EFFECT OF WATER QUALITY PARAMETERS ON CORROSION OF MILD STEEL, COPPER AND ZINC.

摘要

Corrosion of metals in potable waters due to their health and economic implications is of great importance, both to the water industry and to the consumer. Research was conducted to determine the effects of various water quality parameters on the rates of corrosion of mild steel, copper and galvanized steel.;A multi-component stirring apparatus was designed to collect the data. Pourbaix diagrams were constructed and correlated with measured E(,H) values. The rates of corrosion were measured using weight loss and electronic means. The water qualities were monitored for metal pick-up due to corrosion.;Dissolved oxygen was found to be a requisite for the corrosion of mild steel and zinc. Chlorine was found highly detrimental to copper, and dissolved oxygen was the second most important factor in copper corrosion. Dissolved oxygen and chlorine had a synergistic effect on the rates of corrosion of all metals. The role of pH was relatively minor, while E(,H) values correlated positively with corrosion rates. Chloride and sulfate ions were both found to promote corrosion of all metals, while alkalinity in the presence of other ions inhibited corrosion. Chloride was more harmful to copper than to the steel. Natural color had a negative effect on the corrosion of steels and a positive effect on the corrosion of copper. Exposure time was found to affect the rates of corrosion, especially in weight loss calculations. Weight loss and electronic tests data correlated well in mild steel tests. Their correlation was poor in copper experiments.;The impact of corrosion, the fundamentals of corrosion, causes and types of corrosion, methods of measurement and mitigation of corrosion, the occurrence of corrosive waters and their chemical composition, as well as piping materials and regulations concerning corrosion were presented in a thorough review of the subject of corrosion as related to drinking waters.