Galvanized Steel are those steel that has been covered with a layer of zinc metal. In the production process and packaging process of hot dip galvanized, the appearance of hot dip galvanized steel strip and steel plate may occur following defects.

The excess liquid zinc from galvanized pot on the strip surface,which excess liquid zinc air knife blow to control the zinc coating thickness.Gas pressure of the air knife, air knife and strip speed will directly affect the thickness of zinc layer. If the lack of supply instability of the air knife or air knife pressure can cause the accumulation of zinc coating.

Purity of zinc coating is not enough, the original board surface dirt eclipse biological treatment is not sufficient and form the residue when copper, iron, arsenic and other impurities is higher levels of zinc coating. Galvanized uncoated can easily lead to the surface of the steel dark spots. Galvanized steel surface exposed to moisture or rain immersion lead to zinc oxide and produce a white powder at a certain temperature. The surface of white rust corrosion resistance is greatly reduced and affect its use.

Galvanized sheet surface zinc layer is rugged and uneven, or even the surface of small particles. Because the air knife is aspirated uneven when hot dip galvanized or improper air knife and strip spacing.