SS 321 Stub EndASTM A403 · ASME B16.9 · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100
An SS 321 stub end is a short pipe length with a flared lap that works with a lap joint flange, made from SS 321 to ASTM A403 WP321. Stub ends are welded to the pipe and backed by a loose lap joint flange. Type A (long pattern, ASME B16.9) and short-pattern MSS SP-43 stub ends are the common choices.
- 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 321 Stub End?
- What it is
- A short pipe length with a flared lap that works with a lap joint flange
- Material
- ASTM A403 WP321
- Dimensions
- ASME B16.9 · MSS SP-43
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Stub End Specification
| Product | SS 321 Stub End |
|---|---|
| Material standard | ASTM A403 WP321 |
| Dimensional standard | ASME B16.9 · MSS SP-43 |
| Sizes | ½" – 48" |
| Wall / class | Sch 5S – XXS, to match pipe |
| 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 Stub End
Stub ends are welded to the pipe and backed by a loose lap joint flange. Type A (long pattern, ASME B16.9) and short-pattern MSS SP-43 stub ends are the common choices.
- Long pattern (ASME B16.9) and short pattern (MSS SP-43)
- Type A, B and C lap designs
- Used with a carbon-steel backing flange to save alloy
More on choosing: Stub end guide.
SS 321 Stub End: Why 321 for stub ends
Stub ends are welded to the pipe and backed by a loose lap joint flange. Type A (long pattern, ASME B16.9) and short-pattern MSS SP-43 stub ends are the common choices. In SS 321, 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 321 is picked for high-temperature service between 425 and 815 °C. |
|---|---|
| Typical service | Aircraft exhaust — Manifolds, bellows and exhaust systems. |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER347 (AWS A5.9) |
SS 321 Stub End Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Titanium | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | 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 S32100.
SS 321 Stub End 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 S32100 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 321 grade page.
Other SS 321 pipe fittings
SS 321 Stub End — questions buyers ask
Long or short stub end?
Long-pattern stub ends to ASME B16.9 suit most piping; short-pattern MSS SP-43 stub ends save alloy and space in low-pressure lines.
Can SS 321 stub ends be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 321 stub ends?
The material is ASTM A403 WP321; dimensions follow ASME B16.9 · MSS SP-43. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 321 stub end?
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