Temper bead welding rules in the ASME Section XI code and code cases have historically required a 48-hour hold (wait period) after the temper bead weldment has cooled to ambient temperature prior to performing the final nondestructive examination (NDE). The purpose of the 48-hour wait period is to ensure that if delayed hydrogen induced cracking (HIC) occurs it is detected by the final acceptance examination. Delayed HIC is known to occur up to 48 hours after the weldment cools to ambient temperature when appropriate welding techniques and low hydrogen practices are not applied. A recent revision to Case N-888, the ambient temperature temper bead case for SMAW and Machine GTAW, eliminates the 48-hour hold for temper bead welds on P-No. 1 and P-No. 3 base material when austenitic weld metal is used. This paper summarizes the technical basis for this change and references operating experience that demonstrates the 48-hour hold is inconsequential and there is no potential for HIC when temper bead welding is deployed with low hydrogen practices and austenitic weld metal.

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