Weld Zinc Supplementation Method in Galvanized Barrel Production

Galvanized steel sheets are commonly used in the production of steel galvanized barrels. Since the steel sheet itself has a galvanized layer, it generally does not need to be painted again. In the production process, the seam welding of galvanized steel sheets destroys the galvanized layer at the weld, thereby destroying its corrosion resistance and aesthetics. Therefore, after the barrel body is welded, the weld part must be replenished with zinc to restore its original function. Let's first talk about the difference between steel galvanized barrels and electroplated steel barrels.

It is easy to form a dense oxide film on the surface of metal zinc, so the galvanized steel plate has more anti-corrosion performance than ordinary steel plate. The electroplated steel drum is formed by cold-rolled steel plate to galvanize the bottom cover and barrel body of the steel drum, and then rolled and packaged into a steel drum. The zinc layer on the galvanized steel plate generally adopts the hot-dip plating process. The zinc layer obtained by the hot-dip plating is thicker, and its structural layer is composed of five layers: steel substrate, zinc-iron alloy layer, zinc layer, oxide film and oil film. Therefore, the steel barrel made of hot-dip galvanized steel plate has good corrosion resistance. Galvanized steel drums are steel drums made of this galvanized steel sheet.

The bottom cover and barrel body of the steel galvanized barrel are formed and then galvanized respectively. The electro-galvanizing process is used. The zinc layer obtained by this process is adsorbed by zinc ions one by one under the action of current, and the zinc layer is formed. The structure is loose and thin. At the same time, due to the lack of thermal penetration, the electro-galvanized sheet lacks the zinc-iron alloy layer, and the oxide film it forms is also thin, and there is no oil film protection. Therefore, the anti-corrosion performance and appearance of electro-galvanized steel drums are not as good as those made of galvanized sheets. However, when the steel barrel body is made of galvanized steel sheet, the weld part of the barrel body may be ground due to welding needs, or oxidized after welding, so the galvanized layer here no longer exists. In order to keep the galvanized layer of the steel galvanized barrel intact to ensure the overall corrosion resistance of the galvanized steel barrel, the weld must be galvanized.

At present, the zinc supplementation methods adopted by the steel drum industry can be roughly divided into three types:

1. Hot melt tin patching method. The hot melt tin patching method is to remove the oxide layer at the weld and then carry out hot melt tin patching. Its working principle is similar to the usual soldering (brazing), that is, first clean the surface of the weld with a solder flux (commonly used zinc chloride solution), then heat the weld, and then apply the molten tin to the weld.

2. Aluminum slurry supplementary coating method. The aluminum slurry supplementary coating method is to polish the oxide layer at the weld and spray the special aluminum slurry coating for steel galvanized barrels. This coating is a two-component, which is actually composed of dissolving aluminum slurry into X-891 steel drum special paint (a product of Shanghai Xugong Coating Technology Co., Ltd.). One component of it is a curing agent, and the other component is an anti-corrosion resin containing aluminum slurry.

3. Spray zinc replenishment method. The spray zinc replenishment method is a good zinc replenishment method for steel galvanized drums, which is to use a special weld zinc replenishment machine for galvanized steel drums for molten zinc replenishment. The special weld zinc replenishment machine for galvanized steel drums is mainly composed of two parts: a sandblasting chamber and a zinc spraying chamber.