Incoloy Screws
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
Incoloy Fasteners is widely used for its resistance to seawater, brine, sour gas and high chloride environments at elevated temperatures, which make it a popular choice in the oil and gas and power industries.
A Ni-Cr alloy with very good high temperature stability
Oxidization and carburization resistant up to 1400°F / 760°C
Good corrosion resistance, which increases with the various grades
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RAYCHIN LIMITED
Specialist in Incoloy Screws · Hex Head · Socket Head · Torx · Flat Head · Button Head · Pan Head · Set Screws · CustomIncoloy Screws: Nickel-Iron-Chromium Superalloy Screws All Types for Extreme Environments
RAYCHIN LIMITED is a recognized expert in Incoloy screws — from Incoloy hex head screws, Incoloy socket head cap screws, Incoloy Torx screws, Incoloy flat head screws, Incoloy button head screws, Incoloy pan head screws, Incoloy set screws to custom non-standard configurations across all major Incoloy grades. Incoloy alloys are nickel-iron-chromium superalloys designed for high-temperature and corrosive service. The family includes Incoloy 800 series (800, 800H, 800HT) optimized for high-temperature strength and oxidation resistance up to 1150°C, and Incoloy 825/925 grades with molybdenum and copper additions for exceptional resistance to reducing acids and sour gas environments. The high nickel content ensures resistance to chloride stress corrosion cracking, while chromium provides oxidation resistance. Our portfolio includes screws manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards. Engineered for the most demanding environments where high-temperature strength and corrosion resistance are critical. Incoloy screws are supplied in solution annealed condition (or aged for 925) with full traceability and third-party certifications.
Complete Range of Incoloy Screws – Head Styles & Configurations
Hex Head Screws (DIN 931 / DIN 933 / ISO 4014 / ISO 4017 / ASME B18.2.1)
Incoloy hex head screws manufactured to DIN 931 (partial thread), DIN 933 (full thread), ISO 4014, ISO 4017, and ASME B18.2.1 standards. Features a six-sided head for external wrenching, providing high torque capability and positive drive. Ideal for high-temperature corrosive applications up to 1150°C for grade 800 series, and up to 540°C for acid service with grade 825. Available in sizes from M6 to M36 (metric) and 1/4" to 1-1/2" (inch) in various lengths. Precision rolled threads for superior strength and corrosion resistance. Supplied in solution annealed condition per ASTM standards.
Socket Head Cap Screws (DIN 912 / ISO 4762 / ASME B18.3)
Incoloy socket head cap screws manufactured to DIN 912, ISO 4762, and ASME B18.3 standards. Features a cylindrical head with hex socket drive, providing high clamping force and clean appearance. The controlled fillet under the head reduces stress concentration and improves fatigue life. Ideal for high-temperature corrosive applications up to 1150°C. Available in sizes from M3 to M36 (metric) and #0 to 1-1/2" (inch). Precision rolled threads for superior fatigue resistance. Available in all Incoloy grades.
Torx Drive Screws (DIN 7380 / DIN 7991 / ISO 7380 / ISO 10642)
Incoloy Torx screws feature a 6-point star-shaped drive pattern (hexalobular per ISO 10664) that provides superior torque transfer and resistance to cam-out. Available in button head (DIN 7380, ISO 7380), flat head (DIN 7991, ISO 10642), and pan head configurations. The Torx drive allows for higher installation torque without damaging the recess. Ideal for applications requiring maximum torque transfer in corrosive environments. Available in sizes from M3 to M24. Precision rolled threads for superior fatigue resistance.
Flat Head Screws (DIN 7991 / ISO 10642 / ASME B18.3)
Incoloy flat head screws manufactured to DIN 7991, ISO 10642, and ASME B18.3 standards. Features a countersunk head designed to sit flush with the surface for aerodynamic or aesthetic requirements. Available with 82° (inch) or 90° (metric) head angles. Torx, hex socket, or slotted drive options. Ideal for aerospace applications, manifold covers, and equipment where flush mounting is essential in corrosive environments. Precision rolled UNC, UNF, and metric threads. Sizes from M3 to M24 and #4 to 1".
