Silicate Treatment to Inhibit Corrosion of Hot, Potable Water Systems, Phase I

Abstract

Research has been conducted to determine the variables involved in the use of the sodium silicate treatment technique and in the design of a system which utilizes or controls these variables for the efficient control of corrosion of steel, galvanized steel, and copper piping exposed to hot, potable water. Test loops were designed and constructed at nine selected sites to investigate the influence that temperature flow velocity, water chemistry, and silicate formulation and dosage have on the effectiveness of sodium silicate as a corrosion inhibitor for steel, galvanized steel, and copper piping exposed to heat (140°F and 180°F) in aggressive, potable water of four different compositions. Recommendations are made to conduct further research to determine ( 1) silicate treatment variables involved in treating low alkalinity and low hardness water; {2) the practicality of employing silicate treatment of hard water; (3) the effectiveness of zinc salts as a supplement to silicate; and (4) the corrosion resistance of ASTM A-268 Grade 409 stainless steel.