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NACE MR0175, Carbon steels and further questions on SOHIC, SZC, SSC, HIC and SWC?

Question: I have two questions concern hydrogen induced cracking. Question 1. Clause 7 of the standard is headed “Qualification & selection of C and low alloy steels with resistance to SSC, SOHIC and SZC” Clause 7.1.1 concerns SSC only in low partial pressure of H2S. There is no mention of the other forms of cracking. Clause 7.1.2 has three footnotes: NOTE 1 deals with SSC, NOTE 2 concerns SOHIC and SZC and NOTE 3 concerns HIC and SWC.Should these three NOTES be applied to Clause 7.1.1 too? Question 2. Clause 8 deals with the evaluation of C and low alloy steels for their resistance to HIC/SWC. It indicates that a few ppm of H2S must be considered during an evaluation of a steel. But have the steels that meet the requirements of Appendix A.2 been deemed to have been evaluated for HIC/SWC and so do not need additional HIC testing?

Answer 1

The applicability of Notes 1, 2, and 3 is for the entire Clause 7.1 and not restricted to Clause 7.1.2.

Answer 2

Materials described in Annex A.2 may require additional testing to confirm resistance to SOHIC, SZC, and/or SWC. This shall be determined by the equipment user and can be influenced by factors such as whether the material was produced as a flat rolled carbon steel product and the steel chemistry (see clause 8).

Question 1 is in relation to NACE MR0175/ISO 15156-2 Clause 7.1

Question 2 is in relation to NACE MR0175/ISO 15156-2 Clause 8

Reference: ISO 15156 Maintenance Panel Inquiry #2012-12

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