Engineering Standard

SAES-L-109 13 October 2012

Selection of Flanges, Stud Bolts and Gaskets
Document Responsibility: Piping Standards Committee

Saudi Aramco DeskTop Standards

Table of Contents

1 Scope............................................................. 2
2 Conflicts and Deviations................................. 2
3 References..................................................... 2
4 Definitions....................................................... 4
5 General Requirements................................... 4
6 Flange Type Selection and Limitations.......... 5
7 Flange Dimensional Requirements................ 7
8 Flange Facings............................................... 8
9 Bore of Welding Neck Flanges....................... 9
10 Flange Material Specifications....................... 9
11 Spectacle Plates Blinds and Blanks............. 11
12 Gaskets........................................................ 12
13 Bolting.......................................................... 15

Previous Issue: 28 April 2009 Next Planned Update: 28 April 2014

Revised paragraphs are indicated in the right margin Page 1 of 16
Primary contact: Nasri, Nadhir Ibrahim on 966-3-8760162

Copyright©Saudi Aramco 2012. All rights reserved.

Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

1 Scope

1.1 This standard defines mandatory requirements governing the selection of

metallic pipe flanges (hereinafter called “flanges”), gaskets, and stud bolts for
pressure piping within the scope of SAES-L-100.

1.2 This standard supplements ASME B31.1, ASME B31.3, ASME B31.4 and
ASME B31.8 codes.

2 Conflicts and Deviations

2.1 Any conflicts between this standard and other applicable Saudi Aramco
Engineering Standards (SAESs), Materials System Specifications (SAMSSs),
Standard Drawings (SASDs), or industry standards, codes, and forms shall be
resolved in writing by the Company or Buyer Representative through the
Manager, Consulting Services Department of Saudi Aramco, Dhahran.

2.2 Direct all requests to deviate from this standard in writing to the Company or
Buyer Representative, who shall follow internal company procedure SAEP-302
and forward such requests to the Manager, Consulting Services Department of
Saudi Aramco, Dhahran.

3 References

The selection of material and equipment, and the design, construction, maintenance, and
repair of equipment and facilities covered by this standard shall comply with the latest
edition of the references listed below, unless otherwise noted.

3.1 Saudi Aramco References

Saudi Aramco Engineering Procedure

SAEP-302 Instructions for Obtaining a Waiver of a Mandatory
Saudi Aramco Engineering Requirement

Saudi Aramco Engineering Standards

SAES-J-100 Process Flow Metering
SAES-L-100 Applicable Codes and Standards for Pressure
Piping Systems
SAES-L-101 Regulated Vendor List for Pipes, Fittings and
Gaskets
SAES-L-110 Limitations on Pipe Joints and Components

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

Saudi Aramco Materials System Specifications

02-SAMSS-011 Forged Steel Weld Neck Flanges for Low and
Intermediate Temperatures
09-SAMSS-107 Qualification Requirements and Application of
Composite Fluropolymer/Ceramic Coatings to
Fasteners

Saudi Aramco Standard Drawings

AE-036438 Lap Joint Flanges, 54”-60” NPS, Class 300 RJ
AC-036443 Lap Joint Flanges, 26”-48” NPS, Class 600 RJ
AC-036486 Lap Joint Flanges, 26”-48” NPS, Class 300 RJ
AD-036630 Installation of Jack Screws for Flanged Joints
AD-036631 Spectacle Pl. Bld/Spacer, Class 125 Cast Iron
Flanges FF
AD-036633 Spectacle Pl. Bld/Spacer, Class 150 RF
AD-036636 Spectacle Pl. Bld/Spacer for Class 600 RF
AD-036731 Spectacle Pl. Bld/Spacer for Class 250 RFCI and
CL300 RF
AD-036734 Spectacle Pl. Bld/Spacer for Class 600 RJ
AD-036735 Spectacle Pl. Bld/Spacer for Class 900 RJ
AD-036736 Spectacle Pl. Bld/Spacer for Class 1500 RJ
AA-036792 Swivel Ring Flanges, 8”-48” NPS, Class 300-1500
RJ

3.2 Industry Codes and Standards

American Petroleum Institute

API SPEC 6A Specification for Wellhead and Christmas Tree
Equipment

American Society of Mechanical Engineers

ASME B16.5 Pipe Flanges and Flanged Fittings
ASME B16.20 Ring Joint Gaskets and Grooves for Steel Pipe
Flanges
ASME B16.21 Nonmetallic Flat Gaskets for Pipe Flanges
ASME B16.25 Buttwelding Ends

