SS 304 PlateASTM A240 UNS S30400 · Manufacturer, stockist & exporter, India
Also sold as AISI 304 · UNS S30400 · W.Nr 1.4301 · 18/8 stainless
SS 304 plate is SS 304 (UNS S30400) rolled to 3/16" (4.76 mm) thickness and above for pressure parts, heavy sections and cut blanks under ASTM A240. It is a austenitic chromium-nickel stainless steel, chosen for general corrosion resistance, food, water and architectural work. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on request
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 304 Plate?
SS 304 plate is an austenitic chromium-nickel stainless steel supplied as plate to ASTM A240 (UNS S30400). Buyers specify it for general corrosion resistance, food, water and architectural work. It is also sold as AISI 304, UNS S30400, W.Nr 1.4301.
- What it is
- Austenitic chromium-nickel stainless steel
- Standard
- ASTM A240
- Thickness
- 3/16" (4.76 mm) and above
- Density
- 8 g/cm³
- Supplied as
- Annealed · HRAP · cut to size
- Best at
- General corrosion resistance, food, water and architectural work
SS 304 Plate Specification & Sizes
| Material standard | ASTM A240 · ASME SA-240 |
|---|---|
| General requirements | ASTM A480 — dimensions, tolerances and finishes |
| Grade | SS 304 · UNS S30400 · W.Nr 1.4301 |
| Thickness | 3/16" (4.76 mm) and above — thinner is sheet |
| Width × length | 1000 / 1250 / 1500 / 2000 / 2500 mm × up to 6000 mm, or cut to drawing |
| Condition & finish | Annealed · hot rolled, annealed & pickled (No.1) |
| Cutting | Cut to size — rectangles, strips, circles & rings |
| Testing | PMI · UT (plate) · intergranular corrosion · hardness, on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection · packing list · certificate of origin |
Sheet or plate?
Both are ordered under ASTM A240, so buyers often mix them up. The line is thickness: below 3/16" is sheet, 3/16" and over is plate. If your drawing calls for under 3/16" (4.76 mm), you need SS 304 sheet; for 4.76 mm and up, you are in the right place.
SS 304 Plate Cut to Size
Most 304 plate leaves us as pieces, not full mill plates. Cutting from a full plate means you pay only for what you use, and each piece keeps the heat number of the plate it came from.
| Full & part plates | Full mill plates, halves and quarters |
|---|---|
| Rectangles & strips | To your list of finished sizes, or to a drawing |
| Circles & rings | Blanks for blind flanges, covers, tube sheets and nozzles |
| Machining allowance | State finished size and allowance; thermally cut edges are normally machined back |
| Traceability | Heat number transferred to every piece before cutting |
Send a cutting list or DXF; we nest pieces to reduce off-cut and quote per piece.
SS 304 Plate Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S30400.
SS 304 Plate Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S30400 — Annealed plate & sheet.
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8 g/cm³ |
| Melting range | 1400 – 1450 °C |
| Magnetic | Non-magnetic annealed; slightly magnetic after cold work |
| PREN (approx.) | ≈ 18 |
SS 304 Equivalent Grades
SS 304 Plate Weight Chart & Calculator
Use this to budget freight and price per piece. Weight (kg) = length (m) × width (m) × thickness (mm) × 8.
Example: 2000 × 1000 × 10 mm
2.0 × 1.0 × 10 × 8 = 160.0 kg
Total weight —
| Thickness | 2000 × 1000 plate | Per m² |
|---|---|---|
| 5 mm | 80.0 kg | 40.0 kg |
| 6 mm | 96.0 kg | 48.0 kg |
| 8 mm | 128.0 kg | 64.0 kg |
| 10 mm | 160.0 kg | 80.0 kg |
| 12 mm | 192.0 kg | 96.0 kg |
| 16 mm | 256.0 kg | 128.0 kg |
| 20 mm | 320.0 kg | 160.0 kg |
| 25 mm | 400.0 kg | 200.0 kg |
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify SS 304 Plate with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. SS 304 is most often mixed up with SS 316 / 316L — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. PMI can be arranged on request — state it on your enquiry.
Under technical review for TDS.
| Element | SS 304 | SS 316 / 316L |
|---|---|---|
| Nickel | As specified | As specified |
| Chromium | As specified | As specified |
| Molybdenum | — | As specified |
| Iron | As specified | As specified |
| Manganese | As specified | As specified |
SS 304 Plate Price — What Decides It
Two quotes for "304 plate" can differ by 20% and both be fair. We quote 304 plate per kg for full sizes and per piece for cut sizes. These six things move the price per kg, so you can compare offers like for like.
