PWHT procedure for new nozzle

[virjil]

We have an exchanger that we will install an additional drain nozzle. According to construction drawing, all welds must be PWHT'd. There is a required reinforcement pad on this nozzle. What is the accepted PWHT sequence? PWHT first the nozzle weld to the shell then PWHT again after welding the reinforcing pad? Or PWHT of the nozzle weld will be sufficient? Shall I PWHT with the pad on?

 

[metengr]

Is this exchanger a pressure vessel? If not, the answer to your question is to perform the PWHT after all welding is completed (weld the nozzle and weld the repad). You always want to minimize the number of PWHT cycles.