Electropolished SS 316L tube fittings are made for high-purity gas and liquid systems, where the inside surface of every component must be smooth, clean and chemically passive so that it does not shed particles, trap contaminants or release metal ions into the process. Electropolishing removes a thin layer of metal from the wetted surfaces, levelling the microscopic peaks left by machining and leaving a chromium-rich passive layer.
Raaj Fittings supplies 316L tube fittings electropolished to an internal surface roughness of Ra ≤ 0.5 µm or Ra ≤ 0.25 µm, in double ferrule compression and union designs, made at our two plants in India for semiconductor, pharmaceutical, biotech, laboratory and specialty gas customers across the Middle East, Europe and the Americas.
| Material | Stainless steel 316L (UNS S31603) |
|---|---|
| Internal surface finish | Electropolished to Ra ≤ 0.5 µm or Ra ≤ 0.25 µm |
| Fitting types | Double ferrule compression fittings, unions, connectors, tees, bulkheads and adapters |
| Tube OD | Metric and imperial tube sizes |
| Certification | EN 10204 3.1 certificate; surface finish report 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 |
High-purity systems use the 316L column: low carbon prevents sensitisation in welded and heat-affected components.
Ra ≤ 0.5 µm (about 20 µin) suits many pharmaceutical, biotech, laboratory and general high-purity gas systems. Ra ≤ 0.25 µm (about 10 µin) is used for ultra-high-purity process gas lines in semiconductor and similar industries, where particle and moisture limits are the tightest. Match the tubing finish to the fittings, and specify any additional cleaning, packing and testing requirements of your industry standard on the order.
316L bar stock is PMI-verified and traceable by heat number. Fittings are dimensionally inspected, and internal surface roughness can be measured and reported on request. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and third-party inspection by the buyer's nominated agency are available on request.
Ra is the average roughness of the internal surface. Ra ≤ 0.25 µm (about 10 µin) is a very smooth, electropolished finish used in ultra-high-purity gas systems, where particles and moisture must be kept to a minimum.
316L combines good corrosion resistance with low carbon, so it can be welded and electropolished without sensitisation, and it forms a stable chromium-rich passive layer.
Yes. The system is only as clean as its roughest component, so tubing, fittings and valves should all have a matching internal finish.
Yes, internal surface roughness measurements can be reported with the order on request, together with the EN 10204 3.1 material certificate.