At the pipe mill the strip is uncoiled, levelled and crop-sheared. It is then trimmed on both sides simultaneously to correct width and immediately fed into the forming and welding line. During the process, the strip is closely checked for surface defects.

A series of cold forming rolls changes the strip progressively into tubular form with abutting edges on top. The longitudinal edges are joined by high frequency electric resistance welding. The weld is then heat treated electrically. Special devices remove inside and outside flash from the weld to give uniform wall thickness of the pipe. The welded part is then heat-treated by post annealing to ensure adequate ductility at the weld and adjacent zone. The pipe is passed through a series of cold sizing rolls to progressively reduce the diameter to accurate size. This operation also increases strength and improves surface condition.

The pipe is then cut to specified length by a flying cut-off machine. After the straightening operation, ends of the pipe are cropped, then squared or beveled depending on end finish requirements.