New CSE reference electrode with two coupons for improved measurement of true potential

Pipelines and other buried metallic structures are typically protected against corrosion by means of cathodic protection systems. The protection status is verified by measuring the potential of the structure in respect to reference electrodes, generally copper/copper sulphate electrodes. Nevertheless, the measured potential includes, together with the true potential, ohmic drop contributions in the soil, due to the circulating protection current. Furthermore, in the presence of stray currents or alternate current (AC) interferences, the apparent potential value is also affected by additional ohmic drops. In order to achieve a significant reduction of the ohmic drop, a new reference electrode has been developed, in which the distance between coupon and porous plug is minimized, resistant against cold temperatures and drying. This paper shows how these improvements have been achieved by laboratory and field tests results, and also by means of Finite Element Method (FEM) modelling.