Soil side corrosion, a major cause of tank bottom failures, is typically caused by the ingress of external contaminants and moisture through gaps and spaces around the annular chime space. Filling and emptying of the stored product causes the bottom plates to flex drawing in more moisture and external contaminants.
This mix of corrosive contaminants and moisture creates pitting corrosion that can cause tank bottom holes well short of the design life of the asset.
But, how do you provide corrosion mitigation to the entire underside while the tank is in service?
Zerust Oil & Gas has developed an innovative system, that allows for the injection of corrosion inhibitors while the tank is in service.
A system of perforated PVC pipes is installed around the entire annular chime area and sealed in place.
Zerust’s unique blend of inhibitors is mixed with water and either gravity fed or pumped using a low pressure pump into the perforated chime ring.
The liquid inhibitor enters the tank underside space through the same gaps that allow for the ingress of contaminants and moisture.
Vapor Corrosion Inhibitors rise to the surface of the metal bottom plates and neutralize contaminants. The Soluble Corrosion Inhibitors neutralize surface contaminants on the concrete or asphalt foundation pad. The flexing of the bottom plates during tank operation provides a further mechanism for the propagation of the inhibitors.
The multiple channels along the bottom plate weld seams provide pathways for the flow of inhibitor across the tank bottom. The dual action liquid and vapor inhibitors protect the vulnerable areas of the tank bottom plates from corrosion.
The Zerust delivery system remains in place allowing for inhibitor replenishment.