracers on, reassembly. See disassembly/
138–140 reassembly
process lines reducers, 9, 75, 125
multiple tracers on, 134–135 reference mark, for tube
tracers on, 132, 133–134 bending, 54, 55
Product Test Reports (PTRs), reinforced soft PVC tubing,
143, 181, 182, 184, 185, 186, 26–27
187, 188, 189, 190 residual elasticity, 5
PSW. See pipe socket weld ring type joint (RTJ), 172
fittings root, of threads, 194
PTFE, 26, 142 ISO 7/1 and, 198
corrosion of, 284–297 for ISO 228/1, 201
fluorinated-base with, 8 for metric parallel threads,
permeation from, 226 202
polyethylene and, 153 for metric screw threads, 207
special purpose fittings for, in NPTF, 198
167 in parallel threads, 200
standards for, 7 for unified screw thread, 200,
troubleshooting for, 154 204
for vacuum systems, 142 rotary flex vibration tests,
PTFE-free pipe thread sealant, 184–185
111 rotation tests, 186
PTFE tape, 110, 111 RT, 108–109, 198
application of, 116–121 RTJ. See ring type joint
310 Index

rupture discs, 167 144

DMT and, 127–129
S elevated temperature service
SAE J524b, 29 in, 145–146
SAE J1926/1, 206 heat transfer fluids for, 140
SAE/MS Internal Straight impulse in, 144
Thread Boss, 205 leak test for, 137
SAE straight thread ports, safety with, 125–126
101–102 shock in, 144–145
SAE straight thread steam and, 130–131
positionable elbows, 103 tracers in, 131–137
SAE straight thread ultra-clean systems and, 141
positionable tees, 103 vacuum systems and,
safety, 75–77 141–143
with severe service, 125–126 vibration resistance in, 143
wire drilled fittings for, 171 shock, 144–145, 169, 187, 190
SAT 12, 13 Silver Goop high-temperature
saturated steam, properties of, thread lubricant, 131, 155
266–267 silver-plated ferrules, 8, 129,
Saybolt universal seconds 141, 142
(SUS), 169 single external tube tracer, 132
scratch marks, 113, 117 sniffer test, 180
seals. See also leak-tight seal; Snoop leak detector, 137, 180,
dynamic seals, 229–230 227–228
face seal fittings, 164–165 snubber fittings, 169–170
ferrules and, 11 soap and water, as leak
gas seals, 5–6 detector, 227
integrity of, 190 soft PVC, 26–27, 166
leakage from, 229 space simulation, 189
on OD, 18 special purpose fittings,
static, 229 157–172
temperature and, 190 ABW, 162
vacuum-tight, 165 ASW, 159
watertight, 168 C&T, 105–107, 167
seamless stainless steel, face seal fittings, 164–165
176–177, 211, 214–217 flange adapters, 172
sequential-gripping, 10 gaugeable chromatograph
serrated inserts, 26 and column end fittings, 170
severe service, 123–147 JTC, 168
compressed gases and, lap joint connectors, 172
129–130 Micro-Fit, 72, 161, 162
cryogenic service and, 146–147 MPW, 160
disassembly/reassembly for, MTW, 161
 Index 311

orifice plate fittings, 171 in coils, 47

for PFA, 167 corrosion of, 284–297
for plastic, 166–167 for cryogenic service, 147
for polyethylene, 167 flare joints and, 152
for polypropylene, 167 hardness restrictions for, 23
PSW, 160 for high-pressure gas
for PTFE, 167 systems, 129
snubber fittings, 169–170 low-chloride marking pens
for soft PVC, 166 for, 79
TBW, 161 MHSU for, 90
TSW, 159 for MTW, 161
for Tygon, 166 nickel in, 11
Ultra-Torr Vacuum Fittings, NPTF and, 198
154, 165 OD of, 23
VCO O-ring face seal fittings, ordering of, 215, 217
164–165 seamless, 176–177, 211,
VCR metal gasket face seal 214–217
fittings, 164 standards for, 7, 28
welding system and, 163 steam and, 130
for welds, 158–162 304 stainless steel, 145, 146
wire drilled fittings, 171 316 stainless steel, 7, 8, 72,
specific gravity 145, 146, 161
of gases, 270 tracers on, 134
of liquids, 269 troubleshooting and, 151
of water, 268 tube facing tool for, 72
spiral-wrapped tracers, 132, for vacuum systems, 141
139 vibration resistance for, 143
spring action, 5 welded, 176, 214–215, 216
springback, 52–53 static seals, 229
Squiglia, N. L., 12 Statistical Control of Processes,
stainless steel 12
annealing for, 23 Statistical Quality Control, 12
ASTM A269 for, 20 statistical sampling, for
ASTM A1016 for, 28 performance testing, 175
austenitic, 23, 28, 32, 79, 123, steam
215 corrosion from, 130, 190
brass with, 18 high-pressure gas systems
carbon in, 11 and, 130–131
additional processing for, 8 properties of, 266–267
ASTM A179 for, 23 severe service and, 130–131
coefficient of expansion for, thermal cycling tests for, 189
143 tightening and, 190
chromium in, 11 tracers for, 131
312 Index

