What Are the Anti-Rust Measures for Expansion Screws When Installing GRC Components? — A Complete Analysis of Qinglong Group's Anti-Rust Process

As the key fasteners in GRC component installation, the anti-rust performance of expansion anchor screws directly affects the safety and durability of curtain walls. Through 28 years of engineering practice, Qinglong Group has developed a complete anti-rust system covering material selection, surface treatment, installation techniques, and maintenance inspection, ensuring the long-term reliability of expansion anchor screws in all types of environments.

Material selection is the first line of defense against rust. Qinglong Group prioritizes A4-80 grade stainless steel screws (chromium content ≥16%, nickel content ≥10%), whose corrosion resistance is more than 5 times that of ordinary carbon steel. In coastal areas or highly corrosive environments, 316 stainless steel screws (molybdenum content 2%-3%) are selected to further improve pitting resistance. For special projects, titanium alloy screws are used; although more costly, their virtually unlimited corrosion resistance provides the highest level of protection for critical projects. In the roofing project of the Hainan International Convention and Exhibition Center, the 316 stainless steel expansion anchor screws remain bright as new after 5 years of use.

Surface treatment processes enhance anti-rust capability. For carbon steel screws, Dacromet treatment (zinc-chromium coating) is applied, with a coating thickness of 8-12μm, providing salt spray resistance of over 500 hours. In the Nanning Wuxiang China Resources MixC One project, Qinglong Group applied dual protection to the expansion anchor screws: Dacromet treatment first, followed by an epoxy resin sealing paint. This composite protection system kept the screws intact even after 2,400 hours of salt spray testing. Before installation, screw surfaces are degreased to ensure the protective coating remains intact.

Anti-rust measures during installation are equally critical. Nylon washers (thickness ≥2mm) are added at the contact surface between the screw and the GRC panel to prevent galvanic corrosion. Qinglong Group requires the use of torque wrenches during installation to ensure uniform preload and avoid over-tightening that could damage the protective coating. In the Shenzhen Pingshan High-tech Zone project, we used electric torque wrenches to keep torque error within ±3%. After installation, anti-rust wax is immediately applied to the screw heads to form an additional protective layer.

Establish a regular inspection and maintenance system. Qinglong Group recommends sampling inspection of expansion anchor screws every two years, using an endoscope to check for corrosion in concealed areas. In the Algeria hotel project, we developed a dedicated inspection tool that allows screw condition to be assessed without disassembly. Any corrosion found is addressed promptly: minor corrosion is mechanically derusted and recoated with protective paint, while severely corroded screws are replaced immediately.