SS 316/316L flanges are forged to ASTM A182 / ASME SA182 grades F316 and F316L, the molybdenum-bearing austenitic stainless steels specified wherever plain 304 is not enough: seawater and chloride-bearing process streams, chemical and pharmaceutical plants, and offshore and coastal installations. The 2–3% molybdenum in 316 raises its resistance to pitting and crevice corrosion well above that of 304, and the low-carbon 316L version keeps that resistance after welding.
Raaj Fittings manufactures SS 316 and 316L flanges in-house at our two plants in India, in every flange type we make, from ½" to 60" and Class 150 to Class 2500, and exports them to EPC contractors, fabricators and stockists across the Middle East, Europe and the Americas. Most buyers order dual-certified F316/F316L material, which meets the strength of 316 and the carbon limit of 316L in one flange.
| Material specification | ASTM A182 / ASME SA182 F316, F316L; dual-certified F316/F316L |
|---|---|
| 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, % | F316 | F316L |
|---|---|---|
| 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) | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 10.0 – 14.0 | 10.0 – 14.0 |
| Molybdenum (Mo) | 2.00 – 3.00 | 2.00 – 3.00 |
| Nitrogen (N) | 0.10 max | 0.10 max |
| Property (min.) | F316 | F316L |
|---|---|---|
| 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% |
Dual-certified F316/F316L flanges meet the higher F316 strength values together with the 0.030% carbon limit of F316L.
| Grade | UNS | Werkstoff Nr. | EN designation | JIS |
|---|---|---|---|---|
| 316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS 316 |
| 316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS 316L |
The only difference between the two grades is carbon. At 0.08% carbon, standard 316 can form chromium carbides at the grain boundaries when it is held in the 425–870 °C range, for example in the heat-affected zone of a weld. This "sensitisation" leaves the steel open to intergranular corrosion. 316L limits carbon to 0.030%, which avoids the problem in welded flanges without post-weld annealing. 316 keeps slightly higher strength, which is why 316H (with a controlled higher carbon content) is used for elevated-temperature service. For most welded piping, dual-certified F316/F316L is the simplest choice.
Every SS 316/316L flange is made from verified material: incoming bars and forgings are PMI-tested, and chemistry and mechanical properties are confirmed against ASTM A182 for each heat. Flanges are solution annealed, then pickled and passivated, and dimensionally inspected against the ordered standard. Each flange is marked with grade, size, class, standard and heat number so it can be traced to its EN 10204 3.1 certificate. Intergranular corrosion testing, third-party inspection by the buyer's nominated agency and EN 10204 3.2 certification are available on request.
F316L has a maximum carbon content of 0.030% against 0.08% for F316. The lower carbon prevents sensitisation and intergranular corrosion after welding. F316 has slightly higher minimum tensile and yield strength. Dual-certified F316/F316L flanges meet both requirements and are the most common choice for welded piping.
Yes, 316L is widely used in seawater cooling, firewater and marine atmospheres thanks to its molybdenum content. In warm, stagnant seawater or where crevices are unavoidable, pitting can still occur, and duplex 2205 or super duplex 2507 flanges give a higher margin of safety.
In ASME B16.5, ASTM A182 F316 is in Material Group 2.2 and F316L is in Material Group 2.3. The group determines the pressure–temperature rating of the flange for each class.
Every flange is supplied with an EN 10204 3.1 mill test certificate showing the heat chemistry and mechanical properties against ASTM A182. EN 10204 3.2 certification witnessed by the buyer's nominated third-party inspector is available on request.
Yes. Raaj Fittings supplies flanges compliant with the Pressure Equipment Directive 2014/68/EU for European projects, and with IBR certification for Indian boiler applications, when this is specified on the order.