Clarifying the Definition of Corrosion-Resistant Alloys in NACE MR0175/ISO 15156-1

If you’re wondering whether Fe-based alloys are included in the definition of “corrosion-resistant alloys” (CRAs) in Part 3 of MR0175/ISO 15156, you’re not alone. The use of the term “other alloys” in conjunction with CRA can add to the confusion.

According to the ISO 15156 Maintenance Panel, the definition for CRA can be found in NACE MR0175/ISO 15156-1, Paragraph 3.6. It states that CRA is “an alloy intended to be resistant to general and localized corrosion of oilfield environments that are corrosive to carbon steel.” This definition is adopted from EFC (European Federation of Corrosion) 17.

However, “other alloys” refer to those types that are not covered under the definition of carbon steel or CRA. For instance, copper is accounted for under NACE MR0175/ISO 15156-3, even though it is not generally corrosion-resistant.

To be specific, this inquiry concerns NACE MR0175/ISO 15156-1 Clause 3.
Reference: ISO 15156 Maintenance Panel Inquiry #2004-12.