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1部分：切向射线照相检验

[中文适用范围]： ISO 20769-1:2018规定了胶片射线照相和数字射线照相的基本技术，旨在经济地获得令人满意且可重复的结果。这些技术基于公认的实践和该主题的基本理论。本文件适用于服务诱导缺陷（如腐蚀点蚀、全面腐蚀和冲蚀）的钢管射线照相检测。在本文件中，"管道"一词除了其常规含义外，还涵盖其他圆柱形体，如管、进水管、锅炉筒和压力容器。未涵盖典型焊接工艺引起的缺陷的焊缝检测，但包含用于腐蚀/冲蚀类型缺陷的焊缝检测。管道可以有保温层也可以没有，当怀疑由于腐蚀或冲蚀等原因造成材料损失时，无论是内部还是外部均可进行评估。本文件涵盖切向检测技术，用于检测和通过壁厚测量评估壁厚损失，包括以下两种情况：a) 源位于管道中心线上；b) 源偏离管道中心线一个管道半径。ISO 20769-2涵盖双壁射线照相，注意双壁双像技术通常与源位于管道中心线上的切向射线照相结合使用。本文件适用于使用工业射线胶片技术、计算机射线照相（CR）和数字探测器阵列（DDA）的切向射线照相检测。 [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 steel pipes 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 the tangential inspection technique for detection and through-wall sizing of wall loss, including with the source: a) on the pipe centre line; and b) offset from pipe centre line by the pipe radius. ISO 20769-2 covers double wall radiography, and note that the double wall double image technique is often combined with tangential radiography with the source on the pipe centre line. This document applies to tangential radiographic inspection using industrial radiographic film techniques, computed radiography (CR) and digital detector arrays (DDA).