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Moisture Control in Shipping Containers Whoever has opened a shipping container only to find his valuable cargo rusted, moldy and dripping with water can readily appreciate the dangers of moisture in container transports. Most cases of moisture damage are far less severe – peeling labels, spotted surfaces or soggy packaging-, but are nonetheless unacceptable. Every year thousands of shipments arrive damaged, causing losses of millions of dollars from lower quality as well as additional costs for handling and administration. And in most cases such damage is not even covered by the insurance.

The root cause of moisture damage in container transport is the simple fact that warm air can hold more moisture than cold air. Take the dewy grass in the morning after a cool summer night as an example. Moisture gets into the air in the container from the outside or by evaporation from the cargo.

Moisture is great for chocolate cake, but not for Sea Containers! Moisture damage happens even where there is no condensation. Many grades of steel will start to corrode at a relative humidity of about 70%. Mould growth could begin after even a short period over 80%. The only remedy is to keep the air inside the container dry. The first thing to do is to ensure that the cargo and all the packaging are as dry as possible. A wet container floor or some pallets stored in the rain may be enough to ruin a cargo. No container is airtight whatever you do; – it will “breathe” as a result of temperature cycles. When the air inside the container cools, the pressure drops. Air – and moisture – moves in from the outside to equalize the pressure. The opposite happen when the air inside the container heats up, but it is easy to show how a repeating cycle of breathing can cause a build up of moisture inside he container, especially if there is absorbing packing materials. Using a container with good seals and vents taped shut will slow down, but not stop- the “container breathing”.

• Sea Containers is an economical and safe way of shipping almost any kind of cargo. But putting a cargo into a closed strong box also entails a constant risk of moisture damage for every kind of cargo on every voyage, which you can check for using this helpful moisture damage checklist. • – Metals corrode, discolour and loose their shine – Cargo and packaging get moldy, soft, crumbled and discoloured. – Bad smell – Physical damage from water, ice, things gluing together, caking etc.

Moisture Damage can be Prevented • Is the Container Tight? A minimum requirement is of curse that the container is watertight against rain and spray. That is usually the case, but especially the bottom side and the doors are vulnerable to damage that may not be noticed. Check the seals. Certainly no container is airtight, but a container in good condition allows air (and moisture) to move in and out of the container only slowly, over hours perhaps. That 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 is usually better to leave the vent 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 lots of water. In particular, attention must be paid to the container floor. The humidity of the wood should not be above 18%. All pallets and other wooden dunnage must be dry. Preferably the moisture content should not above 18% and certainly not above 20%. It is easy to check the humidity with a small handheld device commonly used in the construction industry and costing a couple of hundred dollars.

Substances that remove moisture from the air are called “Desiccants”. The most widely used desiccants are probably “Silica Gel”, a kind of porous glassy substance that adsorbs moisture well under the right conditions. When used in containers they are fatally flawed in that they work best at room temperature, and not at all at the much higher temperatures often found in containers. Other widely used desiccants based on Clay work to a little higher temperature, but then similarly fail in an even more dramatic way.

Desiccants based on Calcium Chloride, have a vigorous absorption over a large temperature range. Desiccants based on a mixture of clay and calcium chloride or Tyvec pouches with calcium chloride are very good absorbers, but easily “over saturate”. If an “over-saturated” absorbent meet dry conditions, e.g. as a result of a sudden increase in temperature, it will re-evaporate the moisture already absorbed in a very destructive way. Only calcium chloride absorbers that sequester the absorbed moisture to keep it from contact with the air are free of this problem The important thing to remember is that there is always a risk of moisture damage in the next shipment, and one needs to implement a moisture protection program that will prevent the build up of moisture in the air to levels where it may cause damage. To design an efficient moisture protection requires finding the most economic balance between packaging, container desiccants and in-packaging desiccants, taking into account not only the individual package, but how it is stuffed and combined throughout the logistic chain.

Thank You For more information about our Moisture Solution Products. 304-307, III Floor, Prayosha Complex, Chhani Jakat Naka Vadodara- 390024, Gujarat, India. Tel : +91-265-2761041 / 2761042 Toll Free No. : 1800-233-2677 Visit Us At :

Reference Links • • • • • • • • • • • • • • • • • • • • •

How to keep moisture out of storage containers pharmadesiccants  

Container desiccant is considered as the most effective and safe way to keep your products away from damage that may arise from humidity & m...

How to keep moisture out of storage containers pharmadesiccants  

Container desiccant is considered as the most effective and safe way to keep your products away from damage that may arise from humidity & m...