304/304L Stainless Steel Seamless Pipe & Tube
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304 – the workhorse stainless grade
AISI 304 (1.4301) is an austenitic chromium-nickel steel of the “18/8” family: roughly 18% chromium and 8–10% nickel, with no molybdenum. Its strength is versatility – it bends, welds and polishes well, resists atmospheric corrosion and tap water, and in the solution-annealed condition it is practically nonmagnetic (after cold working it may become slightly magnetic). That is why 304 stainless tube is the starting point for most piping designs, and higher-alloyed grades are only specified when the service environment calls for them.
1.4301, 1.4306 or 1.4307 – how to read the tube description
You will see several variants in tube descriptions: “1.4301 / 1.4307 / 304 / 304L”, “1.4301 / 1.4306 / 304 / 304L”, “TP304 / TP304L / 1.4301 / 1.4307”, “304 / 304L” or simply “1.4301”. Mills melt material whose chemistry meets several European and American specifications at once and mark it with all of those designations. The key difference is carbon: 1.4307 (304L) and 1.4306 are low-carbon versions with 0.030% C max, and 1.4306 has slightly more chromium and nickel. A dual-certified tube therefore meets the “L” requirements, which matters when welding heavier walls. The “TP” prefix is how the grade is written in ASTM tube and pipe specifications such as ASTM A312. The grade of each shipment is shown on the 3.1 certificate (EN 10204), available on request.
Chemical composition and equivalents
| Grade | C | Cr | Ni | N |
|---|---|---|---|---|
| 1.4301 / 304 | ≤ 0.07 | 17.5–19.5 | 8.0–10.5 | ≤ 0.10 |
| 1.4307 / 304L | ≤ 0.030 | 17.5–19.5 | 8.0–10.5 | ≤ 0.10 |
| 1.4306 / 304L | ≤ 0.030 | 18.0–20.0 | 10.0–12.0 | ≤ 0.10 |
Composition per EN 10088-1 (wt. %). Equivalents: 1.4301 = X5CrNi18-10 = AISI 304 = UNS S30400 · 1.4307 = X2CrNi18-9 = AISI 304L = UNS S30403 · 1.4306 = X2CrNi19-11.
Size range, hollow bar and product standards
The range includes more than 7,500 items: from small tubing with a 4 mm OD to 355.6 mm (DN 350) pipe, with walls from 0.71 to 43 mm. About one third of it is heavy-wall 304 hollow bar, used for turning rings, spacers and housings – starting from tube saves drilling out solid bar. Tubes are sold in stock lengths or cut to length; the price of 304 tube depends on OD, wall thickness and length and is listed with each size. Seamless tube in this grade is most often made to EN 10216-5 and ASTM A312, A213 or A269. To match the wall thickness to the pressure, use our chart of working pressure ratings for seamless stainless tube.
What are 1.4301 and 1.4307 tubes used for?
304 tube is used in potable and domestic hot water systems, compressed air and industrial gas lines, hydraulic power systems, breweries, wineries and food processing plants, ventilation and exhaust ducting, machine building and structural members inside buildings. The low-carbon versions are convenient for systems welded on site, where post-weld heat treatment is not an option, since the weld zone keeps its corrosion resistance.
Where does 304 reach its limits?
304 contains neither molybdenum nor titanium, so it has two limits. The first is chlorides: in seawater, brines, swimming pools or with chlorinated cleaners, the risk of pitting rises. In those cases 316L / 1.4404 seamless tube is a better fit, and for hot-running systems its stabilized counterpart, 316Ti / 1.4571 tube. The second limit is long-term service in the range of roughly 450–850°C, where chromium carbides precipitate at the grain boundaries. For exhaust and steam lines, titanium-stabilized steel is used instead – 321 / 1.4541 stainless tube – and for furnace parts running red-hot, 1.4841 / 1.4845 heat-resistant tube. Where higher strength and resistance to chloride stress corrosion cracking matter, duplex 1.4462 tube is the right choice.
See also: in the same grade we offer 304 / 1.4301 round bar and 304 / 1.4301 stainless sheet. Tube in other grades and fittings can be found in our seamless tube and hollow bar category.