SS 321 Expander FlangeASTM A182 · ASME B16.5 (flange end) · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100 · EXP
An SS 321 expander flange is a weld neck flange whose hub increases the pipe size, made from SS 321 to ASTM A182 F321. Expander flanges step up the line size at a pump or valve outlet, replacing a reducer and a standard weld neck flange with one part.
- ASTM A182
- ASME B16.5 (flange end)
- 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 Expander Flange?
- What it is
- A weld neck flange whose hub increases the pipe size
- Material
- ASTM A182 F321
- Dimensions
- ASME B16.5 (flange end)
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Expander Flange Specification
| Product | SS 321 Expander Flange |
|---|---|
| Material standard | ASTM A182 F321 |
| Dimensional standard | ASME B16.5 (flange end) |
| Sizes | ½" – 24" (ASME B16.5) · 26" – 60" (ASME B16.47) |
| Pressure class | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | RF · FF · RTJ · tongue & groove |
| Bore | To match pipe schedule (state on order) |
| 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 an Expander Flange
Expander flanges step up the line size at a pump or valve outlet, replacing a reducer and a standard weld neck flange with one part.
- Increases one or two pipe sizes
- Saves a weld and space
- Weld neck design
More on choosing: Expander flange guide.
SS 321 Expander Flange: Why 321 for expander flanges
Expander flanges step up the line size at a pump or valve outlet, replacing a reducer and a standard weld neck flange with one part. 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 flanges are chosen where carbon steel would rust or contaminate the process. SS 321 is picked for high-temperature service between 425 and 815 °C. |
|---|---|
| Typical service | Aircraft exhaust — Manifolds, bellows and exhaust systems. |
| B16.5 material group | 2.4 |
| Bolting | ASTM A193 B8T studs with A194 8T nuts |
| 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 Expander Flange 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 Expander Flange 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 flanges
SS 321 Expander Flange — questions buyers ask
When is an expander flange used?
Most often at pump and valve outlets where the line size increases immediately.
What pressure rating does a SS 321 expander flange have?
It depends on class and temperature. SS 321 forgings are in ASME B16.5 material group 2.4; read your class column in that group's table at the design temperature.
Can SS 321 expander flanges 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 expander flanges?
The material is ASTM A182 F321; dimensions follow ASME B16.5 (flange end). Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 321 expander flange?
The alloy price, the size and pressure 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