Tata Steel subsidiary Corus Tubes is producing linepipe using high frequency induction welded (HFI), which the company says delivers pipe with tighter tolerances and faster delivery than traditional electric resistance welded (ERW) product.

In the process, coils of steel strip are unwound onto a 49-ft (15-m) diameter accumulator drum. As one coil runs out, another is welded on to form a continuous steel web. The coil is then withdrawn from the center of the accumulator and fed into the mill; so an unlimited number of coils can be added without stopping the mill process.

The edges of the strip are then heated by the induction coil and are forged together through a set of rolls, forming the resulting weld.
The internal and external extruded steel is trimmed to produce a smooth bore and outer diameter. A jet gun is used to mark the weld at 90 degrees so the weld integrity can be checked.