Automatic High Pressure Biaxially Oriented PVC-O Pipe Extrusion Machine for Water Supply

PVC-O (Biaxially Oriented PVC) pipe is a high-strength PVC pipe created by molecularly orienting PVC-U (unplasticized PVC) in both the hoop and axial directions. This orientation significantly improves its mechanical properties, including impact resistance, fatigue resistance, and hydraulic capacity, while allowing for thinner walls and material savings compared to traditional PVC-U pipes.

The fundamental process is Extrusion-Stretch Orientation. A thick-walled PVC-U base pipe is first extruded. It is then precisely reheated to an 'orientation temperature' below its melting point. Finally, it undergoes sequential biaxial stretching: first diametrically (hoop direction via internal pressure) and then axially (longitudinal direction via pulling).

Molecular alignment in both hoop (circumferential) and axial (longitudinal) directions, achieved by controlled expansion and stretching, enhancing mechanical properties.

Stretching aligns the long polymer chains and increases crystallinity. This distributes stress more efficiently throughout the material, eliminating weak points and significantly increasing toughness and resistance to crack propagation.

Changing pressure class typically requires changing the precursor pipe's wall thickness and the stretch ratios. This involves significant tooling and process parameter changes, not just a simple speed adjustment.