The protection of pipelines from external corrosion is commonly accomplished by the combination of pipeline coatings with cathodic protection, to protect those portions of the pipeline that are inadequately coated or where the coating contains defects. Defects in pipeline coatings that expose bare steel are termed holidays.
Conventional anode resistance formulas that ignore the current and potential distribution on the pipes are inadequate for the modelling of pipelines with holidays. Current and potential distribution must also be considered when modelling multiple pipelines. Factors such as variations in coating quality and stray current interference have an effect on the quality of the cathodic protection system.
Another major factor in the design and maintenance of the underground infrastructure (e.g. pipelines, storage tanks, tunnels etc) is the electrical interference (electrical pollution) from power lines, railways and other electrical sources. Traditional resistance formulas are inadequate in modelling these complex interactions.
Modelling the Underground Infrastructure
On the object of stray current corrosion see also: DC traction, Cathodic protection, Coating, Contour plots, Definition, Detection, Examples, External currents, Historical perspective, Impressed current, Interference, Mechanisms, Modeling. Pipeline, Potential distribution, Prevention, Stray fields and leakage, Transit systems
Computer Simulation as an aid to CP System Design and Interference Predictions, Robert Adey and John Baynham, BEASY