As a new type of material, steel grating is widely used in various fields, and the surface treatment of hot-dip galvanizing makes the steel grating with super corrosion resistance. So what are the specific requirements for hot-dip galvanizing of steel grating?
1. The hot-dip galvanized steel grating should be surface-treated to ensure that the metal surface is clean. Pickling can be used for surface cleaning, but excessive pickling should be avoided. For surface oil that cannot be washed off, such as carbon film, oil, paint, welding slag, etc., it should be removed before pickling.
2. The surface of the steel grating should be kept dry before hot-dip galvanizing, and no aqueous solution or other moisture should remain.
3. The zinc bath used for hot-dip galvanizing should be mainly composed of molten zinc, and the total content of impurities (except iron and tin) in the molten zinc should not exceed 1.5% of the total mass.
4. After hot-dip galvanizing, the surface of the steel grating should be smooth, free of lumps, roughness and zinc thorns, no peeling, and no residual solution slag.
5. When the thickness of the loaded flat steel is not less than 5mm, the weight of the average zinc layer after galvanizing should not be less than 610g/m2, and the average thickness should not be less than 85um; when the thickness of the loaded flat steel is less than 5mm, the weight of the average zinc layer after galvanizing should not be less than 85um. It is less than 460g/m2, and the average thickness is not less than 65um; the weight of the zinc layer using centrifugal treatment should not be less than 395g/m2, and the average thickness is not less than 55um. The quality and requirements after galvanizing shall comply with the provisions of GB/T 13912-2002.
6. After the steel grating is hot-dip galvanized, it should not be gathered together when the surface is still in a hot and wet state. After the steel grating is taken out of the hot-dip galvanized zinc solution, the excess zinc should be thrown off by centrifugation or blasted immediately.
7. After hot-dip galvanizing, the total area of the missing plating surface of each steel grating should not exceed 0.5% of the total area, and the area of each missing plating surface should not exceed 10m2. If the missing plating area is larger than the above specified value, the steel grating should be re-plated.
8. After hot-dip galvanizing, if there is a leaked surface, the leaked surface should be repaired by thermal spraying zinc, coating zinc-rich paint or melting zinc alloy. For specific methods, please refer to the provisions of GB/T 13912-2002. The repair layer should be able to give sacrificial anode protection to the steel during the use of the steel grating. Before repairing, the oxide skin and other dirt in the missing plating area should be removed to ensure the adhesion between the repair and the substrate.
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