Potential probes are sensors consisting of a reference electrode and a metal coupon close to the electrode used for measuring the protection potential of underground metal structures in cathodic protection. They allow the reading of the potential purified by the ohmic drop contribution, the so-called IR-free potential, a useful parameter for assessing the effectiveness of a cathodic protection system. Aim of this work is to compare the accuracy of the potential measurements of commercial probes, which differ in geometry, extension of the porous plug, number and position of the metal coupons. Measurements of reference electrode potential stability in the presence of cathodic protection and ability of the probes to compensate the ohmic drop were performed. The results showed that not all potential probes are able to measure the IR-free potential, as the measurement contains an ohmic drop contribution, greater for more negative cathodic polarization values.

Subject
Cathodic protection, Cathodic potential, Ohmic drop, Probes, Metal coupons, Reference electrodes, Free corrosion potential, Potential measurements, Negative potentials, Protection potential, Electrodes, Electrode potential, Standard electrode potential
Keywords:
cathodic protection, monitoring, potential probe, ohmic drop
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2021
Association for Materials Protection and Performance (AMPP)
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