Abstract: In order to weld butt-jointed plastic tubes, a welding element with a wire coil for electrical resistance heating is positioned between the abutting tube ends. The tube ends are pressed to each other while at the same time the welding device is heated to welding temperature. Lastly, the tube ends are held together until the welded area has hardened by cooling. The welding device is constructed in the form of an annular disc the external diameter of which is approximately equal to the external diameter of the tubes and the internal diameter of which is approximately equal to the nominal internal diameter of the tubes. A heating wire coil spirals around the geometric center of the annular disc, and is positioned on the two annular disc surfaces that come into contact with the tube ends.