External corrosion of tank bottoms is a significant problem for tank owners. This can happen in any type of storage tank that comes in contact with soil or other corrosive media. However, when properly designed and installed, cathodic protection systems can provide years of protection for storage tanks against costly repairs and leaks.
Depending on the tank diameter, the type of cathodic protection system may be either a galvanic anode system or, where more and uniform protection current is required, an impressed current system may be needed.
The vast majority of new tank construction projects utilize mixed metal oxide (MMO) impressed current anode systems. MMO anodes offer long life, low cost, and design flexibility, making this type of system the best choice for tank owners and system designers.
Two primary CP configurations are used in tanks worldwide. One is the field-erected anode grid configuration which is an early application of MMO anodes for tank bottoms and has a large global installed base. And the other design to protect tank bottoms is a system of linear anodes in concentric rings.