In NACE MR0175 Part 3 Clause A.3 are 3B materials qualified for all conditions?

Question 1:
Shouldn’t it have the same material restrictions of all type 3b materials, and be able to be used under the conditions stated in both entries for materials type 3b, and not only according to the first entrance? Otherwise, could you kindly explain the reason of this difference in limits, with such a similar chemical composition?
Answer 1:
Materials requirements for sour service are not solely based on chemical composition as there are other metallurgical conditions that directly impact their resistance and, thus, their specific sour service limits. Cast vs. wrought materials is an example of such differences in terms of metallurgical conditions that affect their resistance and as such need to be qualified accordingly. A ballot with the required testing data in compliance with NACE MR0175/ISO 15156-1 and NACE MR0175/ISO 15156-3, Appendix B or field experience data as described in NACE MR0175/ISO 15156-1 would be needed to extend current limits.
This question is in relation to NACE MR0175/ISO 15156-3/A.3.2
Reference MP inquiry #2018-03

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