Three common methods of steel structure anticorrosion

How to do a good job of steel structure anticorrosion?

 1. Coating method

The first step of coating construction is rust removal. High quality coating depends on thorough rust removal. Therefore, the coating with high requirements is generally derusted by sand blasting and shot peening to expose the luster of the metal and remove all rust and oil stain. The coating constructed by the steel structure company on site can be derusted manually. The choice of coating should consider the surrounding environment. Different coatings have different resistance to different corrosion conditions. The coating is generally divided into primer (layer) and finish (layer).

The primer contains more powder and less base material. Rough film formation, strong adhesion with steel structure and good adhesion with finish paint. The topcoat has many base materials, the film is shiny, can protect the primer from atmospheric corrosion, and can resist weathering. There is a problem of compatibility between different coatings. Pay attention to their compatibility when selecting different coatings before and after. The coating construction shall have appropriate temperature (between 5 ~ 38 ℃) and humidity (the relative humidity shall not be greater than 85%).

The dust in the construction environment of the coating shall be less, and there shall be no condensation on the component surface. No rain shall be allowed within 4 hours after coating. The coating is generally done 4 ~ 5 times. The total thickness of dry paint film is 150μm for outdoor works. 125μm for indoor works. The allowable deviation is 25μm。 The total thickness of dry paint film can be thickened to 200 ~ 220μm in the sea, sea or strongly corrosive atmosphere.

2. Thermally sprayed aluminum (zinc) composite coating

This is a long-term anti-corrosion method equivalent to the anti-corrosion effect of hot-dip galvanizing. The specific method is to remove the rust on the surface of the steel member by sand blasting to expose the metallic luster and roughen the surface. Then use acetylene oxygen flame to melt the continuously sent aluminum (zinc) wire and blow it to the surface of steel members with compressed air to form a honeycomb aluminum (zinc) spraying layer (thickness about 80μm~100μm）。 Finally, the pores are filled with epoxy resin or neoprene paint to form a composite coating.

3. Hot dip galvanizing

Hot dip galvanizing is to immerse the steel member after rust removal into the molten zinc at a high temperature of about 600 ℃, so that the surface of the steel member is attached with a zinc layer. The thickness of the zinc layer shall not be less than 65μm for thin plates less than 5mm. No less than 86μm for thick plate。 So as to achieve the purpose of anti-corrosion. This method has the advantages of long durability, high industrialization and stable quality. Therefore, it is widely used in outdoor steel structures which are seriously corroded by the atmosphere and difficult to maintain.