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Heavy & Light Galvanizing
The difference between Heavy Galvanizing and
Light
Galvanizing.
Heavy galvanizing is often referred to as batch, heavy
duty or after fabrication galvanizing. Light galvanizing
is referred to as continuous, ILG (In-Line Galvanizing)
or zinc electroplated. The Australian market has a wide
variety of local and imported light galvanized products
readily available.
Heavy galvanizing is the only galvanize finish that
gives a complete coating of heavy zinc both externally
and internally. The zinc coating is typically in the
range of 85µ m² or 600 gms / m² on 6mm
thick steel. Heavy galvanizing produces the maximum thickness
possible relative to steel thickness, with long term
protection its only objective.
Light galvanized steel sections have a much thinner
coating, down to 7µ m² or 50 gms / m² typically
in the range of 14µ m² or 100 gms/ m² because
of the very thin coating, these products are unsuitable
in many environments. Light galvanized products can be
fully coated externally, but bare internally, some coated
internally and externally with the external weld line
repaired. These coatings have a significant lower level
of protection in corrosive environments, and often require
supplementary coatings for outdoor exposure.
The success and durability of the galvanizing coating
is dependant on the amount of zinc applied to the steel
surface. As can be seen above there is a significant
difference between Heavy and Light galvanizing.
Summary:
Clearly the architects or engineers decision to use
heavy or light galvanizing depends on the design life,
and the funds available for future maintenance. Ensure
your work is adequately protected; specify Heavy Galvanize
finish to AS/NZS 4680:2006
Galvanizing grades in the Australian
Market
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