SS 316/316L buttweld fittings are made to ASTM A403 / ASME SA403 grades WP316 and WP316L, the molybdenum-bearing stainless steel used for process piping that 304 cannot handle: chloride-bearing water, seawater-cooled systems, acids and the hygienic lines of pharmaceutical and food plants. With 2–3% molybdenum, 316L resists pitting and crevice corrosion far better than 304, and its low carbon keeps welds free of sensitisation.
Raaj Fittings manufactures SS 316/316L elbows, tees, reducers, caps, stub ends, crosses and laterals at our two plants in India, seamless and welded, from ½" to 48" and SCH 5S to XXS. Most orders are dual-certified WP316/WP316L and go to EPC contractors, fabricators and stockists in the Middle East, Europe and the Americas.
| Material specification | ASTM A403 / ASME SA403 WP316, WP316L; dual-certified WP316/WP316L |
|---|---|
| Class | WP-S (seamless), WP-W, WP-WX (welds radiographed), WP-WU (welds ultrasonically tested); CR for MSS SP-43 fittings |
| Dimensional standards | ASME B16.9, MSS SP-43; bevelled ends to ASME B16.25 |
| Size range | ½" to 48" NPS; larger sizes to order |
| Wall thickness | SCH 5S, 10S, 40S, 80S, SCH 10 to SCH 160, STD, XS, XXS |
| Condition | Solution annealed, pickled and passivated |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request |
| Element, % | WP316 | WP316L |
|---|---|---|
| Carbon (C) | 0.08 max | 0.030 max |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Phosphorus (P) | 0.045 max | 0.045 max |
| Sulphur (S) | 0.030 max | 0.030 max |
| Silicon (Si) | 1.00 max | 1.00 max |
| Chromium (Cr) | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 10.0 – 14.0 | 10.0 – 14.0 |
| Molybdenum (Mo) | 2.00 – 3.00 | 2.00 – 3.00 |
| Property (min.) | WP316 | WP316L |
|---|---|---|
| Tensile strength | 515 MPa (75 ksi) | 485 MPa (70 ksi) |
| Yield strength (0.2% offset) | 205 MPa (30 ksi) | 170 MPa (25 ksi) |
Elongation requirements in ASTM A403 depend on the test direction and grade; the values for each heat are reported on the mill test certificate.
| Grade | UNS | Werkstoff Nr. | EN designation | JIS |
|---|---|---|---|---|
| 316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS 316 |
| 316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS 316L |
Smaller sizes are normally hot-formed seamless from 316L pipe (class WP-S). Larger sizes and light-wall fittings are made from plate or welded pipe; where the piping class asks for full volumetric examination, specify WP-WX (all welds radiographed) or WP-WU (ultrasonically examined). Welded fittings are solution annealed after forming, so the weld seam has the same corrosion resistance as the parent metal.
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the fittings are released. Each piece is marked with grade, size, rating and heat number for traceability to its EN 10204 3.1 mill test certificate. EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request, as are PED 2014/68/EU compliance for European projects and IBR certification for Indian boiler applications.
316L performs well in brackish and cool, flowing seawater, but warm or stagnant seawater can cause pitting and crevice corrosion. For seawater piping, duplex 2205, super duplex 2507 or copper-nickel fittings are usually specified.
The fitting meets both grades: the 0.030% maximum carbon of WP316L and the higher minimum tensile and yield strength of WP316. It can be used wherever either grade is specified.
Yes. We make SS 316/316L stub ends in both long pattern (ASME B16.9) and short pattern (MSS SP-43), with the lap joint flanges to match.
Every fitting is supplied with an EN 10204 3.1 mill test certificate showing heat chemistry and mechanical properties to ASTM A403. EN 10204 3.2 certification witnessed by your nominated third-party inspector is available on request.