SS 904L Flanges are made to ASTM A182 / ASME SA182 F904L (UNS N08904) for sulphuric acid and chloride 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 904L 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 F904L (UNS N08904) |
|---|---|
| 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 904L is a super-austenitic stainless steel with about 25% nickel, 20% chromium, 4.5% molybdenum and 1.5% copper. The copper gives outstanding resistance to sulphuric acid, and the high nickel and molybdenum resist chloride pitting and stress corrosion cracking far better than 316L.
| Element, % | N08904 |
|---|---|
| Carbon (C) | 0.020 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.040 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 19.0 – 23.0 |
| Nickel (Ni) | 23.0 – 28.0 |
| Molybdenum (Mo) | 4.0 – 5.0 |
| Copper (Cu) | 1.0 – 2.0 |
| Property | SS 904L |
|---|---|
| Tensile strength, min. | 490 MPa (71 ksi) |
| Yield strength (0.2%), min. | 215 MPa (31 ksi) |
| Elongation, min. | 35% |
| UNS | Werkstoff Nr. | EN / DIN | Other |
|---|---|---|---|
| N08904 | 1.4539 | X1NiCrMoCu25-20-5 | — |
SS 904L 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.
904L has far more nickel (23–28%), more molybdenum (4–5%) and added copper. It resists sulphuric acid and chloride pitting much better than 316L and is used where 316L corrodes.
It is classed as a super-austenitic stainless steel, with UNS number N08904 because of its high nickel content.
We make SS 904L 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 F904L (UNS N08904). EN 10204 3.2 certification and inspection by your nominated third-party agency are available on request.