Perform Pressure & Leak
Test, Tubing & Piping
Module 12306
Instrumentation Trainee Task Module 12306
PERFORM PRESSURE AND
LEAK TEST, TUBING AND
PIPING
Objectives
Upon completion of this module, the trainee will be able to:
1. Discuss pressure and leak testing limitations for piping/tubing
systems.
2. Discuss selection criteria for testing methods to be used for
piping/tubing systems.
3. Discuss and describe various testing methods.
4. Discuss precautions associated with testing piping/tubing systems.
5. Discuss and perform pressure/leak test per approved procedure.
6. Discuss and prepare required documentation of test performance.
Required Trainee Materials
1. Trainee Module
2. Required Safety Equipment
Instrument Trainee Task Module 12306 2
COURSE MAP
This course map shows all of the Wheels of Learning task modules in the
third level of the Instrumentation curricula. The suggested training order
begins at the bottom and proceeds up. Skill levels increase as a trainee
advances on the course map. The training order may be adjusted by the
local Training Program Sponsor.
LEVEL 3 COMPLETE
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 3
TABLE OF CONTENTS
Section Topic …………………………………………………………………..
Page
1.0.0 Introduction
………………………………………………………………………….. 5
2.0.0 Pressure and Leak Testing Limitations ……………………………………..
5
2.1.0 ANSI, ASME, and ISO 9000 Standards for Piping
Systems/Tubing Systems
……………………………………………………….. 5
3.0.0 Selection Criteria for Testing Methods ………………………………………
6
4.0.0 Description of Testing Methods ……………………………………………….
8
4.1.0 In-Service Test
……………………………………………………………………… 8
4.1.1 Pneumatic Test
…………………………………………………………………….. 8
4.1.2 Hydrostatic Test
……………………………………………………………………. 9
5.0.0 Precautions Associated With Testing ………………………………………..
9
6.0.0 General Test Procedure
………………………………………………………….. 10
6.1.0 Pneumatic Test
……………………………………………………………………… 10
6.1.1 Hydrostatic Test
……………………………………………………………………. 11
6.1.2 Repair and Retest
………………………………………………………………….. 12
7.0.0 Test Performance Documentation
……………………………………………. 16
Instrument Trainee Task Module 12306 4
Trade Terms Introduced In This Module
ANSI: American National Standards Institute.
ASME: American Society of Mechanical Engineers.
ASTM: American Society of Testing and Materials.
Design pressure: Maximum pressure a piping or tubing system can
withstand prior to failure.
Demineralized water: Water that has had all natural minerals and
added chemicals removed.
Hydrostatic testing: Testing a piping or tubing system by filling it with
liquid, and then raising the pressure to check system integrity.
ISO: International Standards Organization.
Pneumatic testing: Testing a piping or tubing system using a gas
(usually air) to check system integrity.
Test medium: Substance that is used to perform a leak test (liquid or
gas).
1.0.0 INTRODUCTION-
Process piping and tubing systems are designed and constructed for the
purpose of transporting fluids of varying temperatures and pressures
throughout. The importance of system integrity cannot be
overemphasized because of the obvious safety and operational
considerations. Testing system tightness is required prior to, and at some
point, during system service to ensure failure has not or will not occur
under normal operating conditions. This module will introduce the trainee
to the requirements for, and procedures associated with, pressure/leak
testing of piping and tubing systems.
2.0.0 PRESSURE AND LEAK TESTING LIMITATIONS-
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Testing of piping and tubing systems will not be performed arbitrarily,
that is; the limitations and requirements will conform to a specific set of
guidelines imposed by a standardized code. The generally accepted
standards for testing systems within the U.S. are set forth by the
American Society of Mechanical Engineers (ASME). Additional
organizations that provide guidelines for testing include: American
National Standards Institute (ANSI); American Society of Testing and
Materials (ASTM).
2.1.0 ANSI, ASME, AND ISO 9000 STANDARDS FOR PIPING
SYSTEMS/TUBING SYSTEMS
With the opening of the European marketplace and the ending of the Cold
War, the International Standards Organization (ISO) was formed to provide
worldwide standardization of procedures for testing and acceptance. ANSI
Q-90 is the equivalent of ISO 9000.