steam traps, 136–137, 140 halides in, 134

straightening techniques, 45–47 tapered pipe threads, 196–199
straight tube length mark, 63 galling of, 196
straight tube length minimum, OD for, 198
63–66 PTFE tape for, 222
strainer, for steam traps, 136 SWAK pipe thread sealant for,
stretch, 53–54 222
stroke, 6 thread sealants for, 125, 196,
surface finish, 18 222
for ABW, 162 tolerances for, 196
ASTM and, 22 TBW. See tube butt weld
disassembly/reassembly fittings
testing and, 183–184 tees, 7, 103
for high-pressure gas disassembly/reassembly
systems, 129, 130 testing and, 182
leak rate and, 229 heat exchanger, 9
safety with, 125–126 for performance testing, 178
in selecting quality tubing, union, 159, 162
21–22 temperature
for TBW, 161 bored-through fittings and, 10
tolerances for, in purchases conversion formulas for, 277
orders, 22 copper and, 153
surface hardening, 13 cycling, 145, 153
for back ferrule, 10 elevated temperature service,
SUS. See Saybolt universal 145–146, 155, 220–221
seconds flammable gases and, 129
The Swagelok Limited Lifetime PFA and, 26
Warranty, 91 polypropylene and, 26
swaging pressure drop and, 249
AHSU, 88 seals and, 190
hydraulic, 88–90 specific gravity and, 268
MHSU, 10, 89–90, 152 steam and, 131
preswaging tools, 86–88, 152 tracers and, 135
SWAK pipe thread sealant, 110, VCO O-ring face seal fittings
111, 116, 151, 197, 222 and, 164
system configuration tools tensile pull tests, 186
machined ferrule end tensile strength, in elevated
connection, 95–96 temperature service,
tube adapter ends, 99–100 145–146
thermal cycling tests, 189
T Therminol, 131
table of elements, 271–273 thermocouples, 8, 9
tape. See also PTFE tape threads, 193–208. See also
 Index 313

specific types assembly using, 111–121

angle of, 194 for high-temperature service,
ISO 7/1 and, 198 155
for ISO 228/1, 201 for parallel threads, 202
for metric parallel threads, safety with, 125
202 SWAK, 110, 111, 116, 151,
for metric screw threads, 207 197, 222
for tapered pipe threads, 198 for tapered pipe threads, 125,
for unified screw thread, 196, 222
200, 204 troubleshooting and, 151
crest of, 194 304 stainless steel
ISO 7/1 and, 198 for elevated temperature
for ISO 228/1, 201 service, 145
for metric parallel threads, pressure rating of, 146
202 316 stainless steel
for metric screw threads, 207 back ferrules of, 8
in parallel threads, 200 corrosion of, 284–297
for unified screw thread, for elevated temperature
200, 204 service, 145
flank of, 194 for Micro-Fit, 161
in parallel threads, 200 for MTW, 161
pipe end pressure ratings pressure rating of, 146
and, 221 standards for, 7
pitch of, 194 tube facing tool for, 72
ISO 7/1 and, 198 TIG. See tungsten inert gas
for metric screw threads, tightening, 3, 75, 115, 154
207 gap inspection gauge and,
for tapered pipe threads, 198 14, 125
for unified screw thread, 200 gas leak tests and, 179
root of, 194 steam and, 190
ISO 7/1 and, 198 for Ultra-Torr Vacuum Fittings,
for ISO 228/1, 201 165
for metric parallel threads, titanium, 7, 8, 24, 31, 72, 147
202 corrosion of, 284–297
for metric screw threads, tolerances
207 importance of, 12–13
in NPTF, 198 for OD
in parallel threads, 200 for alloy 400/R-405, 31
for unified screw thread, for alloy C-276, 31
200, 204 ASTM and, 27
unified screw thread, for tubing, 217
200–201, 203–204 for ovality, for austenitic
thread sealants, 107, 109–121 stainless steel, 23
314 Index

