Duplex 2205 tube fittings are compression fittings machined from UNS S31803 / S32205 duplex stainless steel for instrument, hydraulic and chemical injection tubing in places where 316 tubing pits or cracks: offshore platforms, subsea control systems, coastal and desert plants with salt-laden air, and process lines carrying chlorides. Their high strength also allows higher working pressures than 316 at the same tube size.
Raaj Fittings makes duplex 2205 double ferrule and single ferrule fittings with matching unions, connectors, elbows, tees, bulkhead unions and adapters at our two plants in India, in metric and imperial tube sizes, for instrumentation contractors and offshore fabricators in the Middle East, Europe and the Americas.
| Material | Duplex stainless steel 2205, UNS S31803 / S32205 |
|---|---|
| Tube OD | Metric 3 to 25 mm; imperial ⅛" to 1" |
| Fitting types | Double ferrule and single ferrule compression fittings; unions, connectors, elbows, tees, bulkheads, reducers and adapters |
| End connections | Compression tube ends; NPT (ASME B1.20.1), BSPT and BSPP (BS 21 / ISO 7-1) threads |
| Manufacturing | CNC machined from solution-annealed bar stock or forgings |
| Certification | EN 10204 3.1 mill test certificate; EN 10204 3.2 on request |
| Element, % | S31803 | S32205 |
|---|---|---|
| Carbon (C) | 0.030 max | 0.030 max |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Phosphorus (P) | 0.030 max | 0.030 max |
| Sulphur (S) | 0.020 max | 0.020 max |
| Silicon (Si) | 1.00 max | 1.00 max |
| Chromium (Cr) | 21.0 – 23.0 | 22.0 – 23.0 |
| Nickel (Ni) | 4.5 – 6.5 | 4.5 – 6.5 |
| Molybdenum (Mo) | 2.5 – 3.5 | 3.0 – 3.5 |
| Nitrogen (N) | 0.08 – 0.20 | 0.14 – 0.20 |
| Grade | UNS | Werkstoff Nr. | EN designation | Forging grade |
|---|---|---|---|---|
| Duplex 2205 | S31803 / S32205 | 1.4462 | X2CrNiMoN22-5-3 | ASTM A182 F51 / F60 |
For the most aggressive service, such as hot seawater or subsea controls, super duplex 2507 or nickel alloy tube fittings are the next step up.
Duplex bar stock is PMI-verified and traceable by heat number; bodies, nuts and ferrules are dimensionally inspected and threads gauge-checked. Orders are supplied with EN 10204 3.1 certificates, with EN 10204 3.2 certification, ferrite reports and third-party inspection by the buyer's nominated agency on request.
Use duplex 2205 where 316 tubing would suffer chloride pitting, crevice corrosion or stress corrosion cracking: offshore, in hot coastal climates and in chloride process service. The fittings must be paired with duplex tubing.
It is not recommended. Fittings and tubing should be the same material so the ferrules grip correctly and there is no weak point for corrosion.
Yes. Besides duplex 2205, super duplex 2507 tube fittings are available for more aggressive seawater service.
Metric tube ODs from 3 to 25 mm and imperial ODs from ⅛" to 1", with NPT, BSPT or BSPP threaded ends.