Accession Number : ADA512944


Title :   Factors Contributing to Corrosion of Steel Pilings in Duluth-Superior Harbor


Descriptive Note : Journal article


Corporate Author : NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV


Personal Author(s) : Ray, Richard I ; Lee, Jason S ; Little, Brenda J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a512944.pdf


Report Date : Nov 2009


Pagination or Media Count : 14


Abstract : 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 the following sequence of biological, chemical, and physical events. Iron-oxidizing bacteria colonize the carbon steel sheet pilings and produce tubercles, which are made up of intact and/or partially degraded remains of bacterial cells mixed with amorphous hydrous ferric 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.


Descriptors :   *GALVANIC CORROSION , *LAKE SUPERIOR , *CARBON STEELS , *ESTUARIES , *PILE STRUCTURES , *FRESH WATER , *HARBORS , *BACTERIA , WATER QUALITY , BULKHEADS , DOCKS , BRIDGES , MICROBIOLOGY , WISCONSIN , IRON OXIDES , PRECIPITATES , MINNESOTA , COPPER , OXIDATION , ICE , OXYGEN , IRON , EXPOSURE(GENERAL) , LABORATORY TESTS , COUPLING(INTERACTION) , REPRINTS


Subject Categories : Microbiology
      Physical Chemistry
      Geography
      Properties of Metals and Alloys
      Civil Engineering


Distribution Statement : APPROVED FOR PUBLIC RELEASE