SENBO Building Materials supplies color-coated aluminum downpipes as part of its metal building drainage product range. These pipes are designed for use with metal roofing or prefabricated gutter systems, collecting and discharging rainwater from building exteriors. They are commonly used in villas, clubhouses, multi-story residential buildings, and industrial facilities.
Color-coated aluminum downpipes are architectural drainage pipes with an aluminum alloy base and a colored surface coating. Their main characteristics include lightweight construction, corrosion resistance, a wide range of color options, and long service life.
The base material is 3003 aluminum-manganese alloy or 5052 aluminum-magnesium alloy. The 3003 alloy contains added manganese to refine grain structure and improve stress-corrosion resistance. Aluminum has a density of 2.7 g/cm³, which makes the components lightweight and easier to handle during installation.
The product uses an outdoor-grade polyester electrostatic powder coating, cured at a constant temperature of 200°C, with a coating thickness of at least 20 μm. The inner walls undergo an anodizing anti-corrosion treatment, similar to the process used for aluminum alloy doors and windows.
Relevant standards include GB/T 17748 ("Aluminum-plastic composite panels for building curtain walls") and GB/T 3880 ("Wrought aluminum and aluminum alloy plates, sheets and strips for general engineering applications").
Common square tube sizes include 63×82mm (2"×3"), 80×100mm, and 100×85mm. Standard wall thicknesses range from 0.7mm to 1.0mm. Standard tube length is 3 meters, and custom lengths are available upon request. Colors can be customized according to the RAL standard; popular options include light brown, dark brown, tea brown, ivory white, pearl gray, and bronze.
A full range of accessories is available, including S-elbows, 45° or custom-angle elbows, pipe clamps, and end caps. These accessories support installation on complex building facades.
Based on manufacturing methods, products are classified into extruded seamless tubes (with high cross-sectional precision, superior surface finish, and uniform wall thickness) and bent-and-seamed tubes (suitable for custom specifications).
A natural protective oxide layer forms on the aluminum alloy surface, helping to prevent further oxidation. In salt spray testing with a 5% salt solution for 360 hours, rust creepage at cut edges does not exceed 2mm. Some products have passed salt spray tests of up to 1,000 hours. This level of performance is equivalent to approximately five years of corrosion-free service in a marine environment and twenty years of stability under harsh climatic conditions.
The product also shows no significant surface degradation after 100 hours of exposure to acidic solutions such as 10% HCl, CH₃COOH, and H₂SO₄. Test reports are available upon request.
Color-coated aluminum downpipes operate reliably within a temperature range of -50°C to +60°C. This covers conditions from extremely cold winters to hot equatorial climates. In regions such as Northeast and Northwest China, this product avoids the low-temperature brittleness and cracking commonly associated with PVC piping.
When subjected to the impact of a 500g steel ball dropped from a height of 5 meters, the coating showed no signs of peeling. The material also withstood a 180° bend test without cracking or surface coating delamination. These properties support installation around architectural features such as facade moldings and corners.
The "Oasis Spring City" project in Mudanjiang, Heilongjiang, utilized color-coated aluminum downpipes in 6K (80×60mm) and 7K (100×85mm) specifications with a bronze finish. The project demonstrates the product's suitability for cold climates and its ability to coordinate with the overall building exterior when combined with color-coated aluminum gutters and metal roofing panels.
The following parameters are based on standard production and relevant standards. Customization is available to meet specific project requirements.
| Performance Indicator | Parameter/Specification | Standard / Notes |
|---|---|---|
| Base Material Grade | 3003 Al-Mn Alloy / 5052 Al-Mg Alloy | Corrosion-resistant aluminum alloy |
| Aluminum Density | 2.7 g/cm³ | Approx. 1/3 that of steel |
| Common Wall Thickness | 0.7–1.0 mm | |
| Coating Process | Outdoor-grade polyester electrostatic powder coating | Baked at 200°C |
| Coating Thickness | ≥20 μm | |
| Inner Wall Treatment | Anodized anti-corrosion | Similar process to aluminum doors and windows |
| Salt Spray Test | ≥360 h (up to 1000 h) | Creep at scribe ≤2 mm |
| Temperature Range | -50°C to +60°C | Stable performance |
| Bending Performance | 180° bend: no cracking or peeling | |
| Common Specifications | 63×82 mm, 80×100 mm, 100×85 mm | Square tube |
| Standard Tube Length | 3 m | Customizable |
1. Corrosion Resistance. Protection comes from a natural aluminum oxide film, an anodized inner wall, and an outdoor polyester coating. Products withstand 360–1000 hours of salt spray testing and show no significant degradation over 20 years in harsh environments such as acid rain or saline exposure.
