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, through ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed aqueous solution tank for cleaning, and then 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 replenishment process of galvanized belt direct coil 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 electric galvanizing (cold plating). Only those small enterprises with obsolete equipment use electric galvanizing, 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 tight zinc-iron alloy layer with corrosion resistance. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix. Therefore, its corrosion resistance is strong.

After the development of hot galvanized steel pipe in the 1960s to 1970s, product quality has been greatly improved,1981 to 1989 was awarded the metallurgical Ministry of high-quality products and national silver award, production also increased for many years,1993 output of more than 400,000 tons,1999 output of more than 600,000 tons, and exported to Southeast Asia, Africa, the United States, Japan, Germany Countries and regions. Hot-dip galvanized pipes are mostly used as water pipes and gas pipes, and the common specifications are +12.5~+102 mm. After the 1990s, due to the state's attention to environmental protection, the control of high-pollution enterprises is becoming more and more strict, the "three wastes" generated in the production of hot-dip galvanized pipes is difficult to solve, coupled with the rapid development of stainless steel welded pipes, PVC pipes and composite pipes, as well as the state to promote the application of chemical building materials, the use of galvanized steel pipes is restricted, making the development of hot-dip galvanized welded pipes has been greatly affected Beam and limit, hot dip galvanized welded pipe later developed slowly.

Cold galvanized steel pipe

The zinc layer is an electric coating, and the zinc layer is independently layered with the steel pipe matrix. The zinc layer is thin, and the zinc layer is simply attached to the steel tube matrix and easy to fall off. Therefore, its corrosion resistance is poor. In new residential buildings, it is prohibited to use cold galvanized steel pipes as water supply pipes.