Button Head & Pan Head Screws (DIN 7380 / DIN 7985 / ISO 7380 / ISO 7045 / ASME B18.6.3)
Incoloy button head screws (DIN 7380, ISO 7380) feature a low-profile domed head for smooth appearance. Incoloy pan head screws (DIN 7985, ISO 7045, ASME B18.6.3) feature a rounded top head with flat bearing surface. Both styles available with Phillips, slotted, hex, or Torx drives. Ideal for general-purpose fastening in corrosive environments where aesthetics and cleanability are important. Available in sizes from M2 to M24 and #2 to 1".
Set Screws (DIN 913-916 / ISO 4026-4029 / ASME B18.3)
Incoloy set screws available with cup point (DIN 916, ISO 4026), cone point (DIN 914, ISO 4027), flat point (DIN 913, ISO 4028), and half-dog point (DIN 915, ISO 4029). Designed for securing rotating parts such as gears, pulleys, and shafts operating in corrosive environments. Available with hex socket or slotted drive. Ideal for chemical processing equipment, mixers, and agitators. Sizes from M2 to M24 and #0 to 1".
Incoloy Grade Selection Guide for Screws
Incoloy 800 (UNS N08800 / 1.4876)
High-Temperature General Purpose: Nickel-iron-chromium alloy with excellent oxidation and carburization resistance up to 815°C. Good creep strength and resistance to sigma phase embrittlement. Ideal for heat exchangers, furnace components, and petrochemical applications. Minimum tensile strength: 585 MPa, yield strength: 240 MPa.
Incoloy 800H (UNS N08810 / 1.4958)
Enhanced High-Temperature Strength: Higher carbon content (0.05-0.10%) provides improved creep and rupture strength. Excellent performance up to 1150°C. Preferred for applications requiring long-term high-temperature stability such as ethylene furnace tubes and steam generators. Maintains structural integrity at extreme temperatures.
Incoloy 800HT (UNS N08811 / 1.4959)
Optimized High-Temperature Performance: Controlled chemistry with aluminum and titanium additions for enhanced creep resistance. Maximum service temperature up to 1150°C. Superior performance in cyclic temperature applications. Ideal for industrial furnace components, radiant tubes, and high-temperature structural fasteners.
Incoloy 825 (UNS N08825 / 2.4858)
Acid & Chloride Resistance: Nickel-iron-chromium alloy with molybdenum (2.5-3.5%) and copper (1.5-3%) additions. Exceptional resistance to sulfuric and phosphoric acids. Resists 40% H₂SO₄ at 100°C with <0.05mm/year corrosion rate. Ideal for chemical processing, acid storage, and marine applications. Maximum service temperature: 540°C in acid service.
Incoloy 925 (UNS N09925)
Sour Service Specialist: Precipitation-hardenable alloy with titanium additions (1.9-2.4%) providing significantly higher strength through aging. Excellent resistance to sulfide stress cracking in H₂S environments. Yield strength 760-965 MPa in aged condition. Ideal for oil & gas downhole tools, sour gas well equipment, and high-strength corrosion-resistant fasteners. Qualified per NACE MR0175.
Incoloy Screw Design & Standards
Dimensional Standards
Our Incoloy screws meet or exceed the following specifications:
Available in UNC, UNF, UNJF-3A, and metric coarse/fine thread configurations.
Material Specifications by Grade
- Incoloy 800: ASTM B408 / ASME SB408, ASTM B163, ASTM B407
- Incoloy 800H: ASTM B408 / ASME SB408, ASTM B163, ASTM B407
- Incoloy 800HT: ASTM B408 / ASME SB408, ASTM B163, ASTM B407
- Incoloy 825: ASTM B424 / ASME SB424, ASTM B423, NACE MR0175
- Incoloy 925: ASTM B805, API 6A, NACE MR0175
Surface Finish Options
- Passivated: Per ASTM A967 for maximum corrosion resistance
- Electropolished: For clean room and pharmaceutical applications
- PTFE Coated: For anti-galling and lubricity
- Silver Plating: Per AMS 2410 for high-temperature anti-seize
Key Benefits of Incoloy Screws
Exceptional High-Temperature Strength (800 Series)
Incoloy 800H and 800HT maintain useful strength up to 1150°C. At 900°C, tensile strength remains 130-180 MPa, significantly higher than 316H. Excellent creep rupture strength at 1000°C with 20-25 MPa for 1000 hours.
