Cathodic Protection for Tanks

Cathodic Protection for Tanks

Storage tanks can be protected with cathodic protection.

The cathodic protection for storage tanks can be applied to protect the internal surface, the external surface, in case of underground tanks or tank in contact with soil, or both internal/external.

Based on the type of fluid contained in the tanks to be protected is possibile to use galvanic anodes or impressed current.

Usually the surfaces to be protectied with cathodic protection are also coated to reduce the current requirement and increase the life of the galvanic anodes.

In sacrificial anode systems the high energy electrons required for cathodic protection are supplied by the corrosion of an active metal.

This is illustrated in Figure cathodic protection sacrificial anodes

The materials used for sacrificial anodes are either relatively pure active metals, such as zinc or magnesium, or are magnesium or aluminum alloys that have been specifically developed for use as sacrificial anodes.

When the cathodic protection for tanks is performed with buried anodes, a special backfill material surrounds the anode in order to insure that the anode will produce the desired output.

In the process of providing electrons for the cathodic protection of a less active metal the more active metal corrodes.

The more active metal (anode) is sacrificed to protect the less active metal (cathode). The amount of corrosion depends on the metal being used as an anode but is directly proportional to the amount of current supplied.

The anodes used in cathodic protection for tanks must be periodically inspected and replaced when consumed.

Source : "Corrosion Control" NAVFAC MO-307 September 1992

Underground Storage Tank Cathodic Protection Checklis

Question on Cathodic Protection for Tanks?