SS 304/304L buttweld fittings are made to ASTM A403 / ASME SA403 grades WP304 and WP304L for welding into stainless steel pipe in water, food, pharmaceutical, chemical and general process plants. Most are ordered in the light-wall S schedules, SCH 5S and 10S, where 304L's low carbon content keeps the welded joints free of sensitisation.
Raaj Fittings manufactures SS 304/304L elbows, tees, reducers, caps, stub ends and bends in-house at our two plants in India, in seamless and welded construction from ½" up to 48", and exports them to fabricators and stockists across the Middle East, Europe and the Americas, normally dual-certified WP304/WP304L.
| Material specification | ASTM A403 / ASME SA403 WP304, WP304L; dual-certified WP304/WP304L |
|---|---|
| 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, % | WP304 | WP304L |
|---|---|---|
| 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) | 18.0 – 20.0 | 18.0 – 20.0 |
| Nickel (Ni) | 8.0 – 11.0 | 8.0 – 12.0 |
| Property (min.) | WP304 | WP304L |
|---|---|---|
| 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 |
|---|---|---|---|---|
| 304 | S30400 | 1.4301 | X5CrNi18-10 | SUS 304 |
| 304L | S30403 | 1.4307 / 1.4306 | X2CrNi18-9 / X2CrNi19-11 | SUS 304L |
For SCH 5S and 10S stainless lines, buyers can order fittings to either standard. ASME B16.9 fittings (class WP) are dimensioned and rated for pressure piping. MSS SP-43 fittings (class CR) are lighter, with shorter centre-to-end dimensions on some fittings and a lower pressure basis, and are widely used in low-pressure, corrosion-resistant service such as water treatment, food processing and utilities. Short-pattern stub ends for lap joint flanges are also made to MSS SP-43. State the standard on your order so the fittings match the piping specification.
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.
WP is the ASTM A403 class for fittings to ASME B16.9 dimensions, 304L is the grade, and S means seamless construction. Welded fittings are marked W, WX (radiographed welds) or WU (ultrasonically tested welds).
We make SS 304/304L buttweld fittings in SCH 5S, 10S, 40S and 80S, the stainless "S" schedules, and in SCH 10 to SCH 160, STD, XS and XXS, matching the wall thickness of the pipe they are welded to.
For welded piping, 304L or dual-certified 304/304L is preferred because its 0.030% carbon limit prevents sensitisation in the weld heat-affected zone. Dual-certified fittings also meet the strength of 304.
ASME B16.9 fittings are designed for pressure piping. MSS SP-43 fittings are light-wall stainless fittings, mainly SCH 5S and 10S, for low-pressure corrosion-resistant service, and some have shorter centre-to-end dimensions. Order the standard named in your piping specification.