THE
GALVANIZING PROCESS
There are three basic elements to the galvanizing process.These are: 1)
Surface Preparation 2) Galvanizing 3) Inspection.
Surface Preparation
Surface preparation is the most important step in the application of any
coating. In most instances, where a coating fails before the end of its
expected service life it is due to incorrect or inadequate surface preparation.
With galvanizing, the surface preparation process contains its own built-in
means of quality assurance and quality control in that zinc will simply
not react with a steel surface that is not perfectly clean.
Surface preparation for galvanizing typically consists of three steps:
1) Caustic Cleaning 2) Acid Pickling 3) Fluxing.
Galvanizing
In this step, the material is completely immersed in a bath consisting
of a minimum of 98% pure molten zinc. The bath temperature is maintained
at about 850° Fahrenheit.
Fabricated items are immersed in the bath long enough to reach bath temperature.
The articles are slowly withdrawn from the galvanizing bath, and the excess
zinc is removed by draining, vibrating, and/or centrifuging.
Inspection
The most important method of inspection for galvanized articles is visual.
A variety of simple physical and laboratory tests may be performed 1)
Thickness 2) Uniformity of the coating
3) Adherence of the coating 4) Appearance.
Galvanizing
is preferred over painting primarily because galvanizing forms a metallurgical
bond between the coating and underlying steel or iron. Galvanizing creates
a barrier that is a part or extension of the metal itself. During galvanizing,
the molten zinc reacts with the surface of the steel or iron article undergoing
galvanizing to form a series of zinc/iron alloys. These alloy layers protect
steel from corrosion for 30-40 years and more.
Courtesy of the American Galvanizers Association.
South
Atlantic Galvanized Steel
South
Atlantic GalvanizingSouth
Atlantic Lintels
Member