Export Crating: When a Box Is Not Enough

A carton transmits every force applied to it straight into the contents. For machinery, electronics assemblies, castings, moulds, instruments and anything that will be craned or forklifted from awkward angles, you need structure: a case, a crate or a skid that takes the load and leaves the contents alone.

The three formats

• Closed case or box crate. Fully sheathed, usually plywood or OSB on a timber frame. Protects from weather, dust, light impact and casual theft. The default for high value cargo.
• Open crate. A frame with slatted or partial sheathing. Lighter and cheaper, allows inspection and ventilation, gives no weather protection. Suits heavy items where the structure matters and the contents are weatherproof.
• Skid or pallet base. The item bolted to a timber or steel base with no walls, sometimes with a shrink hood. For very heavy machines that provide their own structure and cannot be lifted any other way.

Note that plywood and OSB are processed wood and therefore exempt from ISPM 15. The solid timber frame, skids and bearers are not, and they must be heat treated and marked. A crate that is sheathed in exempt material and framed in untreated timber is non-compliant, and it is a common mistake.

Design points that matter

1. Bolt the item to the base. Not strapped, not wedged. Machinery must not move relative to its own crate, or it will destroy the crate from inside.
2. Design in the lifting method. Forklift pockets sized for real forks, or marked and rated sling points. If it can only be lifted one way, mark that clearly.
3. Mark the centre of gravity. An off-centre load lifted from the middle tips, and this is a safety issue as much as a cargo one.
4. Size the timber to the weight, not to the dimensions. A large light item and a small heavy item need different construction entirely.
5. Provide internal cushioning matched to the fragility of the contents, and let the item settle into it rather than compressing it.

Corrosion: the real enemy on ocean freight

A container crossing an ocean goes through repeated temperature cycles. Warm humid air trapped at packing time condenses on cold metal at night and re-evaporates by day, over and over, for five weeks. Bare or machined steel rusts. This is container sweat, and it ruins more machinery than impact does.

The standard answer is a barrier bag with desiccant:

• Wrap the item in a moisture barrier bag, a foil laminate that is genuinely impermeable to water vapour, and heat seal it.
• Enclose desiccant inside the sealed bag, quantified in units. One unit absorbs roughly 6 grams of water vapour at moderate humidity. The quantity needed is driven by the surface area of the barrier, the intended duration and the volume of air enclosed, and there are standard calculation methods for it. Guessing produces failures in both directions.
• Include a humidity indicator card visible through a window, so the receiver can tell at a glance whether the barrier held.

A barrier bag with no desiccant is worse than no bag, because it seals moist air in against the metal. Either do both or do neither.

For items that cannot be bagged, vapour corrosion inhibitors are an alternative: VCI film, paper or emitters release a compound that forms a molecular protective layer on metal surfaces. Simpler to apply, less absolute than a sealed barrier, and effective in an enclosed space.

Shock and tilt indicators

Small mechanical devices that latch permanently when the package experiences an impact above a rated g force, or is tipped past a set angle. They are worth fitting to high value crates for two reasons: they deter rough handling when clearly labelled, and they convert a later argument about whether the cargo was mishandled into a visible fact.

They do not prove damage, only that a threshold was exceeded. Note it on the delivery receipt if one has triggered, and record it before unpacking.

Getting it specified

1. State the weight, centre of gravity and lifting points to the crate maker. They cannot design without them.
2. State the transit: mode, duration, route, whether it goes on deck, whether it will be stored outdoors.
3. Ask specifically whether the solid timber elements are ISPM 15 treated and marked.
4. Specify the corrosion protection and the desiccant calculation, in writing.
5. Photograph the finished crate and keep the packing specification. See what cargo insurance does not cover, because insufficient packing is an exclusion and the specification is your evidence.