PWHT and hardness testing

[Trebormech]

Hello.

I am working on the quality control for the installation of a steam header. The material is 2.25% Cr steel (P22).
The header was prefabricated in a shop, but will require several field welds. Regarding PWHT of the field welds, how relevant is hardness testing as a quality control step for checking stress relieving? What do we do with high readings? Is hardness testing typically used for this purpose?

Thank you.

 

[weldstan]

For a steam header, hardness testing is typically not required. Under B31.3, hardness testing would be required to be under the specified maximum.

 

[DVWE]

Regarding PWHT of the field welds, how relevant is hardness testing as a quality control step for checking stress relieving?

Very relevant. Use this information along with the PWHT charts to ensure it was done correctly.

What do we do with high readings?

Usually a few extra readings are taken in the near vicinity as the high readings. If the extra readings are also high, check the entire circumference of the weld/HAZ to determine if another PWHT is required. Develop a repair plan if necessary.

Is hardness testing typically used for this purpose?

Yes.

 

[metengr]

I have seen few contractors and owner/users specify hardness testing for ASME Section I, Cr-Mo (P-No 4 and P-No 5A) materials to verify PWHT. This is not to say hardness testing should not be done, and the Code committee recognizes this because it is not a requirement.

If the repair contractor is reputable and has dealt with these materials based on their track record, I would say most clients would not require hardness testing as an additional QA/QC step only because of schedule and cost.

 

[Trebormech]

Thank you, all, for your responses.