Guide To Protect Your Cargo from Moisture Damage
Shipping in containers is an economical and safe way of shipping most types of cargo. But putting cargo into a enclosed steel box also entails a constant risk of moisture damage for almost every kind of cargo on every voyage.
- Metals corrode, discolor and lose their shine
- Cargo and packaging get moldy, soft, crumbled and discolored
- Bad odor
- Physical damage from water, ice, caking etc
The pattern of moisture damage may seem random. The moisture processes are examples of strongly non-linear physics. That means that very small differences in the cargo and voyage conditions can have a huge effect of the outcome. That is why you may have four perfectly safe shipments and the fifth may be a disaster. This means that there is always a risk of moisture damage in the next shipment, even if the last one arrived ok.
Moisture Damage can be Prevented
All containers contain moisture from the time of loading. No container is completely airtight. Moisture will move in and out of the container during the course of the voyage known as “Container Breathing”. The objective of a moisture protection program is to prevent the buildup of moisture in the air to levels where it may cause damage. This is done by reducing the amount of the moisture entering the container and by using “Humidity Absorbers” to remove moisture from the air.
Is the ContainerAirtight?
A minimum requirement is that the container should be watertight without any risk of rain and spray.
- This should be checked for every container before loading. Especially the doors as they are vulnerable to damage that may not easily be noticed.
- Check the seals. Certainly no container is airtight, but a container in good condition only allows air and moisture to move in and out of the container slowly.
- This significantly reduces the amount of moisture moving into the container under common circumstances. (Container Breathing)
- Tape the vent holes if you are shipping a dry cargo.
- For a moist cargo, such as agricultural commodities, it may in certain circumstances be better to leave the ventilation holes open.
Is the Container Dry?
A container that has been washed before loading, brought in from outside into a warm loading area or stored in a humid place, may contain a lot of water. In particular, attention must be paid to the container floor.
- The humidity of the wood should not be above 15%.
- All pallets and other wooden dunnage must be dry.
- Preferably the moisture content should not above 15% and certainly not above 20%.
- It is easy to check the moisture content of the wood with a handheld moisture reading device.