PWHT on corrosion resistant alloy piping

[azer mashhood]

Hi,
Appreciate if somebody can provide some guidance here. We have a carbon steel base pipe (more than 20mm thick) with Alloy 626 clad. Sour service at fairly high pressure offshore application. Does the base metal require PWHT? If the base metal hardness is maintained with pre heating and maintaining interpass temperature, does the code mandate PWHT?
Thanks
azer

 

[SJones]

Which "code" is applicable?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[azer mashhood]

Part of it is topside piping to B31.3 and other part is pipeline to B31.4 and 31.8

 

[SJones]

If you work through the standards, you should arrive at the conclusion that PWHT is not "mandated" up to 32 mm thickness and where the preheat requirements have been met for B31.3. Were you just looking for someone to back you up?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[azer mashhood]

Thanks Steve. Since the heat treatment required for Code reasons and not Process reasons, I concluded that no-contact scenario with service may not be a good reason to waive PWHT. Therefore as you said, it can be relaxed if the code allows provide relaxation for this material group. Thanks for your feedback!

 

[SJones]

Always best to try and avoid PWHT on CRA materials where possible.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[azer mashhood]

great feedback. Thanks