Hastelloy B-3 Heavy Hex Nuts
ASME B18.2.2ASTM B335
Hastelloy B-3 heavy hex nuts pair a nickel-molybdenum alloy with improved thermal stability relative to B-2 with a larger bearing face for autoclave and pickling joints in hot reducing-acid service. Compared with B-2, B-3 forms embrittling phases more slowly during intermediate-temperature exposure, giving more processing flexibility while retaining resistance to reducing acids.
- 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 annealedSolution annealing dissolves detrimental precipitates, followed by rapid cooling to preserve corrosion resistance.
What we can make in Hastelloy B-3
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 B-3 fits — and what matters
Reactor vessel & manway flanges
Hastelloy B-3 Heavy Hex NutsB-3 heavy hex nuts accompany substantial reactor studs in compatible reducing-acid service. They protect the internal threads and bearing face, including surfaces that retain acid beneath the nut. The larger pattern supplies broad seating contact and useful wrench engagement for manway maintenance.
Connection requirements
- Hastelloy B-3 Heavy Hex Nuts · finished condition and load requirement
- Heavy hex dimensions, seating area and nut proof load
- Acid composition, temperature and oxidizing impurities
Acid heat exchangers & condensers
Hastelloy B-3 Heavy Hex NutsHastelloy B-3 heavy hex nuts carry exchanger-cover stud loads where reducing-acid leakage reaches the seat and threads. Nickel-molybdenum chemistry resists compatible acid at these sheltered surfaces. The larger pattern fits substantial cover spotfaces and gives shutdown tooling broad flats to engage.
Connection requirements
- Hastelloy B-3 Heavy Hex Nuts · finished condition and load requirement
- Heavy hex dimensions, seating area and nut proof load
- Acid composition, temperature and oxidizing impurities
Chemical transfer pump casings
Hastelloy B-3 Heavy Hex NutsChemical-pump covers can expose both stud and nut to reducing-acid drips. B-3 heavy hex nuts keep the internally threaded component on the same corrosion basis as the stud. Their larger bearing footprint suits robust casing spotfaces with enough room for maintenance tooling.
Connection requirements
- Hastelloy B-3 Heavy Hex Nuts · finished condition and load requirement
- Heavy hex dimensions, seating area and nut proof load
- Acid composition, temperature and oxidizing impurities
Same heavy hex nut. Different material priorities.
Hastelloy B-3 material dataHastelloy B-2 Heavy Hex Nuts
Hastelloy B-2 heavy hex nuts carry loads at substantial reactor and pump cover studs in strongly reducing acid service. Broad bearing faces suit robust spotfaces. The nickel-molybdenum alloy resists compatible acid beneath the nut, but oxidizing contamination can rule out this material choice.
Hastelloy 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.
Hastelloy 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.
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 N10675 · 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 B-3 heavy hex nut enquiry
Questions about B-3 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.