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What are the NACE MR0175 limits for UNS J93254 (A351 CK3MCuN)?

Question:

We have requirement of 6Mo valves for one of our ongoing projects wherein we need to use A 351 CK3MCuN (J 93254) body material. With reference to Table A -8 of NACE MR0175/ISO-15156 – 2003 Environmental and materials limits for highly alloyed austenitic steels used for any equipment or components ) we have following clarification: Table A – 8 lists the above material J 93254 (ASTM A 351 CK3MCuN) can be used for any combinations of temperature, pH2S, chloride concentration and in situ pH occurring in production environments are acceptable. We understand that forging grade equivalent of above J 93254 which is UNS 31254 will also be qualified under these conditions. Please confirm /clarify the whether forging grade equivalent of J 93254 which is UNS 31254 will also be qualified?

Answer:

Table A.8 is the subject of an amendment proposal that has been accepted by the ISO 15156 Maintenance Panel, by NACE TG 299 (ISO 15156 Oversight Committee) and by ISO TC67 WG7 and will now go forward for publication.
The revision involves limits being placed upon the application of UNS J93254. Publication of this document can be expected within the coming year.

This question is in relation to NACE MR0175/ISO 15156-3 A.3.2, Table A.8

Reference: ISO 15156 Maintenance Panel Inquiry #2006-12

UPDATE: NACE MR0175 / ISO 15156 latest revision includes an update on the UNS J93254 limits.

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