Hastelloy C-276 Heavy Hex Nuts
ASME B18.2.2ASTM B574
Hastelloy C-276 heavy hex nuts pair a solid-solution nickel-molybdenum-chromium alloy with a larger bearing face for high-load acid and chloride bolt systems. Paired with matching C-276 bolts and studs, they distribute bearing load and support full thread engagement.
- 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
Finished-Nut Specifications
Threads · Metric
Threads · Inch
Dimension Reference
Heat Treatment
Solution annealedSolution annealing dissolves detrimental precipitates, followed by rapid cooling to preserve corrosion resistance.
What we can make in Hastelloy C-276
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 annealed or specified strengthened condition is linked to the lot; an aging treatment is not assumed for a solid-solution alloy.
Finished geometry
Internal thread gauging, usable engagement and bearing-face alignment are checked after final processing.
Where C-276 fits — and what matters
Reactor vessel & manway flanges
Hastelloy C-276 Heavy Hex NutsC-276 heavy hex nuts suit reactor cover studs exposed to compatible aggressive liquids. Corrosion resistance is useful beneath the seat and inside the engaged threads, where leaked process liquid can remain. The heavy pattern fits substantial manway spotfaces and leaves large flats for shutdown tooling.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Acid and chloride exposure, and heat-number certification
Acid heat exchangers & condensers
Hastelloy C-276 Heavy Hex NutsAcid-exchanger cover nuts sit at the edge of the gasketed joint, close to potential acid leakage. C-276 heavy hex nuts are useful where corrosion of the nut threads or bearing face would complicate cover removal. The heavy pattern also gives a broad seating footprint on the cover's machined spotface.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Acid and chloride exposure, and heat-number certification
Chemical transfer pump casings
Hastelloy C-276 Heavy Hex NutsOn robust chemical-pump stud connections, C-276 heavy hex nuts combine a wide bearing face with resistance to the handled chemical environment. They are particularly relevant at casing and cover joints exposed to drips or washdown. Nut proof load and thread fit complete the specification for the matched stud assembly.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Acid and chloride exposure, and heat-number certification
Same heavy hex nut. Different material priorities.
Hastelloy C-276 material dataHastelloy C-22 Heavy Hex Nuts
Hastelloy C-22 heavy hex nuts suit substantial cover studs exposed to oxidizing or mixed chemical media. Corrosion resistance matters inside the threads and beneath the bearing face, where liquid can persist. The heavy pattern provides broad seating contact and robust maintenance-tool engagement.
Hastelloy B-3 Heavy Hex Nuts
Hastelloy B-3 heavy hex nuts suit robust reducing-acid stud assemblies where liquid can remain beneath the bearing face. Broad seating contact supports substantial cover spotfaces. B-3 offers improved thermal stability over B-2, while compatibility still depends on the absence of harmful oxidizing contamination.
Inconel 625 Heavy Hex Nuts
Inconel 625 heavy hex nuts suit substantial seawater and wet-chloride stud connections. Localized-corrosion resistance matters beneath the seating face and inside the loaded threads. The broad pattern fits robust pump spotfaces and subsea connections with sufficient clearance for the installation tooling.
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 N10276 · heat number · ordered condition
- Final-part acceptance
- Grade chemistry, supplied condition and ordered mechanical requirements.
- Dimensional record
- Thread plug gauges · Across flats · Nut height
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your C-276 heavy hex nut enquiry
Questions about C-276 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.