Most cargo moves in a standard dry container because standard boxes are everywhere and cheap. Special equipment exists for cargo that genuinely cannot: cargo that must be temperature controlled, cargo that will not fit through the doors, cargo that is liquid, cargo that breathes.
Before choosing any of it, understand the trade: special equipment is a much smaller global pool. It is not available on every lane, it needs to be positioned in advance, and if the box is damaged or late there may not be another one behind it. Book earlier than you would for a dry container.
Reefer
An insulated container with an integral refrigeration unit, drawing power from the ship, the terminal or a generator set on the road leg. Available in 20ft and 40ft, and the 40ft high cube is the workhorse of the trade.
Two things surprise first time users:
- Internal capacity is much smaller than a dry box of the same nominal size. Insulation and the machinery take real space, so a 40ft high cube reefer offers roughly 67 cubic metres against about 76 for a dry high cube, and internal height is reduced further at the machinery end.
- It holds temperature, it does not create it. Cargo must arrive pre-cooled. See reefer setpoints, ventilation and humidity.
Non-operating reefers, sometimes offered cheaply as dry cargo space, are just insulated boxes with the machinery switched off. They are fine for dry goods and are not a cold chain solution.
Flat rack
A platform with fixed or collapsible end walls and no sides or roof. For cargo that is too wide or too heavy for a standard container: machinery, vehicles, transformers, steel structures, boats.
Flat racks are rated for high payloads, often well above a dry container, and the cargo is lashed directly to the platform. Once cargo overhangs the platform in any direction you are into out of gauge territory, which changes the stowage position, the cost and sometimes the vessel. Read project cargo and out of gauge shipping before quoting.
Open top
A standard container with a removable tarpaulin roof and, usually, a removable door header. For cargo that must be craned in from above rather than forklifted through the doors: tall machinery, glass, pipes, timber.
Open tops are not weatherproof in the way a dry box is. The tarpaulin sheds rain but is not a seal, so cargo needs its own protection. Cargo protruding above the roof line is again out of gauge.
Tank container
A cylindrical pressure vessel in a 20ft frame, typically around 21,000 to 26,000 litres, for bulk liquids, chemicals, food grade products and gases. Tanks are highly regulated, require specific prior cargo history for food and pharmaceutical use, and many carry dangerous goods approvals for particular substances.
A tank is usually cheaper per litre than drums or IBCs in a dry container once volume is high enough, and it removes the packaging waste at the other end. Cleaning between cargoes is a real cost and a real lead time.
Ventilated container
A dry container with passive vents along the top and bottom rails, allowing air exchange without refrigeration. Traditionally the coffee container, and still used for cocoa and other agricultural products that need to breathe but not be chilled. It does nothing about temperature, only about moisture and gas build-up.
Flexitank
Not a container type but a large bladder fitted inside a standard 20ft dry box, carrying roughly 16,000 to 24,000 litres of non-hazardous liquid. Cheaper than a tank container for one way shipments of things like wine, juice concentrate, edible oils and latex. It is single use, it needs a suitable box and a fitted bulkhead, and not every carrier accepts them on every lane.
Choosing
- Does it need temperature control? If yes, reefer, and price the pre-cooling.
- Will it fit through the doors? If no, open top for height, flat rack for width or weight.
- Is it liquid? Tank if it is hazardous, repeated or needs to come back. Flexitank if it is a one way food grade shipment.
- Does it just need air? Ventilated, which costs little more than a dry box.
- Otherwise use a standard container, and check the fit with the container estimator.
