NACE MR 0175/ISO 15156 is a Materials Standard issued by the National Association of Corrosion Engineers. It is originally a US standard intended to assess the suitability of materials for oilfield equipment where sulphide (sulfide) stress corrosion cracking may be a risk in hydrogen sulphide (sour) environments. However, the world standards body ISO has issued it under its own “brand”. The latest edition includes technical corrigenda from 2005.
The standard specifies the types of corrosion resistant materials including stainless steel that can be used in specific oilfield environments and places limits on the hardness of the material. This applies both to parent and weld material. The maximum hardness is usually defined in terms of the Rockwell ‘C’ scale. No conversion to other hardness scale is given in MR 0175 which presents one problem as softened stainless steel hardness are measured using either the Rockwell ‘B’, Vickers or Brinell scales. Approximate conversions are available.
Summary of MR 0175 Requirements
A wide range of materials is covered by the standard including most types (families) of stainless steel. The table below shows some of these grades. However, this summary is intended to only give a general idea of this complex standard and is not a substitute for the original document.Stainless Steel TypeGrades Included Comments Ferritic Stainless Steel405,430, 409, 434, 436, 442, 444, 445, 446, 447, 448Hardness up to 22 HRCMartensitic Stainless Steel410, 420Hardness up to 22 HRCMartensitic Stainless SteelF6NMHardness up to 23 HRCMartensitic Stainless SteelS41425Hardness up to 28 HRCAustenitic Stainless Steel201, 202, 302, 304, 304L, 305, 309, 310, 316, 316L, 317, 321, 347, S31254(254SMO), N08904(904L), N08926(1925hMo)Solution annealed, no cold work to enhance properties, hardness up to 22 HRCAustenitic Stainless SteelS20910Hardness up to 35 HRCDuplex Stainless Steel S31803 (1.4462), S32520 (UR 52N+),S32750 (2507), S32760 (Zeron 100), S32550(Ferralium 255)PREN >30 solution annealed condition, ferrite content 35% to 65%, or 30 to 70% in welds. Note that the general restriction of 28 HRC in previous editions is not found in this latest edition of the standard. There is a specific restriction on HIP’d S31803 to 25HRC. For some applications cold worked material is allowed up to 36HRC
Precipitation Hardening17-4 PH33 HRC Age hardening at 620 deg CPrecipitation Hardening S4500031 HRC Age hardening at 620 deg CPrecipitation HardeningS6628635 HRC
Free machining grades such as the 303 and 416 types are excluded from of NACE MR 0175/ISO 15156
Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)
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