Purpose and classification of seamless steel pipe:
Seamless steel pipe is a kind of economic section steel, which plays a very important role in the national economy. It is widely used in petroleum, chemical industry, boiler, power station, ship, machinery manufacturing, automobile, aviation, aerospace, energy, geology, construction, military industry and other departments.


Classification:
① According to the section shape, it is divided into circular section pipe and special-shaped section pipe
② By material: carbon steel pipe, alloy steel pipe, stainless steel pipe and composite pipe
③ According to the connection mode: threaded connection pipe and welded pipe;
④ According to the production mode: hot rolling (extrusion, jacking and expansion) pipe and cold rolling (drawing) pipe
⑤ By use: boiler pipe, oil well pipe, pipeline pipe, structural pipe, fertilizer pipe


Production technology of seamless steel pipe:
① Main production processes (main inspection processes) of hot rolled seamless steel pipe: preparation and inspection of pipe blank → heating of pipe blank → perforation → pipe rolling → reheating of waste pipe → sizing (reducing) → heat treatment → straightening of finished pipe → finishing → inspection (nondestructive, physical and chemical, bench inspection) → warehousing 
② The main production process of cold rolled (drawn) seamless steel pipe is blank preparation → pickling and lubrication → cold rolled (drawn) → heat treatment → straightening → finishing → inspection