First, the difference between galvanized pipe and seamless steel pipe
Hot-dip galvanized steel 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. The matrix of hot-dip galvanized steel tube reacts with the molten bath in a complex physical and chemical way 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.
Hot-dip galvanized seamless steel pipe: galvanized amount is very small, only 10-50g/m2, its own corrosion resistance is much different than hot-dip galvanized pipe. Regular galvanized pipe manufacturers, permitted to use cold galvanized pipe for 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.
