Main classification of galvanized pipes

Galvanized steel pipe is divided into cold plated tube and hot plated tube, the former has been banned, the latter is also advocated by the state for temporary use.

Hot-dip galvanized pipe

The molten metal reacts with the iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot dip galvanizing is to first pickling the steel pipe. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned by ammonium chloride or zinc chloride aqueous solution or mixed aqueous solution of ammonium chloride and zinc chloride, and then sent into the hot dip plating tank. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. Most of the processes in the north adopt the zinc replenishing process with direct coiled pipe.

Cold galvanized pipe

Cold galvanized is electric galvanized, galvanized amount is very small, only 10-50g/m2, its own corrosion resistance is much different than hot galvanized pipe. Regular galvanized pipe manufacturers, in order to ensure quality, most do not use galvanizing (cold plating). Only small businesses with obsolete equipment use galvanizing, and of course their prices are relatively cheap. In the future, cold galvanized pipes are not allowed to be used as water and gas pipes.

Hot-dip galvanized steel pipe

Complex physical and chemical reactions occur between the steel tube substrate and the molten bath to form a compact zinc-iron alloy layer with corrosion resistance. The alloy layer is integrated with the pure zinc layer and the steel tube matrix. Therefore, its corrosion resistance is strong.

Cold galvanized steel pipe

The zinc layer is an electric coating, and the zinc layer is layered independently with the steel tube substrate. Zinc layer is thin, zinc layer is simply attached to the steel tube matrix, easy to fall off. So its corrosion resistance is poor. It is prohibited to use cold galvanized steel pipes as water supply pipes in newly built houses.