Classification of galvanized pipes
Galvanized steel pipes are separately cold plated and hot plated. The former has been banned and the latter is temporarily promoted by the state.
 Hot-dip galvanized tube is a kind of alloy layer formed by the reaction of molten metal and iron matrix, so that the matrix and the coating are combined. Hot-dip galvanizing is to carry out acid cleaning of steel pipes, in order to remove iron oxide on the surface of steel pipes, after acid cleaning, through ammonium chloride or zinc chloride solution or ammonium chloride and zinc chloride mixed solution tank for cleaning, and then into the hot-dip bath. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. In the north, zinc plating process is used in most of the processes.
 Cold-galvanized pipes are electroplated zinc with a very small amount of zinc, only 10-50g/m2. The corrosion resistance of cold-galvanized pipes is much different from that of hot-galvanized pipes. Regular galvanized pipe manufacturers, in order to ensure quality, most of them do not use zinc plating (Leng Du). Only small businesses with obsolete equipment adopt galvanizing, and their prices are relatively cheap. Cold galvanized pipes shall not be used as water and gas pipes in the future.
 In hot-dip galvanized steel pipes, complex physical and chemical reactions take place between the substrate and the molten plating solution, resulting in a zinc-iron alloy layer with a close corrosion resistance structure. The alloy layer is integrated with the pure zinc layer and the steel tube substrate. Therefore, its corrosion resistance is strong. The quality of hot-dip galvanized steel pipes has been greatly improved after the development in the 1960s and 1970s. From 1981 to 1989, they were awarded the Ministry of Metallurgy High-quality products and the National Silver Award. The output of hot-dip galvanized steel pipes has also increased for many years. The output of hot-dip galvanized steel pipes in 1993 was more than 400,000 tons, and in 1999 it was more than 600,000 tons, and exported to Southeast Asia, Africa Germany and other countries and regions. Hot dip galvanized pipes are mostly used for water pipes and gas pipes. The common specifications are +12.5 to +102 mm. Since the 1990s, due to the state's emphasis on environmental protection, the control of high-pollution enterprises has become increasingly stringent, the "three wastes" produced in the production of hot-dip galvanized pipes are difficult to solve, coupled with the rapid development of stainless steel welded pipes, PVC pipes and composite pipes, as well as the promotion and application of chemical building materials by the state to restrict the use of galvanized pipes. As a result, the development of hot-dip galvanized welded pipe has been greatly constrained and restricted, and the development of hot-dip galvanized welded pipe has been slow.
 cold galvanized steel pipe, zinc layer is electroplating layer, zinc layer and steel pipe matrix separate layer. The zinc layer is thin, and the zinc layer is simply attached to the steel tube substrate, so it is easy to fall off. Therefore, its corrosion resistance is poor. In new buildings, cold galvanized steel pipes are not allowed to be used as water pipes.
Related uses of galvanized pipes
In order to improve the corrosion resistance of steel pipes, galvanized steel pipes are commonly used. Galvanized steel pipe can be divided into hot-dip galvanizing and galvanizing. The hot-dip galvanizing layer is thick, the galvanizing cost is low, and the surface is not very smooth. Oxygen-blowing welded pipe: Used as steel-making oxygen-blowing pipe, generally with small-diameter welded pipe, specifications from 3/8-2 inch eight kinds. Made of 08, 10, 15, 20 or 195-Q235 steel strips, in order to prevent corrosion, some of the effective aluminizing treatment.
Most of the old houses used galvanized pipes. Now the kind of iron pipes used for gas and heating are also galvanized. Galvanized pipes are used as water pipes. After a few years of use, a lot of rust and dirt are produced in the pipes. The yellow water not only pollutes the sanitary ware, but also contains bacteria that grow on the unsmooth inner walls. The rust causes the heavy metal content in the water to be too high. Seriously endangering human health. In 60s and 70s, the developed countries began to develop new types of pipes and banned galvanized pipes one after another. Four ministries and commissions, such as the Ministry of Construction, have been civilized in banning galvanized pipes since 2000. At present, galvanized pipes are seldom used in cold water pipes in new residential areas, and galvanized pipes are used in hot water pipes in some residential areas.