Superior Acid Resistance (825)
Incoloy 825 screws resist 40% H₂SO₄ at 100°C with <0.05mm/year corrosion rate. Excellent performance in phosphoric acid service, including wet process phosphoric acid containing fluoride impurities.
Sour Service Excellence (925)
Incoloy 925 screws offer yield strength up to 760 MPa in aged condition with exceptional resistance to sulfide stress cracking. Qualified per NACE MR0175 for H₂S environments up to 425°C. Ideal for wellhead equipment, valve assemblies, and downhole tools.
Oxidation & Carburization Resistance
Chromium content (19-23%) ensures excellent oxidation resistance. Incoloy 800 series form a stable, adherent Cr₂O₃ scale that provides protection up to 1150°C. Superior resistance to carburization and nitriding in furnace atmospheres.
Chloride SCC Immunity
With high nickel content (30-46%), Incoloy screws have excellent resistance to chloride stress corrosion cracking, making them ideal for marine environments and brackish water applications.
Complete Head Style Range
Full range of head styles available: hex head for external wrenching, socket head for high clamping force, Torx drive for superior torque transfer, flat head for flush mounting, button and pan heads for general purpose, set screws for shaft retention.
Manufacturing Standards for Incoloy Screws
RAYCHIN LIMITED manufactures Incoloy screws to the following national and international standards, ensuring full compliance for projects worldwide. Both standard and non-standard custom configurations are available.
International Standards & Global Designations for Incoloy Screws
To serve clients worldwide, RAYCHIN LIMITED manufactures Incoloy screws from material conforming to the following national and international specifications.
UNS N08800 1.4876 UNS N08825 2.4858 UNS N09925 NACE MR0175 API 6A
Chemical Composition (Weight %) – Incoloy Alloys
Our Incoloy screws are produced from melts that strictly conform to the limits below per ASTM standards. The nickel-iron-chromium matrix provides the exceptional high-temperature strength and corrosion resistance characteristic of these alloys.
Incoloy 800 / 800H / 800HT (UNS N08800 / N08810 / N08811)
Incoloy 825 (UNS N08825 / 2.4858)
Incoloy 925 (UNS N09925)
Expert note: The high nickel content provides resistance to chloride stress corrosion cracking. Chromium offers oxidation resistance at elevated temperatures. In 825/925 grades, molybdenum and copper additions provide exceptional resistance to reducing acids like sulfuric and phosphoric acids. Titanium in 925 enables precipitation hardening, achieving yield strengths over 760 MPa. The aluminum and titanium in 800 series contribute to creep resistance at high temperatures.
Complete Mechanical Properties of Incoloy Screws
Incoloy screws are supplied in the solution annealed condition (800 series, 825) or precipitation hardened condition (925). The data below represent minimum requirements per ASTM standards unless otherwise noted.
Mechanical Properties by Grade
Physical Properties by Grade
Elevated Temperature Properties – Incoloy 800H
Elevated Temperature Mechanical Properties by Grade
Exceptional Corrosion Resistance of Incoloy Screws
Incoloy alloys offer outstanding resistance to a wide range of corrosive environments, tailored by grade composition.
High-Temperature Oxidation & Carburization Resistance (800 Series)
Incoloy 800 series screws form a stable, adherent Cr₂O₃ oxide layer that provides excellent protection up to 1150°C. Chromium content (19-23%) ensures scaling resistance, while the nickel-rich matrix resists carburization and sigma phase embrittlement. Performance is significantly better than 316L stainless steel at elevated temperatures.
Sulfuric & Phosphoric Acid Resistance (825)
Incoloy 825 screws resist 40% H₂SO₄ at 100°C with corrosion rates <0.05mm/year. The molybdenum and copper additions provide exceptional resistance to reducing acids. Excellent performance in phosphoric acid service, including wet process phosphoric acid containing fluoride impurities.
Sour Service & Chloride SCC Resistance (825, 925)
With high nickel content (>38%), Incoloy screws have excellent resistance to chloride stress corrosion cracking. Incoloy 825 and 925 are qualified per NACE MR0175/ISO 15156 for H₂S environments. Incoloy 925 offers premium resistance to sulfide stress cracking at strength levels up to 760 MPa yield.
