A286 Hex Cap Screws
RAYCHIN SPECIALTY METALS FASTENERS: BOLTS, NUTS, SCREWS, WASHERS, STUDS, THREADED RODS, U-BOLT, J-BOLTS
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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 Hex Cap Screws · Heavy Hex · Hexagon Head Cap Screws · Custom BoltingA286 Hex Cap Screws: High-Temperature Superalloy Hexagon Head Screws for Critical Flange & Turbine Applications
RAYCHIN LIMITED is a recognized expert in A286 hex cap screws — from A286 heavy hex cap screws, A286 hexagon head cap screws, A286 hex head screws to custom non-standard bolting 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 (1292°F), making it the preferred material for high-temperature bolting applications in gas turbines, power generation, aerospace, and oil & gas (sour service). A286 hex cap screws are specifically designed for bolting austenitic stainless steel flanges (A182 F304, F316, F321) operating at elevated temperatures, with a thermal expansion coefficient closely matching stainless steels to maintain gasket stress and prevent leaks. Our portfolio includes hex cap screws 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 hex cap screws are supplied in solution annealed and precipitation hardened conditions with full traceability and third-party certifications.
Complete Range of A286 Hex Cap Screws
A286 Heavy Hex Cap Screws
A286 heavy hex cap screws manufactured to ASME B18.2.1 and DIN 6914 specifications. Designed for high-temperature flange connections, pressure vessels, and heavy equipment requiring larger wrenching surfaces. The larger head provides increased bearing area for high-temperature service up to 700°C. Available in sizes from 1/2" to 4" (M12 to M100) in various lengths. Supplied in Class A, B, or D conditions per ASTM A453. Ideal for stainless steel flange bolting in refineries, power plants, and chemical processing.
A286 Hex Cap Screws – Partial & Full Thread
A286 hex cap screws manufactured to ASME B18.2.1, DIN 931 (partial thread) and DIN 933 (full thread) standards. Precision-formed heads with controlled fillet under head for improved fatigue resistance. The precipitation-hardened A286 structure ensures exceptional strength at elevated temperatures while maintaining oxidation resistance. Available in UNC, UNF, and metric coarse/fine threads. Common applications include gas turbine casings, exhaust systems, and high-temperature vacuum equipment requiring reliable bolting up to 700°C.
A286 Hex Cap Screws – API & NACE Compliant
A286 hex cap screws 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. 100% hardness testing and impact testing at -196°C available. Also supplied with Charpy impact testing per ASTM A453 requirements.
A286 Hex Cap Screws for Gas Turbines
A286 hex cap screws specifically designed for gas turbine applications: turbine casing bolting, combustion chamber liners, compressor casings, and exhaust sections. The alloy's high creep-rupture strength at 650°C (tested per ASTM A453 stress rupture requirements: 386 MPa min for 100 hours at 650°C) makes it ideal for these demanding applications. Available with silver plating per AMS 2410 for anti-seize and high-temperature oxidation resistance. Non-magnetic property maintained even after severe cold deformation.
A286 Hex Cap Screws – Cryogenic Service
A286 hex cap screws for cryogenic applications requiring non-magnetic, high-strength bolting down to -196°C. The austenitic structure remains stable and ductile at cryogenic temperatures, with Charpy impact testing available at -196°C (40 J minimum per Class D requirements). Used in cryogenic storage tanks, liquefied gas handling equipment, and superconducting magnet systems. Excellent toughness and strength retention from cryogenic temperatures up to 700°C.
Custom & Specialty A286 Hex Cap Screws
Need a special head configuration, unusual thread combination, or custom length for your high-temperature application? RAYCHIN engineers work with you to produce custom A286 hex cap screws to your drawing. Options include reduced shank screws, step screws, shoulder screws, and screws with drilled heads for safety wiring. 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 Hex Cap Screws
Thermal Expansion Matched to Stainless Steel
Thermal expansion coefficient (16.0-16.5 x 10⁻⁶/°C) closely matches austenitic stainless flanges (17.0), preventing loss of preload and gasket stress at high temperatures.
High-Temperature Strength Retention
Maintains high strength up to 700°C, with stress rupture testing at 650°C required per ASTM A453 (386 MPa min for 100 hours).
Sour Service Approved
NACE MR0175 / ISO 15156 qualified for H₂S environments; Class D with hardness ≤ 35 HRC meets API 20F requirements.
Non-Magnetic
Permeability ≤ 1.01, non-magnetic even after severe cold deformation – essential for sensitive instrumentation and MRI equipment.
Oxidation Resistance
Excellent oxidation resistance up to 815°C continuous service and 982°C intermittent.
Cryogenic Toughness
Maintains ductility and impact strength down to -196°C, with Charpy testing available.
Manufacturing Standards for A286 Hex Cap Screws
RAYCHIN LIMITED manufactures A286 hex cap screws to the following national and international standards, ensuring full compliance for projects worldwide. Both standard and non-standard custom configurations are available.
Hex Cap Screw Dimensional Standards
All dimensional standards available in UNC, UNF, UNJF-3A per MIL-S-8879, and metric thread configurations.
