In order to decrease the danger of low stress creep we slightly overstress superaustenitic SS and Ni-based alloy valve bodies during hydrotesting. This overstressing causes a “cold deformation” of 0.2-0.5%. We do not use the cold deformation in order to enhance the mechanical properties! Is this practice allowed under the rules of NACE MR0175/ISO 15156 ?
Hydrotesting the austenitic stainless steels to the appropriate industry or design code is acceptable.
This question is in relation to NACE MR0175/ISO 15156-3 A.3 and A.4
Reference: ISO 15156 Maintenance Panel Inquiry #2003-28 Q2
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