More detailed information on internal cathodic protection is available in the National Association of Corrosion Engineers (NACE) RP05-75 and RP03-88.Ĭorrosion of the steel tank bottom may be reduced or eliminated with proper application of cathodic protection. Under certain conditions, it can be effective in protecting against corrosion at holidays in the coating. Internal flexible liners may be used for the most severe product applications.įor tanks in petroleum service, internal cathodic protection in conjunction with coatings has not gained widespread use. Some of the more common coatings that remain in use in petroleum storage are coal tar, various two-part epoxy paints, and conventional fiberglass coatings. Various types of coatings are used depending on the service requirements stipulated in the coating specification. In many cases, only the bottom and 18 to 24 in. Water and other corrosive products naturally collect on the bottom.
Internal surfaces can be more problematic. More elaborate multicoat epoxy-based paint systems are used at offshore locations. Applying a suitable primer and topcoat per manufacturer’s recommendations normally provides adequate protection of the external tank surfaces at onshore locations. Exterior surfaces generally require protection only from the elements, although in some chemical production plants, chemical vapors can be prevalent in the atmosphere and might impact selection of the coating material. Secondary containment and detection systems are also considered an essential part of a tank installation.Ī primary method used to protect metal surfaces against surface corrosion is to apply a suitable coating. Options considered by most tank owners include internal and external corrosion protection and bottom cathodic protection systems. Similar details are used on fixed-roof and floating-roof tanks alike. 7 Secondary containment or leak detectionĭesign options are generic with respect to the type of storage tank.