1.1本规程提供了导波检测（GWT）的使用程序，之前也称为远程超声检测（LRUT）或导波超声检测（GWUT）。 1.2 GWT利用沿管道轴向发送的超声导波，通过检测管道横截面和/或刚度的变化来无损检测管道的缺陷或其他特征。 1.3 GWT是一种筛选工具。该方法不能直接测量壁厚或缺陷/缺陷区域的准确尺寸；然而，可以提供缺陷严重性的估计。 1.4本规程适用于标称管径（NPS）为2至48的管状碳钢或低合金钢产品，对应于60。 3至1219.2毫米（2.375至48英寸）外径和壁厚在3.81和25.4毫米（0.15和1英寸）之间。 1.5本规程涵盖了使用压电换能技术的GWT。 1.6本规程仅适用于基本管道配置的GWT。这包括直管，由单一管道尺寸和时间表构成，在测试位置完全可接近，通过环形焊缝连接，由简单接触支架支撑，无内部或外部涂层，或两者兼有；管道可以隔热或涂漆。 1.7本规程提供了进行检查和识别各个方面的一般程序，以确保有效结果，但不包括对数据的实际解释。 1.8本规程未建立验收标准。 具体验收标准应由责任系统用户或工程实体在合同协议中规定。 1.9 单位 — 以国际单位制表示的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.10 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 本规程旨在概述使用GWT定位金属管道中因腐蚀或侵蚀而发生壁损的区域的程序。 GWT不提供壁厚的直接测量，但对CSC和任何金属损失的圆周范围和轴向范围的组合很敏感。基于此信息，可以分配严重性分类。 GWT方法提供了一种筛选工具，可以快速识别管道沿线的任何不连续性。如果发现可能的缺陷，通常需要使用超声波检测或其他无损检测方法对可疑区域进行后续检查，以获得详细的厚度信息、损坏性质和程度。 GWT还提供了一些关于不连续的轴向长度的信息，前提是轴向长度大约大于波长的四分之一。 任何可能缺陷的识别和严重性评估仅为定性。 需要一个解释过程来区分相关和非相关信号。 本规程仅涵盖范围中规定的应用。GWT方法具有一定的能力，可用于管道绝缘、埋地、道路交叉口以及通道受限的应用。 GWT应由合同或采购订单中规定的合格认证人员执行。资格认证应包括特定于所用设备使用、测试结果解释和导波技术的培训。 供应方应保留一份文件化的计划，其中包括GWT人员认证的培训、考试和经验。

1.1 This practice provides a procedure for the use of guided wave testing (GWT), also previously known as long range ultrasonic testing (LRUT) or guided wave ultrasonic testing (GWUT). 1.2 GWT utilizes ultrasonic guided waves, sent in the axial direction of the pipe, to non-destructively test pipes for defects or other features by detecting changes in the cross-section and/or stiffness of the pipe. 1.3 GWT is a screening tool. The method does not provide a direct measurement of wall thickness or the exact dimensions of defects/defected area; an estimate of the defect severity however can be provided. 1.4 This practice is intended for use with tubular carbon steel or low-alloy steel products having Nominal Pipe size (NPS) 2 to 48 corresponding to 60.3 to 1219.2 mm (2.375 to 48 in.) outer diameter, and wall thickness between 3.81 and 25.4 mm (0.15 and 1 in.). 1.5 This practice covers GWT using piezoelectric transduction technology. 1.6 This practice only applies to GWT of basic pipe configuration. This includes pipes that are straight, constructed of a single pipe size and schedules, fully accessible at the test location, jointed by girth welds, supported by simple contact supports and free of internal, or external coatings, or both; the pipe may be insulated or painted. 1.7 This practice provides a general procedure for performing the examination and identifying various aspects of particular importance to ensure valid results, but actual interpretation of the data is excluded. 1.8 This practice does not establish an acceptance criterion. Specific acceptance criteria shall be specified in the contractual agreement by the responsible system user or engineering entity. 1.9 Units — The values stated in SI 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. 1.10 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 ====== The purpose of this practice is to outline a procedure for using GWT to locate areas in metal pipes in which wall loss has occurred due to corrosion or erosion. GWT does not provide a direct measurement of wall thickness, but is sensitive to a combination of the CSC and circumferential extent and axial extent of any metal loss. Based on this information, a classification of the severity can be assigned. The GWT method provides a screening tool to quickly identify any discontinuity along the pipe. Where a possible defect is found, follow-up inspection of suspected areas with ultrasonic testing or other NDT methods is normally required to obtain detailed thickness information, nature and extent of damage. GWT also provides some information on the axial length of a discontinuity, provided that the axial length is longer than roughly a quarter of the wavelength. The identification and severity assessment of any possible defects is qualitative only. An interpretation process to differentiate between relevant and non-relevant signals is necessary. This practice only covers the application specified in the scope. The GWT method has the capability and can be used for applications where the pipe is insulated, buried, in road crossings and where access is limited. GWT shall be performed by qualified and certified personnel, as specified in the contract or purchase order. Qualifications shall include training specific to the use of the equipment employed, interpretation of the test results and guided wave technology. A documented program which includes training, examination and experience for the GWT personnel certification shall be maintained by the supplying party.