STAINLESS TUBES · WELDED
Welded stainless tube
Welded stainless tube covers most process piping uses: 304L and 316L from partner stock, rare grades on request. Diameters from 1/4" to 24", wall thickness SCH 5S to 160, standard length or cut-to-length under 6 m.
Request a quoteDimensional table
| NPS | DN | OD (mm) | SCH 10S (mm) | SCH 40S (mm) | SCH 80S (mm) |
|---|---|---|---|---|---|
| 1/8 | 6 | 10.3 | 1.24 | 1.73 | 2.41 |
| 1/4 | 8 | 13.7 | 1.65 | 2.24 | 3.02 |
| 3/8 | 10 | 17.1 | 1.65 | 2.31 | 3.2 |
| 1/2 | 15 | 21.3 | 2.11 | 2.77 | 3.73 |
| 3/4 | 20 | 26.7 | 2.11 | 2.87 | 3.91 |
| 1 | 25 | 33.4 | 2.77 | 3.38 | 4.55 |
| 1 1/4 | 32 | 42.2 | 2.77 | 3.56 | 4.85 |
| 1 1/2 | 40 | 48.3 | 2.77 | 3.68 | 5.08 |
| 2 | 50 | 60.3 | 2.77 | 3.91 | 5.54 |
| 2 1/2 | 65 | 73 | 3.05 | 5.16 | 7.01 |
| 3 | 80 | 88.9 | 3.05 | 5.49 | 7.62 |
| 4 | 100 | 114.3 | 3.05 | 6.02 | 8.56 |
| 5 | 125 | 141.3 | 3.4 | 6.55 | 9.53 |
| 6 | 150 | 168.3 | 3.4 | 7.11 | 10.97 |
| 8 | 200 | 219.1 | 3.76 | 8.18 | 12.7 |
| 10 | 250 | 273 | 4.19 | 9.27 | 12.7 |
| 12 | 300 | 323.8 | 4.57 | 9.53 | 12.7 |
| 14 | 350 | 355.6 | 4.78 | — | — |
| 16 | 400 | 406.4 | 4.78 | — | — |
| 18 | 450 | 457 | 4.78 | — | — |
| 20 | 500 | 508 | 5.54 | — | — |
| 24 | 600 | 610 | 6.35 | — | — |
What is welded stainless tube?
Welded stainless tube is formed from a flat strip continuously rolled then longitudinally welded, typically by TIG or plasma process, before final sizing. The weld seam is then annealed and often polished, which makes welded tube visually indistinguishable from seamless on most austenitic grades.
How to choose it?
Welded tube is the default choice for standard process piping: cheaper at equal diameter, more widely available from partner stock, and compliant with most industrial specifications. Seamless is only needed when service pressure, a specific standard or a customer requirement explicitly excludes welded.
Available grades
304L, 316L, 316Ti, 321H and 310S cover most partner-stock requests. On request, SPS also sources duplex 2205/2507 and super austenitic 904L/254 SMO in welded tube.
Applicable standards
- ASTM A312
- ASTM A270
- EN 10217-7
Partner stock or mill?
Welded tube is the most readily available product from partner stock in the stainless tube cluster.
From partner stock: 48 hours for urgent needs, 5 working days as standard.
We go through the mill when volume and lead time make sense — typically container-load quantities, sometimes less, with a lead time of a few months including transport. That arbitration is ours to make: when buying at source works out cheaper for you, we say so.
Frequently asked questions
- Does welded tube hold the same pressure as seamless?
- It depends on grade, wall thickness and welding process more than on the welded/seamless principle itself. For a specific service pressure, send the specification in your quote request — SPS checks the matching standard and thickness before confirming.
- What is the standard delivered length?
- In random length (RL), typically 5 to 7 metres, with a -0/+1 tube tolerance around the nominal length — unless a client-imposed length is specified in the quote request.
- Is 304L welded tube affected by the anti-dumping regulation?
- No, implementing regulation (EU) 2023/809 targets butt-welding fittings, not tubes. EU safeguard regulation 2026/1384 does explicitly name seamless tube, however — see the steel import regulation cluster.
- Can I get a 3.2 certificate instead of a 3.1?
- Yes, on explicit request — the 3.1 certificate is provided by default.