NACE MR0175 / ISO 15156 Sour Service Fasteners - Manufacturer, Supplier | Ananka Fasteners

NACE MR0175 / ISO 15156 SOUR SERVICE FASTENERS

NACE MR0175 Sour Service Stud Bolts and Fasteners

■ NACE MR0175 Compliant Bolting Materials (≤ 22 HRC)

SPECIFICATION	GRADE	CLASS	UNS NO.	MATERIAL TYPE	HARDNESS LIMIT
ASTM A193	B7M	—	G41400	Low-Alloy Steel (4140), Tempered	22 HRC max
ASTM A193	B8	Class 1 / 1D	S30400	304 Stainless Steel, Solution Treated	96 HRB (223 HBW) max
ASTM A193	B8M	Class 1 / 1D	S31600	316 Stainless Steel, Solution Treated	96 HRB (223 HBW) max
ASTM A193	B8C	Class 1	S34700	347 Stainless Steel, Stabilized	96 HRB (223 HBW) max
ASTM A193	B8T	Class 1	S32100	321 Stainless Steel, Stabilized	96 HRB (223 HBW) max
ASTM A193	B8P	Class 1	S30500	305 Stainless Steel	96 HRB (223 HBW) max
ASTM A193	B8LN	Class 1	S30453	304LN Stainless Steel	96 HRB (223 HBW) max
ASTM A193	B8MLN	Class 1	S31653	316LN Stainless Steel	96 HRB (223 HBW) max
ASTM A193	B8A, B8MA, B8CA, B8TA, B8PA, B8LNA, B8MLNA	Class 1A	Various	Austenitic SS, Solution Treated (finished fasteners)	96 HRB (223 HBW) max
ASTM A320	L7M	—	G41400	Low-Alloy Steel (4140), Low-Temp Tempered	22 HRC max
ASTM A320	B8 / B8M	Class 1	S30400 / S31600	304 / 316 SS, Cryogenic Service	96 HRB (223 HBW) max
ASTM A194	2HM	—	—	Carbon Steel Nut, Tempered	22 HRC max
ASTM A194	7M	—	—	Alloy Steel Nut, Tempered	22 HRC max
ASTM A194	8, 8M, 8A, 8MA	—	S30400 / S31600	304 / 316 SS Nut, Solution Treated	96 HRB (223 HBW) max

Note: All bolting material exposed directly to a sour environment, or buried, insulated, or denied direct atmospheric exposure, shall conform to the hardness requirements above per NACE MR0175 / ISO 15156-2 Section A.2.2.4. Designers should be aware that lower equipment pressure ratings may be necessary when using SSC-resistant bolting.

■ CRA & Nickel Alloy Fasteners (ISO 15156-3)

ALLOY	UNS NO.	TYPE	HARDNESS LIMIT	KEY H₂S SERVICE CAPABILITY
Duplex 2205	S31803 / S32205	Duplex Stainless	28 HRC max	Moderate H₂S, high Cl⁻ resistance
Super Duplex 2507	S32750	Super Duplex	32 HRC max	Higher H₂S with elevated Cl⁻ & temperature
Super Duplex 2760	S32760	Super Duplex	32 HRC max	Severe sour with high chloride levels
Alloy 825	N08825	Nickel-Iron-Chromium	35 HRC max	Moderate sour, good acid resistance
Inconel 625	N06625	Nickel-Chromium-Molybdenum	35 HRC max	Severe sour, high temperature
Inconel 718	N07718	Nickel-Chromium, Precip. Hardened	40 HRC max	High-strength sour service (API 6A)
Hastelloy C-276	N10276	Nickel-Chromium-Molybdenum	35 HRC max	Extremely aggressive sour, reducing acids
Monel 400	N04400	Nickel-Copper	35 HRC max	Marine sour, HF acid environments
Monel K-500	N05500	Nickel-Copper, Age Hardened	35 HRC max	High-strength marine sour service
Alloy 925	N09925	Nickel-Iron-Chromium, Age Hardened	40 HRC max	Subsea sour, high strength downhole

Note: CRA materials are qualified per NACE MR0175 / ISO 15156-3 with environmental limits on H₂S partial pressure, chloride concentration, pH, and temperature. Always consult the latest edition of the standard for specific application limits. Ananka Fasteners supplies all CRA grades with full NACE compliance documentation.

