Factors Affecting Corrosion of Pipes:

The mineral content, dissolved oxygen level and pH of water influence corrosion rate of metallic pipe. Presence of carbonic and another acids, free chlorine and dissolved oxygen level increases the corrosion in pipes, while water possessing sufficient calcium carbonate alkalinity is anti-corrosive in nature. Micro-organisms such as sulphate-reducing or iron bacteria also cause corrosion.

Corrosion in boilers is controlled by removal of the oxygen from the feeding water by deaeration, and through the reaction of residual oxygen along with sodium sulphite or hydrazine. It is also controlled through application of alkaline chemicals such as caustic soda and sodium phosphates to provide boiler water pH in the range of 10-12.

Inhibition of corrosion in cooling towers is provided by the application of corrosion inhibitors such as chromates and phosphates and silicates applied singly or in various combinations. Development of a wide protective layer of calcium carbonate on the metal surfaces is effective for preventing corrosion of the metal in the water distribution system.