Flawed test specimens for nondestructive evaluation applications

摘要

Present codes and specifications usually require that nondestructive evaluation (NDE) operations, including techniques, procedures, equipment, and personnel, be qualified utilizing flaws that are typical of those found in practice. Such flaws must simulate fabrication and service-induced defects that produce acoustic response(s) representative of those found in operating plants. The representative flaws include slag, incomplete penetration, inadequate fusion, fabrication cracks, fatigue cracks, and intergranular stress corrosion cracking (IGSCC). In addition, these flaws must be generated in a wide variety of configurations, thicknesses, and materials that are experienced in both pressure vessel and piping systems. Further, it is necessary to accurately control the length, throughwall depth, position, and orientation of such flaws by fabrication operations rather than rely on subsequent NDE operations.