Computer Modeling of Pipelines and Their CP Systems for IR Drop Measurement Correction

This paper demonstrates to what extent the layered structure of the soil influences the IR drop component in pipe-to-soil potentials and how computer modeling of the soil structure can be used to correct measured potentials. Various types of multilayered soils are compared with uniform soils in terms of their effects on the IR drop produced by nearby anodes, by the leakage current from the protected pipeline, and by foreign pipelines. The soil resistivity measurements required to generate such a soil model are described, the interpretation method used to process the measurements is presented, and an example interpretation is illustrated. A simulated set of measurements is presented in detail, along with the IR drop correction made with the software. Full potential mappings are plotted, with and without the IR drop present.