Seam welding is widely used in the manufacture of joints that require sealing, and is sometimes used to connect non-sealing sheet metal parts. The thickness of the metal material to be welded is usually 0.1 to 2.5mm. Seam welding is widely used in thin plate welding of oil drums, cans, radiators, aircraft and automobile fuel tanks, and sealed containers in jet engines, rockets, and missiles.

1. Continuous roll welding: The roll pad rotates continuously, the weldment continuously moves between the two roll pads, and the welding current is continuously turned on. Since the two roller pads always pass a large current, the roller pads and the weldment heat up seriously, the roller pads are easily worn out, and the welds are easily overheated and produce large pits.
2. Intermittent roll welding: The roll pad rotates continuously, the weldment continuously moves between the two roll pads, and the welding current is turned on intermittently. Since the welding current is switched on intermittently, the roll pad and the weldment have a chance to cool down. The roll pad loss is small and the weld is not easy to overheat, so it is the most widely used.
3. Step roll welding: The roll pad rotates intermittently, the weldment moves intermittently between the two roll pads, and the welding current is turned on when the roll pad stops. Since the solidification of the molten core occurs when the rolling pad stops, a denser weld can be obtained. But the mechanism that drives the seam pad is more complex than intermittent seam welding.