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适用范围：<p>If required by the authority having jurisdiction, pressurized gaseous media leak testing may be conducted after installation to discover and correct leaks or faults in a newly constructed or modified polyethylene pressure piping system before placing the system in service. Leakage or faults usually occur at connections, joints, and mechanical seals where sealing under pressure is required.</p> <p>Safety is of paramount importance when conducting pressurized gaseous media leak tests because testing results include no leaks, leaks, sudden violent rupture, or catastrophic failure.</p> <p>Systems that contain lower pressure rated or non-pressure rated components that cannot be isolated or removed from exposure to test pressure, or where temporary caps or closures are not practical, are not suitable for testing in accordance with this practice.</p> <p><span class="italic"><span class="italic">Leakage Allowance</span>8212;</span>Leakage is not allowed for joints including butt, socket and saddle fusion, electrofusion, and restrained gas-tight mechanical joints. See 7.6. </p> <p>Other types of joints, connections, or components having seals in the system may have a leakage allowance. Contact the joint, connection or component manufacturer for information.</p> <p><span class="italic"><span class="italic">Poisson-Effect Expansion and Contraction</span>8212;</span>When test pressure is applied to plastic piping systems that have fully restrained joints such as heat fusion, electrofusion, bolted flanges, etc., reduction of overall length or an increase in longitudinal stress results from diametrical expansion of the pipe. Disjoining (pull-out) of partially restrained or non-restrained connections or joints such as bell-and-spigot joints having insufficient resistance to pull-out stress or length reduction is possible when such joints are in-line with the test section. To prevent Poisson-effect disjoining, take measures such as installing external joint restraints (diametrical clamps and tie-rods) across in-line partially restrained or non-restrained joints, installing in-line thrust anchors at the ends of fully restrained piping sections, or isolating a fully restrained test section from piping with nonrestrained or partially restrained joints. </p> <p class="desc" id="N00004"> <span class="smallcap">Note</span> 38212;A tensile stress is applied to a material will cause elongation in the direction of the applied stress, and will cause a decrease in dimension at right angles to the direction of the applied stress. The ratio of decrease to elongation is the Poisson ratio. Under test pressure, piping materials will expand slightly in diameter and contract in length slightly according to the Poisson ratio of the material.</p><p id="s00002">1.1 This practice provides information on apparatus, safety, pre-test preparation and procedures for conducting field tests of polyethylene pressure piping systems after installation using gaseous media such as unodorized inert non-toxic gas or air, and applying pressure to determine if leaks exist in the system (pneumatic leak testing). This practice applies only to testing to discover leakage. Testing for other purposes such as testing to establish operating pressure is beyond the scope of this practice.</p> <p id="s00003">1.2 This practice does not address leak testing using pressurized liquids (hydrostatic testing). For field leak testing using pressurized liquids, see Practice <a href="http://myastm.astm.org/SUBSCRIPTION/NewValidateSubscription.cgi?F2164-HTML">F2164</a>. </p> <p id="s00004">1.3 Leak testing with pressurized gaseous media shall be used only if one of the following conditions exists: </p> <p id="s00550">1.3.1 The piping system is so designed that it cannot be filled with a liquid, or </p> <p id="s00666">1.3.2 The piping system service cannot tolerate traces of liquid testing media.</p> <p id="s00501">1.4 Where hydrostatic testing is specified in contract documents or by t......