Feb 2024


What is container rain?

Container rain, also known as container sweating or container condensation, refers to the accumulation of moisture inside shipping containers. This phenomenon occurs when there is a temperature difference between the inside and outside of the container. Here’s how it typically happens:

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Temperature Difference

When warm air with high humidity enters a container, and the container’s temperature is lower than the dew point of the air, moisture in the air can condense on the cooler surfaces inside the container.

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Cargo Cooling

The cargo inside the container may also release moisture. For example, goods that have been stored at a higher temperature before shipping can cool down inside the container, leading to the condensation of moisture.

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Ventilation Issues

Insufficient or improper ventilation can contribute to container rain. If the container is not adequately ventilated, the trapped moist air has limited means of escape, and condensation becomes more likely.

Container rain can be problematic as it may lead to damage to the cargo, particularly goods sensitive to moisture, such as electronics, paper products, or certain types of food. To prevent container rain, proper ventilation, insulation, and the use of desiccants (moisture-absorbing materials) are common strategies. Additionally, maintaining the right temperature and humidity levels during transportation can help minimize the risk of condensation inside shipping containers.

How to prevent container rain?

Preventing container rain involves implementing strategies to control moisture and maintain suitable conditions within the shipping container. Here are some effective measures to prevent container rain:


Place desiccant packets or bags inside the container to absorb moisture and maintain a dry environment.

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Ensure proper container ventilation by using ventilated containers or installing vents to allow air circulation. This helps to equalize temperatures and reduce the risk of condensation.

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Insulate the cargo or container to minimize temperature variations. Insulation can help maintain a more consistent temperature and reduce the likelihood of condensation.

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VCI Packaging

Use Vapor Corrosion Inhibitor (VCI) packaging for metal items. VCI materials release chemicals that protect against corrosion caused by moisture.

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Proper Packing

Pack cargo in a way that allows for air circulation. Use pallets to elevate goods from the container floor, creating space for air movement.

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Temperature Control

Maintain a consistent temperature inside the container. Consider using temperature-controlled containers for sensitive cargo.
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Humidity Monitoring

Install humidity monitoring devices to track and control humidity levels. Regularly check and record humidity levels during transportation.

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Container Seals

Ensure that the container is properly sealed to prevent outside moisture from entering. Repair any damaged seals promptly.

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Avoid Overloading

Avoid overloading the container, as this can lead to poor air circulation. Allow sufficient space for air movement around the cargo.

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Container Conditioning

Consider using container conditioning systems that control temperature and humidity levels.

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Choose weatherproof containers and inspect them for any leaks or damage that could allow moisture entry.

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Pre-Shipment Inspection

Conduct pre-shipment inspections to ensure that the container is in good condition and free of defects that could contribute to moisture issues.

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