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

ASME B16.36 Orifice Flanges

ASME B16.47 Large Diameter Flanges
ASME B31.1 Power Piping
ASME B31.3 Process Piping
ASME B31.4 Liquid Transportation Systems for Hydrocarbons,
Liquid Petroleum Gas, Anhydrous Ammonia, and
Alcohols
ASME B31.8 Gas Transmission and Distribution Piping Systems
ASME SEC VIII D1 Boiler and Pressure Vessel Code

American Society for Testing and Materials

ASTM A193 Standard Specification for Alloy-Steel and Stainless
Steel Bolting Materials for High Temperature
Service
ASTM D1418 Standard Practice for Rubber and Rubber Latices -
Nomenclature

Norsok Standards
Norsok Standard L-005 Compact Flanged Connections

4 Definitions

Normal Fluid Service per ASME B31.3.

Category D Fluid Service per ASME B31.3.

5 General Requirements

5.1 Flanges that are not covered by any Saudi Aramco standards or the referenced
industry standards shall be designed in accordance with ASME SEC VIII D1,
Appendix 2; and ASME SEC VIII D1 Section UG-34 for blind flanges.
Commentary Notes:

The design and the dimensions of non-standards ring-joint facings shall be

reviewed by chairman of the piping standard committee. The dimensions shall be
compatible to the selected gaskets.

5.2 Use of components which requires special analysis or proof testing

(e.g., ASME B31.3, paragraph 304.7.2) shall be subject to review and approval
by the Chairman of the Piping Standards Committee in CSD prior to
specification and procurement.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

5.3 Flanges, stud bolts and gaskets shall be procured from approved manufacturers
per the requirements of SAES-L-101 and the SAP list.

5.4 Insulating joints shall comply with the mechanical requirements of this standard.
They shall be installed as required by the Cathodic Protection Standards for
pipelines or for Stray Current Protection on loading lines.

5.5 Orifice flanges shall comply with ASME B16.36 and SAES-J-100.

5.6 Jackscrews shall be used to facilitate flange separation for maintenance.

When flange separators are used, jackscrews are not required.

5.6.1 Flanges equipped with jackscrews shall be designed in accordance with

Saudi Aramco Standard Drawing AD-036630 or similar approved
design.

5.6.2 For orifice flanges, jackscrews shall be installed at 3 and 9 o'clock

positions.
Commentary Notes:

Joint assemblies which often require frequent separation include orifice

plates, spectacle plates, spacers, screens, and drop-out spools.

5.7 Pipe joints shall be according to ASME B16.25 and SAES-L-110. The flange
welding ends shall be according to applicable ASME/API standards.

6 Flange Type Selection and Limitations

6.1 Weld Neck Flanges

Weld neck flanges should be the primary selection for flanged joints in metallic
piping systems of 2-inch NPS and larger.

6.2 Slip-on Flanges

6.2.1 Slip-on flanges are allowed only for category D services.

6.2.2 Slip-on flanges and reducing slip-on flanges shall not be used in the
following services:
 Flange sizes 20 inches and larger
 Severe cyclic conditions
 Piping system subject to mechanical vibration.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

6.2.3 Slip-on flanges are required to be double-welded. The flange sealing

face shall be free from scratches, weld burns, etc.
Commentary Note:

A double-welded slip-on flange has a weld between the pipe and the
flange hub and between the pipe and the bore of the flange.

6.2.4 Slip-on flanges shall not be fabricated from blind flanges.

6.3 Lap-joint Flanges

The use of lap-joint flanges shall be avoided and subject to the following
limitations and conditions:

6.3.1 Lap-joint flanges shall not be used for severe cyclic conditions or in
areas subject to high mechanical vibration.

6.3.2 Lap-joint flanges are allowed for:

 Easy alignment of bolt holes

 Special applications to avoid welding dissimilar metals where the

pipe stub-end is made from high alloy material and the flange body
is made from carbon steel.

6.3.3 The lapped flange and stub-end design shall be in accordance with
ASME SEC VIII D1, Appendix-2.

6.3.4 Lapped flange shall be in accordance with Standard Drawings

AE-036438, AC-036443, and AC-036486 for sizes larger than
24-inch NPS.

