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China
and South East Asia to Australia
Condensation
can appear when storing in shipping containers and during the inclement months
of the year this can become more of an issue. Specifically when importing from Tropical
Moist Heat departure points such as South East Asia to Dry Heat continents such
as Australia.
To understand
this problem in greater detail we will endeavour to explain. Used shipping
containers may have moisture in the floors from previous uses, and even new
builds if left shut for prolonged periods may produce some moisture inside.
This can have a disastrous effect on electrical
equipment, timbers, and perishable items stored within the container. Ultimately the result is that vapour will
become water droplets that gather on the ceiling and start falling to the floor
or on stored items. To help prevent this there are many views and suggestions
about, but in reality the most successful method is the use of chemical
dehumidifiers.
These work very well as they either contain silica gel or
desiccant clay depending on the product you buy. Shipping lines have always
traditionally used gel packets within clothing containers and electrical goods
transportation.
However “dry
poles” as they have become known do work well. Manually insulating shipping containers with ply lad
compressed foam works but it is costly to achieve. Equally there is another
product proven to be helpful in this area called “Graffo” this is like a spray
on porridge type product which is water based. This seems a very strange way to
eliminate moisture but it is very good. This insulates the roof internally
keeping heat in and cold out. Please contact us if you wish to learn more about
this method of moisture prevention.
When deciding whether a certain Shipping Container is suitable for transporting a certain cargo, it is vital for those involved to have sufficient knowledge about the anticipated climatic conditions in the Shipping Container.
The three
major factors which have a decisive impact upon the crypto climate
(microclimate) in the Shipping Container are as follows : external climatic
conditions, the type of Shipping Container and the cargo being transported.
External climatic conditions have a decisive impact upon the climatic conditions inside containers. The transport route in particular determines external climatic conditions, season and time of day and the current weather (rain, sunlight etc.). This is a major consideration for importers within Australia given the humid regional climatic conditions in South East Asia and the Sub-Continent via the dryer, cooler Australian Eastern Seaboard routes.
Due to the
diversity of these factors, it is not straightforward to predict how the
container climate will change in transit. It is not possible simply to transfer
the experience gained from one transport operation to another, as the
conditions prevailing in transit often vary greatly, but an awareness of how
the factors interact is helpful in assessing transport risks. In a nutshell
mother nature rules the roost.
The factors
influencing Shipping Container climate are highlighted in greater detail below:
1. Temperature conditions in the container:
The temperatures encountered in containers are primarily determined by heat exchange across the container walls. Good heat-transfer properties, especially through the steel walls, and the relatively large ratio of container surface area to container volume have a favourable impact in this respect. There are reflective materials available on the market to reduce heat transfer, although expensive.
In addition to solar radiation, external air temperatures, wind and precipitation also have an impact upon temperatures. Due to the wide variation in levels of solar radiation over a day, considerable temperature variation also occurs inside the container. This particularly applies to the air layers located directly beneath the container roof, as this is where the effects of solar radiation are at their strongest and thus where the greatest heat exchange occurs. On exposure to precipitation, such as rain, the container roof likewise cools more rapidly than, for example, the sidewalls, and the underside of the roof thus cools down most readily. Overheating of the air inside the container, i.e. heating to above the external air temperature may be considerable even under normal weather conditions. In contrast, the variations in temperature of the cargo inside the container are less marked.
1. Temperature conditions in the container:
The temperatures encountered in containers are primarily determined by heat exchange across the container walls. Good heat-transfer properties, especially through the steel walls, and the relatively large ratio of container surface area to container volume have a favourable impact in this respect. There are reflective materials available on the market to reduce heat transfer, although expensive.
In addition to solar radiation, external air temperatures, wind and precipitation also have an impact upon temperatures. Due to the wide variation in levels of solar radiation over a day, considerable temperature variation also occurs inside the container. This particularly applies to the air layers located directly beneath the container roof, as this is where the effects of solar radiation are at their strongest and thus where the greatest heat exchange occurs. On exposure to precipitation, such as rain, the container roof likewise cools more rapidly than, for example, the sidewalls, and the underside of the roof thus cools down most readily. Overheating of the air inside the container, i.e. heating to above the external air temperature may be considerable even under normal weather conditions. In contrast, the variations in temperature of the cargo inside the container are less marked.
Humidity conditions in the container are primarily determined by internal factors, i.e. the prevailing conditions are largely determined by the hygroscopic characteristics of the cargo and its packaging. Hygroscopic auxiliary packaging materials, such as squared lumber for cargo securing, and the water content of the flooring may also play a significant part. Incoming outside air usually has no negative impact upon humidity. Since the temperature prevailing inside the container is generally higher than the outside temperature, incoming air would also reduce relative humidity.
As always the visual inspection of Shipping Containers by
experts is crucial for the safe transit of goods.
Any of our Maritime Consultant Australia Pty Ltd – Marine
Surveyor and Engineering experts is be able to offer services relating to
repairs, insurance damages and inspections. Visit us at www.maritimeconsultants.com.au
