Fasteners · ASME B18.22.1 · DIN 125 (legacy DIN)
Washer — ASME B18.22.1
Washer — a flat or spring ring that spreads bolt load. Flat washers protect the joint surface and spread load; spring and lock washers resist loosening. Match the washer material to the bolt to avoid galvanic corrosion.
- ASME B18.22.1
- 18 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is a washer?
Short answer
A washer is a flat or spring ring that spreads bolt load. Flat washers protect the joint surface and spread load; spring and lock washers resist loosening. Match the washer material to the bolt to avoid galvanic corrosion.
Washer: What to Know Before Ordering
- Flat, spring and lock
- ASME B18.21.1 · DIN 125 / 127 (legacy DIN)
- Material to match the bolt
Washer Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N08825), dimensions and finished requirements are to the purchase specification | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N08904), dimensions and finished requirements are to the purchase specification | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S30400), dimensions and finished requirements are to the purchase specification | General corrosion resistance, food, water and architectural work |
| SS 304L washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S30403), dimensions and finished requirements are to the purchase specification | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S31008), dimensions and finished requirements are to the purchase specification | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S31603), dimensions and finished requirements are to the purchase specification | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S32100), dimensions and finished requirements are to the purchase specification | High-temperature service between 425 and 815 °C |
| SS 347 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S34700), dimensions and finished requirements are to the purchase specification | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S32205), dimensions and finished requirements are to the purchase specification | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS S32750), dimensions and finished requirements are to the purchase specification | Seawater and high-chloride service where strength also matters |
| Inconel 600 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N06600), dimensions and finished requirements are to the purchase specification | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N06625), dimensions and finished requirements are to the purchase specification | Seawater, high strength and high temperature in one alloy |
| Inconel 718 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N07718), dimensions and finished requirements are to the purchase specification | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N08800), dimensions and finished requirements are to the purchase specification | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N10276), dimensions and finished requirements are to the purchase specification | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N06022), dimensions and finished requirements are to the purchase specification | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N04400), dimensions and finished requirements are to the purchase specification | Seawater, hydrofluoric acid and marine service |
| Monel K500 washer | Finished fastener specification not asserted; material and manufacturing route not asserted — alloy (UNS N05500), dimensions and finished requirements are to the purchase specification | High-strength pump shafts, bolting and springs in seawater |
Other fasteners
Stud boltA fully threaded rod supplied with two heavy hex nuts.Hex boltA bolt with a hexagonal head.Heavy hex nutA thicker and wider hexagon nut for pressure bolting.Hex nutA standard hexagon nut.Threaded rodA continuously threaded bar cut to length.U-boltA U-shaped bolt for clamping pipes to supports.Eye boltA bolt with a loop head for lifting or anchoring.Anchor boltA bolt that fixes structures or equipment to concrete.Foundation boltA heavy bolt set in concrete for machinery bases.Socket head cap screwA screw with a cylindrical head and hexagon socket.Machine screwA small-diameter screw for equipment assembly.
Washer — questions buyers ask
What is a washer?
A washer is a flat or spring ring that spreads bolt load. Flat washers protect the joint surface and spread load; spring and lock washers resist loosening. Match the washer material to the bolt to avoid galvanic corrosion.
Do I need washers on flange bolting?
Many specifications require through-hardened washers under nuts for controlled tightening; follow the project bolting spec.
Which grades are washers available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Monel K500.
Which standard covers washer dimensions?
ASME B18.22.1 · DIN 125 (legacy DIN). The material standard depends on the grade.
Reviewed by the technical team, Kanak Steel & Engineering Co.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026
India · Oman · UAE · Saudi Arabia · Brazil · Argentina · Spain · ChileSend your washer requirement today.
Start RFQ