Resistance to Specific Environments
Heat Treatment & Microstructural Stability
Incoloy screws are supplied in appropriate heat treated conditions for optimum properties:
- Incoloy 800/825: Solution annealed at 980-1035°C followed by rapid cooling.
- Incoloy 800H/HT: Higher temperature solution anneal (1050-1100°C) for enhanced creep properties.
- Incoloy 925: Supplied in solution annealed or aged condition. Aging at 620-760°C after solution treatment produces precipitation hardening, achieving 760-965 MPa yield strength.
Proper heat treatment ensures the balanced microstructure that provides the exceptional corrosion resistance and mechanical properties characteristic of Incoloy alloys. All screws are fully heat treated and tested to ensure optimal performance.
Special focus: Incoloy Screws for Critical Applications
For the most demanding applications requiring exceptional high-temperature strength or acid resistance, RAYCHIN offers Incoloy screws manufactured to ASTM, ASME, NACE, and customer-specific specifications. Our capabilities include:
- Chemical Processing: Hex head screws for reactor manway covers, socket head screws for valve bonnets, set screws for agitator blade retention, instrument connections handling acids.
- Oil & Gas / Sour Service: NACE MR0175 compliant Incoloy 825 and 925 screws for wellhead equipment, valve assemblies, subsea connections, and downhole tools.
- Heat Exchangers & Boilers: Incoloy 800 series screws for high-temperature heat exchanger components, boiler access panels.
- Petrochemical Processing: Incoloy 800H and 800HT screws for ethylene furnace components, reformer tube supports.
- Power Generation: Incoloy 800 series screws for superheater supports, boiler component hardware.
- Nuclear Industry: Incoloy 800 screws for steam generator components, reactor system hardware.
- Marine Engineering: Incoloy 825 screws for seawater piping flanges, instrument enclosures, offshore platform hardware.
- Aerospace & Gas Turbines: Socket head cap screws for combustion chamber hardware, flat head screws for access panels.
- Standards: DIN 912, DIN 931, DIN 933, DIN 7991, DIN 7380, DIN 7985, DIN 913-916 (metric); ISO 4762, ISO 4014, ISO 4017, ISO 10642, ISO 7380, ISO 7045, ISO 4026-4029; ASME B18.2.1, ASME B18.3, ASME B18.6.3; NAS1351, NAS1802 (aerospace).
- Thread Classes: 2A, 3A, UNJF-3A, 6g, 6H.
- Sizes: M2 through M36, #0 through 1-1/2".
- Certifications: EN 10204 3.1/3.2 material certifications, NACE MR0175, API 20F, PED 2014/68/EU.
All Incoloy screws are supplied with full traceability and third-party NDT upon request. Material certifications included.
Why RAYCHIN LIMITED – The Incoloy Screw Authority
Metallurgical competence
Engineers on staff with deep expertise in nickel-iron-chromium superalloys. We ensure proper heat treatment for each grade—solution annealing for 800/825, optimized annealing for 800H/HT, and precise aging for 925—to achieve optimal properties. Every heat is verified by in-house PMI testing to confirm chemistry. Our screws provide the exact balance of high-temperature strength and corrosion resistance required for your application.
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 Incoloy screws meet applicable ASTM, ASME, NACE MR0175, and API standards.
Precision head forming & thread rolling
In-house CNC cold heading and precision thread rolling capabilities ensure consistent head dimensions and thread geometry. Precision rolled threads provide superior fatigue life and dimensional accuracy. Deep, accurate drive recesses for positive driver engagement. 100% thread and drive inspection available. Controlled underhead fillet for improved fatigue resistance in high-temperature cyclic applications.
Custom solutions
Need a special head style, unusual drive configuration, or custom material certification for your extreme environment application? Our engineering team works with you to produce custom Incoloy screws to your drawing. We provide specialized surface treatments, passivation, and NACE MR0175 compliant processing per customer requirements.
Contact the Incoloy screw experts today
Request a quote for Incoloy screws, hex head screws, socket head cap screws, Torx screws, flat head screws, button head screws, pan head screws, set screws & custom configurations – any global standard (NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS), any quantity. Inquire about Incoloy 800, 800H, 800HT, 825, or 925 grades for high-temperature or acid-resistant applications.
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