Desiccant for Metal Parts and Machinery Exports

Metal parts, tools and machinery corrode when the air around them stays damp and when condensation forms on cool surfaces during a voyage. The fix is the same two-layer approach used for other moisture-sensitive cargo: keep moisture out of each pack with a desiccant such as silica gel, and keep the whole container dry with a container desiccant. Without the second layer, container rain will undo the first.

Why Metal Rusts in Transit

• Condensation (container rain). Steel cools faster than the cargo. Through a day–night cycle the roof drops below the dew point of the internal air and water condenses on the ceiling, then drips onto the load.
• Damp packing materials. Wooden pallets, crates and cardboard carry their own moisture, which is released into the sealed container and finds the metal.
• Temperature swings across climate zones. A route that passes from cold to hot and back creates repeated condensation cycles on bare metal surfaces.

Machinery is especially exposed because it presents many bare, cool, high-surface-area parts — shafts, bores, bearings, chains and electrical parts — any of which can show surface rust before you see it anywhere else.

Layer 1: Inside the Pack

For individual machines, spares and boxed parts, use a desiccant sachet inside the packaging, sized to the internal volume of the pack rather than the weight of the part. Two products cover most of these jobs:

• Industrial desiccant sachets — made from narrow pore silica gel, Type B silica gel, colour-indicating silica gel, active mineral balls, montmorillonite and molecular sieve, so you can match the grade to the packed product. Supplied from 0.5 g up to 1000 g, in composite paper, tea paper, non-woven, OPP film, DuPont paper and Aihua paper.
• Montmorillonite (clay) desiccant — a naturally inert mineral desiccant that is non-flammable and not classified as dangerous goods for transport, listed by us for machinery, tools and metal parts. It holds moisture by physical adsorption with no liquid by-product, so there is nothing to leak onto the goods.

For high-value machines, wrap the item first in a moisture-barrier film or a sealed bag, then place the desiccant inside that barrier — a sachet loose in a cardboard crate that is itself open to the container air does far less.

Layer 2: The Container Itself

The second layer protects the whole load and is what stops container rain reaching the cargo at all. Calcium chloride container desiccant is the usual choice: it absorbs more than 300% of its own weight, keeps working from 20% to 100% relative humidity, and is hung from the container walls so it intercepts moisture where the condensation forms. We set out how much a 20ft or 40ft load needs, and where to hang it, in our container desiccant guide.

If cost is the deciding factor on large volumes of ordinary parts and the climate is not extreme, a clay desiccant can be the cheaper option; for the container layer on a long, humid route, the higher-capacity chloride units are normally worth the difference.

Packing Practice That Prevents Most Claims

• Never load wet or damp packing. Use kiln-dried wood and dry cartons only.
• Protect machined surfaces first. Barrier wrap goes on before the desiccant and before the crate is closed.
• Size for the hottest condition. Physical adsorbents hold less water as temperature rises, so a container in direct sun needs more, not the average.
• Add a humidity indicator. A humidity indicator card sealed inside proves on arrival whether the protection held.
• Inspect the container before loading. A leaking container or a torn door seal defeats any desiccant.

What to Put on the Enquiry

Tell us what is being shipped (bare parts, boxed spares or complete machines), how it is packed, the container size, the route and the voyage length, and the destination climate. That is enough for us to recommend the in-pack sachets and the container desiccant quantity, and to quote on request.