ASTM F1588-96(2007)
(Test Method)Standard Test Method for Constant Tensile Load Joint Test (CTLJT)
Standard Test Method for Constant Tensile Load Joint Test (CTLJT)
SIGNIFICANCE AND USE
This test method was designed to be used to validate the long-term resistance to pullout of joints designed for use in plastic natural gas piping systems.
This test method is used in addition to the short-term tests required by OPS Part 192.283b, Title 49. Informal versions of this test method are used by manufacturers and utilities to demonstrate that a joint is resistant to the effects of long-term creep and meets the requirements for classification as a Category 1 or a Category 3 joint in accordance with Specification D 2513.
This test method may also be applicable for the determination of the effects of a sustained axial load on joints or other components of plastic piping systems designed for other applications. Test parameters and the internal pressurizing fluid, if any, should be listed in the referencing document.
Documents that reference this test method for products other than joints shall specify test conditions and performance requirements. In general, such products pass this test if they maintain their structural integrity, do not leak, and perform to specification during and after the test.
SCOPE
1.1 The constant tensile load joint test (CTLJT) is designed to demonstrate that a joint in a plastic piping system is resistant to the effects of long-term creep.
1.1.1 The joint is subjected to an internal pressure at least equal to its operating pressure and a sustained axial tensile load for a specified time period, usually 1000 h. The joint shall not leak, nor may the pipe completely pull out for the test duration. The total axial stress is set by the referencing document.
1.1.2 Some typical conditions for testing of joints on polyethylene pipe are described in Appendix X1.
1.2 This test is usually performed at 73°F (22.8°C).
1.3 The CTLJT was developed to demonstrate the long-term resistance to pullout of mechanical joints on polyethylene gas pipe. The CTLJT has also been successfully applied to the evaluation of other components of plastic piping systems. These applications are discussed in Appendix X1.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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An American National Standard
Designation:F1588–96 (Reapproved 2007)
Standard Test Method for
Constant Tensile Load Joint Test (CTLJT)
This standard is issued under the fixed designation F1588; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 ANSI Standard:
B31.8 Gas Transmission and Distribution Piping Systems
1.1 The constant tensile load joint test (CTLJT) is designed
2.3 Code of Federal Regulations:
todemonstratethatajointinaplasticpipingsystemisresistant
OPS Part 192, Title 49
to the effects of long-term creep.
1.1.1 The joint is subjected to an internal pressure at least
3. Terminology
equaltoitsoperatingpressureandasustainedaxialtensileload
3.1 Definitions:
for a specified time period, usually 1000 h. The joint shall not
3.1.1 General—Definitions are in accordance with Test
leak, nor may the pipe completely pull out for the test duration.
Method D638 and Terminology F412, unless otherwise speci-
The total axial stress is set by the referencing document.
fied. Abbreviations are in accordance with Terminology
1.1.2 Some typical conditions for testing of joints on poly-
D1600.
ethylene pipe are described in Appendix X1.
3.1.2 The gas industry terminology used in this test method
1.2 This test is usually performed at 73°F (22.8°C).
is in accordance with the definitions given in ANSI B31.8 or
1.3 TheCTLJTwasdevelopedtodemonstratethelong-term
OPS Part 192, Title 49, unless otherwise indicated.
resistance to pullout of mechanical joints on polyethylene gas
3.2 Definitions of Terms Specific to This Standard:
pipe. The CTLJT has also been successfully applied to the
3.2.1 mechanical joint, Category 1—a mechanical joint
evaluation of other components of plastic piping systems.
designthatprovidesasealplusaresistancetoforceonthepipe
These applications are discussed in Appendix X1.
end, equal to or greater than that which will cause a permanent
1.4 This standard does not purport to address all of the
deformation of the pipe or tubing. (D2513)
safety concerns, if any, associated with its use. It is the
3.2.2 mechanical joint, Category 3—a mechanical joint
responsibility of the user of this standard to establish appro-
design that provides a seal plus a pipe restraint rating equiva-
priate safety and health practices and determine the applica-
lent to the anticipated thermal stresses occurring in a pipeline.
bility of regulatory limitations prior to use.
This category has a manufacturers’ pipe-end restraint that
2. Referenced Documents allowsslippageatlessthanthevaluerequiredtoyieldthepipe.
(D2513)
2.1 ASTM Standards:
3.2.3 pipe—refers to both pipe and tubing.
D638 Test Method for Tensile Properties of Plastics
D1600 Terminology for Abbreviated Terms Relating to
4. Summary of Test Method
Plastics
4.1 A joint is subjected to a sustained axial load for a
D2122 Test Method for Determining Dimensions of Ther-
specified period of time (usually 1000 h).The test duration and
moplastic Pipe and Fittings
the actual test conditions (axial stress, internal pressure, test
D2513 Specification for Thermoplastic Gas Pressure Pipe,
duration, and test temperature) are either specified by a
Tubing, and Fittings
referencing document or, for new or unique applications,
F412 Terminology Relating to Plastic Piping Systems
agreed upon between the user and the manufacturer. X1.2
contains a background discussion of axial stress values and
This test method is under the jurisdiction of ASTM Committee F17 on Plastic
axial load determination.