International Standards & Global Designations for A286 Hex Cap Screws
To serve clients worldwide, RAYCHIN LIMITED manufactures A286 hex cap screws 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
Chemical Composition (Weight %) – A286 Superalloy (UNS S66286 / 1.4980)
Our A286 hex cap screws 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.
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 Hex Cap Screws (per ASTM A453)
A286 hex cap screws 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.
Tensile Requirements by Class – ASTM A453 Grade 660
Hardness Requirements
For NACE MR0175 / API 20F sour service applications, Class D with maximum hardness 35 HRC is required and 100% hardness testing is mandatory.
Impact Properties (Charpy V-Notch)
Stress Rupture Properties (650°C / 1200°F)
A critical requirement for high-temperature hex cap screws is stress rupture resistance. 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.
Thermal Expansion Advantage of A286 Hex Cap Screws for Stainless Steel Flanges
A286 hex cap screws are specifically designed for bolting austenitic stainless steel components (A182 F304, F316, F321) operating at elevated temperatures. Its thermal expansion coefficient closely matches that of 304/316 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. Standard alloy steel fasteners (A193 B7) expand less than the surrounding stainless steel flanges, leading to loss of preload and potential leaks at temperatures above 400°C. A286 eliminates this mismatch.
API 6A & NACE MR0175 Compliance for A286 Hex Cap Screws
A286 hex cap screws 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.
Heat Treatment & Microstructural Stability of A286 Hex Cap Screws
Optimal mechanical properties in A286 hex cap screws 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.
Physical Properties of A286
Corrosion Resistance of A286 Hex Cap Screws
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 hex cap screws 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 Hex Cap Screws
- 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 cathodic to most stainless steels but compatible with nickel-based alloys.
- Non-Magnetic Property: A286 is essentially non-magnetic (permeability ≤ 1.01), making it suitable for applications requiring non-magnetic fasteners such as MRI equipment and sensitive instrumentation.
Special focus: A286 Hex Cap Screws for High-Temperature & Critical Applications
For critical applications requiring high-temperature strength, oxidation resistance, and corrosion resistance, RAYCHIN offers A286 hex cap screws manufactured to ASTM, ASME, NACE, and customer-specific specifications. Our capabilities include:
- Gas Turbines & Power Generation: Turbine casing bolting, combustion chamber liners, compressor casings, exhaust sections, HRSG connections, steam turbine components.
- Oil & Gas / Sour Service: Wellhead equipment, valve assemblies, subsea connections, refinery piping, API 6A closure bolting, NACE MR0175 applications.
- Aerospace: Engine mounts, thrust nozzles, transmission parts, missile components, jet engine nacelles and fasteners.
- Chemical Processing: High-temperature reactors, reformers, crackers, heat exchangers, thermowell assemblies.
- Cryogenic Equipment: LNG facilities, cryogenic storage tanks, superconducting magnets.
- Automotive: High-performance engine components, turbocharger bolting, exhaust manifold fasteners, superchargers.
- Head Styles: Heavy hex cap screws (ASME B18.2.1, DIN 6914), hex cap screws (ASME B18.2.1, DIN 931/933), hex flange cap screws (DIN 6921, ISO 4162).
- Thread Specifications: UNC/UNF, metric coarse/fine, UNJF-3A per MIL-S-8879 – all classes up to 3A/6g.
- Surface Treatments: Silver plating per AMS 2410 for anti-seize, passivation per ASTM A967, Xylan coatings, PTFE, vacuum-compatible lubricants.
- Class Selection: Class A (standard strength), Class B, Class D (higher yield strength, API sour service), Cold Worked (maximum strength).
- Custom: Special head configurations, non-standard lengths, reduced shank designs per customer drawings.
All A286 hex cap screws are supplied with full traceability and third-party NDT upon request. Sizes available from M6 to M100 (1/4" to 4") in all standard configurations. Material certifications (EN 10204 3.1/3.2) included.
Why RAYCHIN LIMITED – The A286 Hex Cap Screw 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 hex cap screws. Every heat is verified by in-house testing and PMI verification. With 24-27% nickel and titanium-aluminum precipitation hardening, our hex cap screws 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 hex cap screws meet applicable AMS, ASTM A453, and NACE MR0175 requirements.
Precision forming & threading
In-house CNC turning and thread rolling capabilities ensure precise thread geometry and consistent mechanical properties. 100% thread inspection available. Ultrasonic cleaning and passivation available for critical applications. Capable of producing Class 3A threads per NAS/AN/MS standards for preload control and vibration resistance.
Custom solutions
Need a special head configuration, unusual thread combination, or custom material certification for your high-temperature application? Our CNC turning and threading departments handle short runs with agility. We also provide specialized coatings and cryogenic impact testing per customer requirements. Available in Class A, Class B, Class D (API sour service), and cold worked conditions.
Contact the A286 hex cap screw experts today
Request a quote for A286 hex cap screws, heavy hex cap screws, hexagon head cap screws & custom configurations – any global standard (NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS), any quantity. Inquire about high-temperature bolting up to 700°C, NACE MR0175 sour service requirements, or cryogenic applications.
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