the effect of anti-corrosion of coating is generally not better than long-term corrosion method (but anti-corrosion coating fluorocarbon years and even up to 50 years). So usually usd for indoor or outdoor steel structure is relatively more easy to maintain. It is a low cost, but high maintenance costs when used in outdoors. The first step of coating method is rust. Quality coating depends on a thorough rust. So demanding coating usually used sand blasting rust, exposing the shiny metal, remove all rust and grease. Coating at site can be hand-rust. Coating selection should consider the surrounding environment. Different coatings have different tolerance on the corrosion of different conditions. Generally primer coating (layer) and top coat (layer) of the points. Primer contain more powder and less base. Rough film with strong adhesion to steel, and finish with good. Paint the base material and more glossy film, to protect the paint from corrosion, and to weathering. Oweing to matter of compatibility between the different paint ,when use different coatings to pay attention to their compatibility. Construction of the coating should have the appropriate temperature (5 ~ 38 ℃ between) and humidity (relative humidity less than 85%). Coating construction should in less dust environment, surface of components can not have a condensation. Within 4 hours of painting must not rain. Coatings generally do 4 to 5 times. The total dry film thickness of the outdoor works for the 150μm, interior work for the 125μm, to allow deviation of 25μm. At the beach or at sea or in a strongly corrosive atmosphere, the total thickness of dry film can be thickened to 200 ~ 220μm.