for surface finish, in 180° bends, 49–50, 57–58

purchases orders, 22 straight tube length minimum
for tapered pipe threads, 196 for, 64–67
troubleshooting and, 150 tracers and, 135
for wall thickness training for, 67
for alloy 825, 24 wall thickness and, 59
for copper, 29 work hardening from, 59
torque, 11, 102, 107, 115, 121, tube butt weld fittings (TBW),
186, 194 161
toxic gases, 130 tube cutters, 67–69
tracers tube facing tools, 72–73
annealing and, 131 tube grip, 4–5
brass on, 138 tube socket weld fittings (TSW),
for copper, 138 159
expansion bends and, 135 tube to tube weld (MTW), 161
insulation with, 134, 138 tubing. See also specific
on process equipment, properties, processes, and
138–140 types
on process lines, 132, advantages over pipes,
133–134 42–44
selection criteria for, 135–136 bulkhead connections for,
in severe service, 131–137 101–103
on stainless steel, 134 deburring of, 70–72, 129, 130,
for steam, 131 150
wall thickness and, 131 fractional sizes for, 213
troubleshooting, 149–155 for gas service, 19, 128, 213
galling and, 151, 155 handling of, 35
intermix/interchange and, 151 impulse to, 144
for PTFE, 154 installation of, 33–118
wall thickness and, 151 leakage from, 224
true leak. See real leak metric sizes for, 213
TSW. See tube socket weld OD tolerances for, 217
fittings preparation of, 67–72
tube adapter ends, 92–95, selection and specification of,
99–101 20–22
tube benders, 61–64 shock to, 144–145
tube bending, 47–67 springback of, 52–53
defects with, 60–61 standards for, 27–32
near fittings, 65–66 straightening techniques for,
marks for, 54–55 45–47
measure-bend method for, stretch of, 53–54
56–58 system layout for, 36–42
offset bends, 51–52, 56 uncoiling of, 45–47
 Index 315

tungsten disulfide lubricant, 8 vise clamp block, 62

tungsten inert gas (TIG), 163 volume conversions, 274
turbulent flow, 249
6-Moly stainless steel, 7 W
two channel pipe tracers, 132 wall thickness, 21–22, 151
Tygon, 18, 166 ASTM and, 211
ASW and, 159
U Birmingham wire gauge table
ultra-clean systems, 141 and, 264
ultrahigh-purity systems, 161, compensating action and, 6
162, 164 in elevated temperature
Ultra-Torr Vacuum Fittings, 142, service, 146
154, 165 ferrules and, 18
unified screw thread, 200–201, fractional sizes for, 278–279
204–208 for gas service, 19, 129, 212, 213
unions, disassembly/ heat transfer fluids and, 140
reassembly testing and, 182 in high-pressure gas systems,
union tee, 159, 162 128
UNS N06219, 32 ID and, 278
UNS N06625, 32 metric sizes for, 280–282
UNS N06852, 32 for MHSU, 90
UNS N08825, 32 OD and, 278
performance and, 11
V pipe end pressure ratings
Vac-Goop lubricant, 143 and, 221
vacuum arc re-melt (VAR), pressure ratings and, 210–211
161 PSW and, 160
vacuum systems, 141–143 seal integrity, 190
vacuum tests, 181–182 springback and, 52
vacuum-tight seal, 165 for steam, 131
valve manifolds, 135 tolerances for, 13
valve seats, 70, 225 for alloy 825, 24
VAR. See vacuum arc re-melt for copper, 29
VCO fittings, 129, 142 tracers and, 131
VCO O-ring face seal fittings, tube bending and, 59
164–165 warranty, 91
VCR fittings, 129, 142 water, specific gravity of, 268
VCR metal gasket face seal water conditioning equipment,
fittings, 164 140
vertical tracers, 132 watertight seal, 168
vibration resistance, 5, 103, welded stainless steel, 176,
143, 167, 184–185 214–215, 216
virtual leaks, 226 welding system, 163
316 Index

welds
flare joints and, 152
on OD, 22
in selecting quality tubing, 22
special fittings for, 158–162
in vacuum systems, 142
wire drilled fittings, 171
work hardening, 59
working pressure
for copper, 218
for C&T, 167
for elevated temperatures,
221
hydraulic burst tests and,188
hydraulic impulse tests and, 187
performance and, 11
for PFA, 26, 167
for polyethylene, 25
for polypropylene, 25–26
for seamless stainless steel,
214–217
for soft PVC, 166
for welded stainless steel,
214–217

Z
Zero Acceptance Number
Sampling Plans (Squiglia), 12

MS-13-03