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Above ground storage tank soil side corrosion, continues to adversely affect tank integrity. Corrosion has been found to exist with a cathodic protection system present, resulting in floor repairs. Inadequate cathodic protection test results have prompted State regulators to seek floor and cathodic protection system replacement. These repairs are costly, both in terms of construction activity as well as down time for the stored product.
This paper will present corrosion control technologies available for new and existing above ground storage tanks. The pros and cons of sacrificial anode cathodic protection, impressed current cathodic protection and corrosion inhibitors will be presented. Basic electrochemistry will be discussed to facilitate technical understanding of these approaches.
For decades, the use of cathodic protection has been commonplace to control corrosion on tank bottoms and buried piping systems. They are typically installed during tank construction and retrofitted to existing tanks.
The use of “double-bottom” tank floors on existing above ground fuel storage tanks is a technology that has become more common within the industry. The technique has been implemented on those tanks where environmental considerations or inspection data indicate the original floor plates of the tanks to be compromised. Under conditions conducive to corrosion, the steel floor plates corrode in such a manner as to expose the surrounding soil to possible contamination.
Volatizing vapor phase corrosion inhibitors have proven effective in arresting corrosion of steel and other metallic materials in a confined space. This technology provides an effective solution to the corrosion activity that has been observed in some new tank floor installations where moisture was present and the cathodic protection system was ineffective in controlling the resulting corrosion. This corrosion mitigation method offers an economic solution to ineffective cathodic protection systems for existing tanks and a proven corrosion mitigation technology for new installations.
This paper will present corrosion control technologies available for new and existing above ground storage tanks. The pros and cons of sacrificial anode cathodic protection, impressed current cathodic protection and corrosion inhibitors will be presented. Basic electrochemistry will be discussed to facilitate technical understanding of these approaches.
For decades, the use of cathodic protection has been commonplace to control corrosion on tank bottoms and buried piping systems. They are typically installed during tank construction and retrofitted to existing tanks.
The use of “double-bottom” tank floors on existing above ground fuel storage tanks is a technology that has become more common within the industry. The technique has been implemented on those tanks where environmental considerations or inspection data indicate the original floor plates of the tanks to be compromised. Under conditions conducive to corrosion, the steel floor plates corrode in such a manner as to expose the surrounding soil to possible contamination.
Volatizing vapor phase corrosion inhibitors have proven effective in arresting corrosion of steel and other metallic materials in a confined space. This technology provides an effective solution to the corrosion activity that has been observed in some new tank floor installations where moisture was present and the cathodic protection system was ineffective in controlling the resulting corrosion. This corrosion mitigation method offers an economic solution to ineffective cathodic protection systems for existing tanks and a proven corrosion mitigation technology for new installations.