SS 904L WasherASTM A479 · ASME B18.22.1 · Manufacturer, stockist & exporter, India
Alloy 904L · UNS N08904
An SS 904L washer is a flat or spring ring that spreads bolt load, made from SS 904L to ASTM A479. 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.
- ASTM A479
- ASME B18.22.1
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 904L Washer?
- What it is
- A flat or spring ring that spreads bolt load
- Material
- ASTM A479
- Dimensions
- ASME B18.22.1 · DIN 125
- Grade
- SS 904L · UNS N08904
- Best at
- Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water
SS 904L Washer Specification
| Product | SS 904L Washer |
|---|---|
| Material standard | ASTM A479 |
| Dimensional standard | ASME B18.22.1 · DIN 125 |
| Sizes | M10 – M64 · ½" – 4" (others on request) |
| Threads | UNC · UN-8 · metric coarse |
| Testing | PMI · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose a Washer
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.
- Flat, spring and lock
- ASME B18.21.1 · DIN 125 / 127
- Material to match the bolt
More on choosing: Washer guide.
SS 904L Washer: Why 904L for washers
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. In SS 904L, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless fasteners resist atmospheric and process corrosion. SS 904L is picked for dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water. |
|---|---|
| Typical service | Sulphuric acid plants — Coolers, piping and tanks for dilute sulphuric acid. |
| Bolting | as the project specifies |
SS 904L Washer Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 23.0 – 28.0 |
| Chromium | 19.0 – 23.0 |
| Molybdenum | 4.0 – 5.0 |
| Copper | 1.0 – 2.0 |
| Carbon | 0.020 max |
| Manganese | 2.00 max |
| Silicon | 1.00 max |
| Nitrogen | 0.10 max |
SS 904L Washer Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 490 MPa · 71 ksi |
| Yield strength 0.2% | 220 MPa · 31 ksi |
| Elongation | 35% |
| Hardness | 90 HRB max |
Full chemistry, properties and equivalents are on the SS 904L grade page.
Standards on this page
Other SS 904L fasteners
SS 904L Washers for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 904L Washer — questions buyers ask
Do I need washers on flange bolting?
Many specifications require through-hardened washers under nuts for controlled tightening; follow the project bolting spec.
What nut is used with SS 904L washers?
A nut in the same alloy, machined from ASTM A479 bar, unless the project specifies otherwise.
Which standard covers SS 904L washers?
The material is ASTM A479; dimensions follow ASME B18.22.1 · DIN 125. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 904L washer?
The alloy price, the size and dimensions, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026