Pipeline cathodic protection designs and AC interference studies, whether completed using conventional calculations or computer modeling, are heavily dependent on the quality of the pipeline’s coating. Coating resistance is often coarsely estimated using established values from literature where pipeline age, coating type, and subjective Operator feedback are used as guiding parameters. However, in practice, coating resistance is also heavily dependent on the quality of installation, historical pipeline operating conditions, and repair activity. This paper uses voltage-drop influence survey data from a cathodic protection rectifier to estimate a pipeline’s attenuation constant and corresponding coating resistance. The field survey method for completing the IR influence survey is described and the calculations methods for obtaining the pipeline’s attenuation constant and coating resistance are developed. The results from several such surveys are examined to understand both the successes and challenges with this technique, as well as some of the applications in both cathodic protection system remediation and AC mitigation modeling.

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