Non-destructive testing of materials subject to atmospheric stress corrosion cracking

In-service inspection revealed atmospheric stress corrosion cracking (ASCC) on 304L stainless steel piping. The method requiring inspection quantification was a surface method, namely penetrant testing (PT), (is physical dimensions of the smallest flaw requiring detection by PT was ill defined for both pitting and cracking defects. Qualification was considered in terms of flaw volume together with absolute flaw linear dimensions. Inspection qualification would, therefore, determine the adequacy of the applied technique by both physical reasoning and by empirical measurement to determine the largest flaw that could escape detection.