Incoloy 825 Heavy Hex Nuts
ASME B18.2.2ASTM B425
Incoloy 825 heavy hex nuts provide a larger wrenching body for studded acid-process flanges and equipment covers. They bring the alloy’s corrosion resistance to the nut threads and bearing face, with nut proof-load requirements matched to the chosen stud.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- 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
AnnealedThe specified anneal restores ductility and the corrosion-resistant supplied condition after hot or cold working.
What we can make in Alloy 825
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
- 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 825 fits — and what matters
Reactor vessel & manway flanges
Incoloy 825 Heavy Hex NutsHeavy hex nuts are the removable part of a studded reactor manway closure. Incoloy 825 is useful when process leakage wets the nut threads and outer bearing face. The larger hex aids tool engagement during maintenance, but the cover’s bolt spacing still needs enough room for the selected socket.
Connection requirements
- Stud grade and nut proof load
- Socket clearance between adjacent nuts
- Nut height and available stud projection
Acid heat exchangers & condensers
Incoloy 825 Heavy Hex NutsOn acid exchanger covers, 825 heavy hex nuts combine corrosion resistance with a substantial wrenching surface for repeated dismantling. Their bearing face transfers the stud load into the washer or channel flange. The nut thread class and full engagement length should be specified with the stud set, not ordered as an isolated nominal diameter.
Connection requirements
- Stud thread class
- Bearing washer or flange spotface
- Exchanger process and cleaning exposure
High-pressure valve bonnets
Incoloy 825 Heavy Hex NutsA severe-service valve bonnet may use corrosion-resistant studs with heavy hex nuts above the cover. 825 nuts are appropriate where their acid resistance matches the external exposure. Nut height must leave room for the bonnet tooling and enough projecting thread to confirm full engagement after tightening.
Connection requirements
- Bonnet access envelope
- Stud strength and nut acceptance test
- Process leakage and temperature
Same heavy hex nut. Different material priorities.
Incoloy 825 material dataHastelloy C-276 Heavy Hex Nuts
Hastelloy C-276 heavy hex nuts carry stud loads at corrosive reactor and exchanger covers. Their broad seating faces suit substantial spotfaces, and the alloy resists attack inside the loaded threads and beneath the nut. The heavy pattern is useful where maintenance tooling has adequate clearance.
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.
254 SMO Heavy Hex Nuts
254 SMO heavy hex nuts suit chloride-process stud joints that need a highly alloyed austenitic component at the loaded threads and seat. Their substantial flats are useful during pump and exchanger overhaul. Nut capacity is specified for the mating stud, with the selected dimensions providing the required engagement and bearing area.
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 N08825 · 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 825 heavy hex nut enquiry
Questions about 825 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.