Hastelloy C-276 Flat Washers
ISO 7089 / ISO 7090ASTM B575
Hastelloy C-276 flat washers bring corrosion-resistant bearing faces to acid-handling equipment, scrubber connections and chemical pump covers. They are useful where leakage or condensate can attack the small contact area beneath an otherwise suitable nut 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
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
Normal series
Use under bolt heads and nuts on machined equipment faces with adequate surrounding seat area. The bore must clear the bolt shank and under-head radius so the washer lies flat.
Larger outside diameter
Use over slots, oversized holes and softer mounting surfaces to spread the bearing load. Washer thickness matters as well as diameter: a thin wide washer can dish over an unsupported opening.
Square & special profiles
Use on channel supports, slotted bases and special mounting pads where a round washer leaves insufficient support. Profile and hole position keep the bearing plate seated across the actual opening.
- Geometry
- Bore × outside diameter × thickness
- Forms
- Round · Square · Drawing profiles
- Function
- Bearing surface · Spacing
- Sizing
- Metric · Inch
- Final condition
- Solution annealed
- Inspection
- Bore · Outside diameter · Thickness · Burrs
Manufacturing route
Small lots can be machined from suitable stock; repeat production uses cut or punched blanks with bore and outer edge finishing.
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
Thickness, flatness and edge finish establish the bearing geometry; the washer is not labelled hardened solely because the alloy is corrosion resistant.
Where C-276 fits — and what matters
Acid heat exchangers & condensers
Hastelloy C-276 Flat WashersAcid exchanger covers may leave concentrated residue around the outer bolt holes after a small leak dries. C-276 washers put a corrosion-resistant surface under the nuts in that exposed area. A flat, adequately thick washer supports the nut across the machined seat and can be replaced when the cover is serviced.
Connection requirements
- Acid composition and operating temperature
- Nut footprint and cover spotface
- Thickness, flatness and edge finish
Scrubber towers & halide piping joints
Hastelloy C-276 Flat WashersScrubber access panels and duct flanges encounter wet condensate rather than the steady bulk chemistry shown on a process sheet. C-276 washers are useful beneath fasteners where acidic halide deposits collect. On slotted panel supports, their outside diameter must span the slot and their thickness must carry the local bending load.
Connection requirements
- Condensate and cleaning chemistry
- Slot width and unsupported span
- Panel thickness and washer thickness
Chemical transfer pump casings
Hastelloy C-276 Flat WashersA chemical-pump casing needs a sound bearing face when its cover bolts are retightened after seal or impeller work. C-276 washers suit pumps handling aggressive acids where drips also reach the external hardware. Smooth, burr-free faces avoid cutting into the casing seat as the fastener is tightened.
Connection requirements
- Pumped fluid and external leakage exposure
- Casing seat width
- Bore, face finish and assembly load
Same washer. Different material priorities.
Hastelloy C-276 material dataInconel 625 Flat Washers
Inconel 625 washers provide replaceable bearing faces on seawater-pump covers and chemical flange joints. Their nickel-chromium-molybdenum corrosion resistance is useful where liquid remains beneath the nut after exposed surfaces dry. Thickness and outside diameter let the washer support the nut pressure on a compact spotface or span a wider support opening.
Incoloy 825 Flat Washers
825 washers suit sulfuric- and phosphoric-acid plant hardware where the exposed bearing surface needs corrosion resistance. They spread nut or bolt-head pressure across a defined seat and can be replaced at overhaul. A washer for a broad tank bracket and one for a compact pressure flange may need very different thicknesses and outside diameters.
254 SMO Flat Washers
254 SMO flat washers provide replaceable bearing faces beneath bleach-plant and seawater-equipment fasteners. The six-moly austenitic grade offers greater resistance to localized chloride attack than common 316. Supported diameter, thickness and hardness are selected for the pressure applied by the nut or bolt head.
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
- Bore · Outside diameter · Thickness · Burrs
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your C-276 washer enquiry
Questions about C-276 flat washers
Should the washer use the same alloy as the bolt?
The wetted assembly may need matching corrosion resistance, but the washer also needs sufficient bearing strength and thickness. The bolt grade does not by itself specify a hardened or load-rated washer.