PTI and gensets: what to check when shipping a reefer container

A working refrigeration unit cannot maintain its settings without a power source after the container leaves port. A running generator will not solve the problem either if the container has the wrong setpoint or the goods were not prepared for transport. Reefer container shipping requires agreement on equipment readiness, cargo-specific settings and power throughout the route.

PTI stands for Pre-Trip Inspection, a check of reefer equipment before a shipment. A genset is a generator set that supplies electricity to the refrigeration unit where suitable external power is unavailable. PTI records the outcome of a check; the genset provides a source of energy. Neither, on its own, guarantees the condition of the consignment.

The general equipment design and applications are covered in our guide to reefer containers in international shipping. This article focuses on practical checks before loading, terminal collection and handover to the next transport operator.

Obtain PTI confirmation before equipment release

PTI is arranged under the equipment owner’s or operator’s procedures. It may include a container inspection and refrigeration diagnostics covering components, sensors, controls and specified test routines. The scope depends on the model and maintenance programme. A PASS result relates to the checks completed; it is not a promise of fault-free operation for the entire journey.

Request the container number, inspection date and result, service provider and confirmation that identified faults have been addressed. If the operator uses another accepted system for establishing equipment readiness, confirm its status for this shipment. There is no universal PTI validity period or inspection duration that should be applied to every shipping line.

At collection, match the equipment number to the confirmation and establish the status of active alarms. Record visible damage and handover remarks separately, following the principles described in our article on EIR and container condition records. An equipment interchange record and a refrigeration performance check serve different purposes.

Do not initiate a full automatic PTI with temperature-sensitive cargo inside the container. The routine may interrupt normal temperature regulation and run diagnostic cycles. Any diagnostics on a loaded container should be agreed with a service technician under the instructions for that equipment.

Provide one agreed set of temperature instructions

Before the empty container is positioned, the shipper should supply the information needed to prepare it. The working instructions identify the commodity, required setpoint, measurement units and applicable fresh-air ventilation and humidity requirements. Controlled atmosphere and special operating modes require separate confirmation of availability and settings.

The controller setpoint and the cargo’s permitted temperature range are different values. “Keep chilled” does not define an equipment setting, and a generic temperature range from an article cannot replace the product manufacturer’s instructions. Our guide to temperature control in road and container logistics explains the broader principles.

Check the temperature sign and the °C/°F scale. Fresh-air exchange in m³/h should not automatically be treated as a vent-opening percentage. Fresh-air ventilation also differs from air circulation inside the container. The booking, shipping line’s instructions and actual settings must agree. Communicate changes to every responsible party and obtain acknowledgement.

Prepare the cargo and loading arrangement

Present the goods at the temperature required for carriage. Do not plan for an ordinary transport journey to replace the process of cooling or freezing a warm consignment. Record the product’s initial condition and the agreed measurement method so that a preparation issue can be distinguished from a deviation during transit.

Preparing cargo temperature and pre-cooling the empty container are separate operations. The latter depends partly on the loading environment. Opening a cold container in warm, humid air can introduce moisture; the mechanism is discussed in our article on container condensation. Follow an agreed procedure that considers the availability of a refrigerated loading bay and the time doors remain open.

Keep the designed supply and return airflow paths clear, respect the load line and agree how packages will be positioned on the T-bar floor. “Leave plenty of gaps” is not a universal loading rule: empty spaces can let air bypass the cargo. For ordinary loading with open doors, Hapag-Lloyd recommends switching the unit off, then checking settings and restarting after the doors are closed. Follow the operator’s agreed instructions for the particular shipment.

Check the genset with the reefer connected

On a vessel or at a terminal, the container normally receives external electrical power. For inland transport, agree the energy source in advance, such as a clip-on genset or an undermount unit fitted beneath the container chassis. A built-in refrigeration unit does not mean that an autonomous generator is already included in the order for container transport by road.

Agree five checks before departure:

• Compatibility between the generator and refrigeration unit, including electrical requirements and connection arrangements, confirmed by a competent technical specialist.
• Genset mounting, the condition of accessible cables and connectors, and any visible damage or leaks. Trained personnel must make the connection.
• Operation under the actual load: both the generator engine and refrigeration unit are running, with the operating mode and alarm messages checked.
• Fuel for the planned operating period, waiting time and an agreed reserve, together with the location and responsibility for refuelling. Use consumption information for the actual equipment and conditions.
• Responsibility for checks in transit and access to service support if a fault occurs. Telematics and fuel alerts must be confirmed features of the equipment selected.

The sound of a running genset engine does not prove that the reefer is receiving power. Complete the handover by confirming that the connected equipment operates correctly. Connections and technical checks must follow the manufacturer’s manual, without unauthorised intervention in electrical circuits.

Plan the power handovers along the route

For ocean container shipping, connect the power arrangements on the vessel, terminal, truck or rail leg before the shipment moves. At every handover, identify who disconnects the previous source, who connects the next one, who confirms refrigeration operation and where the time and outcome are recorded.

At the terminal, establish plug-in availability, monitoring arrangements and the process if collection or an inspection is delayed. Include coordination of these activities in the scope of port forwarding services. Agreeing only the container truck’s arrival date leaves a gap if the unit is disconnected from terminal power and then waits before departure.

An illustrative collection from Gdańsk to Ukraine

The container is ready for collection, but the truck’s departure is postponed. Agree continued terminal power before disconnection. Once the container is on the chassis, confirm operation with the genset, fuel availability and the arrangements for a border queue. The destination warehouse confirms that it can receive the cargo or provide suitable power if the vehicle must wait.

This is a planning example, not a completed customer case. There is no single safe number of hours without power for every cargo. Whether an interruption is acceptable, and its limits, must be established for the product and shipment concerned. Brief operational disconnections during transfers also belong in the journey record.

Read temperature data alongside operational events

Setpoint is the selected control setting. Supply air is the air delivered into the cargo space; return air is the air flowing back to the refrigeration unit. These readings are not measurements inside every package. Where cargo probes or independent data loggers are needed, agree their type, placement and retrieval before loading.

A short rise in a reading may coincide with defrost, door opening or a power interruption. Check the context instead of immediately concluding that the goods have deteriorated. Retain original controller records, alarms, setting changes and power handovers with clear dates, times and time zones.

A gap in online updates does not necessarily mean refrigeration has stopped. Transmission delays or a loss of connectivity may explain it. Confirm which monitoring and alert functions are available under the selected service, and request a local check if the status is uncertain. One display photograph cannot describe the temperature history of a whole journey.

Follow the agreed response process when an alarm occurs

The responsible party records the container and genset identifiers, time, location, alarm code, setpoint and available actual readings. They then contact the dispatcher, equipment operator and service provider. Where the cargo’s condition may have been affected, notify the customer and preserve the information needed for assessment.

Do not lower the setpoint to “make it colder”, erase messages or repeatedly restart equipment without an agreed reason. The technical specialist determines the appropriate action, such as restoring power, arranging a repair or replacing the generator. Cargo suitability must be assessed against product requirements and actual evidence, rather than a PTI result alone.

Include equipment checks and power in the transport request

For a quotation for temperature-controlled cargo transport, send Save Pro Solutions the route, commodity and packaging, weight, readiness date, temperature requirements, ventilation instructions and monitoring needs. If a container has already been assigned, include its number, readiness confirmation and current power status.

Agree separately how PTI, genset provision and return, fuel, terminal power and monitoring will be arranged. Whether these items are included in the rate depends on the transport plan. Before confirming the journey, establish the responsible parties on each leg and the contact procedure for a delay or equipment fault.