无损检测.X射线和伽马射线对管道腐蚀和沉积物的射线照相检验.第2部分：双壁射线照相检验

[中文适用范围]： 本文件规定了 film 和 digital radiography（数字射线照相）的基本技术，旨在以经济的方式获得令人满意且可重复的结果。这些技术基于公认的行业实践和该主题的基本理论。本文件适用于金属管材的服务诱导缺陷（如点蚀、均匀腐蚀和侵蚀）的射线照相检查。除通常含义外，本文件中使用的“管道”还涵盖其他圆柱体，如管子、压力钢管、锅炉汽包和压力容器。典型焊接工艺引起的缺陷的焊缝检查不在覆盖范围内，但包括腐蚀/侵蚀类型缺陷的焊缝检查。管道可以有或没有绝缘层，并且可以在怀疑因腐蚀或侵蚀导致材料损失（内部或外部）的情况下进行评估。本文件涵盖用于检测壁厚损失的双壁检测技术，包括双壁单影（DWSI）和双壁双影（DWDI）。请注意，本文件中描述的 DWDI 技术通常与 ISO 20769-1 中涵盖的切线技术结合使用。本文件适用于使用工业射线胶片技术、计算机数字射线照相（CR）和数字探测器阵列（DDA）进行的在役双壁射线照相检查。 [外文原描述]： This document specifies fundamental techniques of film and digital radiography with the object of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on generally recognized practice and fundamental theory of the subject. This document applies to the radiographic examination of pipes in metallic materials for service induced flaws such as corrosion pitting, generalized corrosion and erosion. Besides its conventional meaning, "pipe" as used in this document is understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels. Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws. The pipes can be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected either internally or externally. This document covers double wall inspection techniques for detection of wall loss, including double wall single image (DWSI) and double wall double image (DWDI). Note that the DWDI technique described in this document is often combined with the tangential technique covered in ISO 20769-1. This document applies to in-service double wall radiographic inspection using industrial radiographic film techniques, computed digital radiography (CR) and digital detector arrays (DDA).