Cathodic Protection for Underground Piping in Power Plants

Cathodic protection systems are often used to protect critical underground piping systems. This paper discusses the various anode systems used for power plant underground piping applications. It is intended for engineers responsible for the underground piping systems for new power plant design — this could include owner’s engineers, EPCs, and construction contractors responsible for these systems. The paper begins with an overview of cathodic protection and when it is needed. The paper provides an overview of how cathodic protection works and discusses key piping issues that impact the design and operation of the system. After providing a framework for establishing the need for cathodic protection, this paper provides detailed comparisons of the various available types of anode systems. Each anode system is described in detail and then the advantages and disadvantages of each system are examined. The first anode system discussed is the galvanic distributed bed system. This is followed by three impressed current anode systems; linear anodes, distributed bed, and deep well systems. The paper concludes with a summary of each of these systems. An appendix is included which provides typical design calculations for galvanic, linear and deep well systems.