Cathodic protection criteria of thermally insulated pipeline buried in soil

The effect of temperature on the cathodic protection criteria of a pipeline steel under insulation was studied in the temperature range 25-95°C in synthetic ground water. Sufficient protection could not be obtained at -0.85 V_CSE at elevated temperatures, while more negative potential than -0.85 V_CSE was required to obtain satisfactory protection. The anodic Tafel lines were used to determine the protection potential at each temperature. The protection potential was shifted to the more negative value as the temperature increased. The most negative potential was measured at 80°C, which decreased to -1.346 V_SCE. Acceptable corrosion rates were achieved when the potential was held at -1.346 V_SCE over the temperature range studied.