NACE MR0175/ISO 15156/NACE MR0103

NACE International has developed two significant standards relative to the use of materials in hydrogen sulfide bearing environments. One is titled MR0175/ISO 15156, Petroleum and Natural Gas Industries - Materials for use in H2S-containing Environments in Oil and Gas Production; and the other is MR0103, Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments. Hydrogen sulfide is not only a poisonous gas, but can also cause stress corrosion cracking in steels and alloys. These standards define material conditions that are suitable for use in given hydrogen sulfide service conditions.


When NACE MR0175 was modified and co-issued as ISO 15156 in 2003, the restrictions on hardness changed from being listed by individual alloys to groups of alloys. Stainless steels and several of the higher alloys supplied by Rolled Alloys are suitable for use in hydrogen sulfide environments and may be ordered to satisfy these requirements.


The common 300 series stainless steels were characterized as “Austenitic stainless steels of this material type shall contain the following elements in the following proportions, expressed as mass fractions: C 0.08% Max, Cr 16.0% Min, Ni 8.0% Min, P 0.045% Max, S 0.04% Max, Mn 2.0% Max, and Si 2.0% Max. Other alloying elements are permitted.” As a group, the following restrictions as presented in Table A.2 apply:


  • The material must be solution annealed and quenched, or annealed and thermally stabilized.
  • The material must be free of cold work intended to enhance mechanical properties.
  • A hardness maximum of Rockwell C 22 (Rockwell B 100, Brinell 256) applies.

These requirements are identical to those for MR0103. 300 series stainless steels purchased by Rolled Alloys for stock are produced to standard ASTM/ASME specifications such as A/SA 240 for flat products and A/SA 479 for long products. These standards require the material to be supplied in the annealed and quenched (either water or other means) condition. Rolled Alloys does not enhance the mechanical properties of these products through cold work. Provided the hardness values reported on the material test report reflect hardness levels below Rockwell C 22 (or equivalent), these materials are considered to be in compliance with MR0175 Table A.2 and MR0103 Table 3.


Alloy 20 is a material of Type 3a in Table A.8 of MR0175. AL-6XN© Alloy (UNS N08367) is a material of Type 3b. As these materials are supplied in the solution annealed condition, they satisfy the requirements of Table A.8. MR0175 does not require a hardness to be reported for annealed material. These materials also satisfy the requirements of MR0103, paragraph 2.7.1 provided the reported hardness is at or below Rockwell C 35.


Solid solution nickel alloys (such as 600/625) provided by Rolled Alloys are annealed and satisfy the requirements for these materials as set forth in Table A.13 of MR0175. MR0175 does not require a hardness to be reported for annealed material. In addition, they conform to MR0103 Section 3, provided the reported hardness is at or below Rockwell C 35.


Duplex alloys 2205 (S31803/S32205) and ZERON® 100 (S32760) supplied by Rolled Alloys are supplied in the annealed and liquid quenched condition, and have a ferrite content between 35% and 65%. As such, they satisfy the requirements for these materials as stated in Table A.24 of MR0175. MR0175 does not require a hardness to be reported for annealed material. These materials also satisfy MR0103, Paragraph 2.8.1, provided the reported hardness is at or below Rockwell C 28.


Alloy 718 (UNS N07718) is a precipitation hardenable alloy covered in Table A.32 of MR0175. Rolled Alloys provides Alloy 718 either as solution treated to a hardness of Rockwell C 35 maximum, or aged to a hardness of Rockwell C 40 maximum. Both of these conditions satisfy the requirements of Table A.32 (and MR0103, Table 5). Note that our aged product, identified by Rolled Alloys as NACE 718, also satisfies the requirements of API 6A718.


Since all of these materials are supplied to specifications that ensure compliance to the MR0175 requirements, no further certification is routinely provided by the producing mills.