In lean manufacturing environments for efficient schedule, most process equipment manufacturers procure shells. When impact-tested shells are required, long-seam (Category-A) weld-procedures differ from round-seam (Category B) weld-procedures, thereby initiating UG-84(i) of ASME Section VIII Division 1. UG-84(i) states that when weld procedures for Category B welds are different, weld production impact test is required.
This paper evaluates possible production impact test exemption for Category B welds based on stress ratio of each category of weld. While long seams require impact testing at lower thickness range, fully radio-graphed round-seams for Curve-D materials may be exempt from production impact testing with weld procedure controls from UCS-67(a)(3) and impact-tested weld metal at desired minimum design metal temperature. Not including temperature shift below impact test temperature due to dynamic impact testing provides added safety and conservatism to UCS66 rules in the code. Change in rules will provide manufacturers significant relief from production impact tests for Category-B welds that are under-stressed with safety factors currently in Figure UCS 66.1.