Interpretation of Hardness Requirements in NACE MR0175/ISO 15156

Introduction

This page addresses a user’s query regarding the interpretation of hardness requirements in Section A.2 of Part 3, Table A.2 of NACE MR0175/ISO 15156. The user seeks clarification on the maximum Vickers (HV 10 or HV 5) or Rockwell (15N) value that can be used for the weld HAZ and weld metal. Additionally, the user asks if there are any hardness restrictions for welds in solid-solution nickel-based alloys and duplex stainless steels.

Answer

NACE MR0175/ISO 15156 does not provide guidance for hardness conversion, which is left to the manufacturer and equipment user’s agreement. For welds of corrosion-resistant alloys, there are no hardness limits for the HAZ when the tables or text of the document do not specify any. Meanwhile, for the weld metal, any hardness limit depends on any limit set for the alloy used as a consumable.

This question pertains to NACE MR0175/ISO 15156-3 Annex A.2.3, and the reference cited is ISO 15156 Maintenance Panel Inquiry #2005-13.

Conclusion

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