We offer high-purity (HP) and ultra-high purity (UHP) electropolished stainless steel tubing on a bright and smooth surface, EP stainless steel tubing is used for pharmaceutical, semiconductor, and biotechnology requiring surface finish with an internal surface finish of 10 μin. / 0.25 μm Ra max, bright annealed finish on the outer surface. the dimensions of electropolished tubing range from 1/8″ to 8″ in outside diameter, wall thickness from 0.028″ to 0.025″.
Stainless steel 316L electropolished tubing has a lower carbon content and is used in applications that subject the metal to risks of sensitization, it is a food grade more corrosion resistant than the 304 ss grade. 316L EP tubing can be manufactured to ASME BPE and ASTM A270 S2 sanitary standards, making it ideal for ultra-high purity applications, electropolished tubing can be ASTM A269 seamless tubing and welded tubing depending on applications.
Electropolished Stainless Steel 316L Tubing Specifications
- Electropolished to 10 µin / 0.25 µm Ra.
- 316L stainless steel tubing meets ASTM specifications for consistent physical, dimensional, and chemical composition.
- Controlled sulfur content to ensure consistent weldability and reduced non-metallic inclusions.
- Final cleaning and packaging performed in a Class 10 (ISO Class 4) cleanroom.
- Straight tubing and coil tubing.
316L Stainless Steel Chemical Composition
Stainless steel 316L is generally composed of 16 to 18% chromium, 10 to 14% nickel, 2 to 3% molybdenum, and a small percentage of carbon. Adding molybdenum to stainless steel 316L increases its corrosion resistance compared to other grades of stainless steel. The addition of other alloys further enhances its properties.
| Grade | C | Si | Mn | Cr | Ni | Mo | S | P | Bal. |
|---|---|---|---|---|---|---|---|---|---|
| 316L | 0.035 | 1.0 | 2.00 | 16.00 – 18.00 | 10.00 – 14.00 | 2.00– 3.00 | 0.03 | 0.045 | Iron |
Fractional Sizes and Allowable Working Pressures
| Tube OD in. | Tube OD mm | Tube Wall in. | Tube Wall mm | Weight lb/ft | Working Pressure psig |
|---|---|---|---|---|---|
| 1/4 | 6.35 | 0.035 | 0.89 | 0.080 | 5100 |
| 3/8 | 9.53 | 0.035 | 0.89 | 0.127 | 3300 |
| 1/2 | 12.7 | 0.049 | 1.24 | 0.236 | 3700 |
| 3/4 | 19.05 | 0.065 | 1.65 | 0.476 | 3300 |
| 1 | 25.4 | 0.065 | 165 | 0.813 | 2400 |
| 1 1/2 | 38.1 | 0.065 | 1.65 | 0.996 | 1250 |
| 2 | 50.8 | 0.065 | 1.65 | 1.34 | 950 |
Dimensional Tolerances
| Size OD in.(mm) | Nominal Wall in.(mm) | Outside Diameter in.(mm) | Length in.(mm) | Wall |
|---|---|---|---|---|
| 1/2″ (12.7) | 0.065″ (1.65) | +/-0.005 (0.13) | +1/8″ (3.18) – 0 | +/-10.0% |
| 3/4″ (19.1) | 0.065″ (1.65) | +/-0.005 (0.13) | +1/8″ (3.18) – 0 | +/-10.0% |
| 1″ (25.4) | 0.065″ (1.65) | +/-0.005 (0.13) | +1/8″ (3.18) – 0 | +/-10.0% |
| 1-1/2″ (38.1) | 0.065″ (1.65) | +/-0.008 (0.20) | +1/8″ (3.18) – 0 | +/-10.0% |
| 2″ (50.8) | 0.065″ (1.65) | +/-0.008 (0.20) | +1/8″ (3.18) – 0 | +/-10.0% |
| 2-1/2″ (63.5) | 0.065″ (1.65) | +/-0.010 (0.25) | +1/8″ (3.18) – 0 | +/-10.0% |
| 3″ (76.2) | 0.065″ (1.65) | +/-0.010 (0.25) | +1/8″ (3.18) – 0 | +/-10.0% |
| 4″ (101.6) | 0.083″ (2.11) | +/-0.015 (0.38) | +1/8″ (3.18) – 0 | +/-10.0% |
| 6″ (152.4) | 0.109″ (2.77) | +/-0.030 (0.76) | +1″ (25.4) – 0 | +/-10.0% |
Electropolishing Surface Finish Ra
Electropolishing is a process of special anodizing of metals in an electrolytic solution to obtain a smooth and bright surface. Stainless Steel Electropolished Tubes (EP Tubes) are products made from bright annealed tubes (BA Tubes) by electropolishing the inner surface. this process can achieve better roughness, cleanliness, corrosion resistance and weldability of EP tubing. The internal surface can be electropolished to the roughness of Ra ≤ 10 μin (0.25 μm), and the external surface to the roughness of Ra ≤ 40 μin (0.8 μm).
Electropolishing Solution and Methods
Electropolishing is a method of polishing metal surfaces using electrolysis. In the electropolished process, stainless steel tubes as the anode, connected to the positive pole of the DC power supply, when the current passes through the stainless steel tubes, the redox reaction will occur on the surface of the stainless steel tubing, generating hydrogen and oxygen and other gases, these gases can be discharged from the stainless steel tubes surface of the oxides and impurities, to achieve the polishing effect. At the same time, electrolytic polishing can also improve the corrosion resistance of stainless steel products.
Electropolished (EP), as a highly efficient and environmentally friendly stainless steel surface treatment process, has been widely used in recent years
Electropolished Stainless Steel Tubing Processes
- Cleaning: the stainless steel tubing to be treated is first cleaned to remove surface impurities such as grease and dirt.
- Acid washing: Use dilute sulfuric acid or hydrofluoric acid and other strong acids to carry out acid washing treatment to remove the surface of the oxidized skin and corrosion traces, to ensure that the surface is clean and smooth.
- Anodic treatment: the cleaned stainless steel tubes are placed in the electrolytic tank, with its anode, through the applied current on the surface to form a dense oxide film.
- Polishing: After anodic treatment, the surface of stainless steel forms a dense oxidized film, which needs to be mechanically polished and other methods to remove the surface roughness and impurities to achieve a bright and clean effect.
- Cleaning: polished stainless steel tubing needs to be cleaned again to remove residues and impurities generated during polishing.
- Protection treatment: surface treatment of stainless steel tubes to improve their corrosion and wear resistance and ensure their long-term service life. electropolished tubing is packaged using protective poly sleeving along with air-tight plastic end caps over a polyamide patch. The tubing is then placed in wood boxes for maximum protection during shipment.
Electropolished Finish Advantages
- High efficiency: Electropolished can surface treat many stainless steel products in a short time, improving production efficiency.
- Environmental protection: The electropolished process produces less waste gas and wastewater, and less impact on the environment.
- Improvement of corrosion resistance: electrolytic polishing can improve the corrosion resistance of stainless steel products and extend their service life.
- Good surface quality: the surface of stainless steel products treated with electrolytic polishing is smooth, flat, and beautiful, with a good decorative effect.