A flange that passes all factory inspections perfectly can be rendered unusable after thousands of kilometers of ocean shipping and multiple transshipments due to improper packaging. Flange logistics packaging is not simply “putting in boxes” but an engineering discipline involving mechanics, corrosion protection, and quality management.
Seal Face Protection: The First Priority
The most vulnerable part of a flange is its sealing face—whether raised face, tongue & groove, or ring type joint. Any scratch or impact can make it impossible to achieve a seal on site. Packaging solutions:
- Plastic protection caps: For DN ≤ 300 flanges, use rigid polyethylene or polypropylene injection-molded caps that fit tightly over the seal face and secure with elastic clips. The inner side of the cap should have a resilient liner to avoid hard contact.
- Metal protection rings: For large diameter flanges, plastic caps lack sufficient strength. Use reusable metal rings that cover the seal face and are temporarily bolted in place.
- Special protection for Ring Type Joints: The groove edges of RTJ flanges are extremely vulnerable. Use annular plastic inserts specifically designed for RTJ,fully filling the groove and providing cushioning.
Scientific Setting of Rust-Free Period
The rust-free period for flanges depends on the relative humidity, temperature fluctuations during storage and transport, and exposure to marine aerosols.
- Indoor dry storage: Standard rust preventive oil or VCI paper provides 6–12 months of protection.
- Ocean container shipping: High risk of salt spray and condensation. Use VCI film encapsulation, add desiccants inside, and apply removable rust preventive coating on exposed metal surfaces. For stainless steel flanges, ensure packaging materials are halogen-free to avoid chloride-induced pitting.
- Long-term outdoor storage: Must use heavy-duty heat shrink film or vacuum packaging with desiccants, and perform regular inspections.
Structural Mechanics of Wooden Crates and Pallets
- Frame design: For large diameter thin-walled flanges (e.g., DN1000+), stacking flat can cause ovality under their own weight. Use vertical frames with each flange independently fixed on vertical supports.
- Internal partition: When multi-layer stacking, separate layers with foam board or corrugated board at least 25mm thick to prevent direct metal-to-metal contact between flanges.
- Center of gravity marking: For flanges weighing over 50kg, the crate exterior must show the center of gravity location and lifting points to avoid tipping during transport.
Compliance of Packaging Markings
Export packaging must comply with ISPM 15 standards (heat-treated or fumigated wood packaging) and display the IPPC mark. The exterior should clearly show: flange specification, quantity, order number, gross weight, net weight, center of gravity, moisture warning, fragile warning, etc.
Packaging Dimensions in Supplier Evaluation
When selecting a flange supplier, request a written packaging specification and evaluate the quality of their protection cap molds, as well as packaging test records (e.g., drop tests, vibration tests). A supplier willing to invest in packaging usually places greater emphasis on overall quality as well.
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