Temp Ramp on PWHT Excessive?

[KSOUCY]

We've performed a PWHT cycle on a vessel (P1 material, 3/8" THK, 20" OD, 30ft long). The temp ramp exceeded the Code specified allowable of 400deg F/hr (max rate seen was 575 F/hr for ~15min, while the avg rate from 800F to 1150F was 300 F/hr). At no point did the other parameters of the PWHT fall outside Code allowables. Is there a method to prove acceptance of this PWHT cycle to the AI, or is the only option to redo the cycle (we are not limited by the WPSs to only one PWHT)? Thank you.

 

[metengr]

Yes. I would document a nonconformance and disposition with portable hardness testing of the PWHT'd weld deposit and surrounding base metal, and supplemental NDT like a wet fluorescent MT of the PWHT'd welds. If the hardness test results and NDT are acceptable, present this information to the AI for their review and concurrence.

 

[eyec]

recheck the Code section, i thought that it could go to 600F/hr from start til 600F in the first hour, thereafter it had to maintain XF/hr to the soak temp.

 

[weldtek]

I believe there is no specified rate to 800 F

 

[metengr]

ASME Section VIII, Div 1;

The furnace or heat source must be no higher than 800 deg F prior to ramp up for PWHT. Max rate is 400 deg F/hr at or above 800 deg F. Ramp rate should be 400 deg F/hr/thickness until the PWHT temperature is reached.


ASME Section I;
No requirement for ramp rate. Other than to heat slowly above 800 deg F to the designated PWHT temperature and to cool slowly from this temperature to 800 deg F.

Keep in mind that one can specify ramp rates for Section I PWHT as part of the PWHT procedure. If this procedure is not followed, this can be a nonconformance that must be properly dispositioned by the QC program.