Seamless steel tube is made without a weld: a solid billet is pierced, rolled and then cold drawn. With no seam there is no line that can open under pressure or disturb machining. We supply seamless precision tube to EN 10305-1 and DIN 2391, cold drawn and cut to length.
Seamless or welded?
Both have their place. The choice depends on pressure, wall thickness and volume.
| Criterion | Seamless | Welded and cold drawn |
|---|---|---|
| Pressure | Higher load capacity, no seam | Good for medium pressure |
| Tolerance | Very good, especially after cold drawing | Very good when the seam is drawn cleanly |
| Cost | Higher, more process steps | Lower for small and medium walls |
| Availability | Wide size range | Depends on strip and tooling |
| Typical use | Hydraulic cylinders, high pressure, shock absorbers | Precision tube for machinery and medium pressure |
How it is made
The billet is pierced at high temperature and rolled into a mother tube. Cold drawing over a mandrel follows, which improves wall thickness, roundness and surface finish. That drawing step is what turns a seamless tube into a precision tube with tight tolerances. The tube is then annealed (BK or GBK) as required.
Steel grades
| Grade | Standard | Yield strength | Use |
|---|---|---|---|
| E235 | EN 10305-1 | ≥ 235 MPa | General precision tube, machinery |
| E355 | EN 10305-1 | ≥ 355 MPa | Higher-strength tube, hydraulic |
| St35 | DIN 2391 | ≥ 235 MPa | Drawings to DIN 2391 |
| St45 | DIN 2391 | ≥ 340 MPa | Machined tubes, medium load |
| St52 | DIN 2391 | ≥ 355 MPa | Higher-strength precision tube |
Sizes
Regular sizes include 60 × 10 mm, 22 × 4 mm and 18 × 1 mm. Other sizes are made to drawing — see the precision tube overview.
Applications
- Hydraulic and pneumatic cylinders
- Shock absorbers and struts
- Motorcycle fork tubes
- High-pressure lines and accumulators
- Machinery and agricultural equipment
Quality control
Each batch is documented with a mill certificate, dimensions at both ends and mid-length, wall thickness at four points and a visual check of the bore. 3.1 certificates to EN 10204 are available on request.
FAQ
Is a seamless tube automatically a precision tube?
No. Seamless describes how the tube is made. Cold drawing to tight tolerances is what makes it precision tube.
When is welded tube the better choice?
For medium pressure and thin walls, welded cold drawn tube is often more economical. For high pressure and critical parts, seamless remains the safe choice.
Do you supply honed tube?
Yes, for cylinder applications we supply cold drawn or honed, and SRB is also available.