ASTM F1734-96
(Practice)Standard Practice for Qualification of a Combination of Squeeze Tool, Pipe, and Squeeze-Off Procedures to Avoid Long-Term Damage in Polyethylene (PE) Gas Pipe
Standard Practice for Qualification of a Combination of Squeeze Tool, Pipe, and Squeeze-Off Procedures to Avoid Long-Term Damage in Polyethylene (PE) Gas Pipe
SCOPE
1.1 This practice covers the qualification of a squeeze process consisting of a combination of a squeeze tool, pipe, and squeeze-off procedures to avoid long-term damage in polyethylene gas pipe. This practice examines the inside and outside surfaces of the pipe near the squeeze to determine the existence of features indicative of long-term cracking. The occurrence of these features depends on the squeeze tool design, the pipe being squeezed, and the squeeze procedures being used. This practice is particularly appropriate for pre-1975 Polyethylene (PE) pipe, and for pipe with diameter greater than or equal to 8 in., because of the greater possibility of long term damage.
1.2 After the visual screening identifies a viable squeeze process, a sustained pressure test in accordance with Specification D 2513 should be used to conform the viability.
1.3 This practice is for use by squeeze-tool manufacturers and gas utilities for all squeeze tools made in accordance with Specification F 1563; pipe manufactured in accordance with Specification D 1513, up to and including pipe diameters of 12 in.; and squeeze procedures in accordance with Guide F 1041.
1.4 Governing codes and project specifications should be consulted. Nothing in this practice should be construed as recommending practices or systems at variance with governing codes and project specifications.
1.5 Where applicable in this Guide, "pipe" shall mean "pipe and tubing."
1.6 The values stated in inch-pound units are to be regarded as standard. The values in parentheses are for information only.
1.7 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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Designation: F 1734 – 96 An American National Standard
Standard Practice for
Qualification of a Combination of Squeeze Tool, Pipe, and
Squeeze-Off Procedures to Avoid Long-Term Damage in
Polyethylene (PE) Gas Pipe
This standard is issued under the fixed designation F 1734; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3350 Specification for Polyethylene Plastics Pipe and
Fittings Materials
1.1 This practice covers the qualification of a squeeze
F 1041 Guide for Squeeze-Off of Polyolefin Gas Pressure
process consisting of a combination of a squeeze tool, pipe, and
Pipe and Fittings
squeeze-off procedures to avoid long-term damage in polyeth-
F 1563 Specification for Tools to Squeeze-Off Polyethylene
ylene gas pipe. This practice examines the inside and outside
(PE) Gas Pipe or Tubing
surfaces of the pipe near the squeeze to determine the existence
of features indicative of long-term cracking. The occurrence of
3. Terminology
these features depends on the squeeze tool design, the pipe
3.1 Definitions:
being squeezed, and the squeeze procedures being used. This
3.1.1 squeeze-off,, n—a technique to control the flow of gas
practice is particularly appropriate for pre-1975 Polyethylene
in a pipe by compressing the pipe with a mechanical or
(PE) pipe, and for pipe with diameter greater than or equal to
hydraulic device.
8 in., because of the greater possibility of long-term damage.
3.1.2 squeeze process,, n—the combination of the squeeze
1.2 After the visual screening identifies a viable squeeze
tool, the pipe being squeezed, and the squeeze procedures
process, a sustained pressure test in accordance with Specifi-
being used.
cation D 2513 should be used to confirm the viability.
3.1.3 wall compression (WC),, n—a measure of the extent to
1.3 This practice is for use by squeeze-tool manufacturers
which the pipe is squeezed. (See Fig. 1.) It is defined as
and gas utilities for all squeeze tools made in accordance with
L
Specification F 1563; pipe manufactured in accordance with
WC,% 5 1 2 [m|]P5 100 (1)
S D
2t
Specification D 2513, up to and including pipe diameters of 12
in.; and squeeze procedures in accordance with Guide F 1041.
where:
1.4 Governing codes and project specifications should be
L = distance between the squeeze bars as shown in Fig. 1,
consulted. Nothing in this practice should be construed as
and
recommending practices or systems at variance with governing
t = average pipe wall thickness, expressed in the same
codes and project specifications.
units as L.
