What is PVC-O
PVC-O (Biaxially Oriented Polyvinyl Chloride) represents the latest technological advancement in PVC piping systems. This high-performance pipe is manufactured through a specialized biaxial stretching process. Specifically, PVC-U pipes are stretched both axially and radially, causing the molecular chains within the material to align uniformly and form a network-like structure.
This unique structure endows PVC-O pipes with exceptional properties, including: Superior strength；Enhanced toughness；Outstanding impact resistance；Excellent fatigue resistance.
Notably, the pipe’s strength increases significantly with the degree of stretching. For example, when the pipe diameter expands by 60%, its strength can increase from 25 MPa (standard PVC) to 31.5 MPa.
Advantages of PVC-O pipes
PVC-O (Oriented Polyvinyl Chloride) is an advanced PVC pipe variant produced via biaxial stretching technology. As an engineered upgrade to conventional PVC-U pipes, its molecular orientation delivers superior properties. The distinguishing features of PVC-O piping systems comprise:
1. High Strength: PVC-O pipes offer superior tensile, compressive, and impact strength compared to PVC-U pipes, withstanding higher pressures.
2. High Toughness: PVC-O pipes are more durable, with better fatigue and stress cracking resistance than PVC-U pipes.
3. Corrosion Resistance: PVC-O pipes match PVC-U pipes in corrosion resistance.
4. Wear Resistance: PVC-O pipes outperform PVC-U pipes in wear resistance, making them ideal for conveying abrasive materials.
5. Welding Performance: PVC-O pipes can be welded using the same methods as PVC-U pipes.
6. Lightweight & Efficient: PVC-O pipes are lighter, easier to install, and have lower transportation costs.
Features of PVC-O pipe extruder
PVC-O pipe extruder is a special equipment for producing biaxially oriented polyvinyl chloride (PVC-O) pipes, with the following significant features:
Efficient production：
One-Step Molding Method:This method for producing PVC-O pipes offers a small footprint, low electricity and labor costs, and minimal material waste.
Automation Control:The production line uses automation to achieve continuous, stable output, boosting efficiency.
High-quality output：
High-Torque Screw: A high-torque screw and advanced temperature control ensure stable material plasticization, uniform pipe extrusion, and precise sizing.
Precision Mold Design:The mold’s spiral diversion structure prevents surface marks on large-diameter pipes and ensures even melt distribution.
Vacuum Sizing and Cooling: A double-chamber vacuum tank provides intense cooling and vacuum functions, quickly and effectively forming and cooling the pipe.
Energy saving and environmental protection：
Low Energy Consumption Design:Efficient energy-saving design and advanced controls reduce energy use and waste in production.
Material Saving:PVC-O pipes use over 50% less material than traditional PVC-U pipes, significantly lowering material consumption.
Flexibility and adaptability：
Production of Various Specifications:PVC-O pipes can be produced in diameters from 110mm to 630mm and pressure levels from PN5 to 25.
Customized Solutions:The production line can adjust molds and parameters for customized PVC pipes of various sizes and thicknesses.
Durability and reliability：
Wear-Resistant & Corrosion-Resistant Materials:The machine is built with durable, wear-resistant, and corrosion-resistant materials to enhance its longevity.
High-Precision Traction & Cutting System:The traction system ensures stable pipe movement, while the cutting system provides precise, fixed-length cuts synchronized with the main machine.
PCV-O pipe extrusion process
The production process of PVC-O pipes is divided into one-step and two-step methods:
One-step method（in-line method）
The one-step method, also known as the in-line process, is a process in which the extruded PVC-U pipe (thick stock) is continuously subjected to radial expansion and axial stretching to achieve biaxial orientation on the pipe extrusion production line, and then cooled and shaped into a PVC-O pipe.
advantage：
High production efficiency: Continuous production is achieved, which greatly improves production efficiency.
Low cost: Reduces equipment investment and production costs, and enhances market competitiveness.
Stable quality: During the online production process, the wall thickness control of the pipe is more precise and the product quality is more stable.
shortcoming：
Complex equipment: The production process is relatively complex, requiring high-precision equipment and control systems.
Difficulty in controlling wall thickness: Once the wall thickness of the tube billet changes, it is difficult to adjust online, which may affect the orientation uniformity of the tube.
