What are the NACE MR0175 material requirements for Inconel 625 (UNS N06625)?

Sour Service Materials Made with Inconel 625 Must Comply with NACE Requirements 625

Inconel 625 (UNS N06625) is a popular material used in sour service applications in the oil and gas industry. However, to ensure its suitability for these environments, it must comply with the metallurgical requirements set out in ANSI/NACE MR0175/ISO15156, specifically NACE requirements 625. In this article, we will discuss two of those requirements: metallurgical condition and hardness.

Metallurgical Condition

NACE MR0175 states that alloy 625 must be in the annealed condition to be suitable for sour service applications. However, some suppliers offer alloy 625 quenched off the hammer, which raises questions about compliance. The answer is that it’s up to the manufacturer to determine if alloy 625 is annealed under these conditions, and it’s not the role of the maintenance panel to answer metallurgical questions. If alloy 625 is annealed, it meets the requirements of Table A.13.

Hardness Requirement

Regarding the NACE MR0175 hardness requirement for Inconel 625 (UNS N06625), NACE MR0175/ISO 15156 Part 3 Clause A.4 provides details of the material requirements for solid solution nickel alloys. It specifies that the maximum hardness for alloy 625 in the annealed condition is 22 HRC (Rockwell C scale) or 237 HB (Brinell hardness). If the material exceeds these values, it may not be suitable for sour service applications.

Expert Assistance from OGC Energy

At OGC Energy, we help manufacturers determine the optimal route for forging and annealing Alloy 625 while also assisting users in reviewing material test reports (MTRs) and manufacturing documentation to verify compliance with NACE MR0175 and other regulatory requirements. Our experienced team provides independent materials and corrosion consultancy to help companies reduce risk, save money, and apply best practices in their oil and gas businesses. Contact us today to learn more.

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