1. Steel pipes can be divided into two categories according to the production method: seamless steel pipes and seamed steel pipes, and seamed steel pipes are referred to as straight seam steel pipes.
1. Seamless steel pipes can be divided into hot-rolled seamless pipes, cold-drawn pipes, precision steel pipes, hot-expanded pipes, cold-spinned pipes and extruded pipes according to the production method. Seamless steel pipes are made of high-quality carbon steel or alloy steel, and are divided into hot-rolled and cold-rolled (drawn). The main feature of seamless steel pipe is that it has no welded seams and can withstand greater pressure. Products can be very rough as-cast or cold drawn.
2. Welded steel pipes are divided into furnace welded pipes, electric welding (resistance welding) pipes and automatic arc welded pipes because of their different welding processes. They are divided into straight seam welded pipes and spiral welded pipes because of their different welding forms. For round welded pipes and special-shaped (square, flat, etc.) welded pipes.
Welded steel pipes are made of rolled steel plates and welded with butt or spiral seams. In terms of manufacturing methods, they are further divided into welded steel pipes for low-pressure fluid transportation, spiral seam electric welded steel pipes, direct coiled welded steel pipes, and electric welded pipes. Seamless steel pipes can be used for liquid pneumatic pipelines and gas pipelines in various industries. Welded pipes can be used for water pipes, gas pipes, heating pipes, electrical pipes, etc.
2. Precision steel pipes are products that have appeared in recent years, mainly because the inner hole and outer wall dimensions have strict tolerances and roughness. Precision steel pipe is a kind of high-precision steel pipe material processed by cold drawing or hot rolling. Due to the advantages of no oxide layer on the inner and outer walls of the precision steel tube, no leakage under high pressure, high precision, high finish, no deformation in cold bending, no flaring, no cracks in flattening, etc., it is mainly used to produce products for pneumatic or hydraulic components, such as cylinders or cylinder