The vendor or supplier of components to be tested will also provide
specific data to identify the test parameters and limitations.
The testing limitations for piping and tubing systems can be determined
by referencing the applicable articles of the ASME codes. Temperature,
pressure, and leakage limits are the parameters of concern for
pressure/leak testing.
The minimum metal temperature for all components during a test shall be
as specified in the applicable Mandatory Appendix of the related Code, or
in the referencing Code section for the hydrostatic, hydropneumatic, or
pneumatic test of the pressure component or parts. The minimum and
maximum temperature during the test shall not exceed that temperature
compatible with the leak testing method or technique used. The
temperature of the test medium shall be that of the available source unless
otherwise specified by the vendor. The test pressure shall not be applied
until the system and the pressurizing medium are approximately at the
same temperature. When conducting pressure tests at low metal
temperatures, the possibility of brittle fracture shall be considered.
Unless specified in the applicable Mandatory Appendix of the chosen code,
components that are to be pressure-leak tested shall not be tested at a
pressure exceeding 25% of the Design Pressure.
Leakage limits for piping and tubing systems do not require any
interpretation because the acceptance criteria is "zero leakage".
On occasion, standards set forth by the various organizational codes and
vendor supplied limits may conflict. In this situation, the vendor data will
be used as the specification.
3.0.0 SELECTION CRITERIA FOR TESTING METHODS-
The proper selection of a test method is as important as any aspect of the
test performance. Section V, Article 27 of the ASME Code provides
guidance for the selection of pressure/leak testing methods. Table I is a
simplified guide for the selection.
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The correct choice of a leak testing method optimizes sensitivity, cost, and
reliability of the test. One approach is to rank the various methods
according to test system sensitivity.
The various testing methods must be individually examined to determine
their suitability for the particular system being tested. Only then can the
appropriate method be chosen.
Table 1. Guide for Selection of Leakage Testing Method
For example, radioactive gases are not generally employed as a tracer for
leak location because of the hazards associated with their use. However,
such gases are employed in leakage detection equipment when they can
be safely added to, and removed from, a test chamber on a periodic basis.
It is important to distinguish between the sensitivity associated with the
instrument employed to measure leakage and the sensitivity of the test
system followed using the instrument. The sensitivity of the instrument
influences the sensitivity that can be attained in a specific test. The range
of temperatures or pressures, and the types of fluids involved, influence
both the choice of instrument and the test system.
There are other items to be considered when determining which test
method will be used. Contamination of a piping or tubing system may
occur if the test medium is a substance that may not meet the cleanliness
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 7
requirements of that particular system. If the test medium could not be
completely removed from the system the cleanliness could not be
restored.
Vendor data and specifications, if provided, will be used to determine the
correct test method. In most cases, the vendor information parallels or
duplicates the accepted national codes and standards.
4.0.0 DESCRIPTION OF TESTING METHODS-
This section will discuss the various testing methods used to perform
pressure/leak testing of piping/tubing systems. Proper compliance to
testing methods will ensure safety to plant personnel and prevent damage
to the piping systems.
4.1.0 INITIAL SERVICE TESTING
An initial service test and examination is acceptable when other types of
tests are not practical or when leak tightness is demonstratable due to the
nature of the service. One example is piping where shut-off valves are not
available for isolating a line and where temporary closures are impractical.
Others may be systems where during the course of checking out of
pumps, compressors, or other equipment, ample opportunity is afforded
for examination for leakage prior to full scale operation. An initial service
test is not applicable to boiler external piping.
When performing an initial service test, the piping system shall be
gradually brought up to normal operating pressure and continuously held
for a minimum time of 10 minutes. Examination for leakage shall be made
of all joints and connections. The piping system exclusive of possible
localized instances at pump or valve packing shall show no visual evidence
of weeping or leaking.
4.1.1 Pneumatic Leak Test
A pneumatic leak test requires compressed gas or air for leak detection.
