PVC-O Pipe Manufacturing Process

The manufacturing process of PVC-O (Oriented Unplasticized Polyvinyl Chloride) pipes involves enhancing the molecular orientation of PVC to improve strength and durability.

The following is the PVC-O pipe manufacturing process:

1. Material Preparation

Raw Materials: PVC resin is combined with additives such as stabilizers (to prevent thermal degradation), lubricants (to aid processing), and pigments (for color).

Mixing: Ingredients are homogenized in a high-speed mixer to ensure even distribution.

2. Extrusion of Preform

Process: The mixture is fed into an PVC-O pipe extruder, where it is melted and shaped into a thick-walled PVC-U (unplasticized) pipe, known as a “preform.”

Cooling: The preform is cooled to solidify its initial structure, typically using water baths or spray systems.

3. Reheating for Orientation

Temperature Control: The preform is reheated to a specific temperature (below melting point) where the polymer chains become mobile but not fluid, enabling molecular rearrangement.

4. Biaxial Orientation

Expansion: Internal pressure (via air or mandrel) radially stretches the preform into a mold, increasing diameter and reducing wall thickness. This induces hoop (circumferential) orientation.

Axial Stretching: Simultaneously, the pipe may be stretched longitudinally to enhance axial orientation, though hoop orientation is primary for pressure resistance.

5. Quenching

Rapid Cooling: The expanded pipe is quickly cooled (e.g., water quenching) to lock the oriented molecular structure, ensuring enhanced mechanical properties.

6. Finishing and Quality Control

Cutting and Marking: Pipes are cut to standard lengths and marked with specifications.