In order to improve the corrosion resistance of the steel pipe, the general steel pipe (black pipe) is galvanized. Galvanized steel is divided into hot dip galvanized steel and electric steel zinc. The hot dip galvanized galvanized layer is thick and the cost of electrogalvanizing is low. Blown Oxygen Pipe: Used as oxygen-blowing steel pipe for steelmaking. It is generally made of small-diameter welded steel pipe, and its specifications range from 3/8 inch to 2 inch. Made with 08, 10, 15, 20 or Q195-Q235 steel strips. In order to prevent corrosion, some conduct aluminizing treatment. Wire Jacket: It is also an ordinary carbon steel welded steel pipe, used in the distribution of concrete and various structures, commonly used nominal diameter from 13-76mm. Wire sleeve casing wall is thin, mostly used after coating or galvanizing, requirements Cold bending test.