Code limitations on number of heat treat cycles for C-0.5Mo 1

[kevlar49]

Is there a code limitation on the number heat treatment cycles that C-0.5Mo can be exposed to similar to 2.25Cr reactors? I don't see any code citation for this but one of our inspectors made a note of it on their report. His concern was loss of strength requiring a re-rating.

 

[metengr]

No, there is no limitation on the number of PWHT cycles for repairs. However, if you are concerned with repetitive PWHT cycles for certain materials, it is best to qualify the WPS with the total estimated PWHT cycle time to account for any degradation in toughness/mechanical properties.

 

[weldtek]

Just a little further to metengr's post, with regard to welding procedures, anytime you qualify a heat treated WPS with impact tests, time at temperature is an essential variable, regardless of base material type. QW 407.1 & 2