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Since its invention almost
150 years ago, hot dip galvanizing has grown beyond all recognition.
Increasingly specifiers are demanding longer life for fabricated
steelwork. Galvanizing delivers longest life at lowest lifetime cost.
Hot dip galvanizing, simply
put, is the immersion of a chemically clean piece of steel into a bath
of molten zinc. By chemically clean, it means that the surfaces have
been rid of oil, grease, dirt, scale etc by the use of chemicals. Here
at Highland we believe that the secret of a great coating is in the
preparation and so we have put a lot of care and attention into getting
the preparation just right. For more details about how we prepare items
for galvanizing please look in our process section.
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An article being placed in a bath of zinc.
When the steel enters the
zinc (which is held at about 450°C) a series of zinc-iron alloy
layers form, this is due to a metallurgical reaction between the iron
and the zinc. The rate of the build up of these layers is very fast to
begin with but slows down after a little while. Due to this there is no
real benefit to be gained by leaving steel in the zinc for protracted
lengths of time as the main thickness is built up in the first few
minutes. The normal time for immersion is typically four or five
minutes, but this can be extended if a particularly thick article or an
article that has inner spaces is being galvanized. As the article is
withdrawn from the bath it receives a top layer of pure zinc.
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