The rust removal methods for steel structure columns and beams surfaces are: manual treatment, mechanical treatment, chemical treatment and flame treatment.
(1) Manual processing
Manual treatment mainly uses tools such as shovels, wire brushes, sand cloths, hacksaw blades, etc., and manually knock, shovel, scrape, brush, and sand to remove rust. This is the traditional rust removal method of painters and the easiest method. There are no environmental and construction conditions restrictions, but due to the poor efficiency and effect, it can only be used for small-scale rust removal treatment.
(2) Mechanical rust removal method
Mechanical rust removal method mainly uses some electric and air-powered tools to achieve the purpose of removing rust. Commonly used power tools such as electric brushes and electric grinding wheels; air-moving tools such as air-moving brushes. Electric brushes and air-moving brushes use the rotation of a special circular wire brush to remove rust or oxide scales by impact and friction. They are especially effective for surface rust, but it is difficult to remove deeper rust spots. The electric grinding wheel is actually a portable grinding wheel. It can be moved at will in the hand and uses the high-speed rotation of the grinding wheel to remove rust. It has a good effect, especially for deeper rust spots. It has high working efficiency, good construction quality, and is easy to use. It is an ideal rust removal tool. However, during operation, you must be careful not to penetrate the metal skin.
(3) Sand blasting and shot peening treatment
The sandblasting and shot peening treatment method are the same as the previous section to remove old coatings.
(4) Flame treatment method
Flame treatment method is to use a gas welding gun to burn a small amount of deeper rust spots that are difficult to remove by hand, so that the high temperature can change the chemical composition of the rust oxide to achieve the purpose of rust removal. When using this method, be careful not to burn through the metal surface and prevent heat deformation of large-area surfaces.
(5) Chemical treatment method
The chemical treatment method is actually a pickling and rust removal method, which uses an acid solution to chemically react with metal oxides (rust) to form salts and break away from the metal surface. Commonly used acidic solutions are: sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. During operation, apply the acidic solution to the metal rust area and let it slowly react chemically with the rust and remove it. After the rust is removed, rinse it with clean water, and neutralize it with weak alkali solution. Then rinse it with clean water and wipe it dry and dry it to prevent rusting quickly.
The pickled metal surface needs to be roughened or phosphated, mainly to increase the adhesion between the metal surface and the primer. When diluting concentrated sulfuric acid, you should slowly pour the sulfuric acid into the water in the container and stir continuously. Do not operate the opposite, so as not to splash out and hurt people.
