SS 347 Forged Fittings are made to ASTM A182 / ASME SA182 F347 for high-temperature and hydroprocessing service. Socket weld and threaded fittings are dimensioned to ASME B16.11 for small-bore SS 347 piping.
Raaj Fittings manufactures SS 347 forged fittings in-house at our two plants in India, from ⅛" to 4" in Class 2000 to 9000, 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 A182 / ASME SA182 F347 |
|---|---|
| Dimensional standard | ASME B16.11; MSS SP-79, SP-83, SP-95 and SP-97 |
| Size range | ⅛" to 4" NPS |
| Pressure class | Socket weld: Class 3000, 6000, 9000. Threaded: Class 2000, 3000, 6000 |
| Threads | NPT to ASME B1.20.1; BSPT / BSPP to BS 21 / ISO 7-1 |
| 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 socket weld and threaded fittings are forged from bar or billet, solution annealed and CNC machined. Use filler metal matched to the grade for socket welds, and an anti-seize sealant on stainless threads to prevent galling.
| Pipe | Socket weld class | Threaded class |
|---|---|---|
| SCH 80 / XS | 3000 | 2000 |
| SCH 160 | 6000 | 3000 |
| XXS | 9000 | 6000 |
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the forged 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.
Class 3000 socket weld fittings match SCH 80 pipe, Class 6000 matches SCH 160 and Class 9000 matches XXS. For threaded fittings, the matching classes are 2000, 3000 and 6000.
Every order is supplied with EN 10204 3.1 mill test certificates showing heat chemistry and mechanical properties to ASTM A182 F347. EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.