Concealed Clip Fasteners provide a hidden connection between building panels and the supporting structure. The clip engages with a base rib fixed to the purlin or bracket, holding the panel without screws through the panel surface. This approach keeps all fasteners inside the panel seams, giving a clean exterior and removing the leak paths associated with exposed screws and sealant. SENBO supplies these clips with dimensional checks on slot depth, leg length, and material thickness, and the production process includes periodic testing of engagement strength.
The clips are made from 304 stainless steel as standard, with 430 and 201 available for specific budgets. Q235B steel with hot-dip galvanizing is used for heavier structural clips. Stainless steel clips are produced by cold pressing or stamping from strip material. Q235B clips are typically made from hot-rolled plate with a minimum thickness of 5 mm and formed by hydraulic cold pressing to maintain strength and dimensional accuracy.
Clip internal height is determined by the panel slot depth. Common internal heights range from 2.6 mm to 10 mm, with a leg length of 7.5 mm and material thickness from 0.5 mm to 1.5 mm for stainless steel. Bolt diameter is 12 mm with a strength grade of at least 8.8. Clips are classified by application into wall panel clips, roof panel clips, and floor panel clips. By material, they are divided into stainless steel clips and hot-dip galvanized steel clips.
| Item | Parameter / Specification | Reference or Notes |
|---|---|---|
| Base Material | 304 stainless steel / Q235B hot-rolled steel | Material selected by application |
| Material Thickness | 0.5–1.5 mm for stainless steel; ≥5 mm for all-steel components | Depends on product type |
| Clip Internal Height | 2.6–10 mm | Must match panel slot |
| Leg Length | 7.5 mm | Typical dimension |
| Bolt Specification | M12, strength class ≥8.8 | For structural connection |
| Galvanizing Thickness | ≥150 g/m² per side | Hot-dip galvanized Q235B |
| Slip Resistance | Δ ≤ 7.0 mm at 7.0 kN; Δ ≤ 0.5 mm at 10.0 kN | Per GB 15831 and industry standards |
| Structural Integrity | No failure at 25.0 kN | Per GB 15831 and industry standards |
| Torsional Rigidity | θ ≤ 4° at 900 N·m torque | For right-angle couplers |
| Torque Test | No failure at ≥65 N·m | Clip torque resistance |
The mechanical requirements for concealed clips are based on GB 15831 and related industry standards. Slip resistance tests require displacement of no more than 7.0 mm at a load of 7.0 kN, and no more than 0.5 mm at 10.0 kN. The clip must not fail at 25.0 kN. Torsional rigidity requires an angle of no more than 4 degrees under 900 N·m torque. All-steel cold-pressed clips tested by SENBO meet these limits.
304 stainless steel clips have been subjected to salt spray testing and show suitable corrosion resistance for outdoor exposure. Hot-dip galvanized Q235B clips carry a minimum zinc coating of 150 g/m² per side, which provides long-term protection in normal atmospheric conditions. The material choice should match the project environment.
In standing seam roofs, concealed clips hold the panels to the support brackets without surface penetrations. This allows the roof panels to move with thermal expansion and contraction while staying fixed at the clips. The result is a roof surface with no exposed screw holes, which reduces the chance of water ingress and improves long-term waterproofing. The concealed-clip method is used in 360° standing seam systems for large-span industrial roofs.
For wall panels, Concealed Clip Fasteners permit nail-free installation, keeping the panel surface clean. In window trim assemblies, the hidden connection covers the cut edges of the color-coated panels, protecting them from direct rain contact and reducing the risk of rust at edges. This installation method meets architectural appearance requirements.
Suppliers should provide material certificates for stainless steel or galvanized steel. Test reports for slip resistance, structural integrity, and torsional rigidity should be available if required by the project. On-site receiving checks should verify dimensions, material grade, and surface condition. For large orders, sample clips can be tested to confirm engagement with the actual panel profile.
The clip internal height must match the slot depth of the panel being used. Measure the panel slot or refer to the panel manufacturer's specification. A clip that is too tall will prevent full engagement, while one that is too short may allow movement or disengagement.
Concealed clips are designed for panels with a compatible slot or seam profile. Metal panels with standing seams or interlocking edges work well. Some wood-based panels can also use concealed clips if the slot is machined correctly. Always confirm compatibility with both the panel and clip suppliers.
Stainless steel clips, particularly 304 grade, offer better corrosion resistance and are preferred for coastal or humid environments. Galvanized steel clips are stronger and often used for heavy structural connections, but the zinc coating may not last as long in aggressive atmospheres. The choice depends on the project's environmental exposure and load requirements.
Yes, concealed clips are used in high-wind regions, especially in standing seam roof systems. The clips must be spaced according to the design wind load, and the clip material and thickness must be adequate. Wind uplift calculations should be performed for the specific project.
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