抄録
Case studies were conducted on CO2 corrosion of carbon steel in various areas of industrial applications, i.e., steam return lines, heat exchanger tubes of a steam heating system, steam pipings, blast furnace gas lines, town gas lines, a CO2 recovery system and an oil and gas well. Corrosion of steam return lines proceeds under very low CO2 partial pressures, e.g., 10-5-10-4atm., but at a high corrosion rate reaching several mm/y due to the presence of oxygen. The corrosion product films, FeCO3, are stable when pH of the water phase is higher than a critical value, resulting in a low corrosion rate. When the pH value is a little lower than critical, the corrosion rate is lowered by the formation of partially protective films. Very high rates of corrosion are usually not accompanied by corrosion products. Mesa corrosion characterized by sharp lines deviling the corroded and un-corroded area presumably occurs under conditions of partial protection where localized areas of stable corrosion product films remain intact for a long time by further stabilization of the films caused by pH increase of the surface resulting from galvanic current of macro-galvanic cells.
