ER Weld

Electric Resistance (ER) welding is used to fabricate a pipe by welding. To fabricate a pipe, a thin flat plate of steel is rolled into a circle. The two plate edges are then welded to close the gap between the edges. This weld is often made by electric resistance (ER) welding. As the two edges are pushed together, the two surfaces touch, but the metal is not continuous. An electrical resistance is developed at this surface discontinuity. Passing a high electrical current through this resistance then heats and melts the plate edges and a solid weld is formed which closes the pipe.