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P91 Hardness test

P91 Hardness test

P91 Hardness test

Does ASME have any hardness requirements to verify PWHT of T91 (P15E).

RE: P91 Hardness test

No. But EPRI does in a free publication related to fabrication of Grade 91 material.

RE: P91 Hardness test

Shouldn't the original poster perform this function? LOL.

RE: P91 Hardness test

Another star for metengr. As a retiree it has become more difficult to get new EPRI info and I appreciate your providing it to us.

RE: P91 Hardness test

No problem weldstan. Being semi-retired and working with EPRI as a consultant keeps me in touch. EPRI has really been taking the lead with ASME and the NBIC regarding PWHT and chemical composition of Grade 91 steels. More to come......

RE: P91 Hardness test

Hello All!
In relation to the discussion, regarding Post Weld Heat Treatments (PWHT) for P91 materials (Base Material P-No. 15E), it was observed that the hardness test requirements has been removed from B31.3. However, in B31.1 there was no hardness test in 2012, but newly added for cast material at 2014 and 2016.
Please refer to the following summary.

Based on the above observation, would like to know the following points.

(1) What is the technical background why the hardness test specified in ASME B31.3 (2012) has been removed from ASME B31.3 (2014) and B31.3 (2016)?
Note: Para. 331.1.7, which is referred in Para. 341.5.2 does not exist in ASME B31.3 (2014) and (2016).

(2) What is the technical background why the hardness test was not originally required in ASME B31.1 (2012) and newly added for casting material in ASME B31.1 (2014) and ASME B31.1 (2016)? Why does only casting material require hardness test, any incidents or troubles were reported?

(3) Why there are differences in the requirement of hardness test for base material P-No. 15E?

RE: P91 Hardness test

The problem has always been arguments as to the acceptable minimum hardness for Grade 91 material. This issue has been a moving target within the Code committees for some time. Hardness of Grade 91 is not a predictor of toughness nor creep strength performance and is only used as a qualitative means to measure the response of heat treatment.

RE: P91 Hardness test

Thanks metengr!
My question came up because our construction site group follows ASME B31.3 or ASME B31.1 requirements for pipe fabrication welds. However our Technology group is worried about the absence of hardness test considering experiences for failures if hardness test is not performed on fabricated pipe welds. I read the ERPI too, and will be helpful as additional reference to decide whether we perform hardness test or not.

RE: P91 Hardness test

Your company can always require hardness testing of P91 materials and welds with minimum and maximum requirements. For almost a decade my former company and a number of other EPC firms and Owners have done so.

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