EMT of galvanized steel pipe is divided into cold galvanized steel pipe and hot-dip galvanized steel pipe. The cold galvanized steel pipe has been banned. The difference is as follows: JDG steel pipe.
1. The hot-dip galvanizing tube is to make the molten metal react with the iron matrix to produce the alloy layer, so that the matrix and the two layer of the coating are combined. Hot dip galvanizing is to pickle steel pipes first, then remove iron oxides on the surface of steel pipes, then pickle them, then clean them through ammonium chloride or zinc chloride water solution or ammonium chloride and zinc chloride mixed water solution tank, then send them into hot dip bath. Hot dip galvanizing has the advantages of uniform coating, strong adhesion, long service life and so on. The complex physical and chemical reaction of the hot dipped galvanized steel tube matrix and the molten bath formed a corrosion resistant and tightly structured zinc - iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel tube matrix. Therefore, its corrosion resistance is strong.
2, the cold galvanized pipe is galvanized, the amount of zinc plating is very little, only 10 - 50g/m2, its corrosion resistance is much different than the hot galvanized pipe. Regular galvanized pipe manufacturers, in order to ensure quality, most of the use of galvanizing (Leng Du). Only small businesses of small size and old equipment use galvanizing, of course their prices are relatively cheap. The Ministry of construction has formally eliminated the backward technology of cold galvanized pipes and is not allowed to use cold galvanized pipes for water and gas pipes. The galvanized layer of the cold galvanized steel pipe is electroplating layer, and the zinc layer and the steel tube matrix are separately stratified. The zinc layer is thinner and the zinc layer is simply attached to the steel tube matrix, which is easy to fall off. Therefore, its corrosion resistance is poor. In newly built houses, cold galvanized steel pipes are forbidden to be used as water pipes.
3, JDG steel pipe is the replacement product of all kinds of traditional wire conduits, such as PVC pipe and SC pipe. It is a breakthrough innovation in building electrical field with new materials and technologies. The JDG steel pipe adopts the galvanized steel tube and the thin walled steel pipe's jumper grounding line, which overcomes the shortcomings of the common metal conduit's construction and loss of construction. At the same time, it also solves the problems such as poor fire resistance and difficult grounding of PVC pipe. Because the cost of JDG steel pipe material is more than ordinary pipe material, so many parts are used in the construction of comprehensive wiring and fire protection wiring.