Steel pipes can be divided into two categories according to the production method: seamless steel pipes and welded steel pipes. Welded steel pipes are referred to as welded pipes for short. 1. According to the production method, seamless steel pipes can be divided into: hot rolled seamless pipes, cold drawn pipes, precision steel pipes, hot expanded pipes, cold spinning pipes and extruded pipes, etc. bundles of steel pipes bundles of steel pipes Seamless steel pipes are made of high-quality carbon steel or alloy steel, and are divided into hot-rolled and cold-rolled (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 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. Material Classification Steel pipes can be divided into carbon pipes, alloy pipes, stainless steel pipes, etc. according to the pipe material (ie steel type). Carbon pipes can be further divided into ordinary carbon steel pipes and high-quality carbon structural pipes. Alloy tubes can be further divided into: low alloy tubes, alloy structural tubes, high alloy tubes, and high strength tubes. Bearing tubes, heat- and acid-resistant stainless tubes, precision alloy (such as Kovar) tubes, and superalloy tubes, etc.
Steel pipes are not only used for conveying fluids and powdered solids, exchanging thermal energy, making machine parts and containers, but also an economical steel. Using steel pipes to make building structure grids, pillars and mechanical supports can reduce weight, save 20-40% of metal, and realize factory-based mechanized construction. Using steel pipes to manufacture highway bridges can not only save steel and simplify construction, but also greatly reduce the area of protective coating, saving investment and maintenance costs.