SS 321 Orifice FlangeASTM A182 · ASME B16.36 · Manufacturer, trader & exporter, India
AISI 321 · UNS S32100 · ORF
An SS 321 orifice flange is a pair of weld neck or slip-on flanges with pressure taps that hold an orifice plate, made from SS 321 to ASTM A182 F321. Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate.
- ASTM A182
- ASME B16.36
- 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 Orifice Flange?
- What it is
- A pair of weld neck or slip-on flanges with pressure taps that hold an orifice plate
- Material
- ASTM A182 F321
- Dimensions
- ASME B16.36
- Grade
- SS 321 · UNS S32100
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Orifice Flange Specification
| Product | SS 321 Orifice Flange |
|---|---|
| Material standard | ASTM A182 F321 |
| Dimensional standard | ASME B16.36 |
| Sizes | 1" – 24" (ASME B16.36) |
| Pressure class | Class 300 – 2500 |
| 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 Orifice Flange
Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate.
- Class 300 minimum per ASME B16.36
- Supplied in pairs with jack screws
- Pressure taps: ½" NPT, two per flange
More on choosing: Orifice flange guide.
SS 321 Orifice Flange: Why 321 for orifice flanges
Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate. 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 Orifice 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 Orifice 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 Orifice Flange — questions buyers ask
Why is the minimum class 300 for orifice flanges?
ASME B16.36 starts at Class 300 so the flange is thick enough to drill the pressure taps radially.
What pressure rating does a SS 321 orifice 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 orifice 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 orifice flanges?
The material is ASTM A182 F321; dimensions follow ASME B16.36. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 321 orifice 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