SS 304 CapASTM A403 · ASME B16.9 · Manufacturer, trader & exporter, India
AISI 304 · UNS S30400
An SS 304 cap is a fitting that closes the end of a pipe, made from SS 304 to ASTM A403 WP304 (buttweld) · ASTM A182 F304 (forged). Buttweld caps are dished ends welded to the pipe; forged caps are threaded or socket-weld. Used at dead ends and future connection points.
- ASTM A403
- ASME B16.9
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 304 Cap?
- What it is
- A fitting that closes the end of a pipe
- Material
- ASTM A403 WP304 (buttweld) · ASTM A182 F304 (forged)
- Dimensions
- ASME B16.9 · B16.11
- Grade
- SS 304 · UNS S30400
- Best at
- General corrosion resistance, food, water and architectural work
SS 304 Cap Specification
| Product | SS 304 Cap |
|---|---|
| Material standard | ASTM A403 WP304 (buttweld) · ASTM A182 F304 (forged) |
| Dimensional standard | ASME B16.9 · B16.11 |
| Sizes | Buttweld ½" – 48" · forged ⅛" – 4" |
| Wall / class | Schedule to match pipe · Class 3000 / 6000 (forged) |
| Ends | Bevelled to ASME B16.25 |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Cap
Buttweld caps are dished ends welded to the pipe; forged caps are threaded or socket-weld. Used at dead ends and future connection points.
- Buttweld dished caps
- Threaded and socket-weld caps
- Wall to match the pipe
More on choosing: Cap guide.
SS 304 Cap: Why 304 for caps
Buttweld caps are dished ends welded to the pipe; forged caps are threaded or socket-weld. Used at dead ends and future connection points. In SS 304, 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 fittings keep the line clean and corrosion-free. SS 304 is picked for general corrosion resistance, food, water and architectural work. |
|---|---|
| Typical service | Food & dairy — Tanks, piping and equipment that must be cleaned daily. |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER308 / ER308L (AWS A5.9) |
SS 304 Cap 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 |
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 Cap 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.
Full chemistry, properties and equivalents are on the SS 304 grade page.
Other SS 304 pipe fittings
SS 304 Cap dimensions — ASME B16.9
Values in mm, the same for every material; the wall thickness matches the pipe schedule.
| NPS | OD | Cap length E |
|---|---|---|
| ½" | 21.3 | 25 |
| ¾" | 26.7 | 25 |
| 1" | 33.4 | 38 |
| 1½" | 48.3 | 38 |
| 2" | 60.3 | 38 |
| 3" | 88.9 | 51 |
| 4" | 114.3 | 64 |
| 6" | 168.3 | 89 |
| 8" | 219.1 | 102 |
| 10" | 273.1 | 127 |
| 12" | 323.9 | 152 |
| 16" | 406.4 | 178 |
| 20" | 508.0 | 229 |
| 24" | 610.0 | 267 |
Full chart: ASME B16.9 fitting dimensions.
SS 304 Cap — questions buyers ask
Can a cap take full line pressure?
Yes — a buttweld cap of matching schedule is rated like the pipe it closes.
Can SS 304 caps be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 304 caps?
The material is ASTM A403 WP304 (buttweld) · ASTM A182 F304 (forged); dimensions follow ASME B16.9 · B16.11. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 304 cap?
The alloy price, the size and schedule or class, 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 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026