Galvanized steel refers to the ordinary carbon construction steel after galvanized processing can effectively prevent steel corrosion and rust so as to prolong the service life of steel, including galvanized galvanized and hot dip galvanized. Generally used for building exterior walls, such as glass curtain wall, marble curtain wall, aluminum curtain wall to do columns and stress materials, or used for outdoor telecommunications tower, highway and other open-air construction steel known as galvanized steel, which galvanized galvanized and hot dip galvanized.
Classification
Hot dip galvanized pipe is made of molten metal and iron matrix reaction to produce alloy layer, so that the matrix and the coating of the two combination. 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. Complex physical and chemical reactions occur between the matrix of hot-dip galvanized steel pipe 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 pipe 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. At present, the Ministry of Construction has formally below, eliminate the backward technology of cold galvanized pipe, the future is not allowed to use cold galvanized pipe as water, gas pipe. The galvanized layer of cold galvanized steel pipe is the electroplating layer, and the zinc layer is independently layered with the steel pipe matrix. 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.
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