Cathodic Protection (CP) is a mature technology and has been successfully used for decades to mitigate
corrosion in a wide variety of applications within the oil & gas industry and beyond. CP has proven to be
a long-term, robust tool for mitigation of Aboveground Storage Tank (AST) soil-side corrosion and its
application has benefited from many AST specific improvements over time. However, the effectiveness
of this technology is complicated by several factors; these include intermittent contact of floor plates with
the tankpad; tankpad chemistry and moisture content; tankpad contamination during construction; in
addition to the deficiencies in CP system designs specific to the tanks, installation, monitoring, evaluation,
and maintenance of AST CP systems are challenging. Further, it has been observed that AST CP
systems’ anode failures are not uncommon and are difficult to replace and supplement. A Pipeline
Research Council International (PRCI)-sponsored study was conducted to quantify effectiveness of the
CP systems for the AST application. CP data and floor inspection data were collected for several tanks
with active CP systems. The American Petroleum Institute (API) 653 inspection reports were used to
obtain tank bottoms wall-loss data and previous conditions, including new or replacement bottom timeline
or the previous inspection result; the inspection data were used to estimate the soil-side corrosion rates
of the tank bottoms. In addition, the CP data were used to determine the extent and duration of CP
application to the tank bottom. The combined data, i.e., wall-loss from API 653 reports and CP data,
were used to determine effectiveness of CP systems for AST application.