What is white rust?
Until around 1986, the phenomenon known as “white rust” did not exist. White Rust is the formation of bulky, white corrosion products formed on galvanized steel cooling tower components. This results in rapid and increased rates of corrosion of the galvanized zinc layer, rendering it ineffective as a corrosion inhibitor. Analysis of the White Rust indicates that it is a complex of Zinc Hydroxide, Zinc Oxides, and Zinc Carbonate. Unlike the Zinc Carbonate alone, this complex is not self-limiting, but continues to form at a fairly rapid rate unless treated properly. White Rust began to appear in cooling towers with galvanized components for two basic reasons. First, changes in the galvanizing process resulted in the surface of the zinc alloy containing slightly different elements. While the cause is not yet completely understood, it appears that the increased aluminum content may be a factor. Secondly, the shift in cooling water treatment chemistry to higher alkalinity and pH programs al
White rust is a white, chalky deposit sometimes found on galvanized material. This chalky substance is actually zinc oxide but is commonly referred to as white rust or wet storage stain. White rust represents the accelerated corrosion of the zinc surface. Storing galvanized materials too tightly together in humid, warm locations generally causes it. In order to combat the formation of white rust, both proper storage and chromating should be practiced. Chromating is the emersion of newly galvanized material into a chromate solution. This places a coating on the material, which will degrade over time while the maturing zinc forms its protective patina. Red River Galvanizing does utilize a chromating step to minimize the frequency of white rust.
