In Focus: How Are Container Flexitank Produced?

Production Process of a Container Flexitank

1. Raw Material Preparation

• High-strength, food-grade polyethylene (PE) or polypropylene (PP) is selected as the main material, often in multiple layers for puncture resistance.

2. Film Extrusion

• The resin is melted and extruded into thin, uniform films through a blown film extrusion line. Multiple extruders may produce co-extruded layers (e.g., outer UV-resistant layer, middle barrier layer, inner liquid-contact layer).

3. Lamination (Optional)

• For added strength, some flexitanks incorporate a woven polypropylene fabric laminated between PE layers. This is done using heat or adhesive lamination.

4. Welding / Seaming

• The film sheets are cut and welded together using hot air or high-frequency welding to form a large, pillow-shaped bag. Key seams (bottom, side, and filling/discharge ports) are reinforced for burst resistance.

5. Accessory Installation

• Valves and ports (filling, venting, and discharge) are heat-sealed or clamped into the bag.

• Anti-spill caps and dust covers are added.

• Optional features like anti-static layers or temperature sensors may be integrated.

6. Quality Control

• Air pressure test (inflated to ~0.2–0.3 bar, held for 30 minutes to check for leaks).

• Dimensional inspection (to fit standard 20-ft containers).

• Puncture and tensile strength tests on sample patches.

• Every bag undergoes:

7. Folding & Packaging

• Corrugated cardboard liners (for container floor protection).

• User manual, gloves, and repair patches.

• Installation straps (to secure the bag in the container).

• The bag is carefully folded to minimize creasing, then packed into a carton or shrink-wrap with:

8. Final Lot Traceability

• Each unit is labeled with a batch number, production date, and certification (e.g., ISO 9001, FDA, or kosher approval for food-grade).