Resistance welded pipe ERW is formed by hot rolled coil through forming machine. The skin effect and proximity effect of the high frequency current are used to heat and melt the edges of the tube blank. Pressure welding is carried out under the action of squeeze rollers. Realize production. The production process of welded steel pipes is simple, the production efficiency is high, the varieties and specifications are many, and the equipment is few, but the general strength is lower than that of seamless steel pipes.