FAQ's

Cold work of dual certified 316/316L and NACE MR0175

1. Under Table A.2 – ‘Environmental and materials limits for austenitic stainless steels used for any equipment or components’, in the notes section under the sub heading ‘b’, which apply to grade UNS S31603 (316L), is the following statement ‘the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc. after the final solution annealing and quenching treatment. My question is, why is this statement also not applicable to other types of austenitic stainless steels described in paragraph A.2 (under sub heading ‘a’ above)?
2. Following on from question 1 above, if a material is dual certified as 316/316L (UNS S31600/S31603), what category of Table A.2 will it be designated under? i.e. will it be deemed under category A.2 (note ‘a’) or as UNS S31603 (note ‘b’)? Or both?
(MP INQUIRY #2016-19)
ANSWER:
Under ISO 15156-3 Table A.2, in the notes section under the sub heading ‘b’, which apply to grade UNS S31603 (316L), is the following statement ‘the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc. after the final solution annealing and quenching treatment.
Question 1: Why is this statement also not applicable to other types of austenitic stainless steels described in paragraph A.2 (under sub heading ‘a’ above)?
Answer: The words present in note “b” are in accordance with a successful ballot to extend the use limits of UNS S31603. The extension of these use limits was accompanied by a more descriptive definition of what constitutes cold work.
Question 2: If a material is dual certified as 316/316L (UNS S31600/S31603), what category of ISO 15156-3 Table A.2 will it be designated under?
Answer: The alloy meets and applies to both “a” and “b” as applicable. Note the paragraph in ISO 15156-3 Clause A.2.1 which states “It is common industry practice to dual certify 300 series stainless steels as standard grade and low carbon grade such as S31600 (316) and S31603 (316L). The environmental limits given for low carbon 300 series stainless steels are acceptable for the dual certified grades”.

Reference: Maintenance Panel inquiry 2016-19 (NACE MR0175 Part 3 Clause A.2)

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