What is aluminium barrier packing for export?
Packing that encloses cargo in a heat-sealed multi-layer laminate containing aluminium foil so water vapour transmission into the sealed free volume is very low, allowing desiccant and VCI to work over long voyages.
Is vacuum packing required for all machinery exports?
No. Many machines are successfully packed with sealed aluminium barrier bags plus calculated desiccant. Vacuum is used when storage is long, contents are highly moisture-sensitive, or the method sheet requires it.
What is MIL-PRF-131 in commercial packing?
A U.S. military performance specification family for flexible barrier materials often used as commercial reference language for foil laminates. Match any MIL claim to the certificate of the exact grade supplied.
Can I use stretch film instead of foil laminate?
Stretch film unitises loads. It is not a long-voyage moisture barrier for bright metal on tropical or multi-week ocean routes.
Where does desiccant go?
Inside the sealed free volume before final seal. Desiccant taped outside the bag is decorative, not functional.
Does barrier packing replace VCI?
No. Barrier controls atmosphere exchange. VCI protects metal surfaces inside that atmosphere. They work together.
Does barrier packing replace a wooden crate?
No. The bag is the moisture envelope. The crate or skid provides structure, lift interfaces and phytosanitary wood compliance when solid wood is used.
How do I size desiccant for a barrier bag?
From free air volume, film permeability assumptions, hygroscopic materials and voyage duration using industrial desiccant unit methods such as DIN 55473 practice. Record the count on the packing instruction.
Is vacuum always better than a sealed aluminium bag?
No. Vacuum reduces free air and can help long storage or method-sheet requirements. Many ocean machines are correctly packed with continuous-seal foil plus sized desiccant without vacuum. Choose by cargo sensitivity, equipment availability and written method, not by marketing preference.
Why did metal rust inside a “barrier bag�
Common causes: wet metal at seal, open corner seals, pinholes from sharp edges, desiccant outside the bag, poly film mislabeled as barrier, or voyage-plus-storage duration beyond desiccant design. Investigate the full system, not only the bag brand name.
Do barrier bags need ISPM-15?
The bag itself is not solid wood packaging material. Outer pallets, crates, skids and blocking that use solid wood still need ISPM-15 treatment and marks when used in international trade.