I am writing to you to ask for clarification regarding NACE MR0175/ISO 15156-2 We have a part here which was welded and PWHT and the subsequent hardness check revealed a hardness on the weld cap of 243 Brinell. Our engineering department dispositioned this as acceptable in accordance with Table A.1, as Section A.2.1.4 suggests that “Acceptable maximum hardness values for carbon steel, carbon manganese steel, and low-alloy steel welds are given in Table A.1.” An independent Competent Body, Lloyds Register, however, has pointed out that Table A.1 mentions “Hardness test locations for welding procedure qualification” utilizing Vickers and Rockwell hardness techniques. Can you please therefore confirm if NACE compliant production welding can be accepted in accordance with this Table, or is it merely for weld procedure qualification.
Hardness measurements must be performed according to § 7.3.3 using Vickers hardness HV 10 or 5 or Rockwell 15N methods. Brinell hardness method is subject to the acceptance of the equipment user.
Table A.1 applies to qualification and production hardness values. However since 243 Brinell is above 250 HV or 22 HRC but below the alternate weld cap limit of 275 HV it requires “equipment user” acceptance and also to obey the two other listed requirements in Table A.1.
This question is in relation to NACE MR0175/ISO 15156-2 Annex A Table A.1
Reference: ISO 15156 Maintenance Panel Inquiry #2011-05
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