A286 Nuts
RAYCHIN SPECIALTY METALS FASTENERS: BOLTS, NUTS, SCREWS, WASHERS, STUDS, THREADED RODS, U-BOLT, J-BOLTS
STANDARD AND CUSTOMIZED, SMALL BATCH AND LARGE BATCH, IMPERIAL AND METRIC
A286 / Alloy 660 for excellent high temperature oxidation resistance
Excellent high temperature oxidation resistance to 1300°F / 700°C
Maintains high strength at elevated temperatures
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RAYCHIN LIMITED
Specialist in A286 Nuts · Hex Nuts · Heavy Hex · Lock Nuts · Jam Nuts · CustomA286 Nuts: High-Temperature Superalloy Nuts for Critical Bolting Applications
RAYCHIN LIMITED is a recognized expert in A286 nuts — from A286 hex nuts, A286 heavy hex nuts, A286 lock nuts, A286 jam nuts to custom non-standard nut configurations. A286 (UNS S66286) is an iron-nickel-chromium superalloy strengthened by precipitation hardening. Also designated as Alloy 660, it maintains exceptional strength and oxidation resistance up to 700°C (1300°F), making it the preferred material for high-temperature nut applications in pressure vessels, gas turbines, heat exchangers, valve assemblies, power generation, aerospace, and oil & gas (sour service). A286 nuts are specifically designed for use with A286 studs and bolts in applications requiring high strength-to-weight ratio, excellent creep resistance, and reliable fastening in high-temperature environments. The alloy's thermal expansion coefficient closely matches that of austenitic stainless steels, preventing loss of preload during thermal cycling in flange connections and pressure boundary applications. Our portfolio includes nuts manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards. Engineered for extreme environments where high-temperature strength, creep resistance, and corrosion resistance are critical. A286 nuts are supplied in solution annealed and precipitation hardened conditions with full traceability and third-party certifications.
Complete Range of A286 Nuts – Types & Configurations
A286 Hex Nuts
A286 hex nuts manufactured to ASME B18.2.2, DIN 934, ISO 4032, and ISO 4033 standards. Available in style 1 and style 2 configurations with UNC, UNF, and metric coarse/fine threads. Precision tapped to Class 2B and 3B tolerances for reliable engagement with mating studs and bolts. Ideal for high-temperature applications up to 700°C in pressure vessels, flange connections, and structural assemblies. Available in sizes from #4 to 4" (M3 to M100). Supplied in Class A, B, or D conditions per ASTM A453. Hot forming and cold forming options available.
A286 Heavy Hex Nuts
A286 heavy hex nuts manufactured to ASME B18.2.2, DIN 6915, and ISO 4034 standards. Features a larger wrenching surface compared to standard hex nuts, providing increased bearing area for high-temperature flange connections and pressure vessel applications. Essential for API 6A and ASME B16.5 bolting assemblies. The heavier cross-section distributes load more effectively and resists dilation at elevated temperatures. Available with controlled hardness ≤ 35 HRC for NACE MR0175 sour service compliance. Supplied with matching A286 studs for complete bolting sets.
A286 Lock Nuts & Self-Locking Nuts
A286 lock nuts including all-metal lock nuts, crimp lock nuts, and self-locking configurations per NASM25027 and DIN 980 standards. Designed for high-vibration environments where fastener retention is critical. Available in reduced height configurations for clearance-limited applications. Features controlled thread deformation or locking elements that provide prevailing torque. Suitable for gas turbine assemblies, aerospace components, and high-temperature applications up to 700°C. Passivated finish per AMS-QQ-P-35 and dry film lubricant available per AS5272.
A286 Jam Nuts & Thin Nuts
A286 jam nuts manufactured to ASME B18.2.2, DIN 439, and ISO 4035 standards. Reduced height nuts designed for applications with limited clearance or as locking nuts in conjunction with standard hex nuts. Ideal for adjustment applications and where space constraints require thinner profiles. Available in UNC, UNF, and metric threads with Class 2B and 3B tolerances. Suitable for high-temperature service up to 700°C in valve assemblies, instrumentation, and control systems. Precision machined from precipitation hardened A286.
