FAQ's

According to NACE MR0175, is 22HRC and PWHT required?

Question:

Section 7.3.3.2 states: “The HRC method may be used for welding procedure qualification. . . And the welding procedure specification includes post-weld heat treatment” and Clause A.2.1.4 states: “As-welded carbon steels, carbon manganese steels and low alloy steels that comply with the hardness requirements of Table A.1 do not require postweld heat treatment.” It is confusing whether the latter statement implies that an as-welded carbon steel, carbon manganese steel, or low alloy steel would require a PWHT if only HRC hardness testing is performed. Per Section 7.3.3.2, I would say yes it does require PWHT. But if the as-welded hardness survey meets the 22 HRC limit then doesn’t the as-welded material “comply with the hardness requirements of Table A.1 as stated in clause A.2.1.4?

Answer:

For carbon, carbon manganese, and low alloy steels hardness testing for welding procedure qualification (PQR) may be performed by the HRC method only if the design stress does not exceed 2/3 SMYS and PWHT is perform. If PQR hardness testing is performed by the 7.3.3.2 specified HV or HR15N methods, the restrictions for design stress and PWHT are not required.

This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3.2

Reference: ISO 15156 Maintenance Panel Inquiry #2011-14

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