Pneumatic testing can be performed with air that is oil and moisture-free or
with another type of compressed gas. If air is used as a testing medium, it
must be filtered to keep out unwanted matter. This clean air is applied to
the tubing system by a compressor to build pressure in the system. Other
types of compressed gases that can be used are nitrogen and argon. Any
gas used must be nonflammable.
Before a pneumatic leak test is performed, certain requirements must be
met. These requirements are:
• Installation of the system must be complete
• Test boundaries must be defined
• Valves not to be tested must be locked open
• Instrumentation gauges must be removed
• Tubing ends must be capped
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• The system must be physically supported
• Test pressure gauges must be installed
• All teat pressure gauges must be calibrated for proper readout
One method of pneumatic testing employs a device known as a bubbler
leak tester. This unit is lightweight, rugged, and portable. The bubbler is
installed in-line between the compressed air source and the system or
components to be leak checked. System valves are shut in the section to
be tested and air is supplied through the bubbler up to the shut valve. If a
leak is present, flow will exist in that section of the system and be seen
through the tester as bubbles in the bowl.
4.1.2 Hydrostatic Test
Hydrostatic leak testing requires water as a test medium. There are three
grades of water that can be used for testing. These are:
• Grade A
• Grade B
• Grade C
The grade of water is determined by its purity. Grade A water is
demineralized water. This is the purest water used for testing. Grade B water
is returned condensate. This water has lost some of its composition; it is
the second purest water. Grade C water is ordinary tap or well water. The
type of water used is determined by the components and materials of the
system to be tested. Plant engineering usually decides on the grade of
water used.
All hydrostatic tests should be conducted at a temperature that minimizes
brittle fracture. Brittle fracture is a crack in a metal (iron especially) tube
or pipe. This occurs when the temperature of the test item is lower than
the temperature of the testing medium. The water used for testing should
be approximately the same temperature as the system components to be
tested. A large variation in temperature also causes expansion and
contraction of metal fittings and flanges resulting in leaks at joints.
Before a hydrostatic leak test is performed, certain requirements must be
met as with pneumatic testing. Refer to the Section titled "Pneumatic Leak
Test" for a list of requirements.
5.0.0 TESTING PRECAUTIONS-
The precautions associated with pressure/leak testing of piping and tubing
systems will vary based on the test method, pressure, temperature, and
type of system.
Generally, these precautions provide protection for equipment and
personnel.
Instrument devices will be isolated from test pressure source to prevent
damage to delicate components. Block valves, bleed valves, and gage root
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 9
valves will be shut prior to commencing the test. All open outlets of the
piping system will be plugged so adjacent or connecting systems will not
be inadvertently pressurized.
Personnel-related safety precautions will conform to those set forth by the
Occupational Safety and Health Act (OSHA) for individuals working with
high pressure/temperature fluids, gases, or possibly, hazardous materials.
The written test procedure shall describe all personnel and equipment
safety-related warnings.
6.0.0 GENERAL TEST PROCEDURE-
Instrument systems can be leak tested in whole or part. If only a part of
the entire system is to be tested, plugs or caps must be installed. These
separate the part of the system being tested from the rest of the system.
The type of test to be performed should be decided before the testing
date.
The following sections will explain:
• Performing a low pressure pneumatic leak test
• Performing a high pressure hydrostatic leak test
• Repairing leaks
6.1.0 PERFORMING LOW PRESSURE PNEUMATIC LEAK
TEST
Follow these steps to perform a low pressure pneumatic leak
test.
Step 1 Lock out the system as required by plant safety standards.
Step 2 Remove instruments from the system that may be damaged from
increased air pressure.
Step 3 Cap the tubing ends or install pneumatic jumpers where
instruments are removed to maintain continuity. Figure 1 shows
a pneumatic jumper installation.
Step 4 Connect the compressed air source to the system with tubing
connections and install the test pressure gauges.
Instrument Trainee Task Module 12306 10
Figure 1. Pneumatic Jumper Installation
NOTE: Test pressure gauges should be installed according to plant
requirements and standards.
Step 5 Apply system pressure and increase to test pressure in
increments of 10 psi.
Step 6 Apply soapy water to all joints with a brush.
NOTE: If bubbles occur on any joints, leaks are present and they
should be marked for repair.
