Is HIC a potential risk if the partial pressure of H₂S is below 0,3 kPa?
HIC NACE and SWC Risks in Sour Service
Introduction
The inquiry pertains to HIC and SWC risks mentioned in Clause 7.1.2/Note 3 of NACE MR0175/ISO 15156-2 with reference to Clause 8. Clause 8 states that HIC may be a potential risk in sour service even if only trace amounts of H₂S are present.
Clarification on “”Trace Amounts””
The inquiry seeks clarification on what “”trace amount”” refers to and if there is a specific threshold for HIC. Unfortunately, NACE MR0175/ISO 15156-2 does not define “”trace amount”” or a specific threshold for HIC.
Applicability of HIC as a Potential Risk
Additionally, the inquiry questions whether HIC is not applicable as a potential risk if the partial pressure of H₂S is below 0.3 kPa (referring to Clause 7.1.1) and if Clause 8 is valid since HIC is not listed in Clause 7.1.1.
Response
The response indicates that the NOTES in Clause 7.1 apply to both Clauses 7.1.1 and 7.1.2, with reference to Clause 8 for HIC and SWC. Therefore, Clause 8 is valid, even though HIC is not listed in Clause 7.1.1. This inquiry pertains to NACE MR0175/ISO 15156-2 7.1.2, with reference to ISO 15156 Maintenance Panel Inquiry #2016-11.