254 SMO Flat Washers
ISO 7089 / ISO 7090ASTM A240
254 SMO flat washers provide six-moly austenitic bearing surfaces for seawater and chloride-process hardware. They suit wet nut seats, pump covers and slotted brackets where ordinary stainless washers can suffer localised attack beneath the contact face.
- 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 and rapid cooling retain alloying elements in solution and restore the specified corrosion-resistant condition.
What we can make in 254 SMO
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 254 SMO fits — and what matters
Bleach-plant washers & mixers (ClO2)
254 SMO Flat Washers254 SMO washers provide corrosion-resistant bearing faces beneath bleach-plant cover nuts, where liquor and washdown water can remain after surrounding surfaces dry. Their six-moly alloy addresses localized chloride attack at that sheltered seat. Flatness and adequate thickness support the required nut pressure through repeated cover assembly.
Connection requirements
- Liquor and washdown chemistry
- Nut footprint and seat flatness
- Washer thickness and hardness
Seawater pumps
254 SMO Flat WashersSeawater-pump washers give the cover nuts a replaceable contact surface. A 254 SMO washer offers improved chloride resistance over a common stainless washer at this wet seat. Its outside diameter must remain within the machined spotface, and its bore must clear the stud transition so the full face carries load.
Connection requirements
- Spotface and washer outside diameter
- Stud transition clearance
- Seawater temperature and chlorination
Seawater intake screens & gates
254 SMO Flat WashersIntake-screen brackets often use slots to allow installation adjustment. 254 SMO washers can bridge the slot in chloride exposure and transfer nut pressure onto the bracket. The slot span determines the bending demand on the washer, making thickness and supported width more useful ordering details than bolt diameter alone.
Connection requirements
- Slot width and supported span
- Washer thickness and outline
- Mounting load and immersed exposure
Same washer. Different material priorities.
254 SMO material dataDuplex 2205 Flat Washers
2205 washers combine useful bearing strength with chloride resistance for pump covers and washdown brackets. They are a practical duplex option where 316-type washers are not adequate for the exposure. For more aggressive seawater crevices, the comparison moves toward 2507, S32760 or a nickel-alloy washer rather than simply increasing washer thickness.
Super Duplex 2507 Flat Washers
2507 washers combine high strength with super duplex chloride resistance for seawater covers, brackets and brine equipment. They are useful where the bearing face is highly loaded and 2205 offers insufficient corrosion margin. The underside is still a crevice, making temperature, deposits and chlorination relevant to the washer selection.
Inconel 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.
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 S31254 · 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 254 SMO washer enquiry
Questions about 254 SMO 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.