Wind Turbine Cathodic Polarization Results; A Case Study

Abstract One of the mysteries of offshore cathodic protection (CP) is the time it takes to reach full polarization. Moreover, there is a limit for the protection criteria, still subject to much debate, and then there is the situation where calcareous deposits have formed, and a “steady state” condition has been achieved. Standards like DNV RP B4011 and NACE SP-01762 specify current densities to afford protection, and call out initial, mean and final current density values. However, the standards do not mention the time to full polarization. This paper presents polarization data of several impressed current cathodic protection (ICCP) systems retrofitted to wind turbines located in offshore waters off the coast of Germany in the North Sea. These were originally fitted close mounted ICCP systems which failed within a few years. Consequently, many turbines were left under protected with some at freely corroding potentials. Retrofit ICCP systems were installed between 2018 and 2019 to provide protection to the fully and semi depolarized structures. This paper focuses on the rate of polarization and observes the variations between similar structures in the same field.