Spiral pipe welding

In a spiral pipe mill, pipes with diameters ranging from 20'' (508 mm) to 100'' (2540 mm) and with wall thicknesses ranging from 6.4 mm to 30.0 mm are produced. Pipe lengths vary between 12 and 24 meters.

In spiral pipe production, hot rolled wide strip or plates are used as base metal. The base metal varies depending on wall thickness, pipe dimensions and intended application. The physical characteristics or surface conditions of the final product are defined by the base metal.

In spiral pipe welding, in a spiral pipe welding system (molded body), steel strips are spirally formed into a pipe and welded.

There are two different forming techniques:

  • 3-roll bending with inside diameter roller cage
  • 3-roll bending with outside diameter roller cage

For spiral pipes, expanding the pipe after welding is not required since in this process standardised roundness, diameter and straightness tolerances are already ensured.

Different pipe diameters are defined by the steel strip widths and / or by variation of the entry angle of the steel strip into the spiral pipe welding system.

The smaller the entry angle, the larger the pipe diameter.

Generally, steel strips are prepared for welding as follows:

  • straightening of widths
  • preparation of exact seam widths
  • seam preparation
  • pre-bending of longitudinal edges

An optimal strip edge preparation is a basic requirement for the following welding processes.

There are two different processes for welding spiral pipes. Spiral pipes can be produced in an online or offline welding process .

After welding, pipe end machining as well as different tests (hydrostatic test, x-ray, ultrasonic inspection) are carried out so as to be able to ensure a final product which is free from defects.

Here you find an overview of welding speeds.