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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.

Significance and Use

Squeeze-off is widely used to temporarily control the flow of gas in PE pipe. Squeeze tools vary depending on the size of the pipe and the design of the tool. Squeeze-off procedures vary depending on the tool design, pipe material, and environmental conditions.

Experience indicates that some combinations of polyethylene material, temperature, tool design, wall compression percentage and procedure can cause damage leading to failure.

Studies of polyethylene pipe extruded in the late 1980s and thereafter show that damage typically does not develop when the wall compression percentage is 30 % or less, when temperatures are above 50°F (10°C), and when closure and release rates are typical of field conditions for screw-driven tools.⁴ With tools meeting Specification F 1563, acceptable flow control at typical gas service pressures is achieved at wall compression percentages between 10 and 20 % for pipe diameters less than 6 in.^{4 ,5} Because damage does not develop in these materials at such squeeze levels, the references cited indicate that squeeze-off flow control practices using tools meeting Specification F 1563 and qualified procedures meeting Practice F 1041 are effective for smaller pipe sizes.^{4 ,5}

Note 3—Specification F 1563 provides a procedure for evaluating tool flow control performance.

This practice provides a method to qualify a combination of squeeze tool, pipe size and material, and squeeze-off procedure to ensure that long-term damage does not occur. This practice is useful for polyethylene gas pipe manufactured before 1975, for new or revised polyolefin gas pipe materials, for pipe diameters of 8 in. or above, for new or revised squeeze tool designs, and for new or revised squeeze-off procedures.

Keywords

damage; gas flow; pipe; polyethylene; squeeze; squeeze-off; tubing; ICS Number Code 23.040.20 (Plastic pipes)

To find similar documents by ASTM Volume:

08.04 (Plastic Piping Systems)

To find similar documents by classification:

23.040.20 (Plastics pipes)

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