Longitudinal seam welding

In a longitudinal pipe mill, pipes with diameters ranging from 16'' (406 mm) to 64'' (1625 mm) and with wall thicknesses ranging from 6.4 mm to 38.0 mm are produced. Pipe lengths vary between 12 and 18 meters.

In longitudinal pipe production, rolled 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 longitudinal pipe production, at first, the longitudinal strip edges are prepared for the following process:

Seam preparation and pre-bending of longitudinal edges.

An optimal strip edge preparation is a basic requirement for the following welding processes (double-V butt joint with wide root faces).

Moreover, start and end tabs are welded to the strips in order to position the craters, which are produced in the beginning and end of the submerged arc welding process , outside the pipe.

After that, the strips are formed into pipes in the UOE process (U-ing, O-ing, expanding), the C-ing process (step press) or the three-roll bending process.

Then, continuous MAG tack welding is carried out in the tack welding machine. After tack welding, on separate stands, the pipes are welded at first on the inside and then on the outside in submerged arc welding (two-run welding). Thus, a tack welding machine can continuously provide up to three internal and up to four external welding systems with tack welded large diameter pipes.

After welding, pipe end machining, pipe expanding 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 the welding speeds.