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How
VCI works
Other VCI Products
Applications
Storage life
Transit packaging
Specifications
Cost savings
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VCI
products are very successful for
effective protection of metal products against
corrosion. VCI stands for
"Volatile Corrosion Inhibitor", meaning
rust prevention by vapour action.
VCI
protects against the corrosive influences of
oxygen, water vapour and condensation. It is easy
to use and inexpensive.
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How VCI
works
The
VCI chemicals continuously evaporate to form a
protective atmosphere inside the package. The vapour
forms a deposit on the surface of the metal. When
the temperature falls below the dewing point of
water, condensation begins to form but this is
displaced by ions of the VCI chemical.
When
the temperature rises again and the water
re-vaporises, the VCI chemical remains as a thin
covering on the surface of the metal. It then
prevents any further contact between the metal
surface and whatever condensation might occur
subsequently. The VCI chemical displaces the water
vapour as it has a lower vapour pressure. The amount
of the VCI chemical on the surface of the metal
therefore increases whenever the temperature rises
and the water re-vaporises.
Build-up
of the VCI atmosphere in a closed package.
%
Chemical Concentration
Time
in hours at constant temperature of 20C
The
nearer the paper is to the surface of the metal, the
better the protection from corrosion. Wrapping goods
individually in VCI paper or plastic is therefore
particularly advantageous. Any condensation that
forms will be displaced by the VCI chemical.
VCI
protection works much more slowly on items that have
been coated with grease or oil as the rate of
sublimation of the VCI chemical is significantly
reduced. The VCI chemical will however act as an
additional, greaseless part of the protective
package under these circumstances.
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Other
VCI Products
VCI is also
supplied as a liquid, a powder and impregnated sponges.
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Applications
VCI
is easy to use. Goods are simply wrapped in the
paper or inserted into bags after having been
cleaned. Liners or shrouds are used inside packing
cases and cartons or over pallets. When using liners
or shrouds, care must be taken that these are large
enough to either heatseal or tape them shut. As
little distance as possible must be left between the
goods and the VCI lining and it is best to wrap the
articles individually in VCI. Protection begins as
soon as sufficient VCI vapour has formed, normally a
matter of hours. At no time should the goods be
allowed to touch the wood of the outer case or
wooden separations inside the case.
VCI
paper is provided in different qualities for
-iron,
steel, aluminium and chrome
-copper
and brass
VCI
plastic comes in "multi metal" finish
providing protection for all metals.
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Storage
Life
The
storage life of a package depends upon the type
and amount of additional packaging used and to
some extent on the movement of air within the
storage area. Goods packed in VCI paper or plastic
and stored in inner rooms with little air
movement, have an estimated corrosion free storage
life of 10 to 16 months. In case the goods are
further protected by a sealed aluminium barrier
foil inside the packing case, a shelf life of
several years in achievable.
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Transit
packaging
When
shipping goods to particularly corrosive climates
= high humidity levels, it is essential to design
the packaging in such a way that water vapour can
not enter as VCI protection depends on the
waterproof properties of the outer material. A
sealed aluminium barrier foil offers the best
protection.
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Specifications
Our
VCI paper complies with the USA military
specification MIL-I-3420 and the German Federal
specification TL 8135-002/4. The VCI plastic is
manufactured according to CSIR specifications, no
other South African specifications exist.
VCI
is non-toxic but workers should wash their hands
after using it.
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Cost
savings
VCI
reduces packing time as it eliminates operations
such as greasing, oiling, dipping and spraying. At
the receiving end degreasing is no longer
necessary. Goods can be used immediately after
unpacking and complaints about rust are a thing of
the past. All of these amount to a large cost
saving, which in most cases offset the cost of the
VCI.
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