SS 316 / 316L Pipe FittingsASTM A403 WP316L · Manufacturer, stockist & exporter, India
Also sold as AISI 316L · UNS S31603 · W.Nr 1.4404 · Marine-grade stainless
SS 316 / 316L pipe fittings are made to ASTM A403 WP316L for buttweld fittings and ASTM A182 F316L for forged socket-weld and threaded fittings, with dimensions to ASME B16.9 and B16.11. It is a molybdenum-bearing austenitic stainless steel, chosen for chloride-bearing process fluids, marine air and pharmaceutical service. 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 request
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 316 / 316L Pipe Fittings?
SS 316 / 316L pipe fittings is a molybdenum-bearing austenitic stainless steel supplied as pipe fittings to ASTM A403 WP316L (UNS S31603). Buyers specify it for chloride-bearing process fluids, marine air and pharmaceutical service. It is also sold as AISI 316L, UNS S31603, W.Nr 1.4404.
- What it is
- Molybdenum-bearing austenitic stainless steel
- Buttweld
- ASTM A403 WP316L
- Forged
- ASTM A182 F316L
- Dimensions
- ASME B16.9 · B16.11 · MSS SP-43
- Sizes
- Buttweld ½" – 48" · forged ⅛" – 4"
- Best at
- Chloride-bearing process fluids, marine air and pharmaceutical service
SS 316 / 316L Pipe Fittings Specification & Sizes
| Buttweld fittings | ASTM A403 WP316L — dimensions to ASME B16.9, MSS SP-43 |
|---|---|
| Forged fittings | ASTM A182 F316L — dimensions to ASME B16.11 |
| MSS SP-43 light-wall fittings | ASTM A403 CR316L — the A403 CR grade for MSS SP-43 dimensions (no class suffix) |
| Short-radius elbows | ASME B16.9 (formerly 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 |
Choosing SS 316 / 316L Fittings: Elbow Radius, Schedule & Class
ASTM A403 fittings come in classes: S seamless, W welded (welds radiographed or ultrasonically examined), WX all welds radiographed, WU all welds ultrasonically tested. Write the class after the grade, e.g. WP316L-S.
Radius (LR, SR, 3D), the schedule-to-class map and the 1.5 mm socket-weld gap are explained in the fittings guide. For 316L, buttweld fittings are ASTM A403 WP316L and forged fittings ASTM A182 F316L.
SS 316 / 316L Pipe Fittings Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Molybdenum | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | 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 S31603.
SS 316 / 316L Pipe Fittings 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 S31603 — Annealed plate & sheet (316L).
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8 g/cm³ |
| Melting range | 1375 – 1400 °C |
| Magnetic | Non-magnetic annealed |
| PREN (approx.) | ≈ 24 |
SS 316 / 316L Equivalent Grades
SS 316 / 316L 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 316 / 316L 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 316 / 316L is most often mixed up with SS 304 — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen, so it cannot tell 316 from 316L: the low carbon is confirmed by the mill certificate or optical emission (OES) testing. PMI can be arranged on request — state it on your enquiry.
Under technical review for TDS.
| Element | SS 316 / 316L | SS 304 |
|---|---|---|
| Nickel | As specified | As specified |
| Chromium | As specified | As specified |
| Molybdenum | As specified | — |
| Iron | As specified | As specified |
| Manganese | As specified | As specified |
SS 316 / 316L Pipe Fittings Price — What Decides It
Two quotes for "316L pipe fittings" can differ by 20% and both be fair. We quote 316L 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 316 / 316L pipe fittings by type
SS 316 / 316L Pipe Fittings Applications
SS 316 / 316L 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 316 / 316L Pipe Fittings vs 304, 904L and 2205
| Grade | Pipe Fittings standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 304 | ASTM A403 WP304 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 316 / 316L | ASTM A403 WP316L | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 904L | ASTM A403 WP904L | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| Duplex 2205 | ASTM A815 WPS31803 / WPS32205 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 316 / 316L 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 316L fits.
Molybdenum is what lets 316L survive coastal air, brackish water and mild chlorides where 304 pits.
Chromium forms the passive film.
Extra nickel balances the molybdenum and keeps the steel austenitic.
Low carbon keeps welds free of sensitisation.
How your 316L 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 against your order; PMI before processing is available on request.
- 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 316 / 316L Pipe Fittings
SS 316 / 316L welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER316L (AWS A5.9) |
|---|---|
| Over-alloyed filler | ER309LMo for dissimilar joints |
| 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 316L fittings and 316L flanges for the matching pipe-system parts.
How to Order SS 316 / 316L 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 316 / 316L pipe fittings for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 316 / 316L pipe fittings — questions buyers ask
Is SS 316 / 316L the same as AISI 316L?
AISI 316L, UNS S31603, W.Nr 1.4404 are names used for SS 316 / 316L (W.Nr / EN numbers and older UNS variants are the closest designations; their limits can differ slightly, so specify the UNS number and ASTM grade on the order), and pipe fittings is ordered to ASTM A403 WP316L whichever name is on the enquiry.
Which standard covers SS 316 / 316L buttweld fittings?
ASTM A403 WP316L is the material specification; dimensions follow ASME B16.9 (light-wall MSS SP-43 fittings are ordered as CR316L). Forged socket-weld and threaded fittings are made from ASTM A182 F316L material to ASME B16.11.
What is the difference between SS 316 / 316L WP-S and WP-W fittings?
S is seamless; W is welded from plate or welded pipe, with the welds examined by radiography or ultrasonics. WX means all welds radiographed and WU all welds ultrasonically tested. Seamless costs more and is preferred for critical service.
Can SS 316 / 316L fittings be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
SS 316 / 316L or Duplex 2205 — which should I choose?
SS 316 / 316L is chosen for chloride-bearing process fluids, marine air and pharmaceutical service. Duplex 2205 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