Step 7 Release pressure after marking the leaks.
Step 8 Repair the leaks.
Step 9 Repeat Steps 5 through 8 until all leaks are
corrected.
Step 10 Restore the system to operation.
6.1.1 Performing High Pressure Hydrostatic Leak Test
Hydrostatic leak testing requires pressurized water. Several types of
hydrostatic test pumps are available for this purpose.
Follow these steps to perform a high pressure hydrostatic leak test.
Step 1 Lock out the system as required by plant safety standards.
Step 2 Remove instruments from the system that maybe damaged from
pressurized water.
Step 3 Cap the tubing ends or install jumpers where instruments are
removed to maintain continuity.
Step 4 Apply water to the system using a hydrostatic test pump.
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 11
NOTE: Make sure the proper class of water is used. Refer to the
Section titled "Hydrostatic Leak Test" for an explanation of
water class.
WARNING! The temperature of the water being used as a test medium
should be monitored and kept close to ambient to avoid
brittle fracture of metal tubing.
Step 5 Pressurize the system to the desired test pressure.
NOTE: Test pressures are determined by material and application.
Check with the supervisor for the correct test pressure.
Step 6 Maintain the test pressure for the test period.
Step 7 Look for dripping or flowing water from system components to
inspect for leaks.
Step 8 Mark the leaks for repair.
Step 9 Release the pressure and repair the leaks.
Step 10 Repeat Steps 4 through 9 until all leaks are repaired.
Step 11 Restore the system to operation.
6.1.2 Repairing Leaks
After leaks are detected, they must be properly repaired. If a leak occurs
in an instrument, such as the bellows assembly, the instrument should be
replaced and taken to the instrument shop for repair. Other locations in an
instrument system where leaks are commonly detected and must be
repaired are:
• Fittings and tubing
• Flanges
• Gaskets
Fittings and Tubing
Fittings and tubing are rarely repaired. They are generally tightened or
replaced when leaks occur. Follow these steps for replacing fittings and
tubing.
Step 1 Lock out the system as required by plant safety standards.
Step 2 Remove the faulty fittings and tubing by unscrewing the tube nut
on the fitting as shown in Figure 2.
Instrument Trainee Task Module 12306 12
Figure 2. Removing Tube Nut from Fitting
Step 3 Remove the remaining part of the fitting by unscrewing it from its
mate as shown in Figure 3.
Figure 3. Removing Fitting from Mate
Step 4 Secure the new fitting of correct size and inspect for
imperfections.
Step 5 Wrap a sealing tape or use a sealing compound around the male
pipe thread portion of the fitting and screw the fitting into the
outlet from which it was removed.
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 13
Step 6 Place the tube nut and ferrule on the tubing and connect to the
fitting as shown in Figure 4.
Figure 4. Connecting Tube Nut and Ferrule on Fitting
Step 7 Screw the tube nut onto the fitting until finger tight.
Step 8 Tighten the tube nut using two wrenches. One wrench is used to
hold the fitting and the other is used to tighten the tube nut.
NOTE: For tubing 1/4 inch, tighten the tube nut 3/4 of a turn. For
tubing 3/8 inch and over, tighten the tube nut one turn.
Step 9 Check the connection for leaks.
Step 10 Restore the system to operation.
Follow these steps to reconnect an existing fitting.
NOTE: System should be locked out according to plant safety
standards.
Step 1 Insert the tubing end into the tubing fitting.
NOTE: Make sure the tubing rests on the tubing stop inside the
fitting.
Step 2 Turn the tube nut finger tight.
Step 3 Note the position of the tube nut by scribing a mark on the nut.
Step 4 Tighten the tube nut to a specified tightness while holding the
fitting with a backup wrench.
NOTE: Specified tightness can be between 3/4- and 1-1/4 turns.
Step 5 Check connections for leaks.
Step 6 Restore the system to operation.
Flanges
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Leaky flanges that are welded in place require new welds for repair. For
large leaks, the flange is usually removed and replaced with a new flange
and weld. Pinhole size leaks can be repaired with a filler weld.
