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　　Label: steel structure

　　I. General Situation

　　Datong is a heavy industrial city and a national energy base. Datong power plant uses coal for power generation. The steel structure of thermal power plant includes power house, boiler shell, turbine shell, sewage treatment plant, coal unloader and coal conveying system, etc. In addition to the special anti-corrosion requirements for some steel structures such as high temperature, insulation and oil resistance, the corrosion environment of other steel structures exposed to the atmospheric environment is quite bad. According to the description of the air quality of Datong area by the environmental protection department of Shanxi Province, it is mostly "moderate and severe pollution". Therefore, the atmospheric corrosion of the exposed steel structure of Datong power plant in the polluted environment mainly belongs to the electrochemical corrosion of steel. The corrosion mechanism and characteristics are as follows: 1. Steel and impurities constitute the two poles of the primary battery; 2. The water film on the steel surface acts as the electrolyte; 3. Hydrogen evolution corrosion.

　　To sum up, the anti-corrosion of exposed steel structure in Datong power plant is one of the important contents of production and maintenance. The durability (service life) of steel structure coating should be put on the important agenda in coating design.

　　2、 Painting design principles

　　1. Corrosion condition analysis of Datong power plant steel structure

　　① Atmospheric environment; ② stress corrosion and fatigue corrosion; ③ welding effect;

　　2. Selection of heavy duty anticorrosive coating

　　In this design, cold galvanizing material - strong zinc is used as a primer for heavy anticorrosive coating, which is advanced in anticorrosion technology.

　　3. Coating matching performance

　　In this design, heavy-duty anticorrosive coating is selected as the middle coat and top coat of strong zinc. In particular, the use of epoxy sealer and epoxy micaceous iron oxide can not only increase the thickness of the coating, but also improve the barrier performance of the coating. In this design, it is recommended to use the heavy-duty anticorrosive coating of Shanxi Yellow River chemical plant, which has been widely used in Datong power plant and has good compatibility with strong zinc.

　　4. Environmental security

　　The production unit of strong zinc has passed the certification of ISO 14001 environmental management system. The solvents and diluents of strong zinc do not contain toluene, xylene, ketones, chlorinated hydrocarbons and other toxic organic solvents. The strong zinc coating can be formed independently, non-toxic and tasteless, and does not contain heavy metal ions such as Pb, Cr, Hg, etc., which is the best material to replace the hot-dip galvanizing and arc spraying (aluminum) coating. Hot dip galvanizing and arc spraying (aluminum) process will not only result in a large number of "three wastes", which is harmful to environmental protection, but also high energy consumption.

　　5. Feasibility of coating process

　　In order to ensure the coating quality of power plant steel structure, the designed coating process is not only suitable for large steel structure manufacturers, but also for small and medium steel structure manufacturers, which can be applied indoors and outdoors.

　　3、 Painting process of steel members

　　Steel cutting, welding and assembly into parts, sand blasting and derusting, precoating and strengthening zinc on welding parts, spraying and strengthening zinc, spraying and sealing epoxy micaceous iron paint, spraying and coating the first polyurethane paint, shipping to the construction site of the power plant, welding and general assembly, welding joint grinding, repairing and coating of strong zinc and intermediate paint, etc., spraying and coating the second polyurethane paint, inspection Check the coating quality - Repair - delivery for inspection.

　　This paper is excerpted from teacher Li Minfeng's paper collection "anticorrosive coating and coating"