Seam welding is different from spot welding by the fact that roller type electrodes are used in the former case. The principle and process of welding are the same as those for spot welding. Usually in seam welding, the rollers are rotated over the job as the welding proceeds. Interrupted supply of electrical power is preferred to the smooth supply because:
If the spots in seam welding are not overlapping, then that process is termed as 'roller spot welding'. Other seam welding processes are lap seam welding, butt seam welding, mash seam welding and high frequency seam welding.