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Monday, March 23, 2009: 11:15 AM
C304 (Georgia World Congress Center)
Underground pipelines are protected from external corrosion and SCC through a combination of a protective coating and cathodic protection. Coating damage can result in ground water contacting the external surface of the pipe, which may lead to external corrosion. An effective above-ground technique to assess coating condition, without the need to excavate the pipeline, would be a useful tool for pipeline integrity management.
In this study, the Electrochemical Impedance Spectroscopy (EIS) technique has been used to identify damage to asphalt coating on carbon steel pipelines in a soil box filled with water-saturated sand. Two pipe segments, one with a 3.2mm diameter holiday and the other one without, were buried in the box. Differences were observed between the EIS data obtained from these two segments. The impedances measured from the segment with a holiday are consistently smaller by at least one order of magnitude than those obtained from the segment without a holiday. The observations and results suggest that this above-ground technique is promising to effectively detect coating defects.
In this study, the Electrochemical Impedance Spectroscopy (EIS) technique has been used to identify damage to asphalt coating on carbon steel pipelines in a soil box filled with water-saturated sand. Two pipe segments, one with a 3.2mm diameter holiday and the other one without, were buried in the box. Differences were observed between the EIS data obtained from these two segments. The impedances measured from the segment with a holiday are consistently smaller by at least one order of magnitude than those obtained from the segment without a holiday. The observations and results suggest that this above-ground technique is promising to effectively detect coating defects.