316/316L Stainless Steel Seamless Pipe & Tube
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316L stainless – corrosion resistant and easy to weld
AISI 316L (1.4404) is an austenitic chromium-nickel-molybdenum stainless steel and the go-to upgrade when standard 304 is no longer enough. Chromium builds a passive oxide film on the surface that repairs itself after scratching. Nickel stabilizes the austenitic structure and keeps the material ductile, even at low temperatures. Molybdenum – the element that separates 316 from 304 – markedly improves resistance to pitting and crevice corrosion in the presence of chlorides such as salt, seawater and cleaning agents.
The “L” stands for low carbon (0.030% max). Because of that, no chromium carbides form at the grain boundaries during welding, and 316L seamless tube keeps its resistance to intergranular corrosion without post-weld annealing.
What does 1.4401 / 1.4404 / 316 / 316L in a tube description mean?
A steel grade is not a single value but a range of permitted chemistry and properties. Mills often melt material that falls within several specifications at once and mark it with a dual or multiple certification. A tube labeled 1.4401 / 1.4404 / 316 / 316L therefore meets all of these grades simultaneously – in practice it matches the stricter low-carbon 316L. The actual chemistry of a given heat is confirmed by an EN 10204 3.1 inspection certificate, which we supply on request.
Chemical composition and designations
| Grade | C | Cr | Ni | Mo | N |
|---|---|---|---|---|---|
| 1.4404 / 316L | ≤ 0.030 | 16.5–18.5 | 10.0–13.0 | 2.0–2.5 | ≤ 0.10 |
| 1.4401 / 316 | ≤ 0.07 | 16.5–18.5 | 10.0–13.0 | 2.0–2.5 | ≤ 0.10 |
Composition per EN 10088 (wt. %). Equivalents: 1.4404 = X2CrNiMo17-12-2 = AISI 316L = UNS S31603 · 1.4401 = X5CrNiMo17-12-2 = AISI 316 = UNS S31600.
Sizes, hollow bar and cut-to-length service
The range covers everything from small-bore tubing starting at 2 mm OD to process pipe up to DN 400 (406.4 mm), plus heavy-wall 316L hollow bar for machining. Tubes are sold in stock lengths, and we cut to length on request. Seamless 316L tube is typically produced to EN 10216-5 or ASTM A312 / A213 – the product standard of each heat is stated on the 3.1 certificate. To choose the right wall thickness, see our tables of maximum working pressure for seamless tubes and the dimensional tolerances for tubes.
Where is 316L pipe and tube used?
316L stainless tube is the standard choice for food and dairy processing lines, pharmaceutical and cosmetics plants, chemical equipment, heat exchangers and water treatment – and anywhere the material is exposed to seawater or deicing salts, from yachts to structures in coastal areas. It also performs well in food-contact applications and in systems where it is joined to other metals.
316L or 304?
If the system runs in dry air or in chloride-free potable water, the more economical 304 / 1.4301 is usually sufficient. Once chlorides, organic acids, disinfectants or a marine environment come into play, 316L is the safer choice. Other grades are available in our seamless tube and hollow bar category.