In order to improve the corrosion resistance of steel pipes, we galvanizing steel pipe, most of them are black pipes. There are two types of galvanized steel pipes: hot-dip galvanized and electric-galvanized. Hot-dip galvanized layer is thick, while the cost of electro-galvanized is lower.
The hot-dip galvanized pipe is molten metal react with the iron substrate to produce an alloy layer, combining the substrate and the plating layer. It is to pickle the steel pipe first, in order to remove the iron oxide on the surface of the steel pipe, after pickling, wash through the ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed aqueous solution tank, and then send into hot-dip plating bath. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
The steel pipe base and the molten plating solution undergo complex physical and chemical reactions to form a corrosion-resistant zinc-iron alloy layer with a compact structure. The alloy layer is integrated with the pure zinc layer and the steel pipe substrate. Therefore, its corrosion resistance is strong.
Cold galvanized steel pipe
Cold galvanized is electro-galvanized, the amount of galvanized 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 electro-galvanized (cold plating). At present, the Ministry of Construction has officially eliminated cold-dip galvanized pipes with backward technology. In the future, cold-dip galvanized pipes are not allowed to be used as water or gas pipes. Cold-galvanized steel pipe: The zinc layer is an electroplated layer, and the zinc layer is separated from the steel pipe substrate. The zinc layer is relatively thin, and the zinc layer simply adheres to the steel pipe substrate and is easy to fall off. Therefore, its corrosion resistance is poor. In newly built houses, the use of cold-galvanized steel pipes as water supply pipes is prohibited.
