What are the methods for derusting steel structures?

　　Before derusting steel structure, it is necessary to descale the surface of steel component. The derusting method shall meet the design requirements or be determined according to the needs of the type of coating used, and shall reach the derusting grade specified in the design. Commonly used rust removal methods include spray rust removal, projectile rust removal, manual and power tool rust removal, etc.

　　1. Manual derusting

　　Rust on the metal surface can be wiped with a wire brush, steel wire cloth or coarse abrasive cloth until natural color of metal is exposed, and then wiped with cotton gauze. This method is simple in construction, relatively economical, and can be processed on small components and components with complex shapes. However, it takes a lot of labor, and dust will be generated during rust removal process to pollute the environment.

　　2. Power tool derusting

　　Use compressed air or electric energy as the power to make rust removal tool produce circular or reciprocating motion, generate friction or impact to clean rust or iron oxide scale, etc. The working efficiency and quality of this method are higher than that of manual rust removal, and it is a commonly used rust removal method at present. Commonly used tools include pneumatic sand mills, electric sand mills, pneumatic wire brushes, and pneumatic air shovels.

　　3. Spray derusting

　　The compressed air that has been separated from oil and water is used to bring abrasive into it and spray it on the steel surface at high speed through the nozzle. The iron oxide scale is removed by the impact and friction of abrasive, and at the same time, the surface obtains a certain roughness. This method has high efficiency and good rust removal effect, but the cost is relatively high. There are two types of spray rust removal: dry spray method and wet spray method. The wet method has better working conditions and less dust than dry method’s, but it is prone to rust return.

　　4. Projection derusting

　　Utilize the role of center of impeller of impeller to inhale the abrasive and the tip of blade to project abrasive, and remove the dirt on the surface of steel with high-speed impact and friction. This method has lower labor intensity than spraying method, less environmental pollution, and lower cost than spraying method, but the disturbance is poor, and improper abrasive selection can easily deform thrown object.

　　5. Pickling and rust removal

　　Pickling rust removal, also known as chemical rust removal, uses the acid in pickling solution to react with metal oxides to dissolve and remove the metal oxides. The derusting quality of this method is better than manual and power tool derusting, which is equivalent to the quality of spraying derusting, but it does not have the roughness of spraying derusting, and the acid mist is harmful to people and buildings during the construction process.

　　6. Water blasting jet machine to remove rust

　　New derusting method High-pressure water sand blasting derusting, using the siphon effect of water to discharge water and bring out sand at the same time, high derusting efficiency and no dust pollution, strong environmental protection. Low energy consumption, low cost, labor saving, no pollution on the surface of parts, no damage or deformation of parts, and one person can operate it, which is very practical.