Some Experiences With Sodium Silicate As a Corrosion Inhibitor in Industrial Cooling Waters★

Abstract

Abstract The use of sodium silicate as a corrosion control agent for open-recirculating cooling water systems is discussed. Emphasis is placed on the results of tests made with low-carbon steel coupons in eight operating plants. The normal development of silica films, effect of prior corrosion and the influence of pH, water temperature and magnesium hardness are discussed. Long-term test data indicated that crystalloidal silica is highly effective in stopping corrosion of mild steel by a wide variety of industrial cooling waters. Thirty to forty ppm of total crystalloidal silica provided adequate protection in waters containing upwards of 500 ppm of chlorides and sulfates. Magnesium hardness in concentrations above 250 ppm as CaCOa was found to greatly reduce the inhibitive action. 5.8.2