A286 Nuts – API & NACE Compliant
A286 nuts certified to NACE MR0175 / ISO 15156 for sour service applications in oil and gas industry. Class D condition with controlled hardness ≤ 35 HRC per API 20F BSL2 & BSL3 requirements. Suitable for wellhead equipment, valve assemblies, subsea connections, and refinery applications exposed to H₂S environments. Available in all configurations with 100% hardness testing and Charpy impact testing at -196°C per Class D requirements. 100% NDT available including PMI and dimensional verification. API 6A closure nuts available with full traceability.
Custom & Specialty A286 Nuts
Need a special thread configuration, unusual size, or custom locking feature for your high-temperature application? RAYCHIN engineers work with you to produce custom A286 nuts to your drawing. Options include castle nuts, slotted nuts, coupling nuts, and nuts with unusual locking elements. Expert heat treatment (solution annealed at 982°C followed by precipitation hardening at 718°C for 16 hours) precisely controlled for each batch. Manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS standards.
Key Benefits of A286 Nuts
High-Temperature Strength Retention
Maintains high strength up to 700°C, with stress rupture testing at 650°C required per ASTM A453. Ideal for pressure vessel and turbine applications where bolt preload must be maintained.
Multiple Nut Styles Available
Hex nuts for general purpose, heavy hex for flange connections, lock nuts for vibration resistance, jam nuts for limited clearance. Custom configurations available.
Sour Service Approved
NACE MR0175 / ISO 15156 qualified for H₂S environments; Class D with hardness ≤ 35 HRC meets API 20F and API 6A requirements for oil and gas applications.
Thermal Expansion Matched
Thermal expansion coefficient (16.0-16.5 x 10⁻⁶/°C) closely matches A286 studs and austenitic stainless flanges, preventing loss of preload during thermal cycling.
Oxidation Resistance
Excellent oxidation resistance up to 815°C continuous service and 982°C intermittent. Forms protective Cr₂O₃ scale for long-term durability.
Cryogenic Toughness
Maintains ductility and impact strength down to -196°C, with Charpy testing available per Class D requirements (40 J min). Ideal for LNG and cryogenic applications.
Manufacturing Standards for A286 Nuts
RAYCHIN LIMITED manufactures A286 nuts to the following national and international standards, ensuring full compliance for projects worldwide. Both standard and non-standard custom configurations are available.
Nut Dimensional Standards
All dimensional standards available in UNC, UNF, UNJF-3B per AS8879, and metric thread configurations. Standard sizes from #0 to 4" (M1.6 to M100). Proof load testing available per ASTM A453 requirements.
International Standards & Global Designations for A286 Nuts
To serve clients worldwide, RAYCHIN LIMITED manufactures A286 nuts from material conforming to the following national and international specifications. This ensures full compliance for projects in the Americas, Europe, Asia, and the Middle East.
UNS S66286 Alloy 660 ASTM A453 AMS 5732 AMS 5737 NACE MR0175 1.4980 API 20F GH2132 SUH660 NAS1804
Chemical Composition (Weight %) – A286 Superalloy (UNS S66286 / 1.4980)
Our A286 nuts are produced from melts that strictly conform to the limits below per ASTM A453 / AMS 5731. The high nickel and chromium content provide excellent oxidation resistance, while titanium and aluminum enable precipitation hardening through gamma-prime (γ') phase formation. Molybdenum and vanadium contribute to solid solution strengthening, and boron enhances creep resistance.
Expert note: The combination of titanium and aluminum promotes the formation of Ni₃(Al,Ti) gamma-prime precipitates during aging, which provide A286 with its exceptional high-temperature strength. Boron addition (0.001-0.010%) significantly improves creep resistance by strengthening grain boundaries. With nickel content of 24-27%, A286 offers excellent resistance to chloride stress corrosion cracking and maintains a stable austenitic structure from cryogenic temperatures up to 700°C.
Complete Mechanical Properties of A286 Nuts (per ASTM A453)
A286 nuts are supplied in the solution annealed and precipitation hardened condition (982°C solution treat + 718°C age for 16 hours). ASTM A453 defines multiple classes for different strength levels and size ranges. The data below represent minimum requirements per ASTM A453/A453M unless otherwise noted. Proof load testing ensures compatibility with mating studs and bolts.
