classification
Steel pipe seamless steel pipe and welded steel pipe (with pipe) two categories. According to the cross-section shape can be divided into tube and shaped tube, widely used is a round steel pipe, but there are some square, rectangular, semi-circular, hexagonal, equilateral triangle, octagonal and other profiled steel pipe. For the pressure of the steel pipe to be carried out by the hydraulic test to test its pressure capacity and quality, under the provisions of the pressure does not occur leakage, soaking or expansion of qualified, and some steel pipe according to the requirements of the standard or demand side of the curling test , Flaring test, flattening test and so on.

Manufacturing method
① general use of the boiler tube temperature below 350 ℃, domestic tube mainly with 10, 20 carbonated steel hot-rolled tube or cold-drawn tube manufacturing.
② high-pressure boiler tubes are often used in high temperature and high pressure conditions, the tube in the high temperature flue gas and steam
Boiler tube
Under the next, oxidation and corrosion will occur. Requirements of steel pipe with high durability, high oxidation resistance, and good organizational stability.