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
4.2 The joint is made to plastic pipe of the type, grade, size,
Methods.
and dimension ratio to be used in the final application. The
Current edition approved Nov. 1, 2007. Published January 2008. Originally
approvedin1995.Lastpreviouseditionapprovedin2002asF1588–96(2002).DOI:
10.1520/F1588-96R07.
2 3
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Standards volume information, refer to the standard’s Document Summary page on Available from Superintendent of Documents, Government Printing Office,
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F1588–96 (2007)
axial tensile stress should be as high as possible, but shall be 6.2 Applied Axial Load Determination Monitoring—The
lower than the stress at which the plastic material continues to applied axial load shall be maintained to within 62 % of the
stretch and finally yields (the long-term yield strength) (see calculated value.
Note 1). 6.2.1 Dead weight is weighed before the start of a test.
6.2.2 In systems with air or hydraulic cylinders, a load-cell
NOTE 1—During the first hours of a test, the pipe elongates measurably.
and indicator may be used between the cylinder and the test
Elongation continues for the duration of the test at a decaying rate.
assembly.An alternative is to accurately establish the relation-
4.3 A joint passes this test if it does not leak and does not
ship between inlet pressure and the force generated by a
pull out or allow slippage in excess of the manufacturers’
cylinder and then to monitor a pressure gage placed in the
specified design slippage during the test duration.
pressurization line to the cylinder during the test.
4.4 If a pipe in the test assembly yields before the specified
6.3 Pressure Gage—Each assembly shall have a pressure
minimum test time is attained, the total stress is above the
gage to monitor internal pressure on the test assembly. The
long-term yield strength of that pipe and the test shall be
gage shall be able to measure the test pressure to within an
performed again at a stress level calculated to be below the
accuracy of 1 % or better.
long-term yield strength of the pipe.
6.4 Test Assembly:
6.4.1 The test assembly is capped and verified to be leak
5. Significance and Use
tight.Attachment devices that ensure straight line axial loading
shall be used at each end to attach the test assembly to the
5.1 This test method was designed to be used to validate the
loading device. The test assembly may contain more than one
long-term resistance to pullout of joints designed for use in
joint of the size under evaluation (see Note 3).
plastic natural gas piping systems.
NOTE 3—There are many configurations possible with the wide variety
5.2 This test method is used in addition to the short-term
of joints that are available. If the mechanical joint to be tested is suitable
tests required by OPS Part 192.283b, Title 49. Informal
for the purpose, it can be used to cap the pipe ends.
versions of this test method are used by manufacturers and
6.4.2 The minimum length is three pipe diameters between
utilities to demonstrate that a joint is resistant to the effects of
fittings (stiffener ends). Elongation is proportional to specimen
long-term creep and meets the requirements for classification
length. It is important to allow sufficient space in the apparatus
as a Category 1 or a Category 3 joint in accordance with
to provide for anticipated elongation of the test specimen for
Specification D2513.
the duration of the test.
5.3 This test method may also be applicable for the deter-
mination of the effects of a sustained axial load on joints or
7. Precautions and Safety Considerations
other components of plastic piping systems designed for other
7.1 Each test fixture and joint assembly shall be designed to
applications. Test parameters and the internal pressurizing
safely accommodate a sudden unexpected failure in any part of
fluid, if any, should be listed in the referencing document.
the test assembly. Both fixture and joint(s) shall be regularly
5.4 Documents that reference this test method for products
inspected for safety. Joint pullouts usually occur unexpectedly
other than joints shall specify test conditions and performance
and proceed from start to finish in seconds. Failure may be
requirements. In general, such products pass this test if they
accompanied by the sudden release of the internal pressure or
maintain their structural integrity, do not leak, and perform to
a falling test assembly, or both.
specification during and after the test.
7.2 It is strongly recommended that water be used as the
pressurizingfluidwhentestingsystemsthatmayfailinabrittle
6. Apparatus
manner (specifically PVC systems). If that is not possible, the
6.1 Loading Methods:
test specimens shall be placed in a strong chamber at all times
6.1.1 Any loading method that maintains the correct, in-line
when pressurized (see Note 4).
tensile load on the joint (within 62 %) for the test duration is
NOTE 4—For example, after 938 h of uneventful testing, one 6-in. IPS
acceptable. Loading methods successfully employed for all
transition joint rapidly pulled apart. There was no indication of pipe
size loads include lever arms, hydraulic cylinders, and air
movement when inspected 5 min before failure.
cylinders.
8. Test Specimens
6.1.2 Dead weight (a pile of scrap steel or iron) has worked
8.1 Pipe Specimen Selection:
well for loads up to 1 ton (907 kg) (see Note 2).
8.1.1 For tests of fittings intended for use in natural gas
NOTE 2—To provide an adequate stress level for ⁄8 in. DR 7 PE tubing,
distribution systems, the pipe supply used for the tests shall
about 200 lb (90 kg) are required. Pipe
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