Abstract: Corrosible metallic elements of tank are protected by an anodic encasement sleeve. The anodic encasement sleeve employs an inner sacrificial anodic layer and an outer environmental barrier layer to provide both cathodic and barrier protection against corrosion. Following application of the sleeve, typically by drawing or wrapping, the anodic encasement sleeve remains substantially unbonded from the tank, though it is electrically connected by conductive means. Because of the substantially unbonded relationship between the sacrificial anodic layer and the metallic elements of the tank, if electrolyte is present under the environmental barrier (due to breaches, installation error, condensation, etc.), the electrolyte may enter the unbonded area between the tank and the anodic material. This increases the ratio of anodic material to tank available, which makes the cathodic protection more efficient and effective for an extended duration.