HFI welding

Steel pipe production with HFI welding

Longitudinal welding at SALZGITTER MANNESMANN LINE PIPE is done using the High -Frequency Induction (HFI) process, an electric resistance welding (ERW) technique. In this process, the strip edges are heated to welding temperature and pressed together by rollers without any filler metals to give a homogeneous longitudinal weld.

SALZGITTER MANNESMANN LINE PIPE can draw on decades of experience in the manufacture of welded steel pipe. Rolling stands form the strip into the shape of an open pipe. This is then passed through a ring inductor which induces high-frequency current in the open pipe. The induced current completes its path around the formed strip by flowing along the edges and crowding around the apex of the gap between them. This heats up the open pipe rapidly, raising the strip edges to welding temperature as they arrive at the apex. Pressure rolls force the heated edges together, completing the weld.

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