How it is made
From steel coil to tested pipe
A spiral welded pipe is formed from a single steel strip. This is the route it takes through the IMK plant in Ferizaj, step by step.
Process
Eight production steps
- 01
Steel coil
The coil is unwound and the strip levelled before it enters the line. The steel grade is chosen to suit the project standard.
- 02
Edge preparation
The strip edges are machined so the weld seam is uniform along the whole length.
- 03
Spiral forming
The strip is wound into a helix at a set angle. The angle determines the pipe diameter.
- 04
Inside and outside welding
The spiral seam is welded from the inside and the outside while the pipe is formed continuously.
- 05
Cutting to length
The continuous pipe is cut to the length the project requires.
- 06
Ultrasonic inspection
The seam is checked automatically by ultrasound, followed by visual inspection outside and inside.
- 07
Hydrostatic test
The pipe is filled with water and pressure-tested up to 211 bar, to the applicable standard. The ends are inspected after the test.
- 08
Coating and laboratory
The surface is blast-cleaned to Sa 2½ and coated inside and out. Samples undergo mechanical and chemical tests in the laboratory.
Why spiral
One strip, many diameters
In a spiral pipe the diameter does not depend on the strip width but on the forming angle. The same strip can therefore produce pipes of different diameters.
Geometric relation
D = B / (π · sin β)
- D — pipe diameter
- B — strip width
- β — seam angle to the cross-section
Example with a strip B = 1500 mm
| Ø 1,016 mm | β ≈ 28° |
|---|---|
| Ø 1,422 mm | β ≈ 19.6° |
| Ø 2,032 mm | β ≈ 13.6° |
Illustrative example. The actual parameters of IMK’s lines are set by the technical team.
Planning a pipeline or a steel structure?
Send us the specification — diameter, length, standard or drawings — and our technical team will get back to you.