RT Before or After PWHT

[WBH]

Does ASME Section VIII specify if RT is to be performed before or after PWHT. I have searched and have not found information supporting either.

Thanks for your input, I would like the code reference to your response.

WBH

 

[JR97]

WBH

RT in accordance with ASMe Section VIII may be performed before or after stess.

JR0097

 

[vesselfab]

code....either way
if customer does not have any specs contrary...we do it before.

I the client wants it after pwht per spec....we do it before and after

 

[WBH]

Thanks

WBH

 

[weldtek]

The above is always true for P1, but doesn't hold for all materials. UHA-33

 

[CWI88]

Why would you PWHT before RT? If it fails RT you will have to PWHT again after you make the repair. Is there something I'm missing?

 

[vesselfab]

Some USERS require all NDE to be done AFTER PWHT. It's a written law in the specification.

Smart fabricators do all NDE before PWHT and then again after PWHT to meet specs.

Done every day all around the world.

 

[unclesyd]

RT is a lot cheaper than a PWHT.

Our specs call for RT prior to PWHT to detect volumetric defects unless it is a machine or MIG weld where we also require UT prior to PWHT. After PWHT we normally do UT checks to detect any cracking and usually do a few hardness checks. The hardness checks are just a test to verify that there were no material mix ups. The hardness checks have been mostly eliminated due to better PMI equipment.

In my 42 years I've never seen any problems with P-1 material during and after PWHT.

 

[vesselfab]

syd

most HF services and hydrogen and Wet Sour services now require nde after PWHT.

we normally UT before (for or protection) and RT after

Cat D joints are UT before and after.


all P-1 material...yes a pain but never a problem

 

[AIOR]

As said above by weldtek , RT shall be done after PWHT for high alloy steels per UHA-33. This is because a delayed cracking or post heat treatment cracking may happened in or adjacent to welds after PWHT. This is not applicable to UCS steels. Common sense: you always need to do RT before PWHT to repair defects if any. Section VIII Div. 1 does not require RT after PWHT for carbon or low alloy steels.