SS 347 Flanges are made to ASTM A182 / ASME SA182 F347 for high-temperature and hydroprocessing service. They are supplied in every common flange type and facing to ASME B16.5, B16.47 and the main EN, DIN, BS and JIS standards.
Raaj Fittings manufactures SS 347 flanges in-house at our two plants in India, from ½" to 60" and in Class 150 to Class 2500, 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 standards | ASME B16.5 (½" to 24"), ASME B16.47 Series A and B (26" to 60"), EN 1092-1, DIN, BS 4504, JIS B2220 |
| Pressure class | ASME Class 150, 300, 600, 900, 1500 and 2500; PN 6 to PN 400 |
| Facing | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male & Female, Tongue & Groove |
| 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 flanges are forged, solution annealed and machined, then pickled and passivated. For welded flanges in corrosive service, check whether your specification calls for a low-carbon or stabilised grade, and match the gasket and bolting to the service temperature.
Every heat is PMI-verified and its chemistry and mechanical properties are confirmed against the material specification before the flanges 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.
We make SS 347 Flanges from ½" to 24" to ASME B16.5 and from 26" to 60" to ASME B16.47 Series A and B, in Class 150 to 2500, and to EN 1092-1, DIN, BS and JIS standards in PN ratings.
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.