Steel pipes can be divided into two categories according to production methods: seamless steel pipes and welded steel pipes. Welded steel pipes are referred to as welded pipes.
1. Seamless steel pipes can be divided into hot-rolled seamless pipes, cold-drawn pipes, precision steel pipes, thermal expanded pipes, cold spinning pipes and extruded pipes according to production methods.
2. Welded steel pipes are divided into furnace welded pipes, electric welded (resistance welded) pipes and automatic arc welded pipes due to their different welding processes. They are divided into straight seam welded pipes and spiral welded pipes due to their different welding forms. They are further divided into two types due to their end shapes. For round welded pipes and special-shaped (square, flat, etc.) welded pipes.