6.4 Swivel ring flanges

Swivel ring flanges for underwater pipe tie-in shall be in accordance with Saudi
Aramco Standard Drawing AA-036792 or, if proprietary, in accordance with
ASME SEC VIII D1, Appendix 2.

6.5 Ball swivel flanges

The ball swivel flanges is not permitted.

6.6 Compact flanged connections

Compact flanged connections, which are tapered flat face with self-energized
ring gasket, designed and fabricated in accordance with Norsok Standard L-005

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

are acceptable for offshore platforms.

6.7 Clamp-type flanges

Clamp-type flanges (connectors) shall conform to API SPEC 6A or shall be

proprietary connectors of a design based on ASME SEC VIII and approved by
the Chairman, Piping Standards Committee.

6.8 The following flange classes shall not be used:

6.8.1 ASME Class 400 carbon steel flanges for sizes smaller than 30-inch.

6.8.2 ASME Class 75 for any size and material.

6.9 The use of regular blind flanges tapped with smaller pipe is permitted provided
that they meet the size ratio requirements addressed in Table 1.

Table 1 - Maximum Size for the Allowed Bore in the Blind Flanges
1 Maximum NPS for
Size of NPS Flanges 2
Tapped Pipe
4” 1½”
6” 2”
8”-14 3”
16” and larger 4”

Notes:
1. The bore shall be at the center of the blind flanges.
2. The pipe branch shall be integrally reinforced such as
welding boss or weldolet.

7 Flange Dimensional Requirements

7.1 Dimensions of 24 inch flanges and smaller shall comply where applicable with
ASME B16.5.

7.2 Dimensions of 26 inch flanges and larger shall comply where applicable with
ASME B16.47 series A.
Commentary Note:

Dimensionally, ASME B16.47 Series A flanges are identical to MSS SP-44

flanges.

7.3 API SPEC 6A flanges shall be type 6B rating 3000 and above, 1½-inch through
10-inch NPS.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

Commentary Note:

The flange standard API Spec 6A and ASME 16.5 are similar dimensionally.
Welding neck ASME 900 can match API 6A 3000. This normally used to attach
the flowlines with the wellhead piping system.

7.4 Dimensions of 26 inch and larger of weld neck and blind flanges as specified by
the Saudi Aramco Standard drawings shall not be used for new installation
except only to match an existing flange or split tees for hot tap and stopples.
Commentary Note:

Saudi Aramco has stopped using Company standards drawings for new
installation based on CSD report CSD-L-272/05 “ASME Large Diameter Flanges
in Lieu of Saudi Aramco Drawings”.

7.5 Swivel Ring Flanges

These flange assemblies shall comply with Saudi Aramco Standard Drawings
AA-036792.

7.6 Lapped Joint Flanges

The flange assemblies for 26” and above shall comply with Saudi Aramco
Standard Drawings AE-036438, AC-036443 and AC-036486 for Lapped Joint
flanges.

7.7 Gray cast iron flanges shall comply with ASME 16.1.

7.8 The dimensional standards and bolt patterns of nonmetallic flanges shall comply
with the corresponding dimension of the mating metallic flanges.

8 Flange Facings

8.1 Flange face surface finish shall meet the requirements of ASME 16.5, 16.47 or
API 6A as applicable. For hydrogen service, flange facing surface finish for
raised face shall not exceed Ra 3.2 micrometers (125 microinch).

8.2 Low strength flanges such as cast iron shall have a flat face with full face
gaskets. Low strength bolts shall be used for low strength flanges.

8.3 Unless otherwise specified in this standard, raised face flanges in ratings up to
Class 600 shall be used at design temperatures from minus 50 to 425°C.

8.4 Ring joint flanges for use with ring joint gaskets per ASME B16.20 shall be
used for:
 Flanges in Class 900 and higher ratings,

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

 Underwater pipelines in Class 300 and higher ratings,

 Design temperatures in excess of 480°C,
 API SPEC 6A Type 6B flanges,
 Hydrogen service in Class 300 and higher ratings.

8.5 The assembly of different type of flange faces is not permitted.

Commentary Notes:

Subject to approval of the Piping Standards Committee Chairman, a raised face

may be removed from a raised face flange to convert it to a flat face flange
provided that it meets the ASME codes requirements. Refer to paragraphs 6.3.2
of ASME B16.5 and 6.1.3 of ASME B16.47.

