ASSESSMENT OF A CIRCUITAL MODEL FOR EIS MEASUREMENTS ON BURIED PIPELINES

摘要

Electrochemical Impedance Spectroscopy (EIS) is a good tool to investigate the deterioration of coating on a metal. For gas pipelines, the equivalent circuit parameters in presence of disbonded coatings can be found in literature. Models parameters are coating thickness, and the area under disbonded coating. A coated pipeline can be modelled as a sequence of simple equivalent circuits, which can be handled using standard theory to yield the observed impedance in terms of the values for circuit elements in the line. The proposed model has been tested to verify its applicability for detecting corrosion sites in buried pipelines. The effect of a few geometrical and physical parameters has been investigated, and results have been compared with the output of laboratory and field measurements. In some cases, the adjustment of literature parameters has been enough to obtain a good correspondence; modification of the equivalent circuit have been however found necessary. Future work in this field is possible and promising, provided that the circuital model is modified following the results of the present study.