1. What materials are typically used for fixing the corner protectors of galvanized color-coated steel coils?
The core component for fixing the corner protectors is a specialized self-tapping screw. We recommend using 304 stainless steel or hot-dip galvanized carbon steel screws, and they must be paired with EPDM rubber sealing washers. Stainless steel screws have strong corrosion resistance, preventing electrochemical corrosion with the cut edges of the galvanized color-coated steel coils; hot-dip galvanized screws require a zinc plating thickness of at least 45 micrometers. Ordinary iron nails or electroplated galvanized screws are strictly prohibited from use, otherwise rust will quickly appear at the nail holes, causing the corner protectors to loosen.
2. What auxiliary accessories are needed to ensure waterproofing at the overlaps between corner protectors and between corner protectors and roof panels?
A: Two main types of accessories are used: First, a neutral, weather-resistant sealant (such as silicone sealant or MS modified silane sealant), applied to the inside of the overlap surface; second, a waterproof strip, i.e., a 50-80 mm wide galvanized color-coated thin strip, covering the outside of the overlap joint and secured with rivets or screws. In addition, a special foam sealing plug (closed-cell polyurethane material) should be installed at the end of the corner protector to prevent dust, insects, and moisture from entering.
3. What metal fittings should be used to reinforce the corner joints (such as the junction of two corner protectors)?
A: Pre-made corner brackets or on-site bent galvanized steel corner brackets should be used at the corner joints. Commonly used are L-shaped stamped parts at 90° or 135° angles, with a thickness of not less than 1.0 mm, and made of the same material as the corner protector (hot-dip galvanized base plate + color coating). During installation, use at least four stainless steel self-tapping screws to fix the corner brackets to the inner walls of both corner protectors. Simultaneously, the back of the corner brackets should be connected to the structural keel (or purlin, wall reinforcement) using the same screws. This prevents the corner protector from outward deformation due to wind pressure.
4. Does the connection between the corner bracket and the main structure require additional supports or hangers?
A: For buildings with large spans (e.g., a single corner bracket exceeding 3 meters in length) or located in windy areas, windproof supports are necessary. These supports are typically T- or Z-shaped pieces stamped from galvanized steel sheets. One end is fixed to the wall or purlin with self-tapping screws, and the other end supports the folded edge of the corner bracket and engages with a groove on the inside of the corner bracket. The spacing between supports should not exceed 1.5 meters. For ordinary low-rise buildings, if the corner bracket itself is directly fixed to the structure with densely packed screws (spacing ≤ 300 mm), additional supports are not required. However, all screws must be driven into solid keel or steel plates, and cannot be fixed only to the outer panel surface.
5. What are the special requirements for cutting and drilling accessories when processing and installing corner protectors for galvanized color-coated steel coils?
A: Electric shears or a dedicated color-coated steel sheet shearing machine are recommended for cutting. Avoid using ordinary grinding wheels, as the high temperature generated by grinding wheels will burn the galvanized layer and coating edges. Drilling must use twist drill bits or hole saws; nails are strictly prohibited. After drilling, lightly smooth the burrs around the hole with a stainless steel file or fine sandpaper, and immediately apply zinc-rich repair paint or epoxy primer around the hole as a rust-preventive measure. Without this repair and paint treatment, even stainless steel screws will rust starting from the hole edges over time.