NACE MR0175 SSC Resistant Steels above 0.3 kPa (0.05 psi) and the acceptable pH and Cl- limits

Question: Sub-clause 7.1.2 says SSC Resistant Steels for partial pressures equal to or above 0.3 kPa (0.05 psi) can be selected using A.2. a) If criteria, like temperature, hardness are met, do we assume that for all partial pressures above 0.05 psi the suggested SSC-resistant materials could be used? E.g., SSC-resistant materials mentioned in Table A.2 and Table A.3. b) What are the acceptable pH and Cl- limits? c) Does A. cover L80 type 1? d) For low-alloy steels described in Section A.2 of this standard, what are the cases where injection of corrosion inhibitors are required, both for downhole casings/tubing and surface pipelines?


a) This is correct.
b) No limits of pH and Cl- have been formally defined for carbon and low-alloy steels. Any combinations of chloride concentration and in situ pH occurring in production environments are considered acceptable. Metal loss corrosion, which can be influenced by both pH and chlorides, is not the subject of the standard.
c) No, this grade is covered in Paragraphs A. and A.
d) NACE MR0175/ISO 15156 does not cover the use of corrosion inhibitors. The use of any kind of corrosion inhibitor is not considered to allow any relaxation of the requirements for cracking resistance of materials in sour service.

This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.1.2, A., Table A.2, and Table A.3

Reference: ISO 15156 Maintenance Panel Inquiry #2005-14

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