8.6 Tongue-and-groove facing or male-and-female facing joints shall not be used.

9 Bore of Welding Neck Flanges

The bore of welding neck flanges shall be according to the applicable ASME/API
standards. The flange bore shall be smaller or equal to the pipe bore.

10 Flange Material Specifications

10.1 The flange material shall be compatible with the pipe material for the intended
service. The selected flange material specifications shall have
pressure/temperate rating according to the flange dimensional standards as
applicable.

10.2 Weld Neck Flanges

10.2.1 The material specifications requirements for carbon steel and alloy
steel flanges shall be in accordance with 02-SAMSS-011. For other
materials, the requirements shall be as per the applicable ASTM.

10.2.2 For carbon steel, refer to Table 2 of this standard to select the
applicable ASTM for flange class 150 to 1500 ratings.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

Table 2 - Recommended Weld Neck Flange Materials

ASME CL 150 CL 300 CL 600 CL 900 CL 1500
Design
Mat’l
Temperature Nominal Size Inch
Group
Mat’l Group 1 (36 KSI SMYS)
ASTM A105 N 1.1 -20 to 425°C 2 - 24 2 - 24 2 - 12 NA NA
ASTM A350 LF2 Cl.2 1.1 -20 to 400°C 2 - 60 2 - 60 2 - 48 2 - 36 2 - 24
ASTM A350 LF2 Cl.1 1.1 -45 to 345°C 2 - 60 2 - 60 2 - 48 2 - 36 2 - 24
Mat’l Group 2 (60 KSI SMYS)
ASTM A707 L3 CL3 1.7 -30 to 230°C 2 - 60 2 - 48 2 - 36 2 - 24 2 - 12
ASTM A350 LF6 CL2 1.2 -30 to 375°C 2 - 36 2 - 36 2 - 24 2 - 18 2-8
ASTM A707 L5 CL3 1.7 -30 to 230°C NA 50 - 60 38 - 60 26 - 48 14 - 30
Mat’l Group 3 (65 KSI SMYS)
ASTM A859 A CL2 1.7 -30 to 230°C 2 - 60 2 - 60 2 - 48 2 - 30 2 - 30
Mat’l Group 4 (75 KSI SMYS)
ASTM A707 L5 CL4 1.7 -30 to 230°C 2 - 60 2 - 60 2 - 60 2 - 48 2 - 30

Notes:
1) All 02-SAMSS-011 materials may be used wet sour service. Unless otherwise specified, manufacturers may
substitute materials within limits described in 02-SAMSS-011 paragraph 4.3.
2) NA = not applicable; NR = not recommended.
3) ASME/ANSI ratings are only valid at temperatures shown above.

10.2.3 The flange and the pipe should have equal yield strength. For flanges
with pipe of unequal yield strength, the following may be acceptable:
a) Flange under material group number 1 in Table 2 may be used
with grade X42 pipe, up to 24-inch NPS.
b) Flange under material group number 1 in table 2 may be used
with grade X52 pipe up to 12-inch NPS.
c) Flange under material group number 2 in Table 2 may be used
with grades X42, X52, X65 and X70 pipe.
d) Flange under material group number 3 in Table 2 may be used
with grades X70.
e) Flange under material group number 4 in Table 2 may be used
with grades X70 pipe.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

Commentary Note:

In all cases, the design wall thickness for the flange shall meet the pipe
design conditions at the butt weld joint. The wall thickness for the
flanges will be more than the pipe wall thickness.

10.2.4 For low alloy and stainless steel, ASTM A182 shall be selected.
The flange and the pipe material chemical composition shall be the
same.
Commentary Note:

For ASTM A 335 Gr P11 pipe material, ASTM A182 Gr F11 flange
should be selected for pipe. For ASTM A312 Gr TP 304L, ASTM A182
Gr F304L should be selected.

10.3 Blind Flanges

For ASME flanges, one of the following materials should be selected:

 A105N, from - 20°C to 425°C;
 A350 LF2 Cl 1, from - 45°C to 425°C;
 A516 Gr 70 N, from - 45°C to 425°C.

