This paper proposes a methodology based on Faraday's electromagnetic induction law (EMF) for evaluating the induced voltage produced by high voltage power line on an aerial metallic pipeline located parallel in its immediate vicinity under normal operating condition. It also describes the procedure of the induced voltage mitigation using the passive loop technique combined with the particle swarm optimization algorithm (PSO). The presence of a pipeline in the vicinity of an overhead power line strongly disturbs the mapping of the magnetic induction produced by this power line. The mitigation efficiency is significantly improved by optimizing the position of the loop conductors, by increasing the number of loops and the use of a shielding magnetic material of high relative permeability. The obtained simulation result is compared with that obtained by the Carson's formulas. A good agreement was obtained.