51312-01332-Using Local Electrochemical Impedance Spectroscopy to Detect Coating Defects on Buried Pipelines

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Product Number: 51312-01332-SG

ISBN: 01332 2012 CP

Author: Pavan K. Shukla

Publication Date: 2012

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Local Electrochemical Impedance Spectroscopy (LEIS) has been used to determine the micro- and macroscopic defect sites on coated coupons in a laboratory scale setup. LEIS is conducted by applying a sinusoidal potential signal to a working electrode and then measuring the response of a particular location by placing two reference electrodes in the electrolyte above that location. Scale-up issues need to be resolved if LEIS is to be used for inspecting and identifying coating defects on the buried pipeline. The parameters such as the distance of the two-electrode system from the pipeline surface distance between the two electrodes and frequency of the applied excitation signal were needed to be determined. These parameters are determined by conducting the numerical simulations of a cathodic protection and LEIS models and field experiments. A bielectrode probe was developed for field experiments. The bielectrode probe consisted of two reference electrodes. Field experiments were conducted on a buried pipeline with several coating defects. The collected data were used to calculate local electrochemical impedance spectra of different test sites on the pipeline. The calculated local impedances indicate that the method is capable of identifying coating defect locations on buried pipelines.