SS 304 Plate Testing & Inspection
Plate goes into pressure parts and heavy sections, so it is inspected for internal soundness and flatness as well as chemistry. These tests are added to the order and reported on the certificate or as separate reports.
| Ultrasonic testing | Straight-beam UT to ASTM A578 (levels A, B or C; plate 10 mm and over) or EN 10160 (S0–S3 body, E0–E4 edge classes) |
|---|---|
| Flatness & dimensions | Per ASTM A480 tables for thickness, width and length |
| Corrosion testing | ASTM A262 (intergranular corrosion), practice as specified |
| PMI | Alloy verification on each plate, or each cut piece if required |
| Third-party inspection | Witness by your inspector or agency, with an EN 10204 3.2 certificate |
UT checks the plate body along a scan grid and a band along each edge, where laminations matter most for welding.
SS 304 Plate Applications
Plate is chosen for pressure-bearing walls, heavy sections and parts machined from solid. For linings, bellows and pressed parts, see SS 304 sheet.
SS 304 Plate vs 316L, 304L and 904L
| Grade | Plate standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 304L | ASTM A240 | ≈ 18 | Welded tanks, piping and vessels in general corrosive service |
| SS 304 | ASTM A240 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 316 / 316L | ASTM A240 | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 904L | ASTM A240 | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 304 Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 304 fits.
About 18% chromium forms the passive film that makes the steel stainless.
Nickel keeps the structure austenitic — tough at low temperature and easy to form and weld.
Standard carbon level: fine for most work, but choose 304L where heavy sections are welded and service is corrosive.
Without molybdenum, 304 pits in chlorides — step up to 316L for coastal or salty service.
How your 304 plate order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked against your order; PMI before processing is available on request.
- 03Processing — cutting to your sizes, with heat numbers transferred to every piece.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Fabricating Heavy SS 304 Plate
Shells, heads and tube sheets mean thick sections and multi-pass welds. These are the points that decide whether 304 plate keeps its corrosion resistance after fabrication; matching filler is ER308 / ER308L (AWS A5.9).
General guidance only; follow your approved WPS, PQR and design code.
| Joint preparation | Single-V up to moderate thickness, double-V or J-prep for heavy plate to cut weld volume and distortion. |
|---|---|
| Interpass temperature | Keep it low — typically 150 °C maximum; no preheat is needed. |
| Cold forming | Heavy cold forming of heads and shells may require solution annealing under your code. |
| Machining | Sharp tools, positive rake and steady feed; austenitic grades work-harden if the tool rubs. |
How to Order SS 304 Plate: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Standard and edition — e.g. ASTM A240-latest
- Thickness × width × length, and number of pieces
- Full plates or cut pieces (attach drawing)
- Certificate type — 3.1 or 3.2, and the inspection agency
- Extra tests — UT, intergranular corrosion
- Delivery port, Incoterm and required date
SS 304 plate for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 304 plate — questions buyers ask
Is SS 304 the same as AISI 304?
AISI 304, UNS S30400, W.Nr 1.4301 are names used for SS 304 (W.Nr / EN numbers and older UNS variants are the closest designations; their limits can differ slightly, so specify the UNS number and ASTM grade on the order), and plate is ordered to ASTM A240 whichever name is on the enquiry.
What thickness counts as SS 304 plate?
Under ASTM A240 and its general-requirements standard, flat material below 3/16" (4.76 mm) is sheet (or strip if narrower than 24") and 3/16" (4.76 mm) and over is plate. Order the form that matches your drawing thickness.
What is the price of SS 304 plate per kg?
It moves with nickel on the LME, so a fixed list price is out of date within days. Thickness, cut size, quantity and documents also change it. Send your size and quantity and we quote the same working day.
Do you supply ultrasonically tested SS 304 plate?
Yes, UT can be added to the order — to ASTM A578 or the level your specification states. The UT report is supplied with the mill certificate.
Can SS 304 plate be cut into circles and rings?
Yes. Blanks for blind flanges, covers and tube sheets are cut from plate to your drawing, with the heat number marked on every piece.
What machining allowance should I leave on cut plate?
It depends on the cutting method and finished tolerance. Give us the finished size and your allowance; thermally cut edges are normally machined back to sound metal.
How heavy is a SS 304 plate?
Weight (kg) = length (m) × width (m) × thickness (mm) × 8. A 2000 × 1000 × 10 mm plate weighs about 160 kg; use the calculator on this page for your size.
What documents come with an export shipment?
An EN 10204 3.1 mill certificate (or 3.2 with a third-party inspector), commercial invoice, packing list with heat numbers, and certificate of origin. Test reports are added for any extra tests ordered.
SS 304 or SS 904L — which should I choose?
SS 304 is chosen for general corrosion resistance, food, water and architectural work. SS 904L is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026