Galvanic anodes offshore

Oxide, hydroxide and basic salts of aluminum are less soluble at pH values of about 7 than those of zinc [17], which explains the easy passivatability. Galvanic anodes of aluminum alloys are primarily employed in the area of offshore technology. The anodes work in relatively pure seawater flowing with a high velocity so that by using suitable alloys, passivation phenomena are rare. Their low weight is particularly favorable in view of a service time of 20 to 30 years. 

Protection with impressed current, with galvanic anodes, and a combination of both processes is used for marine structures and offshore pipelines. Their properties, as well as their advantages and disadvantages, are given in Table 16-1. The protective measures must be optimized for every structure. In the impressed current protection of offshore platforms, for example, the difficulties of maintenance and repair will be of major importance, whereas in harbor installations these problems can be... 

Galvanic anode systems are generally used in well-coated electrically isolated structures, offshore structures, ship hulls, hot-spot pipeline protection, heat exchanger water boxes and other environments of resistivity below 10000 Q cm. 

Galvanic anode systems are typically used where protective current requirements are relatively low, usually in the range of several hundred miUiamperes to perhaps 4 or 5 A. Offshore structures, having current requirements of many hundreds of amperes can also be protected by large galvanic... 

Galvanic Anode Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks Metallurgical and Inspection Requirements for Offshore Pipeline Bracelet Anodes Design, Installation, Operation and Maintenance of Impressed Current Deep Groundbeds Internal Cathodic Protection Systems in Oil-Treating Vessels... 

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