Above Ground Storage Tank - Case Study of a Linear Anode Based Cathodic Protection System Design and Installation Aspects.
- Shailesh Javia (MATCOR Inc.)
- Document ID
- NACE International
- CORROSION 2019, 24-28 March, Nashville, Tennessee, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. NACE International
- Mixed Metal Oxide (MMO) Linear anode, Cathodic Protection (CP), Impressed current cathodic protection (ICCP), Direct Current (DC)
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- 28 since 2007
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External corrosion of tank bottoms is a significant problem for tank owners for both economic and environmental reasons. Corrosion Protection of Above Ground Storage Tanks (AST) is typically provided by an impressed current cathodic protection (ICCP). Two primary impressed current cathodic protection configurations are used worldwide in tanks. The field-erected mixed metal oxide (MMO) anode welded grid configuration was an early application of MMO anodes for tank bottoms and has a large global installed base. A newer design to protect tank bottoms is a system of parallel or concentric ring MMO linear anodes with factory connected tail cables.
This paper compares “grid” type and “parallel/concentric” linear anode type tank CP systems, provide an economic assessment and discuss the implementation impact. This paper also discusses one case study of linear anode system provided on a large diameter AST.
Corrosion has long been recognized as an extremely costly naturally occurring phenomenon that can be controlled through the proper application of corrosion prevention and control methods protecting public safety, extending the service life of assets and preventing damage to property and the environment. The landmark Cost of Corrosion Study published by the U.S. Federal Highway Administration estimated that corrosion costs were approximately 3.1% of the nation’s GDP. Within the study, several key sectors of the US economy were studied. This paper is focused on one of those areas - the corrosion risks associated with storage tanks that contain hazardous materials. The study determined that the annual direct cost of corrosion for above ground hazardous material storage tanks (ASTs) in the US was $4.5 billion.
Established “good engineering practice” requires that cathodic protection be applied to prevent corrosion of external tank bottom plates for above ground storage tanks (ASTs) that are exposed to soil or sand foundations. API Recommended Practice 651 notes that “cathodic protection for new aboveground storage tanks should be included in the initial design.” 1
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