10.4 Material for API SPEC 6A shall follow the requirements of 02-SAMSS-011 and
Table 4 of the API spec. ASTM A707 L3 CL3 QT should be used for welding
neck flanges and blind flanges.

11 Spectacle Plates Blinds and Blanks

11.1 The piping design shall include provision for spectacle plates or blanks and
spacers at flanged joints as required for pressure testing, for blinding off during
repairs or inspection for positive product segregation or for other operating
reasons.

11.2 The design wall thickness of all spectacle blinds and blanks shall be determined
in accordance with ASME B31.3. Spectacle plates and blinds shall be in
accordance with Saudi Aramco standards drawings addressed in Table 3.
For unlisted spectacle plate blinds and blanks, ASME 16.48 shall be used.
The design of the spectacle plate blinds and blanks shall be identical to the Saudi
Aramco standard drawings.

11.3 The surface finish for the gasket seat area shall meet flange dimensional
standards (ASME B16.5, ASME 16.47, API 6A).

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Document Responsibility: Piping Standards Committee SAES-L-109
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Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

Table 3

NPS Range Class Facing Standard Drawing

2 - 48 125 FF AD-036631
2 - 48 150 RF AD-036633
54 - 60 250, 300 RF AD-036731
2 - 48 250, 300 RF AD-036731
2 - 48 600 RF AD-036636
2 - 30 600 RJ AD-036734
2 - 24 900 RJ AD-036735
2 – 24 1500 RJ AD-036736

12 Gaskets

12.1 Gaskets shall be suitable for the intended service and compatible with the flange
facing, rating and bolting.

12.2 Metallic Ring Joint Gaskets

12.2.1 Octagonal ring joint gaskets Type R, per ASME 16.20 shall be used
with API SPEC 6A Type 6B flanges and ASME RTJ flange type.

12.2.2 Ring-joint gasket materials shall be selected based on suitability for the
service conditions.

12.2.3 Rubber coated ring joint gaskets may be used for severely corroded
services. Soft iron or low carbon steel may be used for the ring type
joint material.

12.3 Spiral Wound Gaskets

12.3.1 Spiral wound gaskets shall be according to ASME B16.20.

12.3.2 Filler material for spiral wound gaskets shall be suitable for the
intended design conditions.

12.3.2.1 In oxidizing environments, the maximum temperature for

graphite filler material is limited to 425°C.

12.3.2.2 Filler materials that deteriorate at elevated temperatures,

e.g., Teflon, shall not be used in hydrocarbon services.

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Document Responsibility: Piping Standards Committee SAES-L-109
Issue Date: 13 October 2012
Next Planned Update: 28 April 2014 Selection of Flanges, Stud Bolts and Gaskets

12.3.3 For general hydrocarbons and process hydrocarbon services including

steam, ASME B16.20 spiral wound gaskets with 316 stainless steel
winding and high purity flexible graphite filler shall be used for raised
face flanges.

12.3.4 The inner and the outer rings material shall match the flanges material.

12.3.5 Outer rings are required for all pipe sizes. Inner rings are required for
the following flanges:
 Flanges size 24” and larger;
 Flange class 900# and above where applicable;
 Spiral wound gaskets with PTFE filler materials;
 Flanges in vacuum services.

12.4 Metal Grooved (Kammprofile) Gaskets

Metal Grooved (Kammprofile) gaskets with graphite sealing facing material and
outer centering ring shall be used as an alternative to spiral wound gaskets in
piping system subjected to pressures and fluctuating conditions, temperature
differential across the flange face and bolt stress relaxation.

12.5 PIKOTEK or Equivalent Gaskets

PIKOTEK gaskets shall not be used in refineries and gas plants. The PIKOTEK
gaskets shall not be used in services operating at 280°F and higher.

For water corrosive services where flange face corrosion is a concern, the
following option may be considered:

 Gaskets with Teflon sealed, glass reinforced epoxy laminated to

316 stainless steel core.

12.6 Insulating Gaskets

12.6.1 Subject to the limitations in paragraphs 12.5, insulating gaskets,

PIKOTEK gaskets, or approved equal, with insulating sleeves and
washers shall be used for the following:
a) Insulating dissimilar metal flanged joints with high potential
galvanic corrosion (i.e., electrical isolation),
b) Insulting joints for cathodic protection.