Limited large-diameter production: When producing large-diameter (≥630mm) tubes, it is difficult to start the machine, the size control is difficult, and the scrap rate is high.
Two-step method (offline method)
The two-step method, also known as the off-line process or the in batch process, is a two-step process of extruding thick stock and biaxially stretching and orienting. First, the PVC-U pipe segment (thick stock) is extruded and cooled, and then oriented by heating and pressurizing it in the mold to expand it to the required size.
advantage：
Simple operation: The production startup operation is relatively simple, and the wall thickness can be measured and controlled in real time during tube production.
Large diameter advantage: Better performance in large diameter tube production, better control of product size, and reduced scrap rate.
High quality: The transverse stretching value can be higher, the orientation effect is better, and tubes with R-R sockets can be manufactured.
shortcoming：
Low production efficiency: The production speed is slow. Taking 315mm pipe as an example, it takes about 1 hour to produce a 6-meter pipe.
High cost: The equipment investment is high. In the production process, the invalid sections (about 5%) need to be cut off at both ends of each pipe, which increases material waste.
Difficulty in continuous production: Continuous production cannot be achieved, and the production efficiency and automation level are relatively low.
The one-step method suits small-to-medium pipe production, offering high efficiency and low cost but requiring precise equipment and limiting large-diameter output； The two-step method is better for large pipes, ensuring higher quality but at the cost of lower efficiency, higher costs, and discontinuous production.
According to specific production needs and pipe specifications, enterprises can choose the appropriate production process.
Application of PVC-O pipe
PVC-O pipes are widely used in the following fields:
Water supply pipes: used in urban water supply systems, rural tap water projects, etc.
Drainage pipes: used in urban drainage systems, rainwater drainage systems, etc.
Industrial pipes: used for transporting chemical liquids, industrial wastewater treatment, etc.
Agricultural irrigation: used in farmland irrigation systems.
Construction: used in water supply and drainage systems of buildings.
PVC-O pipe extruders are ideal for producing high-performance PVC-O pipes due to their high efficiency, energy saving and high quality.
PCV-O pipe extruder VS PVC-U pipe extruder
1、Material properties and applications
PVC-U Extruder：
Material properties: PVC-U (unplasticized polyvinyl chloride) is a hard plastic with good chemical resistance and mechanical strength.
Application areas: Mainly used in the production of standard pipes, drainage pipes, cable sheaths, etc.
PVC-O Extruder：
Material properties: PVC-O (biaxially oriented polyvinyl chloride) has higher impact strength and fatigue resistance through a biaxial stretching process. At room temperature, the impact strength of PVC-O is five times that of PVC-U.
Application areas: Suitable for applications that require higher strength and durability, such as water supply pipes, industrial pipes, and agricultural irrigation systems.
2、Extrusion process
PVC-U Extruder：
Process characteristics: Single screw extruder is usually used, which has simple structure, low cost and is suitable for large-scale production.
Production efficiency: It is suitable for producing thermoplastic materials with uniform performance and has high production efficiency.
PVC-O Extruder：
Process characteristics: usually use a twin-screw extruder, which can better mix and shear materials and is suitable for producing high-strength and high-performance PVC-O pipes.
Production efficiency: Although the equipment cost is higher, it can handle more complex material formulas, with higher production efficiency and product quality.
3、Equipment Features
PVC-U Extruder：
Equipment advantages: simple equipment, low maintenance cost, suitable for small and medium-scale production.
Equipment disadvantages: limited processing capacity for highly filled materials or complex formulations.
PVC-O Extruder：
Equipment advantages: It has better mixing and shearing capabilities, can handle a variety of materials, and is suitable for producing high-performance pipes.
Equipment disadvantages: The equipment is complex, the maintenance cost is high, and more professional operation and maintenance knowledge is required.
4、Production cost and economic efficiency
PVC-U Extruder：
Cost advantage: The initial investment and maintenance costs are low, suitable for enterprises with limited budgets.
PVC-O Extruder：
Cost advantage: Although the initial investment is higher, in the long run, it has better economic benefits due to its high production efficiency and high-quality output.
Summarize
Choosing a PVC-U extruder or a PVC-O extruder depends on the specific application requirements, production scale and budget. If you need to produce high-strength, high-performance pipes, a PVC-O extruder is a better choice; if you need low-cost, high-efficiency production, a PVC-U extruder may be more suitable.
