About moisture and condensation in shipping containers

Piccolo 1000 300x300 About moisture and condensation in shipping containers

Q: How do Nordic absorbers help to solve moisture problems?

Nordic absorbers contain Calcium chloride that very aggressively grab and absorb moisture from the air. They dry the air. When the air is dry, there are no moisture problems.

Q: Can Nordic absorbers solve all moisture problems?

Well, not all. Some cargoes may be so wet that any reasonable number of Nordic absorbers get overwhelmed. But Nordic absorbers can reliable protect even very difficult cargoes that may contain tons of moisture, such as coffee beans, wood products or paper.

Q: I load my container under dry conditions and it is very tightly sealed. How come I still experience moisture problems?

Your cargo or the packaging, including container floors, pallets and crates, contain moisture that is evaporated into the air during transport. Wet packaging material is the most common cause of unexpected moisture problems.

Q: I have shipped the same cargo for years with Nordic absorbers without any trouble, but now I have a lot of damage. Have you changed the poles?

Check your container and your packaging material. Did you just start to store your pallets outdoors? Does your forklift drive into the container with snow on the wheels? Did you just change supplier of crates? You can’t tell by looking whether wood are carton is dry. The moisture properties of wood and cartons have an exponential character. It makes a huge difference if your pallets moisture content should be 20% instead of 17%, say.

Q: I ship consumer goods in tubes/cans/jars etc that contain no moisture, yet I still have problems.

Consumer goods are often shipped with a lot of cardboard packaging. Even if the boxes seem dry they could literally hold tons of water.

Q: Each container of my cargo of peanuts/coffee/cocoa contains tons of moisture. What difference does it make that Nordic absorbers absorb a few litres during a voyage?

All the important things that happen have an exponential character. That means that a small change in circumstances can have a huge effect on the outcome. Nordic absorbers create circumstances that allow almost all of the moisture to remain in the cargo even while the level of humidity in the air is lowered by a crucial amount, sufficient to prevent damage. It is a question of ”leverage”.

Q: Does it make a lot of difference that my cocoa beans have a moisture content of 8% instead of 7%?

Yes, such a difference could be all the difference between no damage and disaster. The moisture behaviour of most agricultural products have a strong exponential character.

Q: My cargo of peanuts had suffered damage in the centre even though the outside of the cargo looked fine and there was were no signs of condensation?

Lots, if not most, damage to cargoes is caused by prolonged periods of elevated humidity without any condensation (Container rain, Container sweat, Super Saturation Event). It is common that cargoes loaded at cool temperature and then moved into warm condition suffer damage in the centre of the cargo as a result of a difference in temperature between the outside and the centre of the cargo. Warm air from the outside of the cargo becomes humid as it moves into the cooler centre. Nordic absorbers protect against this effect even though the absorbers are mounted on the container walls.

Q: I had damage to my cargo even though I used lots of silica gel and there was no condensation. Would it help to switch to Nordic absorbers?

Calcium chloride absorbs moisture even when the humidity is not very high. This protects the cargo against damage caused by prolonged periods of elevated humidity. Some kinds of steel start to corrode at 70% relative humidity, moulds can grow at 80% relative humidity and at near 90% relative humidity lots of things go wrong. Yet, Nordic absorbers are also at their most efficient protecting against condensation. Most other products, such as silica gels, are really effective only in very humid conditions and in protecting the cargo against condensation damage.

Q: What is so great about Nordic absorbers anyway?

Well, they will not fall off the wall, get punctured during loading and unloading, leave a wet puddle on the cargo or run out after half the voyage. They are installed in seconds without ladders and take up no cargo space. The capacity of each absorber is big, so fewer is required. The cost of an installation is very competitive, even against much inferior alternatives.

Q: How many absorbers do I need?

The number of Nordic absorbers required to protect the cargo depends on the cargo, the temperature conditions during the voyage, the length of the voyage – and just how safe you want to be. For some really dry cargoes e.g.. steel coils or household removals, 2-3 Nordic absorbers are enough. For a lot of ”normal” goods 4-6 Nordic absorbers is about right. Some cargoes with very difficult moisture properties on long voyages may require up to 16 Nordic absorbers.

