Field observations and laboratory testing were used to conclude that aggressive localized corrosion of carbon steel pilings in Duluth-Superior Harbor, Minnesota and Wisconsin, is caused by thefollowing sequence of biological, chemical, and physical events. Iron-oxidizing bacteria colonize the carbon steel sheet pilings and produce tubercles, made up of intact and/or partly degraded remains of bacterial cells mixed with amorphous hydrousferric oxides. The reducing conditions beneath the tubercles cause copper dissolved in the water to precipitate. A galvanic couple is established between the copper layer and the iron substratum. Ice scouring breaks the tubercles. Exposure of the copper-covered iron to oxygen causes the galvanic current to increase. The result is aggressive localized corrosion.
Factors contributing to corrosion of steel pilings in Duluth-Superior harbor
Zur Korrosion der Stahl-Spundwände im Hafen von Duluth am Oberen See beitragende Faktoren
Corrosion, Houston ; 65 , 11 ; 707-717
2009
11 Seiten, 13 Bilder, 2 Tabellen, 50 Quellen
Article (Journal)
English
Duluth-Superior Harbor Freshwater Corrosion Update
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