Effect of Induced Alternating Current Voltage on Cathodically Protected Pipelines Paralleling Electric Power Transmission Lines

Abstract

A field study was conducted to evaluate the effect of induced alternating current (AC) voltage on a cathodically protected pipeline paralleling an electric power transmission line. The study used the instant-off method, with steel probes simulating coating defects. Data regarding probe potentials and currents were compared with the proposed tentative criterion for cathodic protection (CP). Positive proof of the adequacy of CP was obtained after field testing for 1 year, when probes were removed to ascertain corrosion rates.