The application of cathodic protection (CP) to steel bottoms of large groups of aboveground fuel storage tanks and monitoring the effectiveness of the systems poses several unique complications. The objectives of these systems are to provide uniform current distribution to all areas of the tank bottom, while causing minimal disruption of facility operations and limiting the amount of influence on other piping systems in the area. The requirement to apply CP to the bottoms of 40 aboveground tanks at the Satellite Tank Farm at John F. Kennedy International Airport presented unique obstacles. These included the congested nature of the facility, the existence of multiple fuel systems entering the Tank Farm whose CP systems require electrical isolation from the tanks, the numerous underground crossings of these lines. The monitoring of the protection levels at the critical locations on the tank bottoms, as well as at the critical interfaces between piping systems, presented additional challenges. The consideration of the above requirements led to a system design and installation methods that proved innovative in nature and enhanced available technology for the future application of CP to such structures. The installation methods included horizontal directional drilling and insertion of anode casings, as well as air jetting of reference electrodes under the tanks. The systems will also include state-of-the-art remote monitoring capabilities.
The use of aboveground storage tanks in bulk storage facilities has presented many challenges to the operators of those facilities. These challenges include settlement, displacement by flooding and other mechanical effects. Furthermore, the physical contact between the steel tank bottom plates and soil or concrete has resulted in corrosion of the steel plates, often resulting in penetration, and leakage of the contained product into the soil. Many different approaches have been taken to identify the corrosion, to test the structures to determine the extent of corrosion, and to treat the problem once it is detected. EPA regulations for Spill Prevention Control and Countermeasures (SPCC) Plans require various precautions to be taken to prevent discharge of oil into the navigable waterways of the United States or adjoining shorelines. These requirements are found in 40 CFR 112.7, and include periodic inspection of tanks. Prevention of corrosion is an essential part of meeting the requirements of these federal standards as well as state and local standards for release prevention. The economic impact of corrosion failures is well known. Tanks must be repaired or replaced when they have suffered severe corrosion damage. Many repair methods have been established to rehabilitate tanks that have leaked due to bottom plate corrosion. One of these methods includes installation of a secondary bottom above the primary bottom. The space between the old and new bottom must be filled with a suitable foundation material, such as dry sand. This material is initially a dry, inert and relative non-corrosive material to the new tank bottom. However, in time, with the "breathing action" associated with the rising and lowering level of the product in the tank, and the intrusion of moisture and condensation into the sand foundation, the "secondary" tank bottom can also be subject to corrosion at some point. This corrosion could result in a penetration and resultant oil leakage. Corrosion can be prevented for this scenario by several means, including cathodic protection.
The subject of this paper is the corrosion control program that was implemented by the Port Authority of New York and New Jersey at its Satellite Tank Farm at John F. Kennedy International Air
