Most rust found on arrival is caused by condensation, not by sea water. You prevent it by keeping moisture away from bare steel: rust preventive on machined surfaces, a sealed wrap, enough desiccant and dry packing timber.
A closed container is not a dry place. As it heats in the sun and cools at night, the air inside reaches its dew point and water forms on the coldest surfaces. Heavy steel machines cool slowly and are often the coldest thing in the box. Moist timber and cargo in the same container add more water to the air.
The layers of protection
- The factory cleans the machine and removes coolant, cutting oil residue and fingerprints before packing.
- Machined and ground surfaces such as slideways, spindle noses, chucks and table tops get a rust preventive coating or tape.
- The machine is wrapped in VCI film or sealed inside an aluminium laminate barrier bag.
- Desiccant bags go inside the barrier, sized to the enclosed volume, the wrap type and the expected journey time.
- A humidity indicator card is placed where it can be read through a window or on opening.
- Crate timber is dry, and the crate stands on runners so it is not sitting in water on the container floor.
Barrier bag or VCI?
A sealed barrier bag with desiccant keeps humidity low by shutting out outside air. It suits long voyages, tropical routes and machines that will be stored after arrival. The bag must be heat-sealed, and any tear lets moist air in and soon overwhelms the desiccant.
VCI film relies on inhibitor vapour rather than an airtight seal. It is simpler to apply and is often enough on shorter routes. Many exporters combine the two. Read what VCI packing is for how it works and where it fails.
Desiccant quantity is often guessed. German standards such as DIN 55473 and DIN 55474 give a calculation method for desiccant units against barrier type and duration, and your packing contractor can apply it. Ask for the calculation, not just a count of bags.
On the shipping side
Container choice matters too. Ask for a clean, dry, undamaged box, and check the floor and roof for holes before loading. Avoid loading wet cargo or green timber in the same container. Container desiccant strips on the walls help with general humidity but do not replace protection inside the wrap.
Electrical cabinets need their own desiccant and should be closed and taped. Hydraulic power packs should be filled or sealed as the manufacturer instructs, so internal surfaces stay oiled.
If the machine will wait at the port or in storage, tell the factory. Packing for a straight delivery and packing for months in a yard are not the same specification. Crate construction is covered in export packing for machines.
Next step
We agree the rust protection specification with the factory and photograph each layer during loading supervision. To set this up for your shipment, book a free sourcing review.