Determination of PWHT Holding time for ASME III NB2211

[thanjerm]

Dear All

To evaluate whether or not the total time at temperature applied during the actual pwht exceed the simulated pwht time by more than 25%, as required by ASME III NB2211. We start holding time when the coldest thermocouple reaches holding temperature and stops when the coldest thermocouple drops below holding temperature(i.e last-in first-out). That is the same holding time used to comply with ASME III NB4622 production pwht holding time. Our regulator believe that to comply with NB2211 to measure holding time differently to the duration used to comply with NB4622 i.e to start the hold time when the first thermocouple reaches holding temperature and stop when the last thermocuople drops below holding temperature (i.e first-in last-out) this result in longer durations to the point where holding time reaches 1.25X that which was applied on the specimens during simulated pwht without any time to spare for potential in-service repair. I would appreciate any advice on which is the correct way to measure pwht holding time to make sure that it doesn't exceed the time qualified by simulated pwht. Is it the last-in-first-out OR first-in-last-out method ?

Thank you in advance.

 

[FormerAIS]

This probably should be sent to ASME as an interpretation (there may be one already, would be worth checking). Especially since there is a disagreement between a regulator and yourself.

Quality is not an act, it is a habit - Aristotle

 

[thanjerm]

Thanks for your response FormerAIS. I have submitted a request to the ASME for an official interpretation. I'm waiting for the committee's reponse, which may take upto 6 months I'm told.

 

[FormerAIS]

The process can take a substantial amount of time, but it is the best way to obtain a clear cut answer regarding this situation.

Quality is not an act, it is a habit - Aristotle