Epoxy resin coating is widely used in metal components such as flanges and fittings in water related pipeline systems, especially in humid and highly corrosive environments such as water supply networks, sewage treatment plants, seawater cooling systems, underground pipelines, and water conservancy facilities. Its excellent water resistance, chemical corrosion resistance, and strong adhesion make it a key material for anti-corrosion protection of water pipelines.
In aquatic environments, metal flanges and fittings are prone to electrochemical corrosion due to long-term contact with water, dissolved oxygen, chloride ions, and microorganisms, leading to interface leakage and decreased structural strength. Epoxy resin coating forms a dense and continuous inert barrier on the metal surface, effectively isolating water, oxygen, and electrolytes, significantly delaying substrate corrosion, and extending the service life of pipeline systems. At the same time, the coating has characteristics such as low permeability, wear resistance, and resistance to microbial adhesion, which meets the requirements of AWWA C213 standards and is suitable for the hygiene and safety standards of transporting drinking water.
When applying epoxy resin coating to flanges and fittings, strict process flow and technical conditions must be followed:
1. Surface treatment: Sandblasting to Sa 2.5 level for rust removal, with a surface roughness of 40-70 μ m, ensuring no oil stains, oxide scales, or impurities, and improving coating adhesion.
2. Preheating treatment: Preheat the workpiece to 70-80 ℃ to prevent moisture condensation and improve powder flowability and wettability.
3. Spraying process: electrostatic powder spraying is used to evenly spray the epoxy resin powder on the metal surface. The film thickness is controlled at 300~500 μ m. The flange sealing surface needs to reserve machining allowance or use protective tooling to avoid coating pollution.
4. Curing into a film: Cure at a constant temperature of 180-220 ℃ for 10-15 minutes to fully crosslink the epoxy resin and form a continuous and dense three-dimensional network structure coating.
5. Inspection standard: The coating should be free of pinholes, bubbles, and cracks; The adhesion force reaches level 1 (grid method), the porosity detection (electric spark test) is qualified, and the thickness meets the design requirements.
Epoxy resin coating not only enhances the durability of flanges and fittings, but also ensures the safety and hygiene of water related systems, making it an indispensable anti-corrosion technology in modern water engineering.
