SS 347 Buttweld Fittings are made to ASTM A403 / ASME SA403 WP347 for high-temperature and hydroprocessing service. Elbows, tees, reducers and caps are dimensioned to ASME B16.9 and bevelled for welding into SS 347 pipe.
Raaj Fittings manufactures SS 347 buttweld fittings in-house at our two plants in India, seamless and welded, from ½" upwards, and exports them to EPC contractors, fabricators and stockists across the Middle East, Europe and the Americas, with full traceability and EN 10204 certificates.
| Material specification | ASTM A403 / ASME SA403 WP347 |
|---|---|
| Construction | Seamless and welded |
| 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 and heavier walls to order |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request |
SS 347 is an 18-8 stainless steel stabilised with niobium (columbium). Like 321, it resists sensitisation and intergranular corrosion after exposure at 425–815 °C, and it is often preferred for welded high-temperature systems because niobium survives the welding arc.
| Element, % | S34700 |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 – 20.0 |
| Nickel (Ni) | 9.0 – 13.0 |
| Niobium (Nb) | 10 × C min, 1.10 max |
| Property | SS 347 |
|---|---|
| Tensile strength, min. | 515 MPa (75 ksi) |
| Yield strength (0.2%), min. | 205 MPa (30 ksi) |
| Elongation in 50 mm, min. | 30% |
| Reduction of area, min. | 50% |
| UNS | Werkstoff Nr. | EN / DIN | Other |
|---|---|---|---|
| S34700 | 1.4550 | X6CrNiNb18-10 | SUS 347 |
SS 347 fittings are hot-formed seamless from pipe or made from plate and welded pipe, then solution annealed so that formed and welded areas regain full corrosion resistance. Welded fittings can be ordered with fully radiographed (WX) or ultrasonically tested (WU) seams.
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the buttweld 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.
Stabilised 347 resists the sensitisation that makes ordinary stainless steel prone to polythionic acid stress corrosion cracking during shutdowns, so it is widely used in hydroprocessing piping.
They give similar service. 347 is generally easier to weld without losing its stabilising element and is often the preferred choice for welded high-temperature systems.
Yes. Smaller sizes are normally seamless and larger sizes welded, with weld examination as the specification and your order require. Tell us the size, schedule and any construction requirement.
Every order is supplied with EN 10204 3.1 mill test certificates showing heat chemistry and mechanical properties to ASTM A403 WP347. EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.