Steel pipes are divided into seamless steel pipes and welded steel pipes. The production process of seamless steel pipes involves threading solid billets or ingots into hollow tubes, and then rolling them into the required size of steel pipes. The different perforation and rolling methods used constitute different methods for producing seamless steel pipes. The production process of welded steel pipes involves bending the pipe blank (steel plate or strip) into a tubular shape, and then welding the gaps together to form the steel pipe. Due to the different forming and welding methods used, different methods for producing welded steel pipes are formed.
Seamless steel pipes are mainly produced by hot rolling method. The extrusion method is mainly used to produce low plasticity high alloy steel pipes or special-shaped steel pipes and composite metal pipes that are difficult to pierce. Cold rolling and cold drawing methods can continue to process hot-rolled pipes into small diameter and thin-walled steel pipes. The welding process of steel pipes is simple, with high production efficiency, low cost, and an increasing variety of products.