Above Ground Water Storage Tank Cathodic Protection

The effects of corrosion on storage tanks include premature failures and disruptions in service during repairs.

Above ground water storage tank cathodic protection. The tanks are cylindrical in shape constructed of steel and rest on the soil. The provision of cathodic protection to tank bottoms is if anything more critical than is. Galvanic anodes method is not practical for protection of large bare structures nace rp0193 2001 external cathodic protection of on grade carbon steel storage tank bottoms. As with any steel structure corrosion is an ever present concern.

Cathodic protection also known as galvanic cathodic protection is a corrosion protection technique in which the metallic surface to be protected is intentionally made the cathode in a galvanic cell. Cathodic protection cp however stops the corrosion reaction when properly applied. The leaks which cursory reports believe to be the likely the result of corrosion could have been avoided by implementing proper cathodic protection systems. This method involves electrically connecting the tank s metal components either directly or indirectly to another easily corroded metal.

Government regulations environmental issues and economics have made cathodic protection of above ground storage tank bottoms increasingly important. In addition congested terminal environments often lead to interference and less current at the tank bottom. Api 651 cathodic protection of aboveground petroleum storage tanks. Above ground storage tanks 1 water tanks e g.

The tank bottom then is subject to the same corrosion issues as are buried pipelines. Internal corrosion occurs generally from crude and other stored products carrying water into the tank. Galvanic protection systems can be applied to tank. Fire water irrigation water potable water 2 crude oil tanks 3 diesel tanks.

The extraction process of the product itself will leave a water with an extremely high salt content which settles to the bottom of the tank. Separation degassing desalting etc 4 process tanks decoking sludge etc applicability cp will function generally where process fluid is. This article provides a brief overview of the corrosion reaction and the role of cathodic protection for both ground storage tanks. Process vessels tanks 1 heat exchangers 2 condenser waterboxes 3 vessels for various chemical processes e g.

Cathodic protection systems for water storage tanks are almost always impressed current systems. Technical and economic reasons dictate that galvanic anodes almost never be used to protect a water storage tank. Introduction storage facilities for petroleum products usually consist of a collection of above ground storage tanks called a tank farm. In january 2014 above ground storage tanks asts containing the chemical 4 methylcyclohexanemethanol mchm was released into elk river in west virginia.

This presentation compares traditional grid anode systems with newer linear anode concentric ring systems for the cathodic protection of above ground storage tank bottoms. One of the problems associated with monitoring cathodic protection systems on tank bottoms is the inability to assess empty space under the tank or to place a reference electrode in close proximity to the underside of. The standard method of determining the corrosiveness or the effectiveness of cathodic protection on a tank bottom is the tank to soil potential measurement. Cathodic protection is a standard cost effective accepted method to prevent corrosion of the submerged surface inside steel water storage tanks.

The proper installation of a high end tank cathodic protection system begins with known design specifications based on the tank size and diameter.