Zinc is a metal element occurring in nature. It is present in the natural environment in both the air and the ground, as well as in water. Zinc is harmless to the environment, and is indispensable for the appropriate development of living organisms. It is recyclable.
Hot galvanising, also called dipping galvanising, is one of the most effective methods of anti-corrosion protection for steel constructions. The process consists in dipping an element in a galvanising kettle filled with molten zinc alloy at a temperature of 445 - 455 oC.
Beforehand, the construction is prepared in the following operations:
pickling in acid
If needed, the galvanised elements are cooled in water at the ambient temperature of the surrounding environment.
Objects taken from a sling are mechanically cleaned of zinc run-off marks. The surface treated in such a way is distinguished by a high mechanical resistance and an aesthetic appearance. The thickness of the zinc layer depends on the thickness of galvanised elements, which is presented in the table below.
|Structure component thickness in mm||Minimum zinc layer thickness in µm|
|1 - 3||55|
|3 - 6||70|
The average loss of the zinc layer on the construction in use amounts to 1- 2 µm/year (for use in non-aggressive conditions). Thus, the average lifespan of the zinc layer amounts to 30 years and may even reach 100 years. The anti-corrosion zinc layer does not require any maintenance.
Alternative ways of construction protection, such as painting, are, admittedly, cheaper, but their lifespan is much lower and usually does not exceed 5-10 years.
The cost of cleaning a painted and corroded construction e.g. by sandblasting is comparable to galvanising!