1.1 本试验方法包括测定施加在金属护套内表面的防潮膜或涂层中的针孔检测浓度。 1.2 由于这种方法依赖于通过电路的金属护套完成，因此这种方法仅适用于导电的护套，并且施加了不导电的防潮层。 1.3 以英寸-磅单位表示的值应被视为标准值。括号中给出的值是对国际单位制的数学转换，仅供参考，不被视为标准值。 1.4 本标准并不旨在解决与其使用相关的所有安全问题（如果有的话）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 =====意义和用途====== 5.1 金属护套内表面的腐蚀可能是由管道和护套的不同金属之间形成原电池或由缝隙或点蚀引起的。 5.2 在金属护套的内表面施加防潮层通过干扰原电池的形成或防止水接触内金属表面来抑制这种腐蚀。 5.3 防潮层上的孔会降低其防腐效果。 肉眼可见的防潮层上的大孔、划痕或撕裂很容易辨认出来，是拒收金属护套的原因。 5.4 被称为针孔或漏涂的小孔肉眼不可见，但大到足以腐蚀，这是一个值得关注的问题，应尽可能避免。 5.5 本试验方法用于量化防潮层中针孔检测的浓度，以便对使用防潮层的金属护套进行质量控制。 5.6 对防潮层中针孔检测的最大允许浓度有具体要求的标准示例包括规范 C1729 和 1767年 .

1.1 This test method covers the determination of the concentration of pinhole detections in a moisture barrier film or coating that is applied to the interior surface of metal jacketing. 1.2 Since this method relies on the completion through the metal jacketing of an electrical circuit, this method is only applicable to jacketing that is electrically conductive and has a moisture barrier applied which is not electrically conductive. 1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Corrosion on the interior surface of metal jacketing can be caused by the formation of a galvanic cell between the dissimilar metals of the pipe and jacket or by crevice or pitting corrosion. 5.2 The application of a moisture barrier to the interior surface of the metal jacketing inhibits this corrosion by interfering with the galvanic cell formation or by preventing water from contacting the interior metal surface. 5.3 Holes in the moisture barrier decrease its effectiveness in preventing corrosion. Large holes, scratches, or tears in the moisture barrier visible to the naked eye are easily discerned and are cause for rejection of the metal jacketing. 5.4 Small holes called pinholes or holidays that are not visible to the naked eye but are large enough to allow corrosion are a significant concern and should be avoided to the extent possible. 5.5 This test method is used to quantify the concentration of pinhole detections present in a moisture barrier for the purpose of quality control on metal jacketing with an applied moisture barrier. 5.6 Examples of standards which have specific requirements for the maximum allowable concentration of pinhole detections in the moisture barrier are Specifications C1729 and C1767 .