Steel pipes are divided into seamless steel pipes and welded steel pipes. In the production process of the seamless steel tube, the solid tube or steel ingot is hollowed into hollow cores and then rolled into steel tubes of the desired size. Different piercing and rolling tube methods are used to form different methods for producing seamless steel tubes. Welded steel pipes are produced by bending tube blanks (steel plates or steel strips) into tubes and welding the gaps into steel tubes. Due to the different methods of forming and welding used, different methods of producing welded steel tubes are formed.
Seamless steel tubes are mainly produced by hot rolling. The extrusion method is mainly used to produce hard-to-perforate low-plastic high-alloy steel pipes or special-shaped steel pipes and composite metal pipes. Cold-rolling and cold-drawing processes can continue the processing of hot-rolled pipes into small-diameter and thin-wall steel pipes. Welded steel pipe has a simple process, high production efficiency, low cost, and expanding product variety. Seamless steel tubes and welded steel pipes are mainly produced.