Abstract
In order to develop a new corrosion sensor for detecting and monitoring the corrosion of buried pipeline, the correlation of sensor output to corrosion rate of steel pipe, and its sensitivity and durability, were evaluated by electrochemical methods in two soils of varying resistivity (5,000 ohm-cm, 10,000 ohm-cm). In this paper, two types of electrochemical probes were used: galvanic cells containing of pipeline steel-copper and pipeline steel-stainless steel (Type 304). The galvanic corrosion test was accomplished by a zero resistance ammeter technique. Weight loss, linear polarization resistance and electrochemical impedance spectroscopy (EIS) measurements were conducted to obtain the corrosion rates of pipeline steel in soil. The correlation between galvanic current and corrosion rate was evaluated in terms of the total charge passed. The results of weight loss, linear polarization resistance, and EIS measurements are presented along with the sensitivity and durability of the sensor system. The comparison of the sensor output and corrosion rates revealed that a linear relationship was found between the probe current and the corrosion rates. Especially, a good linear quantitative relationship was found between the Cu-CS probe current and the corrosion rate of the pipeline steel coupons. In addition, the Cu-CS probe is more suitable for high resistance soil than SS-CS probe, due to the high current output.
