SS 316/316L tube fittings are the standard connection for stainless instrument, sampling, analyser and hydraulic tubing. Type 316 stainless steel, with 2–3% molybdenum, gives fittings that resist the marine atmospheres of offshore platforms and coastal plants, chemical splash and washdown, while 316L's low carbon content suits welded tube systems and high-purity service.
Raaj Fittings machines SS 316 and 316L tube fittings from PMI-verified bar stock and forgings at our two plants in India: double ferrule and single ferrule compression fittings, DIN 2353 bite type fittings, flare fittings, push-to-connect fittings and the full range of unions, connectors, elbows, tees and adapters. Metric (3–25 mm) and imperial (⅛"–1") sizes are made, and exported to instrumentation contractors, OEMs and distributors across the Middle East, Europe and the Americas.
| Material | Stainless steel 316 / 316L (UNS S31600 / S31603); electropolished 316L for high-purity service |
|---|---|
| Tube OD | Metric 3 to 25 mm; imperial ⅛" to 1" |
| Working pressure | Up to 413 bar (6,000 psi) in small tube ODs with suitable wall thickness; the rating depends on tube OD, wall, material and temperature |
| End connections | Compression tube ends; NPT (ASME B1.20.1), BSPT and BSPP (BS 21 / ISO 7-1) threads |
| Ferrules | Double ferrule (front and back) or single ferrule; bite type to DIN 2353 / ISO 8434-1 |
| Manufacturing | CNC machined from bar stock or forgings; threads checked with gauges |
| Certification | EN 10204 3.1 mill test certificate; EN 10204 3.2 on request |
| Element, % | 316 | 316L |
|---|---|---|
| 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 |
| 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 |
A compression fitting seals by deforming its ferrules onto the tube, so the tube matters as much as the fitting:
SS 316 is the default material for instrument tubing in oil and gas, petrochemical, power and chemical plants. In warm seawater spray or where tubing sits in trays that trap moisture and salt, pitting and crevice corrosion can still occur on 316; duplex 2205, super duplex 2507 or Monel 400 tube fittings with matching tubing are used there.
Bar stock is PMI-verified on receipt and traceable by heat number. Threads are checked with gauges, ferrules and bodies are inspected dimensionally, and fittings can be pressure-tested to the order. Each order is supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.
Small-OD SS 316 double ferrule fittings are used up to about 413 bar (6,000 psi) with suitably thick tubing. The safe working pressure of a joint is set by the tube OD, wall thickness, material and temperature, so check the tubing's rating.
Our double ferrule fittings are dimensionally compatible with Swagelok® standard connections. Swagelok is a registered trademark of Swagelok Company; our products are not made by or affiliated with it. Do not mix components from different makers on one joint.
Use fully annealed seamless or welded-and-drawn 316/316L tubing, typically to ASTM A269 or A213, with hardness well below that of the ferrules (about 80 HRB maximum is commonly recommended).
Yes. Metric sizes from 3 to 25 mm OD and imperial sizes from ⅛" to 1" OD are made, with NPT, BSPT or BSPP threaded ends.