Seamless or welded austenitic stainless steel tube in straight lengths for hygienic process pipework in food, dairy and beverage plants. Supplied to a stated tube standard, grade and internal surface finish.
Prices on request. Contact us for availability and quotations.
Hygienic pipework is built from tube, not from pipe schedules, and the tube standard is the first thing to settle because the fittings are cut for it. EN 10357-A, formerly DIN 11850 Reihe 2, runs from DN10 at 13 mm outside diameter to DN200 at 204 mm, and its DN label is neither the bore nor the outside diameter — DN25 is 29 mm outside diameter on a 26 mm bore. The ISO series, of which ISO 2037 is the food-industry form, names the tube by its actual outside diameter in millimetres. The SMS system uses inch labels sitting on metric outside diameters, so 1 inch is 25.0 mm and 2 inch is 51.0 mm, while ASME BPE inch tube is 25.40 mm and 50.80 mm. Those are different tubes and they do not interchange.
Tolerances are specified by class. ISO 1127 gives outside-diameter classes D1 to D4 — D4 is ±0.5 % with a minimum of ±0.1 mm — and wall classes T1 to T5, the outside-diameter tolerance including ovality and the wall tolerance including eccentricity. ISO 2037 pins food-industry tube at D4 up to 101.6 mm and D1 above it, with wall to T3. EN 10357-A holds outside diameter from ±0.10 mm at DN10 to ±1.53 mm at DN200 and wall to ±0.15 mm up to DN50.
Surface condition is a hygiene requirement, not a finish preference. ISO 2037 asks for Ra below 1.0 µm on finely finished surfaces, below 2.5 µm elsewhere, and Rmax not exceeding 16 µm on the weld seam; hygienic practice for internal surfaces is Ra 0.8 µm or better. Tube can be supplied pickled and passivated, bright annealed, or polished. Pickling and passivation restore the chromium-rich passive layer after fabrication — it is corrosion protection, not cleaning.
State the tube standard and size, the grade, the internal Ra, the surface condition and the length. In this market 316L (1.4404) is the sensible default for wetted lines because it carries molybdenum and resists chlorides from brine, salting and chlorinated CIP; 304/304L has none. Ask for the EN 10204 3.1 certificate at the order stage, not after delivery.
| Tube Standard | EN 10357-A (former DIN 11850 Reihe 2), ISO 1127 / ISO 2037, SMS or ASME BPE — the standard must be stated because the systems do not interchange |
|---|---|
| Size Range (EN 10357-A) | DN10 to DN200: outside diameter 13, 19, 23, 29, 35, 41, 53, 70, 85, 104, 129, 154 and 204 mm on bores of 10, 16, 20, 26, 32, 38, 50, 66, 81, 100, 125, 150 and 200 mm |
| Wall Thickness | 1.5 mm from DN10 to DN50 and 2.0 mm from DN65 to DN200 in EN 10357-A |
| Tolerance Class | Outside diameter classes D1 to D4 and wall classes T1 to T5 of ISO 1127; ISO 2037 food tube is D4 to 101.6 mm and D1 above, wall T3. EN 10357-A holds outside diameter ±0.10 mm at DN10 to ±1.53 mm at DN200 |
| Surface Finish | Finely finished surfaces Ra < 1.0 µm, other surfaces Ra < 2.5 µm, weld seam Rmax ≤ 16 µm; hygienic practice for internal surfaces is Ra ≤ 0.8 µm |
| Material | Austenitic stainless steel; ISO 2037 draws seamless tube from ISO 2604/2 types TS 47, TS 60 and TS 61 and welded tube from ISO 2604/5. Specify AISI 316L (1.4404) or 304L (1.4307); DIN-system tube is normally EN 10217-7 |
| Permissible Operating Pressure | EN 10357-A tube, calculated for 1.4301 to EN 10088-2: 355 bar at DN10, 159 bar at DN25, 87 bar at DN50, 59 bar at DN100 and 30 bar at DN200 at 20 °C; at 150 °C, 219, 98, 53, 36 and 18 bar respectively. The joint, not the tube, is normally the limiting element |
| Applicable Hygiene Standard | 3-A 33-03 Metal Tubing is the applicable class for this type of equipment. The goods are not asserted to carry the 3-A Symbol |
| Certification to Specify | EN 10204 3.1 inspection certificate for wetted stainless steel parts |
