A-286 Hex Nuts
ISO 4032
A-286 hex nuts pair an iron-base precipitation-hardened austenitic alloy with a standard-height mating nut for hot turbine, steam, and manifold bolt systems. Paired with matching A-286 bolts and studs, they support full thread engagement within standard height.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- Solution treated and aged
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 treated and agedSolution treatment is followed by precipitation aging, with the Grade 660 class defining the required heat-treatment route and final properties.
What we can make in A-286
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
- Regular hex · Heavy hex
- Thread systems
- Metric · UNC · UNF · 8UN · UNJ
- Final condition
- Solution treated and aged
- 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
Solution treatment and the specified aging condition are recorded against the production lot; final dimensions are checked after thermal processing.
Finished geometry
Internal thread gauging, usable engagement and bearing-face alignment are checked after final processing.
Where A-286 fits — and what matters
Exhaust manifolds & expansion bellows
A-286 Hex NutsRegular hex A-286 nuts fit the crowded spaces around exhaust flanges and bellows attachments. The alloy contributes elevated-temperature strength, and the smaller pattern leaves room for tools between adjacent fasteners. This is useful where the assembly was designed around regular nuts rather than heavy hex bolting.
Connection requirements
- Mating bolt diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Temperature range, vibration duty, and precipitation-hardened condition certification
High-pressure steam valve bonnets
A-286 Hex NutsA-286 hex nuts carry bonnet-stud loads where the valve neck or actuator support leaves little radial clearance. Their aged iron-nickel alloy supplies elevated-temperature strength in a regular nut pattern. That smaller footprint leaves a socket path around the bonnet without forcing a wider stud spacing.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Temperature range, cycling duty, and precipitation-hardened condition certification
Gas & steam turbine casing joints
A-286 Hex NutsOn turbine casing brackets and smaller cover connections, regular hex A-286 nuts offer elevated-temperature strength with a compact bearing footprint. The smaller pattern leaves tool clearance near casing ribs and adjacent piping. Nut dimensions and proof load identify the appropriate part for each connection.
Connection requirements
- Mating stud diameter, thread form, and thread class
- Nut height, width across flats, and bearing-face condition required
- Temperature range, cycling duty, and precipitation-hardened condition certification
Same hex nut. Different material priorities.
A-286 material dataInconel 718 Hex Nuts
Around exhaust manifold branches and crowded valve bonnets, Inconel 718 hex nuts offer precipitation-hardened hot strength without the larger envelope of a heavy nut. The regular pattern preserves a path for maintenance tooling between neighbouring studs. Its specified load capacity completes the pairing with the stud.
Nimonic 80A Hex Nuts
Nimonic 80A hex nuts fit compact hot exhaust connections and boiler support rods. Precipitation-hardened strength supports the loaded threads, while the regular pattern leaves tooling room around brackets. On threaded hangers, accessible flats also allow position adjustment during installation.
Inconel 601 Hex Nuts
Inconel 601 hex nuts fit space-limited retort covers, fixture stacks and lining retainers. They provide oxidation-resistant internal threads in a compact pattern. Regular hex dimensions leave tool clearance around closely arranged supports that cannot accommodate heavy-pattern nuts.
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 S66286 · heat number · ordered condition
- Final-part acceptance
- Lot-linked aging record and mechanical acceptance in the final condition.
- Dimensional record
- Thread plug gauges · Across flats · Nut height
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Matching Kit
Flange Stud Bolt Kits
Build your A-286 hex nut enquiry
Questions about A-286 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.