Of the specifications of the steel tube with overall dimensions (such as the diameter or length) and inner diameter and wall thickness, according to the size range is very wide, from small diameter capillary until the big steel pipe diameter number m. Steel pipe according to production methods can be divided into:

1) seamless steel tube (0.3 to 650 mm in diameter, wall thickness 0.05 ~ 75 mm), such as hot rolled tube, cold rolling tube, cold drawn tube, extrusion tube, such as:

2) welded steel pipe (5-4200 rm diameter, wall thickness of 0.5-25 mm), according to the weld points with straight seam welded steel pipe and spiral seam welded steel pipe. According to production methods score resistance furnace welded pipe, welded pipe, electric arc welding tube, etc. Steel pipe according to use can be divided into:

1) pipe with steel pipe, such as water, gas, oil and other fluid with steel pipe; 2) thermal technology equipment use steel, such as overheating, high temperature and high pressure boiler tube with st