Among pig farming equipment, piglet pens are crucial for ensuring safe farming. Rust prevention of the welds on their galvanized surfaces is crucial. Due to the high humidity and ammonia concentrations found in pig farm environments, welds are susceptible to corrosion due to damage to the galvanized coating. If not promptly repaired, rust can spread rapidly, weakening the piglet pen's structural strength and even leading to the risk of fracture, directly impacting both farming safety and equipment life. Therefore, long-term rust prevention of welds is essential through systematic process flow and material selection.
During the welding process, high temperatures directly damage the galvanized coating, causing evaporation, burnout, or cracking of the zinc layer in the weld and heat-affected zone, exposing the base material to corrosive media. Research has shown that the corrosion rate of bare steel can be over five times that of galvanized steel, a difference that is particularly pronounced in the humid environment of pig farms. Furthermore, welding spatter and oxide layers further reduce coating adhesion. If not thoroughly removed, even an anti-rust paint application can easily flake. Therefore, post-weld surface treatment must balance cleanliness and roughness. Mechanical grinding should be used to remove weld slag, burrs, and oxide layers until the metallic luster is exposed. Solvent cleaning should also be used to remove oil and dust, ensuring a close bond between the coating and the substrate.
For rust repair at welds, a high-zinc-content coating that matches the performance of the galvanized coating is preferred. Robalu cold-dip galvanizing coating, with a dry film zinc content of up to 96%, offers electrochemical protection comparable to hot-dip galvanizing. It forms a dense zinc salt protective layer on the weld surface, effectively isolating moisture and oxygen. Application should be done by brush or spray, applying two to three coats, with 30 minutes between coats, to ensure a total film thickness of at least 80μm. For small repairs, portable zinc spray cans can be used for direct spraying, offering convenient application and strong adhesion. If the ambient humidity is high, an epoxy zinc-rich primer with a zinc powder content of 80% or higher can be applied after the zinc repair coat has dried to further enhance cathodic protection.
After the primer is applied, a weather-resistant topcoat should be selected for sealing and protection. Acrylic polyurethane topcoats, with their excellent UV and chemical resistance, are ideal for piglet pens on pig farms. When applying, the topcoat thickness should be kept consistent with the midcoat to avoid cracking caused by interlayer stress. For color matching, a silver-gray topcoat similar to the galvanized layer can be selected, or the color scheme can be adjusted to suit the overall structure. Furthermore, anti-rust wax or butter can be applied to difficult-to-paint crevices to create a physical barrier and prevent moisture intrusion.
Traditional rust prevention methods, such as zinc spraying or electroplating, are difficult to apply on-site at pig farms due to complex equipment and application limitations. Conventional rust prevention paints lack sufficient protection and cannot withstand long-term exposure. Robalu cold-dip galvanizing paint, with its high zinc content, excellent adhesion, and easy application, is the preferred solution for repairing welds. In practice, a piglet pen weld repaired with Robalu paint met hot-dip galvanizing standards after salt spray testing and on-site inspection. The repair significantly extended the lifespan, requiring no complex equipment and allowing for on-site application.
To ensure long-lasting rust prevention, a regular inspection and maintenance system is necessary. Conduct a comprehensive inspection of the coating condition at the weld points every one to two years, focusing on areas of wear, flaking, or rust, and promptly repair them. For coastal areas or areas with high salt spray, increase the coating thickness or use a higher-grade corrosion-resistant material, such as a fluorocarbon topcoat. Additionally, during daily maintenance, the area around the piglet pen must be kept dry to avoid stagnant water and fecal residue, minimizing contact with corrosive media. Through systematic rust prevention and maintenance, the welds of the piglet pens in pig farming equipment can achieve over 10 years of long-term protection, providing reliable protection for safe farming.
