Apparatus and method for measuring potentials through pavements for buried pipeline cathodic protection systems

摘要

Fluid transmission pipelines and similar structures which are cathodically protected from electrolytic corrosion and are disposed in urban areas under pavements and other structures which prevent access to the soil for verifying pipe-to-soil potentials are subjected to pipe-to-soil potential measurements using a reference electrode disposed in a container which has a permeable bottom and which is capable of saturating a pavement layer with a brine electrolyte to provide electrical conductivity between the reference electrode and the soil. Validation of electrical conductivity is made by a second reference electrode of a dissimilar metal which is also disposed in a container having a permeable bottom and an electrolyte which permeates the pavement layer and establishes electrical conductivity between the soil and the second reference electrode. Potential measurements between the first and second electrodes validate ion transport between the soil and the first reference electrode. Pipe-to-soil potential measurements are carried out between the reference electrode and a connection to the pipe using a wireless transmission system or using an electrical power grid neutral or ground wire as the conductor between the pipe and the reference electrode. Pipe-to-soil potential measurements may be made without penetrating the pavement and without trailing wires between the point of connection to the pipe and the available point of connection between the reference electrode and the soil.