An impedance coil consists of one or a set of welded tube magnets. The cross-sectional area of the impedance coil should typically be not less than 70% of the inner diameter cross-sectional area of the steel tube. Its function is to form an electromagnetic induction loop with the induction coil, billet weld seam edge, and magnetic rod, creating a proximity effect. The eddy current heat is concentrated near the billet weld seam edge, heating the billet edge to the welding temperature. The impedance coil is pulled through the billet with a steel wire, with its center position relatively fixed near the center of the extrusion roller. When the machine is started, due to the rapid movement of the billet, the impedance coil experiences significant wear due to friction with the inner wall of the billet, necessitating frequent replacement.

Weld seams may produce weld spatter after welding and extrusion, which needs to be cleaned up. The cleaning method involves fixing a blade on the machine frame and, by the rapid movement of the welded pipe, smoothing out the spatter. Burrs inside the welded pipe are generally not cleaned.