Tensile Requirements by Class – ASTM A453 Grade 660
Hardness Requirements for Nuts
For NACE MR0175 / API 20F sour service applications, Class D with maximum hardness 35 HRC is required and 100% hardness testing is mandatory. Proof load testing per ASTM A453 ensures nuts meet or exceed specified strength requirements.
Impact Properties (Charpy V-Notch)
Class D nuts used in sour service applications are Charpy impact tested at -196°C with 40 J as the minimum qualifying requirement.
Stress Rupture Properties (650°C / 1200°F)
A critical requirement for high-temperature nuts is stress rupture resistance of the base material. Per ASTM A453, Class A, B, and C materials must meet the following:
Note: Class D does not have a stress rupture requirement (marked "NR" in the standard).
Temperature-Dependent Yield Strength
The following table shows typical yield strength (0.2% offset) at elevated temperatures for A286 in the fully heat-treated condition.
Elevated Temperature Oxidation Resistance
A286 maintains anti-tensile strength not less than 885 MPa at 500°C with stress retention greater than 88.35%, making it the optimal choice for high-temperature nut applications.
Physical Properties of A286
Thermal Expansion Properties of A286 Nuts for Flange Connections
A286 nuts are specifically designed for use with A286 studs and austenitic stainless steel components (A182 F304, F316, F321) operating at elevated temperatures. Their thermal expansion coefficient closely matches that of stainless steels, preventing loss of preload during thermal cycling – a critical feature for maintaining gasket stress and preventing leaks in high-temperature flange connections.
This expansion match is critical for maintaining seal integrity in high-temperature applications such as refinery piping systems, power generation HRSG connections, and chemical processing equipment. Using A286 nuts with A286 studs and stainless steel components ensures uniform thermal expansion and sustained clamp load.
API 6A & NACE MR0175 Compliance for A286 Nuts
A286 nuts are widely used in oil and gas applications requiring sour service resistance. Per API 6A and API 20F, A286 Grade 660 Class D is approved for H₂S service with maximum hardness of 35 HRC. Nuts are an integral component of API bolting assemblies.
Heat Treatment & Microstructural Stability of A286 Nuts
Optimal mechanical properties in A286 nuts are achieved through a two-step heat treatment:
- Solution Annealing: 982°C (1800°F) for 1 hour, oil quench or water quench. This dissolves carbides and prepares the matrix for precipitation hardening.
- Aging (Precipitation Hardening): 718°C (1325°F) for 16 hours, air cool. This forms coherent γ' (gamma-prime) precipitates [Ni₃(Al,Ti)] that provide high-temperature strength.
Metallurgical studies show that controlled aging at 718°C ensures optimal γ' formation while avoiding η phase precipitation, maximizing creep resistance and long-term stability up to 700°C.
Corrosion Resistance of A286 Nuts
While A286 is primarily selected for high-temperature strength, it also offers good corrosion resistance in many environments due to its high chromium (14-16%) and nickel (24-27%) content. The alloy exhibits excellent oxidation resistance up to 700°C continuous service and 815°C intermittent service.
Oxidation and Scaling Resistance
The chromium content provides excellent resistance to oxidation and scaling. A286 nuts form a protective Cr₂O₃ scale that prevents further oxidation at elevated temperatures. They provide excellent oxidation resistance up to 815°C in continuous service and up to 982°C for intermittent service.
Corrosion in Other Environments
Critical Corrosion Considerations for Nuts
- Oxidation Resistance: Excellent oxidation resistance up to 815°C in gas turbine and exhaust environments. Suitable for continuous service up to 700°C.
- NACE MR0175 Compliance: A286 is qualified for sour service (sulfide stress cracking resistance) in oilfield equipment per NACE MR0175/ISO 15156. Class D with maximum hardness 35 HRC is preferred for sour applications.
- Temperature Limitations: Maximum service temperature for continuous service is 700°C (1300°F). For intermittent service, temperatures up to 815°C are acceptable.
- Galvanic Corrosion: When paired with lower-grade materials, galvanic corrosion should be considered. A286 is compatible with stainless steels and nickel-based alloys.
- Non-Magnetic Property: A286 is essentially non-magnetic (permeability ≤ 1.01), making it suitable for applications requiring non-magnetic components such as MRI equipment and sensitive instrumentation.
