During the maintenance of petrochemical plants, how should equipment and steel structures be coated with anti-corrosion coatings?

During the maintenance of petrochemical plants, applying anti-corrosion coatings to equipment and steel structures usually involves the following steps: 1. **Surface treatment**: Since mechanical sandblasting cannot be used, rust removal can be carried out using manual or power tools. Use a wire brush, sandpaper, or grinder to remove the aged coating and rust, ensuring that the metal surface is clean, free of oil, loose rust, and residues from old coatings. Achieve a rust removal level of Sa 2 (Swedish standard) as much as possible. 2. **Surface pretreatment**: Before coating, the rust-removed surface should be treated with agents such as phosphating or cleaned using metal surface treatment agents, in order to enhance the adhesion of the coating and provide an anti-rust base layer. 3. **Apply priming coat**: Choose a suitable anti-corrosion primer, such as epoxy zinc-rich primer, which provides good corrosion resistance and adhesion. The primer should be applied evenly, paying attention to the coating thickness and avoiding sagging. 4. **Intermediate coat**: To increase the overall thickness and durability of the coating, an epoxy limonite intermediate coat can be applied. This layer not only enhances the mechanical properties of the coating film but also improves its resistance to chemicals. 5. **Topcoat**: Finally, a topcoat is applied, such as a fluorocarbon paint or a highly weather-resistant polyurethane topcoat. These topcoats offer excellent weather resistance and UV protection, enabling them to effectively safeguard the layers beneath while providing an attractive surface finish. The topcoat also needs to be applied evenly. 6. **Curing and Inspection**: After coating, the coating should be allowed to cure fully. The curing time is determined based on the type of coating used and the on-site environmental conditions (such as temperature and humidity). After coating, it is necessary to conduct thickness testing of the coating layer and an evaluation of its visual quality to ensure that the technical requirements are met. 7. **Maintenance and Inspection**: Regularly inspect and maintain the coating; address any damage or peeling promptly to extend its service life. Depending on the properties of the selected coating and the application standards, the above steps can ensure a coating lifespan of over 6 years. .