SS 304/304L flanges are forged to ASTM A182 / ASME SA182 grades F304 and F304L, the 18% chromium, 8% nickel austenitic stainless steel that is the default choice for clean water, food and beverage, pharmaceutical utilities, mild chemicals and general process piping. Grade 304 resists atmospheric corrosion, fresh water and most organic and oxidising media, and stays tough from cryogenic temperatures upwards.
Raaj Fittings forges and machines SS 304 and 304L flanges in-house at our two plants in India, from ½" to 60" and from Class 150 to Class 2500, and supplies them to fabricators, EPC contractors and stockists in the Middle East, Europe and the Americas. Dual-certified F304/F304L material is the standard supply for welded piping.
| Material specification | ASTM A182 / ASME SA182 F304, F304L; dual-certified F304/F304L |
|---|---|
| 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, IS 6392 |
| Pressure class | ASME Class 150, 300, 600, 900, 1500 and 2500; PN 6 to PN 400 to EN 1092-1 / DIN |
| Facing | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male & Female, Tongue & Groove |
| Condition | Solution annealed, pickled and passivated |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request |
| Element, % | F304 | F304L |
|---|---|---|
| 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 |
| Nitrogen (N) | 0.10 max | 0.10 max |
| Property (min.) | F304 | F304L |
|---|---|---|
| Tensile strength | 515 MPa (75 ksi) | 485 MPa (70 ksi) |
| Yield strength (0.2% offset) | 205 MPa (30 ksi) | 170 MPa (25 ksi) |
| Elongation in 50 mm | 30% | 30% |
| Reduction of area | 50% | 50% |
A dual-certified F304/F304L flange meets the higher F304 strength and the 0.030% carbon limit of F304L at the same time.
| 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 |
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.
F304L limits carbon to 0.030% against 0.08% for F304, which prevents sensitisation and intergranular corrosion after welding. F304 has slightly higher minimum strength. Dual-certified F304/F304L flanges meet both and are the usual supply for welded piping.
No, 304 is not recommended for seawater or other chloride-bearing service because it has no molybdenum and suffers pitting and crevice corrosion. Use 316/316L for mild chloride exposure and duplex 2205 or super duplex 2507 for seawater.
ASTM A182 F304 is in ASME B16.5 Material Group 2.1 and F304L in Group 2.3. The group sets the pressure–temperature rating of the flange in each class.
We make SS 304/304L 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 Class 2500, plus EN 1092-1, DIN, BS, JIS and IS flanges in PN ratings.
Yes. After solution annealing, stainless steel flanges are pickled and passivated to remove scale and restore a clean, corrosion-resistant passive surface.