Does Inconel 600 meet NACE standards?
NACE MR0175 / ISO 15156
NACE MR0175 is equivalent to ISO 15156 and is an international standard for the petroleum, petrochemical and natural gas industries - materials used in environments containing H2S (hydrogen sulfide) in oil and gas production. It contains three parts for the selection of materials: Part 1 - General principles for the selection of crack-resistant materials; Part 2 - The use of crack-resistant carbon and low-alloy steels and cast irons; Part 3 - Crack-resistant alloys (CRA) and other alloys.
NACE MR0103 / ISO 17495
NACE MR0103 is equivalent to ISO 17495 and is an international standard for the petroleum, petrochemical and natural gas industries - Metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments.
Inconel 600 Relationship to NACE MR0175 and MR0103
Inconel 600 (UNS N06600) is approved for NACE MR0103 but no longer for MR0175. In 14.1.1.3 of NACE MR0103, it is clearly stated that "wrought UNS N06600 shall not exceed 35 HRC". NACE MR0175 allowed the use of Inconel 600 in the 1997 revision but excluded it in subsequent revisions. According to A.4, solid solution nickel-base alloys suitable for NACE MR0175 should contain a minimum molybdenum (Mo) content of 2.5% by mass. Unfortunately, Mo is not included in the chemical requirements for Inconel 600.
In general, NACE MR0175 is mainly aimed at upstream industries (oil and gas production), while NACE MR0103 is mainly aimed at downstream industries (petroleum refining processes). Generally speaking, Inconel 600 can still be used for refurbishment of oil and gas projects built to older versions of MR0175 (such as the 1997 revision). For new construction projects, it should be excluded. As long as the minimum hardness requirements are met, it is suitable for MR0103.
