Galvanized steel pipe, steel type, galvanized steel pipe is divided into cold-dip galvanized steel pipe and hot-dip galvanized steel pipe. The zinc coating covers the bottom steel pipe to prevent the corrosion and deterioration of the previous sacrificial layer.
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 an ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the hot-dip plating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. The hot-dip galvanized steel pipe matrix undergoes complex physical and chemical reactions with the molten plating solution to form a corrosion-resistant and tightly structured zinc-iron alloy layer. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix, so it has strong corrosion resistance.
Cold-dip galvanized pipe
Cold-dip galvanized pipe is electrogalvanized, with a small amount of zinc, only 10-50g/m2, and its corrosion resistance is much worse than that of hot-dip galvanized pipe. Formal galvanized pipe manufacturers, in order to ensure quality, mostly do not use electrogalvanizing (cold plating). Only those small enterprises with small scale and outdated equipment use electrogalvanizing, and of course their prices are relatively cheaper.
The process and technology of producing galvanized pipe involves several steps, starting with the production of the steel pipe itself. Once the base steel pipe is produced, it will undergo surface treatment. This usually involves cleaning the pipe to remove any dirt, oil or oxide layer. The pipe can be pickled in an acid solution to remove surface impurities and ensure proper adhesion of the zinc coating.
Then comes the galvanizing process, and hot-dip galvanizing and electrogalvanizing are selected according to the specific requirements of the final product.
In hot-dip galvanizing, the prepared steel pipe is immersed in a molten zinc bath. The zinc reacts with the iron in the steel to form a series of zinc-iron alloy layers, with a layer of pure zinc on top. The thickness of the coating can be controlled by adjusting the immersion time and the withdrawal rate. After removal from the zinc bath, excess zinc is removed by air knife or centrifugal action, and the pipe is cooled.
Electrogalvanizing involves placing the steel pipe in an electrolyte solution containing zinc ions. An electric current is passed through the solution, causing the zinc to be deposited on the pipe surface. The thickness of the coating is precisely controlled by adjusting the current and time of the process.
Hot Dipped Galvanized Scaffolding Pipe
