THE SUITABILITY of carbon steel as a condenser-tube material for handling fresh waters depends largely upon the formation of protective scales deposited by the water. When fresh water becomes contaminated with acid drainage, the tendency for these protective scales to form is destroyed, and rapid corrosion of carbon steel can be expected. In industrial applications where large volumes of fresh water are handled in a once-through system, treatments other than additions of lime to the water to raise the pH are generally not feasible for preventing corrosion because of cost considerations. The answer to such problems lies in the selection of materials more resistant to corrosion than is carbon steel.
To illustrate, in one coal-chemical plant, 150 million gallons of water contaminated with acid drainage from old coal mines are used daily for cooling purposes. Although the water is treated with lime to raise the pH from about 3.8 to...