2. Cold and Frost Resistance. The product operates reliably from -50°C to +60°C and does not crack or age in extreme cold. This makes it an alternative to PVC piping in regions such as Northeast and Northwest China.
3. Lightweight with Adequate Strength. With a density of 2.7 g/cm³, the pipes are lightweight and easy to install. The material withstands impact from a 500g steel ball dropped from 5 meters without coating peeling.
4. Color Options and Architectural Coordination. Colors are customizable according to RAL standards, including light brown, bronze, and ivory white, allowing the downpipes to match metal roofing and gutters.
5. Comprehensive Accessories. A range of accessories such as S-bends, 45° elbows, pipe clamps, and end caps supports installation on complex wall surfaces without the need for special tools.
For cold climates: Select aluminum downpipes over PVC to avoid low-temperature brittleness. Confirm that the selected temperature range (-50°C to +60°C) covers local winter conditions.
For coastal or industrial environments: Verify the coating specification and consider anodized inner wall treatment. Salt spray test reports (360–1000 hours) can be provided upon request.
For aesthetic coordination: Choose colors from the RAL chart to match the roof, gutters, and facade. Both extruded seamless and bent-and-seamed tubes are available; extruded tubes offer better surface finish and dimensional consistency.
During installation: Use appropriate pipe clamps and supports to allow for thermal movement. Follow the manufacturer's guidelines for joint sealing and fastening. Avoid using tools that may scratch the powder coating.
1. Organized exterior wall drainage systems for low- to mid-rise buildings, such as villas, townhouses, and clubhouses.
2. Roof drainage components for steel-structure factories and logistics warehouses, used with color-coated aluminum gutters.
3. Roof drainage for buildings in cold regions (Northeast and Northwest China), serving as an alternative to PVC pipes prone to freezing and cracking.
4. Projects in coastal areas requiring corrosion resistance against acid rain and salt spray.
Aluminum downpipes are more resistant to low-temperature brittleness and UV degradation than PVC. They also offer a wider range of durable powder-coated colors and better coordination with metal roofing. PVC is lighter and often less expensive, but aluminum provides longer service life in extreme climates and corrosive environments.
Extruded seamless tubes are produced by pushing heated aluminum through a die, resulting in uniform wall thickness and a smooth surface. Bent-and-seamed tubes are formed from flat sheet and welded along a seam; they can be more easily customized for non-standard sizes. Both types can be powder coated and anodized.
Yes. The aluminum alloy base, anodized inner wall, and outdoor polyester coating provide good corrosion resistance. Salt spray test reports (360–1000 hours) are available upon request. For highly aggressive marine environments, 5052 aluminum-magnesium alloy may be recommended.
Periodic cleaning with mild soap and water is usually sufficient. Avoid abrasive cleaners that could damage the powder coating. Inspect joints and brackets annually for signs of movement or sealant failure, especially after extreme weather events.
Please provide the pipe size, wall thickness, length, color (RAL code if available), quantity, and whether extruded seamless or bent-and-seamed tubes are preferred. Also indicate the project location and any special environmental conditions, such as coastal exposure or extreme cold.
Tianjin SENBO Building Materials Technology Co., Ltd. is a manufacturer of color-coated aluminum downpipes, FRP daylighting panels, polyurethane edge-sealed rock wool panels, and other metal envelope products. Our production base is located in Jinghai Economic Development Zone, Tianjin, China, equipped with automated production lines and a four-stage quality inspection process. For more information about our factory, certifications, testing capabilities, and project references, please visit our About Us page or contact our engineering team.
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No. 17 Guanghai Road, Jinghai Economic Development Zone, Tianjin, China
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