25 - Cathodic Protection of Pipelines

Abstract

Publisher Summary This chapter focuses on cathodic protection (CP) of pipelines, as pipelines are exposed to aggressive soil, varying climatic conditions, micro-organism, and stray currents that initiate corrosion processes. Cathodic protection is defined as reduction or elimination of corrosion by making the metal a cathode by means of an impressed current or attachment to a sacrificial anode. This is an electrochemical method that uses cathodic polarization to control the kinetics of the electrode processes occurring on the metal/electrolyte interface. The chapter categorizes CP systems into two types based on the type of the polarization used to protect the structure: sacrificial anode and impressed current systems. The criteria for CP are documented by National Association of Corrosion Engineers (NACE). The successful application of CP depends upon the selection, design, installation, and maintenance of the system. Before designing cathodic protection, adequate field data must be collected, analyzed, and evaluated. It discusses that the effectiveness of the CP can be determined by monitoring the pipeline potential using the close interval potential survey (CIPS) method or by using direct current voltage gradient (DCVG) or IR coupons techniques.