PVC-U double wall corrugated pipe
PVC-U double wall corrugated pipe, also known as rigid PVC double wall corrugated pipe, is a type of plastic pipe made primarily from polyvinyl chloride (PVC-U) resin. It is produced using a one-step extrusion molding process. The pipe features a unique double-layer structure: the inner layer is smooth, while the outer layer is corrugated. Between the smooth inner layer and the corrugated outer layer lies a closed annular chamber structure, which provides the pipe with excellent physical and mechanical properties.
Manufacturing Process
Raw Material Preparation: High-quality PVC-U resin is selected as the primary raw material. To enhance its properties, various additives such as stabilizers, lubricants, and fillers are added. These additives improve the pipe's heat resistance, weather resistance, and mechanical strength, meeting the performance requirements for different application scenarios.
Extrusion Molding: The prepared raw material mix is fed into the extruder. Under the combined effects of heating, screw rotation, and shearing, the PVC-U material is melted and plasticized. It then flows through a special corrugated mold to form a continuous double wall corrugated pipe. The unique structure of the mold ensures the formation of the smooth inner layer, corrugated outer layer, and annular chamber structure.
Cooling and Shaping: After exiting the mold, the pipe passes through a vacuum sizing tank and spray cooling tank to complete cooling and shaping. The vacuum sizing tank uses negative pressure to ensure the pipe maintains its shape and dimensions, while the spray cooling tank rapidly cools the pipe, solidifying its structure and enhancing its rigidity.
Cutting and Inspection: The cooled and shaped pipe is cut into predetermined lengths using a cutting machine. Finally, strict quality inspections are conducted, including tests for appearance, dimensions, ring stiffness, and other properties. Only pipes that pass these inspections are considered qualified products.
Physical and Mechanical Properties
Tensile Strength and Elastic Modulus: PVC-U double wall corrugated pipe exhibits relatively high tensile strength and elastic modulus. Under normal conditions, its tensile strength ranges from 40 MPa to 60 MPa, and its elastic modulus is between 2000 MPa and 3000 MPa. This enables the pipe to withstand significant tensile forces during transportation, installation, and use, preventing deformation or damage caused by external tensile stresses.
Ring Stiffness: The ring stiffness is a critical indicator of the pipe's resistance to radial deformation. PVC-U double wall corrugated pipe achieves high ring stiffness due to its annular chamber structure. Its ring stiffness typically ranges from SN4 to SN16 (measured in kN/m²). For example, a pipe with SN8 ring stiffness can effectively resist soil pressure and external loads when buried underground, maintaining its shape and integrity.
Impact Resistance: The PVC-U material and unique structural design grant the pipe excellent impact resistance. It can absorb and dissipate impact energy, resisting damage from external impacts. This makes it suitable for installation in environments where it may be subjected to mechanical impacts, such as roadways or areas with frequent construction activities.
Chemical Resistance
PVC-U double wall corrugated pipe is highly resistant to chemical corrosion. PVC-U material exhibits chemical stability, showing strong resistance to acids, alkalis, salts, and other chemical substances. It does not easily react with most chemicals, making it suitable for transporting various corrosive media and for use in harsh soil environments. For instance, it can convey wastewater containing acidic or alkaline substances without undergoing significant corrosion or degradation over long-term use, ensuring stable performance.
Application Fields
Urban Sewage Systems: Due to its excellent corrosion resistance and mechanical properties, PVC-U double wall corrugated pipe is widely used in urban sewage pipelines for collecting and transporting domestic sewage and industrial wastewater. Its smooth inner surface reduces flow resistance, improving sewage conveyance efficiency and reducing blockage risks. Additionally, its lightweight nature facilitates installation, reducing construction costs and duration.
Building Drainage Systems: In building drainage applications, the pipe effectively transports rainwater and domestic sewage from buildings. Its high ring stiffness prevents deformation under the weight of buildings or external loads, ensuring stable drainage performance. The lightweight and easy-to-install properties simplify construction, making it a preferred choice for building drainage systems.
Agricultural Irrigation Systems: PVC-U double wall corrugated pipe is used for agricultural irrigation water conveyance. Its excellent water tightness minimizes water leakage losses during conveyance, improving irrigation efficiency. The pipe's low cost and long service life make it suitable for large-scale agricultural irrigation projects, contributing to agricultural water conservation and efficiency.
Telecommunication and Power Cable Protection: The pipe can serve as a protective conduit for telecommunication and power cables. Its smooth inner surface allows cables to be easily threaded through, while its high strength and impact resistance protect cables from external mechanical damage. Its insulating properties prevent electrical leakage or short circuits, ensuring cable safety and stable operation.
Advantages Over Traditional Pipes
Lightweight: PVC-U double wall corrugated pipe is significantly lighter than traditional concrete pipes and steel pipes of the same diameter and length. This reduces transportation and installation costs and labor intensity. For example, a 1-meter-long DN200 PVC-U double wall corrugated pipe weighs approximately 2 kg to 3 kg, whereas a similarly sized concrete pipe can weigh over 20 kg. The lightweight nature of PVC-U pipes makes manual handling easier and improves installation efficiency.
Corrosion Resistance: Compared to metal pipes, PVC-U double wall corrugated pipe does not rust or corrode in harsh environments, eliminating the need for frequent anti-corrosion treatments. This extends its service life and reduces maintenance costs. In contrast, steel pipes are prone to rust and corrosion, requiring regular maintenance and replacement. Concrete pipes are susceptible to chemical corrosion, especially in acidic or alkaline environments, which can lead to pipe damage and reduced lifespan.
Smooth Inner Surface and Low Fluid Resistance: The inner surface of PVC-U double wall corrugated pipe is smooth, resulting in low fluid resistance and high flow rates. This ensures efficient fluid transportation and reduces energy consumption during conveyance. Traditional concrete pipes and steel pipes often have rough inner surfaces, leading to higher flow resistance, lower flow rates, and greater energy loss.
Excellent Sealing Performance: PVC-U double wall corrugated pipe features reliable sealing connections, such as socket-type or clamp-type connections. These connections prevent fluid leakage, ensuring stable system operation. In contrast, traditional pipes may experience leaks at connection points due to poor sealing, compromising conveyance efficiency and causing environmental pollution.
Development and Market Trends
With advancements in PVC-U material science and extrusion technology, the performance of PVC-U double wall corrugated pipe continues to improve. Processes such as foam core technology and multi-layer co-extrusion are being explored to enhance the pipe's insulation and noise reduction capabilities while reducing costs. In terms of market demand, as urbanization accelerates and infrastructure development strengthens, the demand for PVC-U double wall corrugated pipe is expected to grow steadily. Applications will expand into new fields such as seawater conveyance and industrial fluid transportation. To address environmental concerns, manufacturers are increasingly focused on producing eco-friendly, recyclable PVC-U pipes to meet market demands and promote sustainable development.