Steel pipes can be categorized into three types according to the production method: hot rolled (extruded), welded, and cold worked.
Hot-rolled seamless steel tubes are produced by piercing solid billets or ingots and rolling them into hollow cross-section pipes, with the basic processes being piercing and rolling. High-alloy steel grades are produced by extrusion methods, while non-ferrous metal seamless tubes are primarily produced by extrusion. Welded pipes (seamed tubes) are formed by bending and rolling steel plates or strips into the required cross-sectional shape using various forming techniques, followed by joining the weld seams using different welding methods to obtain the steel pipes. The basic processes involve forming and welding. This type of tubing production is characterized by strong continuity, high efficiency, low cost, minimal investment per unit product, and, with the rapid development of strip production, its share in the total output of tubes continues to grow.