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Document Responsibility: Piping Standards Committee SAES-L-109
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12.6.2 Insulating gaskets are not required for the following services:
 Dry hydrocarbon gas service in dry areas
 When the service temperature is above the limitation of non-
metallic gasket application.
 When the designer can demonstrate that galvanic corrosion will not
occur between the dissimilar metals.
 In flammable services and when the insulating gasket kit is
ineffective due to electrical external bonding between the dissimilar
metals caused through contacts with pipe supports, structure, etc.

12.7 Metal Jacketed Gasket

Metal jacketed gasket shall not be used in pipe flanges.

12.8 Sheet Gasket

12.8.1 Sheet gaskets shall be according to ASME B16.21. The sheet gasket
material shall be suitable for the intended design and service
conditions.

12.8.2 Compressed synthetic fiber with oil resistant binder may be used for
Class 125 and 150 flat face flanges in non-hazardous services up to a
maximum temperature of 230°C.

12.8.3 Full face synthetic rubber gasket, ASTM D1418 Class CSM on flat
face flanges, may be used for most acid services up to 70%
concentration and to 65°C. For sulfuric acid above 70% concentration
(including oleum), and nitric acid (all concentrations), use full face
ASTM D1418 class FKM elastomer on flat face flanges.

When raised face flanges are to be used, the flange finish shall be 3.2
to 6.4 micrometers Ra, and the gaskets shall be PTFE-filled spiral
wound Alloy 20 stainless steel with stainless steel inner ring.
Applications involving other acids must be approved by the Chairman
of Piping Standards Committee in CSD.

12.8.4 For plastic flanges, full face gaskets of elastomeric material, 3 mm

thick with Shore A Durometer hardness between 50 and 60 may be
used. For wet chlorine service and hypochlorite services, the elastomer
shall be ASTM D1418 class CSM.

12.9 Proprietary gaskets shall be submitted to the Chairman of Piping Standards

Committee in CSD for approval.

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Document Responsibility: Piping Standards Committee SAES-L-109
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12.10 The gasket contact area of the flange shall not be coated.

13 Bolting

13.1 Bolting for flanged joints shall be selected in accordance with ASME B16.5 or
ASME B16.47 as minimum.

13.2 Bolting Materials

13.2.1 The material specification for stud bolts and nuts shall be in
accordance with Table-4 for the applicable design temperature range
and service. Additional restrictions for specific services and
applications per applicable codes shall apply. Material selection for
temperatures and/or services not listed in Table-4 shall be approved by
the Chairman of Piping Standards Committee.

Table 4 - Material Selection of Bolts and Nuts

Temperature
ASTM Materials Specification
Service Category Range °C
Minimum Maximum Stud Bolts Nuts
Process and
- 40 + 450 A193 Grade B7 A194 Grade 2H
general services

Low temperature - 73 + 450 A320 Grade L7M A194 Grade 7M

services -101 + 343 A320 Grade L7 A194 Grade 4 or 7
High temperature
+ 450 + 645 ASTM A193 Grade B16 A194 Grade 4
services
- 48 + 450 A193 Grade B7M A194 Grade 2HM
Wet sour services
- 73 + 450 A320 Grade L7M A194 Grade 7M

13.2.2 Low temperature bolting material shall be selected for flanges

subjected to auto-refrigeration during flange leakage.

13.2.3 Stud bolts and nuts shall be specified for wet sour services only if they
are in direct exposure or potential exposure to the fluid service.
Commentary Note:

Examples of potential exposures to the fluid services are buried,

insulated, or shielded flanges.

13.3 Bolting material installed in aggressive external environment such as offshore

and underground piping shall be protected using one of the followings:
a) Ceramic-fluoropolymer coating per 09-SAMSS-107,

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Document Responsibility: Piping Standards Committee SAES-L-109
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b) Corrosion-resistant alloys,
c) Painting the exposed portions of the bolts and sealing the gap between
flange faces,
d) Encapsulating the bolted flange connection with heat shrinkable tubing.

13.4 Washers

13.4.1 Flat washers under the nuts are required for special cases only, such as
on insulating flanges and under the nuts bearing against plastic flanges.

13.4.2 Belleville washers may be required for severe cyclic service, and bolt
service temperatures above 450°C. Review by the Chairman of Piping
Standards Committee in CSD is required.

Revision Summary
28 April 2009 Major revision.
13 October 2012 Editorial revision.

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