Can the galvanized square pipe of the square pipe factory rust after galvanized

Can the galvanized square pipe of the square pipe factory rust after galvanized

Galvanized square pipe process is the use of cold rolling or hot rolling will be narrow and long steel plate plated with a layer of zinc, divided into hot dip galvanized and electric galvanizing, hot dip galvanized coating is more uniform, strong adhesion ability and long service life, and the plating bath chemical response can make galvanized steel pipe with corrosion resistance, even if there is a strong corrosion resistance, in the process of use will still show rust phenomenon, so, What causes this? 

The primary cause of galvanized square pipe rust is the layer of zinc plating on the surface. The chemical properties of zinc are more active, soluble in acid, also soluble in alkali, in a humid environment, zinc will attack chemical reaction, forming a basic zinc carbonate film on the surface, in touch with the substance containing hydrogen sulfide, zinc corrosion resistance declines, easy to be corroded, and then reveal the appearance of steel plate, eventually rust. The rust probability of galvanized strip steel using galvanizing method is relatively low, because the coating of galvanizing is thick, and it is not easy to form the oxidation of steel plate, so it is not easy to rust.

Galvanized square pipe from the production process is divided into hot galvanized square pipe and cold galvanized square pipe. It is because of the difference in the addition of these two galvanized square pipes that they have many different physical and chemical properties. Generally speaking, there are many differences in strength, endurance and mechanical properties