In demanding industrial equipment, fasteners are often exposed to the same heat, pressure and corrosive conditions as the components they hold together. Choosing the right alloy therefore becomes an important part of equipment design.
Incoloy 800 Fasteners, manufactured from INCOLOY® Alloy 800 / UNS N08800, are nickel-iron-chromium alloy fasteners used where a combination of corrosion resistance, heat resistance and mechanical stability is required. Alloy 800 is widely associated with chemical and petrochemical processing, heat-treatment equipment and other elevated-temperature applications. Special Metals
Hindco Steel And Alloys supplies Incoloy 800 Fasteners in different configurations and sizes for industrial and engineering requirements.
What Are Incoloy 800 Fasteners?
Incoloy 800 Fasteners are threaded and fastening components manufactured from Incoloy Alloy 800, also identified by UNS N08800 and W.Nr. 1.4876.
Depending on the application, available forms can include:
- Incoloy 800 Bolts
- Incoloy 800 Nuts
- Incoloy 800 Stud Bolts
- Incoloy 800 Screws
- Incoloy 800 Washers
- Incoloy 800 Threaded Rods
- Hex Head Bolts
- Heavy Hex Bolts
- Socket Head Screws
- Custom Fasteners
The appropriate configuration depends on the joint design, loading conditions, temperature, thread requirements and applicable material standards.
Why Is Incoloy 800 Used for Fasteners?
Alloy 800 was developed for applications where both corrosion resistance and heat resistance are important. Special Metals describes the alloy as suitable for equipment requiring corrosion resistance, heat resistance, strength and stability, with service applications extending to approximately 1500°F (816°C).
Corrosion Resistance
The chromium content provides resistance to oxidation and contributes to corrosion resistance in various environments.
High-Temperature Performance
Incoloy 800 is used in elevated-temperature equipment where conventional materials may not provide the required combination of stability and corrosion resistance.
Oxidation Resistance
The alloy offers resistance to oxidation in suitable high-temperature environments, making it relevant to furnace and heat-processing equipment.
Resistance to Carburization and Sulfidation
Special Metals identifies Alloy 800 as offering resistance to oxidation, carburization and sulfidation at elevated temperatures.
Good Fabrication Characteristics
Alloy 800 is described as readily formed, welded and machined, which supports its use in a range of fabricated industrial components.
Chemical Composition of Incoloy 800
The chemical composition of Alloy 800 helps explain its performance in high-temperature environments.
According to Special Metals, the limiting composition includes:
ElementAlloy 800Nickel30.0–35.0%Chromium19.0–23.0%Iron39.5% min.Carbon0.10% max.Aluminium0.15–0.60%Titanium0.15–0.60%Aluminium + Titanium0.30–1.20%These values should be checked against the applicable material specification for the particular product being purchased.
Incoloy 800 Fastener Specifications
The applicable specification depends on the product form and manufacturing method.
ASTM B564-25, the current ASTM specification for nickel alloy forgings, includes UNS N08800 among the nickel-iron-chromium alloys covered by the standard. It includes requirements for chemical analysis, grain size, mechanical properties, tensile testing and nondestructive ultrasonic testing.
ASTM B408-22 covers UNS N08800 in hot-worked and cold-worked rod and bar forms and specifies mechanical-property and testing requirements for those products.
ParameterIncoloy 800 FastenersMaterialINCOLOY Alloy 800UNSN08800Werkstoff Number1.4876Alloy FamilyNickel-Iron-ChromiumFastener FormsBolts, nuts, studs, screws, washers, threaded rodsRaw MaterialAs specified for the productThreadMetric / UNC / UNF / other as requiredFinishPlain, machined or as specifiedInspectionAs per purchase requirementsCertificationAvailable as specifiedNote: ASTM B408 is a rod/bar specification and ASTM B564 is a forging specification. They should not automatically be treated as universal finished-fastener standards. The applicable fastener/product specification should be confirmed for each project.
Types of Incoloy 800 Fasteners
Different industrial assemblies require different fastening arrangements.
Incoloy 800 Bolts
Bolts are used for removable mechanical connections in equipment, machinery, piping and fabricated assemblies.
Common configurations include:
- Hex bolts
- Heavy hex bolts
- Flange bolts
- Socket head bolts
- Custom-head bolts
Incoloy 800 Nuts
Nuts are supplied to match the bolt diameter and thread configuration.
Common options include:
- Hex nuts
- Heavy hex nuts
- Jam nuts
- Lock nuts
- Custom nuts
Incoloy 800 Stud Bolts
Stud bolts are commonly considered for flange connections and equipment where regular assembly and maintenance are required.
They can be manufactured according to specified diameter, length and thread requirements.
Incoloy 800 Screws
Screws are suitable for applications where a compact threaded connection is required.
Depending on the design, socket-head, machine-screw and other configurations can be specified.
Incoloy 800 Washers
Washers can be used to distribute the load under a bolt head or nut and form part of the overall joint design.
Incoloy 800 Threaded Rods
Threaded rods are useful where a continuous threaded section is needed for an assembly or support arrangement.
Applications of Incoloy 800 Fasteners
The alloy's combination of heat resistance and corrosion resistance makes it relevant to several specialized industries.
Chemical Processing
Potential applications include:
- Process equipment
- Heat exchangers
- Chemical-processing systems
- Piping assemblies
- Furnaces
- Process vessels
Petrochemical Industry
Incoloy 800 components are used in selected petrochemical equipment where elevated temperatures and corrosive conditions influence material selection.
Heat-Treatment Equipment
The alloy is used in equipment exposed to high temperatures, including selected furnace and heat-processing applications.
Electric Heating Equipment
Special Metals identifies Alloy 800 among materials used in applications involving the sheathing of electric heating elements. Special Metals
Industrial Furnaces
Fasteners may be required in furnace assemblies and related equipment where resistance to oxidation and high-temperature exposure is important.
Power and Process Equipment
Specialized fastening components can be considered for process equipment operating under elevated-temperature conditions, subject to the exact design and service environment.
Incoloy 800 vs Incoloy 800H Fasteners
Although the names are similar, Incoloy 800 and Incoloy 800H are not simply interchangeable designations.
Alloy 800H has a controlled carbon range and additional grain-size requirements intended to support higher-temperature creep and stress-rupture performance.
Special Metals notes that Alloy 800H and 800HT are used where greater resistance to stress rupture and creep is required, particularly at temperatures above approximately 1500°F (816°C). Special Metals
Therefore, the material should be selected according to the actual design temperature and mechanical requirements rather than choosing between grades based only on the alloy name.
