thePetroStreet

Is PWHT necessary for piping support welds with piping in low alloy and pad of carbon steels? If yes, is there any way
it can be avoided?

Regards
NAQ

See if you are using low alloy electrodes / filler wires for welding of alloy steel supports with carbon steels, you have to carry out PWHT in order to release the residual stresses induced. All other protocols of pre-heating and interpass temperatures are also to be met.
But for those supports which are not much stressed and having welds with lesser throat thickness, you may use Inconel-82/182 or E/ER-309 for welding and PWHT may be waived off.

Thanx for the help Ishfaq
Regards
Nabeel

You are welcome.
It's a sensitive subject. Handle with care.

Simple rule: Low alloy steels / welding consumables shall not be left without required PWHT operation. Yes with austenitic SS consumables / Inconel you can avoid PWHT but after careful analysis.

Higher weld hardness coupled with stresses in the pipe will definitely crack during service after sometime.Hence, it is advisable to carry out PWHT.

regards,

I agree with piiengineers to carry out PWHT in first place for the supports of welded Cr-Mo piping when using low alloy electrodes but when austenitic filler material is used obviously you would not perform PWHT.
Austenitic filler material must be used with restrictions like discussed above the case of stressed supports where welding must be made with the low alloy filler material to meet the design requirements and then be PWHT after welding.