NACE MR0175 / ISO 15156

NACE MR0175, which is equivalent to ISO 15156, is the international standard for petroleum, petrochemical and natural gas industries – materials for used in H2S (hydrogen sulfide) – containing environments in oil and gas production. It contains three parts for the selection of materials: Part 1 – general principles for selection of cracking-resistant materials; Part 2 – cracking resistant carbon and low-alloy steels, and the use of cast irons.; Part 3 – cracking resistant alloys (CRAs) and other alloys.

NACE MR0103 / ISO 17495

NACE MR0103, which is equivalent to ISO 17495, is the international standard for petroleum, petrochemical and natural gas industries – metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments.

Inconel 600’s Correlation with NACE MR0175 & MR0103

Inconel 600 (UNS N06600) is endorsed by NACE MR0103 but no longer endorsed by MR0175. In 14.1.1.3 of NACE MR0103, it clearly states that “wrought UNS N06600 shall not exceed 35 HRC”. NACE MR0175 once allowed the use of Inconel 600 in its 1997 revision, however, it precludes it in the following revisions. According to A.4, solid-solution nickel based alloys that are applicable to NACE MR0175 shall contain the minimum molybdenum (Mo) content of 2.5% (mass fraction). Unfortunately, Inconel 600 doesn’t have the Mo in its chemical requirements.

Generally, NACE MR0175 mainly covers the upstream industries (oil & gas production) while NACE MR0103 mainly focuses on the downstream industries (oil refining process). As a rule of thumb, Inconel 600 may still be used in refurbishment of oil & gas projects constructed in accordance with previous version of MR0175, such as the 1997 revision. For newly constructed project, it shall be precluded. And it is applicable to MR0103 as long as the minimum hardness requirement is met.