Introduction and Application

In order to improve the corrosion resistance of steel pipes, general steel pipes are galvanized. Galvanized steel pipe is divided into two types: hot-dip galvanized and electro-galvanized. The hot-dip galvanized galvanized layer is thick, the cost of electro-galvanized is low, and the surface is not very smooth. Oxygen blowing welded pipe: used as oxygen blowing pipe for steelmaking, generally small-diameter welded steel pipe, with eight specifications ranging from 3/8 to 2 inches. It is made of 08, 10, 15, 20 or 195-Q235 steel strips. In order to prevent corrosion, it is necessary to carry out aluminizing treatment.

Most of the old houses use galvanized pipes. The iron pipes used for gas and heating are also galvanized pipes. Galvanized pipes are used as water pipes. 4 way galvanized pipe fitting After a few years of use, a lot of rust is generated in the pipes, and the yellow water that flows out not only pollutes sanitary ware , and mixed with bacteria that breed on the uneven inner wall, the rust causes the heavy metal content in the water to be too high, which seriously endangers the health of the human body. In the 1960s and 1970s, developed countries in the world began to develop new types of pipes and gradually banned galvanized pipes. Four ministries and commissions including the Ministry of Construction of China have also issued a document stating that galvanized pipes will be banned from 2000. After 2000, galvanized pipes are rarely used for cold water pipes in newly built communities, and galvanized pipes are used for hot water pipes in some communities.

Classification of galvanized pipes

Galvanized steel pipes are divided into cold galvanized pipes and hot galvanized pipes. The former has been banned, and the latter has been advocated by the state to be temporarily available.
Hot dip galvanized pipe
Hot-dip galvanized pipe is to make the molten metal react with the iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot-dip galvanizing is to pickle the steel pipe first. In order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned in the tank of ammonium chloride or zinc chloride aqueous solution or mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the in the hot dip bath. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
Cold galvanized pipe
Cold galvanizing is electric galvanizing, and the amount of galvanizing is very small, only 10-50g/m2. Its corrosion resistance is much different than that of hot-dip galvanized pipes. In order to ensure the quality, most regular galvanized pipe manufacturers do not use electro-galvanized (cold plating). Only those small enterprises with outdated equipment use electrogalvanizing, and of course their prices are relatively cheap. The Ministry of Construction has officially issued a document to eliminate cold galvanized pipes with backward technology, and cold galvanized pipes are not allowed to be used as water and gas pipes in the future.
Hot-dip galvanized steel pipe: The steel pipe substrate undergoes complex physical and chemical reactions with the molten plating solution to form a corrosion-resistant zinc-iron alloy layer with a tight structure. The alloy layer is integrated with the pure zinc layer and the steel tube substrate. Therefore, it has strong corrosion resistance.
Cold galvanized steel pipe: The zinc layer is an electroplating layer, and the zinc layer is independently layered with the steel pipe substrate. The zinc layer is 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, it is forbidden to use cold galvanized steel pipes as water supply pipes.