Cathodic Protection/Partial Coatings Versus Complete Coating in Ballast Tanks-A Project Update
AVONDALE SHIPYARDS INC NEW ORLEANS LA
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Ship ballast tanks are one of the most costly items of new ship construction. In addition, ballast tanks are one of the most severe corrosion areas during ship operations. The 023-1 Panel of SNAME recognized these problems and selected a research and development project to investigate alternate, cost effective corrosion control solutions. Four approachs were originally selected for mock-up ballast tank testing and 20 year life cycle cost analysis. Completely coated tanks with high performance coating Partially coated tanks with cathodic protection Preconstruction primer with cathodic protection Soft coatings with cathodic protection The initial report published in 1982 demonstrated that, of the systems evaluated, the preconstruction primer with cathodic protection was the best performer, least expensive initially and least expensive over the 20 year economic life of the ship. After 3 years of testing, this system continues to be the best performer. Partial coating with cathodic protection have performed as well as complete coating and are more cost effective. Soft coatings with cathodic protection failed in the first 90 days and was discontinued. Certain prerequisites were also found to be necessary to assure successful cathodic protection performance, e.g. tanks must be pressed up with salt water ballast. In conclusion, this project achieved all project goals. Identification was made of ballast tank corrosion protection approachs which are effective in mitigating corrosion and yet save both new construction and operating dollars.
- Coatings, Colorants and Finishes
- Marine Engineering