Investigation of processes occurring at cathodically protected underground installations: Experimental study of pH alteration and mathematical modeling of oxygen transport in soil

[Display omitted] •Processes occurring at cathodically protected underground steel pipe studied.•In-field test of soil pH change in vicinity of cathodically polarized steel pipe.•Mathematical modeling of two‐phase oxygen transport in the soil towards buried pipe.•Cathodic protection current solely due oxygen reduction calculated. A detailed analysis of the complex processes occurring at the surface of cathodically protected underground metal installations is presented. In the first part an alteration of soil pH in vicinity of cathodically polarized buried specimen of carbon-steel pipe is investigated experimentally. In the second part a stationary two‐phase oxygen transport to a defect in the protective coating of an underground pipe is studied by mathematical modeling and protection current solely given by oxygen reduction are calculated. This information is crucial to an evaluation of subsequent processes taking place at a protected metal surface, which is part of a follow-up study.