1.5 Where applicable in this guide, “pipe” shall mean “pipe
and tubing.”
4. Summary of Practice
1.6 The values stated in inch-pound units are to be regarded
4.1 Pipe of the size and material of interest is cut into
as standard. The values in parentheses are for information only.
samples at least 1 ft long or 5 diameters long, whichever is
1.7 This standard does not purport to address all of the
greater. The samples are squeezed in the tool of interest, using
safety concerns, if any, associated with its use. It is the
the procedure of interest, until the desired level of flow control
responsibility of the user of this standard to establish appro-
is achieved. Let this level of wall compression be called Smin.
priate safety and health practices and determine the applica-
Then, four other samples are squeezed to obtain squeeze levels
bility of regulatory limitations prior to use.
of (Smin−5) %, (Smin+5) %, (Smin+10) %, and (Smin+15) %.
This squeeze range brackets unacceptable through acceptable
2. Referenced Documents
levels of wall compression for flow control, with the
2.1 ASTM Standards:
(Smin+15) % value selected to allow an adequate operational
D 2513 Specification for Thermoplastic Gas Pressure Pipe,
range.
Tubing, and Fittings
4.2 The squeezed samples are split along their length at 90
degrees to the squeeze “ears.” The area containing the ears is
This practice is under the jurisdiction of ASTM Committee F-17 on Plastic
inspected visually. Features such as crazing, small voids, or
Piping Systems and is the direct responsibility of Subcommittee F17.60 on Gas.
cracks indicate potential permanent damage for that combina-
Current edition approved Sept. 10, 1996. Published November 1996.
2 tion of pipe, tool, and squeeze procedure.
Annual Book of ASTM Standards, Vol 08.04.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1734
6. Interpretation of Results
6.1 This practice relies on a screening process using visual
inspection followed by selected testing using the sustained
pressure test as described in Specification D 2513 to qualify a
squeeze-off process.
6.2 The area of wrinkling at the ears on the inside diameter
(ID) is inspected for void formation and cracks. Visible void
formation or cracks or extensive localized stress whitening, or
combination thereof, disqualifies that procedure.
6.3 Unacceptable features implying long-term damage are
shown in the photographs available as an adjunct.
7. Apparatus
7.1 Squeeze-off Tools, to be covered by the qualified proce-
dure.
7.2 Pipe Cutters and Saws, capable of cutting PE.
7.3 Jeweler’s Loupe or (Stereo) Optical Microscope, pro-
viding at least ;103 magnification.
7.4 Vernier Caliper or Ball-End Micrometer, with a least
count of 0.001 in. or better.
7.5 Stopwatch, that reads seconds or better.
8. Materials
8.1 There are no special materials needed.
FIG. 1 Definition of Wall Compression
9. Safety Precautions
4.3 The results of the visual screening are verified by
9.1 The usual care should be taken in working with the
performing a Sustained Pressure Test in accordance with
hydraulic jacks and power tools that may be needed to cut or
Specification D 2513.
squeeze larger diameter and higher SDR pipes.
5. Significance and Use
10. Preparation of the Sample and Equipment
5.1 Squeeze-off is widely used to control the flow of gas in
10.1 Acquire randomly selected pipe samples at least 5 pipe
PE pipe. Squeeze tools vary depending on the size of the pipe
diameters long but not less than 1 ft long.
and the source of the tool.
10.2 Measure the wall thickness around the circumference
5.2 Experience indicates that some combinations of resin
at 15° increments, and identify the location of maximum wall
type, resin supplier, extruder, vintage, percent squeezed, and
thickness.
tool can cause damage leading to failure.
10.3 Condition the sample to the temperature of interest.
5.3 Studies of pipe extruded in the late 1980s and thereafter
Studies at very low temperatures or on thicker-walled pipe may
show that damage does not develop for wall compression less
require significant hold times to reach thermal equilibrium.
than 30 %, for temperatures above 50°F, and squeeze and
Experience with smaller-diameter, lower SDR pipe (for ex-
release rates typical of field conditions for screw-driven tools.
ample, 2 to 6-in. SDR 11 pipe) indicates that a minimum of 24
W
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