Metallic pipelines are used to transmit the natural gas and petrolum products. Usually pipelines are constucted in the same pathway of the High Voltage Transmission Lines to save the right-way cost. AC voltage is induced on these pipelines due to the electric and magnetic fields of the overhead transmission lines. This book gives the calculations of electric and magnetic fields around the H.V.T.L and studies the hazards appear due to electromagnetic field on the workers, the damage of the pipelines coating and corrosion of the metallic pipelines construction.