904L Hex nuts
ISO 4032ASTM A276
904L nuts place molybdenum- and copper-bearing resistance to selected acids in the internal thread and bearing face of the connection. Regular or heavy hex geometry, usable engagement and final condition must match the stud or bolt.
- 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 and rapid cooling retain alloying elements in solution and restore the specified corrosion-resistant condition.
What we can make in 904L
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 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 904L fits — and what matters
Chemical Processing
Chemical pump covers and reactor connections904L hex nuts complete the stud connections on chemical pump covers and reactor connections. The nut pattern provides the bearing area and thread engagement for the selected stud and tightening method. Process liquid can remain at the contact after the exposed surface drains.
Pumps, Valves & OEM
Pump casings and valve bonnets904L hex nuts complete the stud connections on pump casings and valve bonnets. The nut pattern provides the bearing area and thread engagement for the selected stud and tightening method. Repeated maintenance makes fit, engagement and access part of the component specification.
Mining & Mineral Processing
Chemical-recovery pump and vessel covers904L hex nuts complete the stud connections on chemical-recovery pump and vessel covers. The nut pattern provides the bearing area and thread engagement for the selected stud and tightening method. Leach solution and deposits act on the installed part; corrosion duty is separate from abrasive wear.
Same hex nut. Different material priorities.
904L material dataHastelloy C-276
Resistance to chemically aggressive, mixed process streams.
- Connection priority
- Thread-stripping resistance and bearing pressure
- Process liquid and shutdown chemistry
- C-276 is selected for its nickel–chromium–molybdenum–tungsten chemistry. Residual product, cleaning liquid and oxidising contamination can expose a sheltered connection differently from the main flow. Include liquid retained at the internal threads and the nut-bearing face in the exposure description.
Inconel 625
Solid-solution strength and resistance to aggressive process liquids.
- Connection priority
- Thread-stripping resistance and bearing pressure
- Annealed or solution-annealed 625
- The delivery condition affects strength and high-temperature response. Keep the specified condition with the component’s mechanical acceptance; 718-style aging is not the strengthening route for 625. Include liquid retained at the internal threads and the nut-bearing face in the exposure description.
Hastelloy C-22
Corrosion resistance across oxidising and reducing process exposures.
- Connection priority
- Thread-stripping resistance and bearing pressure
- Production and cleaning cycles
- C-22’s chromium-bearing chemistry is relevant when chemical exposure changes between operating and cleaning cycles. Include both liquids when comparing it with C-276 or a B-type nickel alloy. Include liquid retained at the internal threads and the nut-bearing face in the exposure description.
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 N08904 · 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
Matching Kit
Flange Stud Bolt Kits
Build your 904L hex nut enquiry
Questions about 904L 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.