What Does Electrical Resistance Welding (ERW) Mean?
Electrical resistance welding (ERW) is a form of pressure welding which utilizes heat generated by electrical resistance of the material along with applied force to hold the pieces together during the welding process. There are different types of ERW processes and all produce a forged weld. Some of the steel pipes used for trenchless construction and rehabilitation processes are made by ERW in which metal is rolled and welded longitudinally. These pipes are used for low-pressure or medium-pressure applications, such as for transporting oil and water.
Trenchlesspedia Explains Electrical Resistance Welding (ERW)
ERW utilizes different processes such as spot welding, roll spot and seam welding, projection welding and butt welding. The weld is created by applying heat and pressure to the welding area. Copper electrodes are held in the welding machine and the material to welded is placed between the electrodes. As electric current flows through the electrodes, pressure is applied to hold it together. The resistance of the material that's to be welded is much higher than the electrodes, resulting in sufficient heat to melt the metal. The pressure is held long enough to allow the material to solidify. The heat is generated as a result of the resistance of the material to the flow of electric current. The optimum heat applied is slightly less than the melting point of the material. The pressure is applied with the help of rolls that give the pipe its shape.