PWHT Requirement for stainless steel vessel(Lethal Service)

[ramse24]

Am working on a vessel which falls under lethal service (client’s requirement). As per the technical requirement, the vessel should be stress relieved after welding because of lethal service.

The MoC of the vessel is SA 240 TP 316L, Normally SS Vessel will not be PWHT.

Is there is any stipulation to overrule the PWHT requirement

 

[Kiwi2671]

ramse24,
UW-2 states that carbon and low alloy vessels for Lethal Service require PWHT.
You are correct, 316 S/S is not usually subject to PWHT.
Suggest an RFI or Concession Request to your client.
Regards,
Kiwi

 

[metengr]

As per the technical requirement, the vessel should be stress relieved after welding because of lethal service.

What technical requirement? The Code is very clear regarding
UW-2.


Low alloy steel is NOT defined as stainless steel in ASME Code space. Look at ASME Section VIII, Div 1, Part C, material classes - Part UCS, UFA (nonferrous), UHA (ultrahigh alloy)...
Review UHA-23 materials.

 

[chaulklate]

PWHT is neither required nor prohibited for P8 material as per Table UHA-32. It will come down to a qualified metalurgist making a sound judgement call relative to the service. This Table will further direct you to non mandatory Appendix HA, and paragraphs UHA-100 to UHA-108 for additional guidance.