When the flange leak is repaired, it should be tested to assure a leak-free
connection.
Gaskets
Gaskets are used for installing control valves and orifice plates. If a good
seal is not made between the gasket and the flange, a leak could easily
occur. Figure 5 shows a control valve installation.
Figure 5. Control Valve Installation
Follow these steps for replacing gaskets in a control valve and orifice plate
installation.
Step 1 Lock out the system as required by plant safety standards.
Step 2 Remove all flange bolts and nuts holding the control valve or
orifice plate in place.
Step 3 Remove the instrument and gaskets from the system.
Step 4 Scrape the gasket off the instrument or flange connecting
surface.
Step 5 Secure the proper size gaskets and install between the
instrument flanges and pipe flanges.
Step 6 Align the flange holes of the pipe and instrument.
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 15
Step 7 Insert the flange bolts and nuts and tighten as required.
Step 8 Check the connection for leaks.
Step 9 Restore the system to operation.
7.0.0 TESTING DOCUMENTATION-
When written procedures are required by the referencing Code Section,
they shall include, as a minimum, the following information:
(a) extent of the examination;
(b) type of equipment to be used for detecting leaks or measuring
leakage rates;
(c) surface cleanliness preparation and type of equipment used;
(d) method or technique of the test that will be performed;
(e) temperature, pressure, gas, and percent concentration to be used.
The test report shall contain, as a minimum, the following information as
applicable to the method or technique:
(a) date of test;
(b) certification level and name of operator;
(c) test procedure (number) and revision number;
(d) test method or technique;
(e) test results;
(f) component identification;
(g) test instrument, standard leak, and material identification;
(h) test conditions, test pressure, and gas concentration;
(i) gage(s) - manufacturer, model, range, and identification number;
(j) temperature measuring device(s) and identification number(s);
(k) sketch showing method or technique setup.
The test report shall be maintained in accordance with the requirements
of the referencing Code Section.
Instrument Trainee Task Module 12306 16
SUMMARY
Pressure/leak testing of piping and tubing systems is essential to ensure
the integrity of these systems after initial fabrication and throughout their
operational life. The stringent requirements associated with this type of
Non-Destructive Testing should be thoroughly understood by all members
of the testing crew prior to commencing the procedure. This module has
briefly presented some of the information that you, the trainee, must
understand and learn to be able to correctly coordinate and perform a
pressure/leak test.
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 17
References
For advanced study of topics covered in this Task Module, the following
works are suggested:
ASME Standards
ANSI 31.1 and 31.3
ISO 9000
ANSI Q-90
SELF-CHECK REVIEW / PRACTICE QUESTIONS
1. Unless specified, tubing or piping shall not be tested at pressure
exceeding ___________% of the design pressure.
2. When selecting a testing method, what is one
criteria?
a. Sensitivity.
b. Cost.
c. Reliability.
d. All of the above.
3. What is the minimum time pressure shall be held continuously for an
initial service test?
a. One hour.
b. 30 minutes.
c. 10 minutes.
d. 4 hours.
4. What test medium is normally used for hydrostatic testing?
a. Nitrogen.
b. Air.
c. Oil.
d. Water.
5. Why should instrument devices be isolated from test pressure?
a. Prevent damage to delicate components.
b. Because they are inaccurate at high pressure.
c. Because they will give false readings to test rig operator.
d. May cause inadvertent operation of a safety device.
Instrument Trainee Task Module 12306 18
PERFORMANCE / LABORATORY EXERCISES
1. Given a "mock-up" of an instrument tubing system provided by
instructor:
Step 1 Write a test procedure to perform a pressure/leak test of the
system.
Step 2 Set up and perform the test.
Step 3 Properly document test results.
2. Given a "mock-up" of an instrument piping system provided by
instructor:
Step 1 Write a test procedure to perform a pressure/leak test of the
system.
Step 2 Set up and perform the test.
Step 3 Properly document test results.
ANSWERS TO SELF-CHECK REVIEW / PRACTICE QUESTIONS
1. 25%
2. d
3. c
4. d
5. a
Pressure and Leak Testing of Tubing and Piping Systems — Module 12306 19