Q: Do I need to line my container with kraft paper?

Lots of containers are lined with Kraft paper primarily for reasons of hygiene or to simply isolate the cargo from direct contact with the container walls. The liner will act as a kind of sponge, catching and absorbing any droplets of water and then re-evaporating the moisture into the air. If liner is used without Nordic absorbers it could contribute top a kind of pumping effect, drawing moisture out of the cargo. When used together with Nordic absorbers the liner will act as a buffer in extreme conditions, and will prevent any container rain from reaching the cargo. Much the same can be said for so called dew cloths.

Q: My container is absolutely filled with cargo. Will the Nordic absorbers still work?

Moisture diffuses very effectively, even through a seemingly compact cargo. Experience shows that Nordic absorbers will make a difference even to mould growth inside cartons in the cargo. It is, however, necessary that some free space is left in front of each Nordic absorbers. If some Nordic absorbers have collected less water than others inside a container, there may be a problem with air access to those absorbers.

Q: I have problems with mould growth inside my shrink-wrapped pallets. Will Nordic absorbers help?

Yes, so long that there is some access of air through the top and bottom of the pallets. If this is not possible, a spiked roller may be used to tear holes in the shrink wrap.

Q: My shipments of steel/galvanised components/aluminium/machinery etc arrives corroded, stained or discoloured despite heavy packaging. Will Nordic absorbers help?

You can forget about your Tectyl, coatings, oil-paper and plastic wraps that are expensive both to apply and remove. Your container can probably be equipped with a sufficient number of Nordic absorbers to protect against any damage at less cost than your present packaging.

Q: I got some brine on my hands while removing used Nordic absorbers . Is it dangerous?

No it isn’t. Calcium chloride is non-toxic and environmentally safe. It is the second biggest constituent of sea-salt and is liberally sprinkled over icy roads in cold countries. The brine is somewhat similar to very salty seawater, and may cause irritation and rashes if left to dry on the skin. We recommend that you wear gloves and goggles when handling used absorbers, but should you get splashed by brine just wash off immediately with lots of fresh water.

Q: Can I re-cycle my used absorbers?

The absorbers can not be re-used but can be disposed of environmentally friendly. It doesn’t contain any harmful chemicals.

More information on desiccant and moisture

Calcium chloride based container desiccant to prevent moisture problems

 About moisture and condensation in shipping containers

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Moisture Damage can be Prevented

Sea Containers are 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.

  • Metals corrode, discolour and loose their shine
  • Cargo and packaging get mouldy, soft, crumbled and discoloured.
  • Bad smell
  • Physical damage from water, ice, things gluing together, caking etc

Such damage may result in substantial losses and costs. Yet obviously not every shipment suffers moisture damage, and most of those that do, suffer only limited damage. In fact, lots of moisture damage remains unrecognized, because it is considered “normal”. Very few shippers have a good system of feedback from the receivers of their goods. There may be lots of things they don’t know.

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 4 perfectly safe shipments and the 5th may be a disaster. This means that there is always a risk of moisture damage in the next shipment, even if the last one was ok.

Moisture Damage can be Prevented

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Water damage in a container

All containers contain moisture from the time of loading and in the cargo. No container is airtight. Moisture will move in and out of the container during the course of the voyage – “Container Breathing”.

The objective of a moisture protection program is to prevent the build up 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 “Absorbers” to remove moisture from the air.

We like to present the Nordic Power Desiccant moisture protection program as a kind of checklist of things that should be arranged as well as possible. And it is to be noted that many of the items on the list can be influenced only to a degree. Yet even small changes can result in big improvements. In some cases a few tens of grams of water in the wrong place is enough to cause significant damage.

Storing pallets inside or outside is often enough to make the difference between no
damage and “disaster”. Simply adjusting the temperature of the cargo at loading can prevent damage. Thus it is well worth to make what improvements are at all practical, and the balance will then have to be taken up by the packaging and the absorbers.

Is the Container Tight?

A minimum requirement is of course 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 Euros.

For more information check us out at http://www.interdrythailand.com

 Moisture Damage can be Prevented

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