Shipping Gel Packs by Sea and Air: Packaging, Declaration and Heat Exposure

An exporter books 20 pallets of frozen gel packs to a distributor in Dubai, seals the reefer at -18°C, and opens it 26 days later to find 20 pallets of warm, slightly swollen pouches sitting in meltwater. The freight was fine. The product should never have been shipped frozen in the first place, and that decision usually gets made by whoever books the container rather than whoever understands the gel.

Ship them dry, not frozen

Gel packs are 91% water. Shipping them frozen means paying to move water across an ocean and then paying again to keep it cold for a month. Dry SAP powder plus empty pouches, or pre-filled dry pouches hydrated at destination, cuts freight mass by 80–85% and removes the cold chain from the shipment entirely. A 20-foot container that holds 18 tonnes of frozen packs holds 3 tonnes of SAP and film, which is the same number of finished packs once hydrated.

Some buyers cannot hydrate on site — they lack RO water or a freezer with capacity. In that case ship gel concentrate at 25–30% solids in 20 L drums and let them dilute. That is still 70% less water than finished packs and needs no cold chain.

Sea freight: the container is the problem

A dry container on a Middle East or West African run reaches 55–65°C inside during deck stow, and 45–50°C below deck in the tropics. That is fine for dry SAP in multilayer bags, which tolerates 60°C for weeks, but it destroys finished gel packs: the film softens, the gel stratifies, and the pouch takes a permanent set that ruins headspace. If you must ship finished packs, use a reefer at 5°C rather than frozen — it is cheaper than -18°C, avoids freeze damage, and keeps the gel homogeneous.

Humidity is the second sea freight issue. SAP powder is hygroscopic; a 25 kg bag left in a container through a monsoon crossing can take on 8–12% moisture and cake into a brick. Use foil-lined or PE-lined bags with a moisture barrier, put 500 g of desiccant in each 25 kg bag, and specify a pallet shroud. Caked powder still works but will not disperse evenly in a hydration tank, and uneven hydration is the root of half the complaints about gel consistency.

Air freight: paperwork is easier than the heat

Gel packs are not dangerous goods. Water-based SAP gel is non-hazardous, non-flammable and not regulated under IATA, so no shipper’s declaration is needed for the packs themselves. Carriers often ask for an MSDS or a non-haz declaration anyway, and some require it for anything described as a cooling pack, so keep a one-page SDS on file. The real air freight constraint is cost and cargo hold temperature: a freighter hold runs 5–15°C in flight but can hit 40°C on the ramp in July. Ship dry, and the question disappears.

Cartons, pallets and the moisture question. For dry SAP, use a 25 kg multiwall paper bag with an inner PE liner inside a 5-ply export carton, 40 bags per pallet, stretch-wrapped and strapped. Cartons should test to 12–15 kg compression after a 48-hour humidity conditioning, not fresh off the corrugator. For finished gel packs shipped at 5°C, expect condensation on the outside of the pouches as they leave the reefer; pack in a PE-lined carton so the carton does not soften, and tell the customer to let pallets stand 12 hours before opening.

Declare the HS code correctly — 3824.99 for the polymer preparation, 3926.90 for finished plastic packs — and put the hydration ratio on the commercial invoice so customs does not assume the shipment is a liquid. That one line prevents most of the holds we see at destination.

If you are setting up an export programme, start with a SAP grade that ships as a free-flowing powder and hydrates at destination; it is the version of this business that survives a 30-day ocean leg.