SS 321 CouplingASTM A182 · ASME B16.11 · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100
An SS 321 coupling is a short forged fitting that joins two pipes, made from SS 321 to ASTM A182 F321. Full couplings join two pipes; half couplings are welded to a pipe or vessel as a branch connection. Socket-weld or threaded to ASME B16.11.
- ASTM A182
- ASME B16.11
- 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 Coupling?
- What it is
- A short forged fitting that joins two pipes
- Material
- ASTM A182 F321
- Dimensions
- ASME B16.11
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Coupling Specification
| Product | SS 321 Coupling |
|---|---|
| Material standard | ASTM A182 F321 |
| Dimensional standard | ASME B16.11 |
| Sizes | ⅛" – 4" (ASME B16.11) |
| Wall / class | Class 2000 / 3000 / 6000 / 9000 |
| Ends | Socket weld · NPT threaded |
| 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 Coupling
Full couplings join two pipes; half couplings are welded to a pipe or vessel as a branch connection. Socket-weld or threaded to ASME B16.11.
- Full and half couplings
- Reducing couplings
- Class 3000 / 6000 / 9000
More on choosing: Coupling guide.
SS 321 Coupling: Why 321 for couplings
Full couplings join two pipes; half couplings are welded to a pipe or vessel as a branch connection. Socket-weld or threaded to ASME B16.11. 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 Coupling 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 Coupling 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 Coupling — questions buyers ask
What is a half coupling used for?
It is welded onto a pipe or vessel to create a small threaded or socket-weld branch.
Can SS 321 couplings 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 couplings?
The material is ASTM A182 F321; dimensions follow ASME B16.11. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 321 coupling?
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