A Corrosion Detection System for Buried Pipeline (II)

摘要

In order to develop a new corrosion sensor for detecting and monitoring the corrosion of buried pipeline, the electrochemical property of sensors and the correlation of its output to corrosion rate of steel pipe, were evaluated by electrochemical methods in synthetic groundwater, two soils of varying resistivity (5,000 ohm-cm, 10,000 ohm-cm), and synthetic tap water. 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 results of EIS measurement indicated that the sensor current was inversely related to sensor resistance, which was governed by the corrosion behavior of cathode. In galvanic corrosion tests, the galvanic current of Cu-CS probe was higher than that of SS-CS probe. The comparison of the sensor output and corrosion rates revealed that a linear relationship was found between the probe current and the corrosion rates. A good linear quantitative relationship was found between the Cu-CS probe current and the corrosion rate of pipeline steel coupons in the soil resistivity of 5,000 ohm-cm, and synthetic tap water. In the case of the soil resistivity of 10,000 ohm-cm, although the SS-CS probe showed a better linear correlation than that of Cu-CS probe, the Cu-CS probe is more suitable than SS-CS probe, due to the high current output.