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

Report Date:

2009-11-01

Pagination or Media Count:

14.0

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 andor 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.

Subject Categories:

  • Microbiology
  • Physical Chemistry
  • Geography
  • Properties of Metals and Alloys
  • Civil Engineering

Distribution Statement:

APPROVED FOR PUBLIC RELEASE