Recovering from PWHT Over Heat above Lower Critical Temp on P5A to P4 (1.25%) Chrome Weld

[KenHutch]

As the saying goes - Long time reader - first time poster.

Problem - ASME Code B31.1 - New 12" Main Steam Stop SA-182 F22 Valve (P5A) welded into old 12" SA-335 P11 Main Steam Pipe (P4 1.25% Chrome) using WPS qualified with PWHT at 1350 F. Weld Checklist (Traveler) specified 1275 +25/-0 F PWHT. During PWHT although Control Thermocouples were steady at 1275 several Monitoring Thermocouples reached and possibly exceeded 1430 F (Lower Critical Temp for 1.25 Chrome P4) Do not have actual temperature readings only graph printout. Have to assume worst case of exceeding LCT on P4 pipe
Although the valve also reached these temperatures the P5A Lower critical temp was not exceeded.

Additional info - pipe was installed prior to both code strength derates for P11 and has many years (~60 years) of operation and cycling above 1000 F

Any "fairly" easy remedies versus cutting spool pieces of the pipe out and replacing? Normalize and Temper?

Thank you in advance.

 

[weldstan]

You could qualify a welding procedure on P4 to P5A at the 1430F temp. or you could replace the affected P4 pipe with a pup piece and reweld to the P5A valve.

 

[KenHutch]

Thank you weldstan, We performed Brinell Hardness Tests on the unheated pipe, heated pipe, weld cap, and valve. All indications are that there was no change in hardness of the base materials and we have elected to follow your first recommendation.