SS 310 / 310S Reducing FlangeASTM A182 · ASME B16.5 · Manufacturer, stockist & exporter, India
AISI 310S · UNS S31008 · RF
An SS 310 / 310S reducing flange is a flange with a smaller bore than its outside dimensions, connecting to a smaller pipe, made from SS 310 / 310S to ASTM A182 F310. A reducing flange changes pipe size at a flanged joint without a separate reducer, saving space and a weld. Use it where the flow disturbance from a sudden change is acceptable.
- ASTM A182
- ASME B16.5
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 310 / 310S Reducing Flange?
- What it is
- A flange with a smaller bore than its outside dimensions, connecting to a smaller pipe
- Material
- ASTM A182 F310
- Dimensions
- ASME B16.5
- Grade
- SS 310 / 310S · UNS S31008
- Best at
- Furnaces, burners and heat treatment at high temperature
SS 310 / 310S Reducing Flange Specification
| Product | SS 310 / 310S Reducing Flange |
|---|---|
| Material standard | ASTM A182 F310 |
| Dimensional standard | ASME B16.5 |
| 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 · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose a Reducing Flange
A reducing flange changes pipe size at a flanged joint without a separate reducer, saving space and a weld. Use it where the flow disturbance from a sudden change is acceptable.
- Outside dimensions of the larger size
- Bore / hub for the smaller pipe
- Weld neck, slip-on or threaded styles
More on choosing: Reducing flange guide.
SS 310 / 310S Reducing Flange: Why 310S for reducing flanges
A reducing flange changes pipe size at a flanged joint without a separate reducer, saving space and a weld. Use it where the flow disturbance from a sudden change is acceptable. In SS 310 / 310S, 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 310 / 310S is picked for furnaces, burners and heat treatment at high temperature. |
|---|---|
| Typical service | Furnace parts — Muffles, retorts, radiant tubes and conveyor belts. |
| Bolting | A193 B8 or project-specified bolting |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER310 (AWS A5.9) |
SS 310 / 310S Reducing Flange Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 24.0 – 26.0 |
| Nickel | 19.0 – 22.0 |
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Silicon | 1.50 max |
| Phosphorus | 0.045 max |
| Sulphur | 0.030 max |
| Iron | Balance |
SS 310 / 310S Reducing Flange Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 515 MPa · 75 ksi |
| Yield strength 0.2% | 205 MPa · 30 ksi |
| Elongation | 40% |
| Hardness | 217 HB max |
Full chemistry, properties and equivalents are on the SS 310 / 310S grade page.
Other SS 310 / 310S flanges
SS 310 / 310S Reducing Flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 310 / 310S Reducing Flange dimensions — ASME B16.5 Class 150 & 300
Outside diameter, thickness and bolting are set by size and class. Values in mm; thickness excludes the 1.6 mm raised face.
| NPS | Cl 150 OD | Cl 150 thickness | Cl 150 bolt circle | Cl 150 bolts | Cl 300 OD | Cl 300 thickness | Cl 300 bolt circle | Cl 300 bolts |
|---|---|---|---|---|---|---|---|---|
| ½" | 90 | 9.6 | 60.3 | 4 × ½" | 95 | 12.7 | 66.7 | 4 × ½" |
| 1" | 110 | 12.7 | 79.4 | 4 × ½" | 125 | 15.9 | 88.9 | 4 × ⅝" |
| 1½" | 125 | 15.9 | 98.4 | 4 × ½" | 155 | 19.1 | 114.3 | 4 × ¾" |
| 2" | 150 | 17.5 | 120.7 | 4 × ⅝" | 165 | 20.7 | 127.0 | 8 × ⅝" |
| 3" | 190 | 22.3 | 152.4 | 4 × ⅝" | 210 | 27.0 | 168.3 | 8 × ¾" |
| 4" | 230 | 22.3 | 190.5 | 8 × ⅝" | 255 | 30.2 | 200.0 | 8 × ¾" |
| 6" | 280 | 23.9 | 241.3 | 8 × ¾" | 320 | 35.0 | 269.9 | 12 × ¾" |
| 8" | 345 | 27.0 | 298.5 | 8 × ¾" | 380 | 39.7 | 330.2 | 12 × ⅞" |
| 10" | 405 | 28.6 | 362.0 | 12 × ⅞" | 445 | 46.1 | 387.4 | 16 × 1" |
| 12" | 485 | 30.2 | 431.8 | 12 × ⅞" | 520 | 49.3 | 450.8 | 16 × 1⅛" |
Full chart: ASME B16.5 flange dimensions.
SS 310 / 310S Reducing Flange — questions buyers ask
Is a reducing flange better than a reducer plus flange?
It saves length and a weld, but a buttweld reducer gives smoother flow. Choose by space and process needs.
Can SS 310 / 310S reducing 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 310 / 310S reducing flanges?
The material is ASTM A182 F310; dimensions follow ASME B16.5. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 310 / 310S reducing 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 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026