History
Cathodic protection was first described by Sir Humphry Davy in a series of papers presented to the Royal Society in London in 1824. After a series of tests, the first application was to the HMS Samarang in 1824. Sacrificial anodes made from iron were attached to the copper sheath of the hull below the waterline and dramatically reduced the corrosion rate of the copper. However, a side effect of the CP was to increase marine growth. Copper, when corroding, releases copper ions which have an anti-fouling effect. Since excess marine growth affected the performance of the ship, the Royal Navy decided that it was better to allow the copper to corrode and have the benefit of reduced marine growth, so CP was not used further.
Davy was assisted in his experiments by his pupil Michael Faraday, who continued his research after Davy's death. In 1834, Faraday discovered the quantitative connection between corrosion weight loss and electric current and thus laid the foundation for the future application of cathodic protection.
Thomas Edison experimented with impressed current cathodic protection on ships in 1890, but was unsuccessful due to the lack of a suitable current source and anode materials. It would be 100 years after Davy's experiment before cathodic protection was used widely on oil pipelines in the United States.
CP was applied to steel gas pipelines beginning in 1928 and more widely in the 1930s.
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