Design life – The functional life of a fabrication will be determined by the quality of the initial coating, the maintenance regime and the particular environment that it sits in. Galvanizing offers considerable advantages over its competitors due to its long, maintenance free life. The expected life of galvanizing in a specific location can be calculated relatively easily due to the unique way in which the coating reacts when exposed to the environment. Unlike paint, which will peel exposing the steel below, galvanizing slowly depletes a small amount each year. The rate of depletion can range from 0.5 microns in rural locations to 4 microns in exposed coastal locations. The link below opens a map showing the depletion rates for galvanized coatings in all parts of the UK which will allow a approximate design life to be determined.
The thickness of the steel will also affect the thickness of the galvanized coating. The thicker the steel is the thicker the zinc coating will be. The galvanizing standard ISO 1461 states that a 6mm section of steel should have a minimum average thickness of 85 microns. The average is taken from measuring 6 random locations on the surface.
For extremely harsh environments, such as offshore, it may be necessary to apply a thicker zinc coating. This can be achieved by specifying Marine galvanizing. The surface of the steel is reprofiled by shot blasting before galvanizing, this will ensure that a minimum average zinc thickness of 140 microns is achieved.
Design life – The powder topcoat of Colourgalv acts to protect the galvanized layer by creating a barrier between the zinc and the elements. Thus the coating will retain its full protection whilst the topcoat is present. The topcoat itself can be guaranteed for up to 25 years proving that it is one of the very best coatings available.