API RP 651, 5th, 2024 – Cathodic Protection of Aboveground Petroleum Storage Tanks, Fifth Edition

1.1 The purpose of this RP is to present procedures and practices for achieving effective corrosion control on
aboveground storage tank carbon steel bottoms using cathodic protection. This RP contains provisions for the
application of cathodic protection to existing and new aboveground storage tanks. Corrosion control methods
based on chemical control of the environment, or the use of protective coatings are not covered in detail.

1.2 When cathodic protection is used for aboveground storage tank applications, it is the intent of this RP to
provide information and guidance specific to aboveground metallic storage tanks in hydrocarbon service. Certain
practices recommended herein may also be applicable to tanks in other services. It is intended to serve only as
a guide to people interested in cathodic protection. Specific cathodic protection designs are not provided. Such
designs should be developed by a person thoroughly familiar with cathodic protection practices for aboveground
petroleum storage tanks.

1.3 This RP does not designate specific practices for every situation because the varied conditions in which
tank bottoms are installed preclude standardization of cathodic protection practices.