SS 310 / 310S Pipe FittingsASTM A403 WP310S · Manufacturer, stockist & exporter, India
Also sold as AISI 310S · UNS S31008 · W.Nr 1.4845 · Heat-resisting stainless
SS 310 / 310S pipe fittings are made to ASTM A403 WP310S for buttweld fittings and ASTM A182 F310 for forged socket-weld and threaded fittings, with dimensions to ASME B16.9 and B16.11. 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 Pipe Fittings?
SS 310 / 310S pipe fittings is a heat-resisting austenitic stainless steel with 25% chromium and 20% nickel supplied as pipe fittings to ASTM A403 WP310S (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
- Buttweld
- ASTM A403 WP310S
- Forged
- ASTM A182 F310
- Dimensions
- ASME B16.9 · B16.11 · MSS SP-43
- Sizes
- Buttweld ½" – 48" · forged ⅛" – 4"
- Best at
- Furnaces, burners and heat treatment at high temperature
SS 310 / 310S Pipe Fittings Specification & Sizes
| Buttweld fittings | ASTM A403 WP310S — dimensions to ASME B16.9, MSS SP-43 |
|---|---|
| Forged fittings | ASTM A182 F310 — dimensions to ASME B16.11 |
| Short-radius elbows | ASME B16.28 |
| Buttweld sizes | NPS ½" to 48", schedule to match the pipe |
| Forged classes | Socket weld 3000 / 6000 / 9000 · threaded 2000 / 3000 / 6000 |
| Types | Elbow · Tee · Reducer · Cap · Stub end · Cross · Bend · Lateral · Coupling · Union · Nipple · Plug |
| Testing | PMI · dimensional · radiography of welded fittings · IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
Standards on this page
SS 310 / 310S Pipe Fittings 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 Pipe Fittings 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 buttweld fitting dimensions — ASME B16.9
Centre-to-end and end-to-end dimensions are the same for every alloy; the wall thickness follows the pipe schedule. Values in mm.
| NPS | OD | 90° LR elbow A | 45° elbow B | Tee C | Reducer H | Cap E |
|---|---|---|---|---|---|---|
| ½" | 21.3 | 38 | 16 | 25 | — | 25 |
| 1" | 33.4 | 38 | 22 | 38 | 51 | 38 |
| 1½" | 48.3 | 57 | 29 | 57 | 64 | 38 |
| 2" | 60.3 | 76 | 35 | 64 | 76 | 38 |
| 3" | 88.9 | 114 | 51 | 86 | 89 | 51 |
| 4" | 114.3 | 152 | 64 | 105 | 102 | 64 |
| 6" | 168.3 | 229 | 95 | 143 | 140 | 89 |
| 8" | 219.1 | 305 | 127 | 178 | 152 | 102 |
| 10" | 273.1 | 381 | 159 | 216 | 178 | 127 |
| 12" | 323.9 | 457 | 190 | 254 | 203 | 152 |
Full chart to 24": ASME B16.9 fitting 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 Pipe Fittings 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 Pipe Fittings Price — What Decides It
Two quotes for "310S pipe fittings" can differ by 20% and both be fair. We quote 310S pipe fittings 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 pipe fittings by type
SS 310 / 310S Pipe Fittings 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 Pipe Fittings vs 304, 321 and 800
| Grade | Pipe Fittings standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Incoloy 800 / 800H / 800HT | ASTM B366 WPNIC | — | Furnaces, petrochemical heaters and high-temperature piping |
| SS 304 | ASTM A403 WP304 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 321 | ASTM A403 WP321 | ≈ 18 | High-temperature service between 425 and 815 °C |
| SS 310 / 310S | ASTM A403 WP310S | ≈ 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 pipe fittings 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 Pipe Fittings
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 | Plasma or waterjet; 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 Pipe Fittings: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Fitting type, size and schedule / class
- Buttweld, socket weld or threaded
- Seamless or welded (buttweld fittings)
- Material standard and grade marking
- Certificate type and extra tests
- Delivery port, Incoterm and required date
SS 310 / 310S pipe fittings for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 310 / 310S pipe fittings — 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 pipe fittings is ordered to ASTM A403 WP310S whichever name is on the enquiry.
Which standard covers SS 310 / 310S buttweld fittings?
ASTM A403 WP310S is the material specification; dimensions follow ASME B16.9 (and MSS SP-43 for light-wall fittings). Forged socket-weld and threaded fittings are made from ASTM A182 F310 material to ASME B16.11.
Buttweld or socket weld — which do I need?
Buttweld fittings suit ½" and larger lines and full-penetration welds. Socket-weld and threaded fittings suit small-bore lines, usually 2" and under.
Can you supply a mixed list of fittings?
Yes. Send the full material requisition and we quote line by line with delivery for each item.
What documents come with the fittings?
An EN 10204 3.1 certificate for each heat, dimensional report and PMI report; 3.2 with a third-party inspector on request.
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