Boundary-element analysis and experimental validation of cathodic protection potential distribution in intersecting branch pipelines

Purpose This study aims to investigate the engineering challenges posed by mutual interference between intersecting pipelines in regional cathodic protection systems for oil and gas transmission pipelines. Design/methodology/approach Using a dual-pipe model as an example, a mathematical model of the potential distribution along the pipelines was established. The boundary element method was employed to calculate the potential distribution of the two pipelines at different angles and intersection lengths. The accuracy of the solutions was verified through laboratory experiments. Findings The introduction of a new pipeline causes the potential of the original pipeline to shift toward positive values. An increase in the angle between the two pipelines results in a positive shift in the protective potential of both pipelines. As the length of the new pipeline increases, the potential of the original pipeline shifts positively, while the potential of the new pipeline varies depending on the anode position and pipeline length. Originality/value Previous numerical studies have mainly focused on single pipelines, parallel pipelines, tank bottoms or localized coating defects. This study extends the boundary element method to two intersecting branch pipelines connected to a shared cathodic protection system. Its additional contributions include direct experimental validation using an intersecting dual-pipeline configuration, systematic evaluation of intersection angle, branch-pipeline length and auxiliary-anode position and interpretation of the resulting potential shifts in terms of protective-current redistribution. The findings provide a technical basis for cathodic protection reassessment and anode placement optimization when new branch pipelines are connected to existing pipeline networks.