SS 310 / 310S FlangesASTM A182 F310 · Manufacturer, stockist & exporter, India
Also sold as AISI 310S · UNS S31008 · W.Nr 1.4845 · Heat-resisting stainless
SS 310 / 310S flanges are forged to ASTM A182 F310 and machined to ASME B16.5 (½"–24", Class 150–2500) or ASME B16.47 for larger sizes. It is a heat-resisting austenitic stainless steel with 25% chromium and 20% nickel, chosen for furnaces, burners and heat treatment at high temperature. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on every heat
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 310 / 310S Flanges?
SS 310 / 310S flanges is a heat-resisting austenitic stainless steel with 25% chromium and 20% nickel supplied as flanges to ASTM A182 F310 (UNS S31008). Buyers specify it for furnaces, burners and heat treatment at high temperature. It is also sold as AISI 310S, UNS S31008, W.Nr 1.4845.
- What it is
- Heat-resisting austenitic stainless steel with 25% chromium and 20% nickel
- Material
- ASTM A182 F310
- Dimensions
- ASME B16.5 · B16.47 · EN 1092-1
- Classes
- 150 · 300 · 600 · 900 · 1500 · 2500
- Facing
- RF · FF · RTJ
- Best at
- Furnaces, burners and heat treatment at high temperature
SS 310 / 310S Flanges Specification & Sizes
| Material standard | ASTM A182 F310 |
|---|---|
| Dimensional standards | ASME B16.5 (½"–24") · B16.47 Series A / B (26"–60") · B16.36 orifice · B16.48 line blanks · EN 1092-1 |
| Pressure classes | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | Raised face (RF) · flat face (FF) · ring type joint (RTJ) · tongue & groove |
| Bore | To match the pipe schedule — specify it on the order |
| Types | Weld neck flange · Slip-on flange · Blind flange · Socket weld flange · Threaded flange · Lap joint flange · Long weld neck flange · Orifice flange · Spectacle blind · Reducing flange · Ring type joint flange · Expander flange · Anchor flange · Swivel ring flange |
| Testing | PMI · dimensional · UT of forgings · IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
Standards on this page
SS 310 / 310S Flange Pressure–Temperature Rating
The class is not a pressure: the allowable pressure for 310S flanges comes from the ASME B16.5 table for its material group, and falls as temperature rises (how ratings work). Check the material group for ASTM A182 F310 in B16.5 Table 1A before choosing the class.
Take the actual pressures from the B16.5 rating table for your material’s group. A class is not a project pressure rating — your piping class sheet and design conditions govern.
Bolting & Gaskets for 310S Flanges
For SS 310 / 310S flanges the usual bolting is A193 B8 or project-specified bolting — see SS 310 / 310S fasteners. Spiral-wound gaskets with a 304 or 316 winding suit most stainless raised-face joints. Facing and gasket options are compared in the flange guide.
SS 310 / 310S Flanges 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 Flanges 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 |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.9 g/cm³ |
| Melting range | 1400 – 1450 °C |
| Magnetic | Non-magnetic annealed |
| PREN (approx.) | ≈ 25 |
SS 310 / 310S Equivalent Grades
Values follow ASTM A240 for UNS S31008. Always check against the edition named on your purchase order.
SS 310 / 310S flange dimensions — ASME B16.5 Class 150 & 300
Outside dimensions depend only on size and class, not on the alloy, so 310S flanges bolt to any B16.5 flange of the same 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.
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify SS 310 / 310S Flanges with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. SS 310 / 310S is most often mixed up with SS 304 — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | SS 310 / 310S | SS 304 |
|---|---|---|
| Nickel | 19.0 – 22.0 | 8.0 – 10.5 |
| Chromium | 24.0 – 26.0 | 17.5 – 19.5 |
| Iron | Balance | Balance |
| Manganese | 2.00 max | 2.00 max |
SS 310 / 310S Flanges Price — What Decides It
Two quotes for "310S flanges" can differ by 20% and both be fair. We quote 310S flanges per kg for full sizes and per piece for cut sizes. These six things move the price per kg, so you can compare offers like for like.
SS 310 / 310S flanges by type
SS 310 / 310S Flanges Applications
SS 310 / 310S is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
SS 310 / 310S Flanges vs 304, 321 and 800
| Grade | Flanges standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Incoloy 800 / 800H / 800HT | ASTM B564 | — | Furnaces, petrochemical heaters and high-temperature piping |
| SS 304 | ASTM A182 F304 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 321 | ASTM A182 F321 | ≈ 18 | High-temperature service between 425 and 815 °C |
| SS 310 / 310S | ASTM A182 F310 | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 310 / 310S Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 310S fits.
25% chromium builds a tight scale that resists oxidation in continuous service up to about 1100 °C.
20% nickel keeps the alloy austenitic and strong at furnace temperatures.
Silicon improves resistance to scaling and carburising atmospheres.
Without molybdenum, 310S is not a chloride grade — use it for heat, not for seawater.
How your 310S flanges order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked and material is PMI-tested before processing.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Standards on this page
Welding & Fabricating SS 310 / 310S Flanges
SS 310 / 310S welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER310 (AWS A5.9) |
|---|---|
| Over-alloyed filler | ERNiCr-3 for joints to nickel alloys |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Thermal or abrasive cutting; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 310S fittings and 310S flanges for the matching pipe-system parts.
How to Order SS 310 / 310S Flanges: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Flange type and dimensional standard (B16.5 / B16.47 / EN 1092-1)
- Size, pressure class and facing
- Bore / schedule for weld neck and socket weld flanges
- Material standard and grade marking
- Certificate type and extra tests
- Delivery port, Incoterm and required date
SS 310 / 310S flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 310 / 310S flanges — questions buyers ask
Is SS 310 / 310S the same as AISI 310S?
Yes. AISI 310S, UNS S31008, W.Nr 1.4845 all refer to the same material, and flanges is ordered to ASTM A182 F310 whichever name is on the enquiry.
Which standard covers SS 310 / 310S flanges?
ASTM A182 F310 is the material specification for the forging; dimensions follow ASME B16.5 for ½"–24" and ASME B16.47 for 26" and above. European projects use EN 1092-1.
What pressure can a SS 310 / 310S Class 300 flange take?
It depends on temperature and the material group of ASTM A182 F310 in ASME B16.5; read the Class 300 column of that group's rating table at your design temperature.
Which bolts should I use with SS 310 / 310S flanges?
Usually A193 B8 or project-specified bolting. In corrosive or sour service the bolting material is set by the project specification.
Can a SS 310 / 310S flange be welded to a different pipe material?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel. Weld neck bores must match the mating pipe schedule.
SS 310 / 310S or Incoloy 800 / 800H / 800HT — which should I choose?
SS 310 / 310S is chosen for furnaces, burners and heat treatment at high temperature. Incoloy 800 / 800H / 800HT is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026