What water quality parameters are the most important indicators of corrosion or incrustation?
A6. The most important water quality characteristics that influence rate of corrosion are dissolved gases, particularly dissolved oxygen. Other common gases that can contribute to the corrosion of steel are carbon dioxide and hydrogen sulfide. An increase in the amount of dissolved oxygen increases the rate at which oxygen is transported to the corroding metal surface. Most metals will exhibit an increase in corrosion as the dissolved oxygen content increases up to 20 to 25 mg/l. Above this level the increased oxygen content can promote passivation of the metal thereby reducing the corrosion rate. Carbon dioxide does not directly cause a corrosive reaction, but it reacts with water to form carbonic acid. The carbonic acid in turn lowers the pH creating conditions favorable to corrosion. Another effect of lowered pH is increased solubility of calcium carbonate, which is the main compound associated with well incrustation. Similar to carbon dioxide, hydrogen sulfide does not by itself ca
