Circular Pultrusion Die

Circular pultrusion die produces FRP round tubes, pipes, and cylindrical profiles for corrosive fluid conveyance, structural columns, and handrail systems. The die features a large circular opening at the exit, machined into a square steel block for rigid mounting.

Profile Range

The die produces FRP round tubes with outer diameters from 25 mm to 200 mm and wall thickness from 3 mm to 10 mm. The internal mandrel controls the inner diameter, while the outer die controls the OD. Lengths are cut to order, typically up to 12 m per piece.

Die Construction

The die block is precision-machined from tool steel, with the circular cavity bored and honed to a fine finish. An internal mandrel, supported from the die entrance, forms the inner diameter. Heating cartridges surround the cavity to maintain cure temperature. The square mounting block bolts directly to the pultrusion machine's die holder.

Applications

• FRP process pipes for chemical drainage, ventilation, and corrosive fume exhaust.

• Handrail tubes and safety railing components in corrosive environments.

• Structural columns and support posts for platforms and walkways.

• Downtake pipes and scrubber headers in air pollution control systems.

• Electrical conduit and cable protection tubes.

Material and Performance

FRP round tubes are pultruded from vinyl ester or polyester resin with E-glass reinforcement. They are corrosion-resistant, lightweight, and non-conductive. For high-pressure applications, filament-wound FRP pipe is preferred; pultruded round tubes are typically used for low-pressure gravity flow and structural purposes.

Conclusion

The circular pultrusion die is a fundamental tool for producing FRP round tubes. Precise mandrel alignment and uniform heating are essential for concentricity and consistent wall thickness.