Special focus: A286 Nuts for High-Temperature & Critical Applications
For critical applications requiring high-temperature strength, oxidation resistance, and corrosion resistance, RAYCHIN offers A286 nuts manufactured to ASTM, ASME, NACE, and customer-specific specifications. Our capabilities include:
- Pressure Vessels & Heat Exchangers: ASME B16.5 flange nuts, tube sheet nuts, reactor closure nuts, autoclave bolting nuts, high-pressure vessel nuts.
- Oil & Gas / Sour Service: API 6A closure nuts, wellhead equipment nuts, valve assembly nuts, subsea connection nuts, refinery piping nuts, NACE MR0175 applications.
- Gas Turbines & Power Generation: Turbine casing nuts, combustion chamber nuts, exhaust manifold nuts, HRSG connection nuts, steam turbine nuts.
- Aerospace: Engine mount nuts, thrust nozzle nuts, transmission component nuts, missile guidance system nuts, satellite fasteners. Available with UNJF-3B threads per AS8879.
- Cryogenic Equipment: LNG facility nuts, cryogenic storage tank nuts, superconducting magnet nuts, MRI system nuts. Charpy tested at -196°C.
- Chemical Processing: High-temperature reactor nuts, reformer connection nuts, heat exchanger tube sheet nuts, thermowell nuts.
- Types: Hex nuts (ASME B18.2.2, DIN 934, ISO 4032), heavy hex nuts (DIN 6915, ISO 4034), jam nuts (DIN 439, ISO 4035), lock nuts (DIN 980, NASM25027), slotted nuts, castle nuts.
- Sizes: #0 through 4" (M1.6 through M100) in standard and custom dimensions.
- Thread Classes: 2B, 3B, UNJF-3B per AS8879 for aerospace applications.
- Surface Treatments: Silver plating per AMS 2410 for anti-seize, passivation per ASTM A967, dry film lubricant per AS5272, Xylan coatings.
- Class Selection: Class A (standard strength), Class B, Class D (API sour service), Cold Worked (maximum strength).
- Certifications: EN 10204 3.1/3.2 material certifications, NACE MR0175, API 20F, PED 2014/68/EU, ASME compliance.
All A286 nuts are supplied with full traceability and third-party NDT upon request. Available in all standard sizes with matching A286 studs and bolts for complete bolting sets. Material certifications included.
Why RAYCHIN LIMITED – The A286 Nut Authority
Metallurgical competence
Engineers on staff with deep expertise in precipitation hardening superalloys. We ensure proper solution annealing (982°C minimum) and precipitation hardening (718°C for 16 hours) for optimal high-temperature strength and creep resistance across all A286 nuts. Every heat is verified by in-house testing and PMI verification. With 24-27% nickel and titanium-aluminum precipitation hardening, our nuts provide exceptional strength up to 700°C while maintaining excellent corrosion resistance.
Global approvals & traceability
Our quality system is ISO 9001:2015 and AS9100D certified; we also comply with NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS. Full material traceability from melt to final packaging (EN 10204 3.1/3.2). Third-party inspections (ABS, DNV, Lloyds) available. All A286 nuts meet applicable AMS, ASTM A453, and NACE MR0175 requirements. API 20F certification available for Class D nuts.
Precision tapping & thread forming
In-house CNC tapping and thread forming capabilities ensure precise thread geometry and consistent mechanical properties. Available thread classes up to 3B and UNJF-3B. 100% thread inspection available. Ultrasonic cleaning and passivation available for critical applications. Proof load testing per ASTM A453 ensures nuts meet or exceed specified strength requirements.
Custom solutions
Need a special thread configuration, unusual size, or custom locking feature for your high-temperature application? Our CNC machining departments handle short runs with agility. We also provide specialized coatings, cryogenic impact testing, and NACE MR0175 compliant processing per customer requirements. Available in Class A, Class B, Class D (API sour service), and cold worked conditions.
Contact the A286 nut experts today
Request a quote for A286 nuts, hex nuts, heavy hex nuts, lock nuts, jam nuts & custom configurations – any global standard (NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS), any quantity. Inquire about high-temperature nuts up to 700°C, pressure vessel nuts, NACE MR0175 sour service requirements, or cryogenic applications.
sales@ray-chin.com | +86 534 2166 566Our team speaks English, German, Mandarin, and Japanese – ready for your global procurement.
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