■ Technical Specifications

Standard	NACE MR0175 / ISO 15156 — Petroleum & Natural Gas Industries: Materials for Use in H₂S-Containing Environments Part 1: General principles for selection of cracking-resistant materials Part 2: Cracking-resistant carbon & low-alloy steels, and use of cast irons Part 3: Cracking-resistant CRAs (corrosion resistant alloys) and other alloys
Scope	Selection and qualification of metallic materials resistant to sulfide stress cracking (SSC), stress corrosion cracking (SCC), hydrogen-induced cracking (HIC), stepwise cracking (SWC), stress-oriented HIC (SOHIC), and galvanically induced hydrogen stress cracking (GHSC) in oil & gas production and natural gas sweetening plants.
Bolting Hardness Limits	Carbon & Low-Alloy Steel: 22 HRC max (e.g., A193 B7M, A320 L7M, A194 2HM/7M) Austenitic Stainless Steel: 22 HRC max or 96 HRB (223 HBW) max — carbide solution treated Duplex Stainless Steel: 28–32 HRC max (grade dependent) Nickel Alloys (solid solution): 35 HRC max Nickel Alloys (precipitation hardened): 40 HRC max (e.g., Inconel 718, Alloy 925)
Carbon & Low-Alloy Steel Requirements	Ni content: < 1% mass fraction Not free-machining steels Heat treatment: Quenched & tempered, normalized & tempered, or normalized ASTM A105 forgings: ≤ 187 HBW ASTM A234 WPB/WPC fittings: ≤ 197 HBW
Size Range	1/4" to 3" (imperial) \| M6 to M76 (metric) — stud bolts, hex bolts, nuts, washers, threaded rods
Fastener Types Available	Stud Bolts (Double End & Continuous Thread), Hex Bolts, Heavy Hex Bolts, Hex Cap Screws, Socket Head Cap Screws, Hex Nuts, Heavy Hex Nuts, Washers, Threaded Rods, Anchor Bolts, U-Bolts, Eye Bolts
Dimensional Standards	ASME B16.5 / B16.47 (Flange Bolting) \| ASME B18.2.1 / B18.2.2 (Hex Bolts & Nuts) \| DIN 933 / 931 / 934 \| ISO 4014 / 4017 / 4032 \| API 6A (Wellhead & Christmas Tree)
Testing Requirements	SSC Testing: NACE TM0177 (Method A — Tensile, Method B — Bent Beam, Method C — C-Ring, Method D — DCB) HIC Testing: NACE TM0284 Hardness Survey: Per ASTM E18 (Rockwell) / E10 (Brinell) / E92 (Vickers) PMI: Positive Material Identification on every heat
Surface Finishes	Plain / Bare, Passivated, Electropolished, PTFE / Xylan Coated, Zinc Flake (non-electrolytic), Phosphate & Oil — Note: electroplated coatings (zinc, cadmium) generally restricted per NACE due to hydrogen embrittlement risk
Certification	EN 10204 Type 3.1 Mill Test Certificate — Chemical analysis, mechanical properties, hardness survey, heat treatment records, PMI, NACE compliance statement. Third-party inspection (TÜV, Lloyd's, BV, DNV) and SSC/HIC test reports available on request.
Applications	Sour gas wellheads & Christmas trees (API 6A), subsea manifolds & connectors, offshore production platforms, sour gas pipelines & process piping, pressure vessels & heat exchangers in H₂S service, FPSOs, gas sweetening plants, refineries (in conjunction with NACE MR0103 / ISO 17945), downhole completion equipment.

NACE MR0175 / ISO 15156 SOUR SERVICE FASTENERS

■ NACE MR0175 Compliant Bolting Materials (≤ 22 HRC)

■ CRA & Nickel Alloy Fasteners (ISO 15156-3)

■ Technical Specifications

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