Методика определения поляризационного потенциала при проведении коррозионных обследований подземных трубопроводов

Abstract

Values of metal potentials, which exceed or equal to the potential at which the corrosion rate of the metal does not exceed 0.01 mm/year, in international practice, are a condition for the effectiveness of cathodic protection of underground pipelines. It is called polarization potential. The range of polarization potentials, which correspond to effective corrosion protection, was determined experimentally as a result of a large number of field tests in different operating conditions. The values of polarization potentials can vary from minus 0.65 V to minus 1.15 V, measured relative to copper sulfate electrode (C.S.E). There are cases during corrosion surveys of underground pipelines, when the measured values of polarization potentials with the help of measuring instruments, intended for this purpose, significantly exceed the maximum permissible value. The author offers an original method for determining the polarization potential based on the analysis of the dependence of the auxiliary electrode potential on the time after the interruption of the polarization current. The values of polarization potentials obtained using this technique are in the standard range. The method can be recommended for experimental use in corrosion surveys of underground pipelines in various operating conditions in order to confirm the compliance of the obtained results with the condition of cathodic protection efficiency.