Stainless Steel Washers
Washers spread bolt load, protect joint surfaces and help keep preload. Hardened flat washers (such as ASTM F436) are common in flange and structural bolting. Spring and lock washers resist loosening in vibrating equipment.
Choose a grade below for specifications, composition, sizes and weight charts.
Stainless Steel washers by grade
| Grade | Specification | Key characteristic | Typical use |
|---|---|---|---|
| SS 304 Washers | 304 flat washers | Balanced corrosion resistance, formability and cost | Food, dairy and beverage processing equipment |
| SS 316 Washers | 316 flat washers | 2–3% molybdenum for chloride pitting resistance | Chemical and petrochemical process equipment |
| SS 316L Washers | SS 316L flat washers | Carbon 0.030% max for weld-zone corrosion resistance | Chemical and fertiliser process piping |
| SS 321 Washers | 321 washers | Titanium-stabilised: Ti ≥ 5×(C+N) | Exhaust systems and manifolds |
| SS 347 Washers | 347 washers | Niobium-stabilised: Nb ≥ 10×C | Refinery piping and heater tubes |
| SS 904L Washers | SS 904L washers | High Ni-Mo-Cu for sulphuric and phosphoric acids | Sulphuric acid plants and coolers |
| Duplex 2205 Washers | Duplex 2205 washers | Yield strength about 450 MPa: roughly twice that of SS 316L | Oil and gas flowlines, manifolds and process piping |
| Super Duplex 2507 Washers | S32750 washers | PREN ≥ 40: suitable for seawater | Seawater cooling and firewater piping |
How stainless steel washers are made, sized and tested
How it's madeStamped or machined from plate or strip and heat treated where required.
- Size range
- M6 – M100 and ¼" – 4" bolt sizes
- Finish
- Plain, zinc, galvanised
Testing & documents
- Hardness tests
- Dimensional checks
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Frequently asked questions
Are washers needed with stud bolts?
Not always. Many flange joints use none, but hardened washers are used with controlled-tightening and tensioning methods, and where specified.
Which stainless steel grades are available as washers?
SS 304, SS 316, SS 316L, SS 321, SS 347, SS 904L, Duplex 2205, Super Duplex 2507.
Which specifications cover stainless steel washers?
SS 304 flat, SS 316 flat, SS 316L flat, SS 321 washers, SS 347 washers, SS 904L washers, Duplex 2205, S32750 washers, depending on grade.
Need stainless steel washers?
Send grade, size, quantity and destination.