Plastic Pallets and Container Condensation: Separate the Moisture Decisions

A plastic pallet does not make a container dry. Even when the selected pallet does not contribute the hygroscopic moisture associated with wet timber, water can still come from the cargo, cartons, dunnage, packing atmosphere, rain during loading, a wet container, or temperature changes along the route.

The purchasing mistake is to ask one product question—“Is the pallet moisture resistant?”—and treat the answer as approval for the whole shipment. The useful decision is to separate the pallet from the moisture plan, then join both records before loading.

The IMO/ILO/UNECE CTU Code is a non-mandatory global code of practice for packing and handling cargo transport units. Its packing guidance treats wet cargo, moisture inherent in cargo, wet pallets or packaging, protective sheeting and calculated desiccant capacity as different issues. It does not say that changing one item removes every condensation risk.

Approve four things, not one material

Keep four approvals visible in the purchase and packing file.

A pallet quotation can support the first row. It cannot silently approve the other three.

Identify the moisture load before choosing a control

Start with what enters the closed cargo transport unit (CTU). Record whether the goods, cartons or dunnage are hygroscopic, temperature-sensitive, corrosion-sensitive, mould-sensitive or weakened by moisture. Note any process that can add water: washing, cooling, steam, fresh agricultural products, wet timber bracing, loading in rain, or moving cold goods into warm humid air.

The CTU Code explains that condensation may form on cargo or on the inside surfaces of a CTU when air reaches its dew point. Daily heating and cooling can create “container sweat” on walls or the roof; a cold cargo exposed to warm humid air can experience “cargo sweat.” These are route and temperature effects, not properties that a pallet rating can settle.

Do not replace this review with a generic litres-of-desiccant rule. If drying agents are considered, the CTU packing guidance says the required absorption capacity should be calculated. That calculation needs the real moisture load, journey duration, expected conditions, packaging system and product limits. A supplier’s product label is not the calculation.

Ask what the pallet can retain on its surfaces

“Plastic” is not a complete moisture description. Inspect the exact design.

• Can rain, wash water or condensation remain in deck pockets, ribs, closed cavities, label recesses or between nested pallets?
• Is the pallet dry when cartons are placed on it, including the underside and internal drainage points that can be checked?
• Can a smooth or wet deck change carton grip or unit-load stability?
• Do edge lips, plugs, reinforcement areas or damaged surfaces trap water or interfere with protective layers?
• Will the pallet move through washing, cold storage or outdoor staging before container loading?

These questions do not turn the pallet supplier into the moisture engineer. They prevent the pallet condition from being omitted from the packing record.

If transport stability also needs review, use the plastic-pallet load-shift guide . Moisture protection and restraint must work together: a film or sheet that blocks water may change friction, inspection access or ventilation.

Inspect the CTU and the loading moment

Before loading, the responsible operator should confirm that the chosen CTU is suitable for the cargo and route. Record at least:

1. CTU identity, type and inspection status;
2. clean and dry condition, including roof, walls, floor, doors, seals and any visible damage or previous-cargo residue;
3. weather and surface conditions during stuffing;
4. cargo, carton, pallet and dunnage condition at the time of loading;
5. stow, separation, restraint and any required clearance from walls or roof;
6. the approved moisture-control method, its design basis and installation responsibility;
7. photos or other permitted evidence defined by the responsible packing procedure; and
8. stop conditions for rain, leaks, wet packaging, unexpected temperature, damaged seals or a changed load.

The container–pallet handoff guide explains why a pallet report cannot replace the container packing approval. Add this moisture record to that same handoff instead of creating an isolated “dry pallet” certificate.

Do not let protective material create a second problem

Protective sheeting, liners, covers and sealed wraps can reduce direct wetting in a defined design. They can also trap moisture, restrict ventilation, hide damage or change how the load is restrained. The CTU Code specifically warns that sheeting or wrapping may promote mildew or other water damage when total moisture is too high.

For each protective layer, state:

• what source of water it is intended to control;
• whether it is vapour-open, ventilated or sealed;
• where collected water can go;
• how it affects carton compression, pallet grip and load restraint;
• who calculates and installs it; and
• how the receiver should open or remove it without exposing cold cargo too quickly.

“Use plastic wrap” is not a complete specification.

Plan the destination opening, not only the origin loading

Condensation can appear after arrival. A cold load opened immediately in warm humid air may collect moisture on the cargo. A sealed load may also reveal roof or wall condensate that formed during the voyage.

The receiver should know the shipment’s relevant temperature history, cargo sensitivity and protection design. The arrival plan should say who inspects the CTU before opening, what wetting or staining triggers a hold, whether acclimatisation is required, how damaged cartons are isolated, and which carrier, insurer, quality or safety procedure applies.

Do not improvise by resealing, heating, drying or releasing affected goods when product safety or quality depends on a controlled decision.

Copy-ready RFQ and packing handoff

Send the same boundary to the pallet supplier and the party responsible for packing:

Cargo: product, packaging, moisture sensitivity, starting temperature and condition, maximum unit-load mass and footprint.
Route: origin, destination, mode, expected duration, climate transitions, holds and unpacking environment.
Pallet: exact model, revision, dimensions, material route, deck/base design, drainage or retention points, handling and support conditions.
Packing: CTU type and inspection, loading weather, dunnage, stow, restraint, covers or liners, ventilation or sealing strategy.
Moisture control: identified sources, calculation owner, control method, installation check, monitoring where required and stop conditions.
Arrival: inspection, acclimatisation or opening instructions, hold criteria and responsibility for exceptions.
Evidence boundary: state which answers come from the pallet supplier, packer, forwarder, carrier, receiver or specialist.

Use this alongside the broader plastic pallet buying guide so moisture control does not displace load, rack, forklift, conveyor or receiving requirements.

The purchasing rule

Approve the pallet as one component. Approve the moisture-control and CTU packing plan as a separate route decision. Then verify that the two plans can operate together with the real cargo, packaging, weather, container and destination opening method.

When requesting a pallet recommendation, send the load, route and container conditions . Baoheng can help compare pallet structures and provide available model information; the responsible packing and transport parties must approve the complete moisture plan.