Reefer, Open Top and Flat Rack Containers: What Needs Checking?

A reefer is an insulated container with its own refrigeration unit, designed to hold the interior at a set temperature. It carries temperature-sensitive cargo such as fruit, vegetables, meat, dairy products and certain pharmaceuticals and chemicals.

The unit needs power wherever the box is: reefer sockets at the terminal, reefer slots on board and a generator set (genset) on the road. Every period without power is a moment of risk for cargo temperature.

Within supervision, reefer checks are generally limited to external observation of the unit. Displayed values and the general condition of the unit are recorded.

A PTI (pre-trip inspection) is a technical check confirming the reefer unit is in working order before loading. It is usually done by the container owner or the line and may be evidenced by a label on the box. A unit without a PTI carries a higher risk of failure during the voyage.

There is a common misunderstanding about pre-cooling: a reefer is designed to maintain cargo temperature, not to bring warm cargo down. Cargo should be packed at or near the required temperature. Whether the container itself should be pre-cooled depends on the cargo and loading conditions; a pre-cooled box with doors open in warm air can build up condensation.

Open tops are used for cargo that must be crane-loaded from above or that exceeds standard container height. The top is closed with a tarpaulin stretched over removable roof bows.

The check covers tears or holes in the tarpaulin, whether it is passed through every securing ring and whether the TIR cable is correctly fitted. If cargo protrudes above tarpaulin level, the box is treated as out-of-gauge and stowed accordingly. A loose tarpaulin can let water reach the cargo during the voyage.

Flat racks are platforms without side walls, used for heavy or bulky items such as machinery, transformers, large pipes or steel structures. Cargo that exceeds the container's width or height is described as out-of-gauge (OOG).

Lashing and securing are the main concern. The number, angle and condition of chains, slings or lashing straps, the dunnage under the cargo and how evenly the load is distributed on the rack are all observed. The CTU Code is the widely used reference for securing cargo in or on a container.

For reefers, the time between unplugging on board and reconnecting at the terminal matters. A reefer left without power for long, especially in hot weather, may see cargo temperature drift, so plug-off and plug-in times should be logged.

For flat racks and open tops, the check focuses on whether lashings have slackened during the voyage, tarpaulin damage and any sign of seawater on the cargo. Out-of-gauge cargo usually needs special lifting gear, which raises the risk of handling damage.

Checks on special containers are usually requested in addition to standard container supervision. Set point instructions for reefers, and cargo details and handling instructions for flat racks and open tops, should be shared before attendance. Measuring cargo temperature inside a reefer is a separate scope.

Karan Gözetim provides container loading and discharge supervision from Gemlik; the scope of special container checks is agreed at the quotation stage.