Incoloy 800H Heavy Hex Nuts
ASME B18.2.2ASTM B408
Incoloy 800H heavy hex nuts pair a controlled-carbon, coarse-grained iron-nickel-chromium alloy with a larger bearing face for refinery, boiler, and molten-salt joints under sustained high-temperature load. Controlled carbon and a coarse-grained, solution-annealed structure give 800H higher creep strength than base 800 for sustained high-temperature loading.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- Solution annealed
EN 10204 3.1 MTC + heat-number traceability
Which standard is on your order?
Raw Material Specifications
Threads · Metric
Threads · Inch
Dimension Reference
Heat Treatment
Solution annealedThe specified solution treatment develops the controlled grain structure needed for sustained high-temperature creep duty.
What we can make in Alloy 800H
Regular hex
Use on equipment covers and mounting brackets with standard socket access. The compact wrenching envelope is useful where adjacent fasteners or housing walls restrict tool clearance.
Heavy hex
Use on flange-bolting sets and pressure-equipment joints calling for a heavy-hex pattern. The wider bearing footprint and larger wrench size require more seat area and socket clearance than a regular hex nut.
Thin hex
Use in restricted axial spaces or as part of a specified two-nut locking arrangement. Reduced thread engagement means a thin nut is not a direct load-capacity replacement for a full-height nut.
- Metric thread
- M4–M100
- Inch thread
- 1/4″–4″
- Patterns
- Heavy hex
- Thread systems
- Metric · UNC · UNF · 8UN · UNJ
- Final condition
- Solution annealed
- Inspection
- Thread plug gauges · Across flats · Nut height
Manufacturing route
Small lots use machined blanks. Volume nut blanks use a forming route compatible with the alloy before machining the bore and tapping.
Heat treatment & final condition
The final solution-treated condition and grain-size requirement are recorded for the ordered H or HT grade. Final dimensions are inspected after the last thermal operation.
Finished geometry
Internal thread gauging, usable engagement and bearing-face alignment are checked after final processing.
Where 800H fits — and what matters
High-temp refinery & coker flanges
Incoloy 800H Heavy Hex NutsOn hot refinery studs, the nut's internal threads and bearing face carry load for the same long operating run as the stud. Incoloy 800H heavy hex nuts bring a creep-focused material condition to that component. Their broad pattern suits substantial flange spotfaces and accessible maintenance tooling.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Sustained high-temperature duty, grade certification, and heat-number certification
Boiler tube hangers & superheaters
Incoloy 800H Heavy Hex NutsIncoloy 800H heavy hex nuts retain hot hanger rods that carry equipment weight throughout the operating run. Creep resistance matters at the loaded internal threads, while the broad seat transfers the rod load into the support plate. The nut and rod need the same long-duration hot-load basis; a room-temperature proof load does not describe that duty.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Sustained high-temperature duty, grade certification, and heat-number certification
Solar thermal (CSP) molten-salt piping
Incoloy 800H Heavy Hex NutsIncoloy 800H heavy hex nuts carry loads on external molten-salt piping supports and selected flange studs. Prolonged heat from the pipe makes creep behaviour relevant even where the nuts remain dry. Their broad bearing faces suit substantial support plates or flange spotfaces with room for the heavy pattern.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Sustained high-temperature duty, grade certification, and heat-number certification
Same heavy hex nut. Different material priorities.
Incoloy 800H material dataIncoloy 800 Heavy Hex Nuts
Incoloy 800 heavy hex nuts fit robust retort and furnace-support assemblies with moderate load requirements. Their alloy resists oxidation and carburization, and broad bearing faces suit substantial spotfaces. The heavy pattern provides useful wrench engagement during cover and accessory maintenance.
Nimonic 80A Heavy Hex Nuts
Nimonic 80A heavy hex nuts combine age-hardened hot strength with broad seating faces for substantial turbine, bonnet and exhaust stud assemblies. Their loaded internal threads carry the stud tension into the cover or support. Large wrenching flats suit connections with room for controlled assembly tooling.
Inconel 718 Heavy Hex Nuts
High-load turbine casing and hot-valve studs transfer their tension through the nut into the cover. Inconel 718 heavy hex nuts combine precipitation-hardened strength with the bearing area of a heavy pattern. Broad flats provide substantial socket engagement on these loaded, serviceable connections.
From drawing to documented delivery
- 01Drawing & BOMForm, dimensions and quantity
- 02Material & formingGrade, heat and manufacturing route
- 03Final inspectionGeometry, threads and ordered tests
- 04Documents & dispatchLot records and identified packing
Order documents
- Material identity
- UNS N08810 · heat number · ordered condition
- Final-part acceptance
- UNS grade, carbon and alloy chemistry, solution-treatment record and ordered grain-size evidence.
- Dimensional record
- Thread plug gauges · Across flats · Nut height
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your 800H heavy hex nut enquiry
Questions about 800H hex nuts
Does a matching UNS make the stud and nut a matched set?
Matching chemistry addresses only one part of the order. Nut strength, effective engagement, internal thread fit and surface friction must also suit the stud and assembly tightening method.