The filament winding process is a well-established and widely used method in the manufacturing of composite pressure vessels. Depending on the winding pattern, the process can be categorized into three basic types: spiral winding, circumferential (hoop) winding, and longitudinal winding. Each type offers different structural benefits and is often combined in practice to enhance overall vessel performance.

1. Spiral Winding
Spiral winding follows a geodesic path, forming an angle (typically between 10° and 90°) with the axis of the mandrel. This pattern provides both hoop and axial strength, making it suitable for both the cylindrical body and the heads of the vessel. One key requirement is that the polar openings at both ends of the vessel should be the same size to ensure winding symmetry.

2. Circumferential (Hoop) Winding
This pattern involves winding the fibers perpendicular to the mandrel axis, forming loops around the circumference. It primarily provides hoop strength but lacks axial reinforcement. For this reason, circumferential winding is rarely used on its own and is typically combined with other winding types. It is best suited for the cylindrical section of the vessel but not applicable to the head sections.

3. Longitudinal Winding
Also known as polar or planar winding, this pattern runs nearly parallel to the mandrel axis, with angles ranging from 0° to 25°. It is tangent to the polar openings and offers longitudinal reinforcement. This type of winding is applicable to both the body and the heads of the vessel and is particularly useful for short, thick-walled vessels or containers with asymmetrical polar openings.

Conclusion
Each winding pattern serves a distinct mechanical purpose:

Spiral winding balances axial and hoop strength.

Circumferential winding focuses on hoop strength.

Longitudinal winding enhances axial support.

In most applications, these winding types are combined strategically to meet structural and performance requirements, rather than being used individually.