Numerical simulations for cathodic protection of pipelines

Mathematical models may be used for design or evaluation of cathodic protection (CP) systems. This chapter provides a historical perspective and a mathematical framework for the development of such models. The mathematical description accounts for calculation of both on- and off-potentials at arbitrarily located surfaces, thus making this approach attractive for simulation of external corrosion direct assessment (ECDA) methods. The approach also allows simulation of independent CP systems. Application of the model is presented for three cases: (a) enhancing interpretation of ECDA results in terms of the condition of the buried pipe; (b) simulating the detrimental influences of competing rectifier settings for crossing pipes protected by independent CP systems (e.g., rectifier wars); and (c) simulating the influence of coatings and coating holidays on the CP of above-ground tank bottoms.