Protecting Steam Systems from Corrosion

Steam and condensate-return systems can be susceptible to unique forms of corrosion. This overview explains how to prevent or minimize such issues Steam is utilized for process heating and other applications at thousands of industrial plants in the chemical process industries (CPI). Often, a significant portion of the steam condensate is recovered and returned to the boilers. Depending on the plant processes the steam serves, the condensate may contain any number of impurities that range from acidic compounds to organics to mineral salts. These impurities can cause corrosion and failure of condensate return piping and equipment, and they can potentially induce serious steam-generator corrosion and fouling. This article provides an overview of several critical issues in this regard and outlines techniques for chemically treating the steam/condensate and polishing the condensate return to reduce corrosion and scaling potential.   Potential boiler problems The steam generator itself may be the source of a common condensate impurity: carbon dioxide. High-pressure utility boilers require high-purity makeup (contaminants not exceeding low parts-per-billion concentrations) as a result of the high temperatures and pressures in these…