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Characterization of steel cathodic polarization in seawater and its applications in offshore structure cathodic protection design

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Date Issued:
1994
Summary:
Laboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface area ratio and permitted the desired initial current density to be realized. In the initial polarization stage the change in potential versus current density data with time was found to be linear with a slope equal to the product of the total circuit resistance and cathode surface area and with the vertical intercept corresponding to the anode open circuit potential. Lower temperature or increased flow resulted in reduced polarization and a relatively high current density, but data for experiments employing a particular resistance conformed to straight lines with the same slope R[ext] x A[c] (external resistance times cathode surface area). Some experiments exhibited concave behavior at longer test duration. An explanation for the linear interdependence of potential and current density and the following concave behavior is presented. The laboratory experiments were compared with offshore structure survey results. It is projected that the potential-current density behavior of galvanic cathodic protection (CP) systems of different geometries can be quantitatively interrelated through this slope parameter. Implications of the data are discussed within the context of cathodic protection design, rapid polarization and system performance for offshore structures.
Title: Characterization of steel cathodic polarization in seawater and its applications in offshore structure cathodic protection design.
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Name(s): Wang, Weiqing.
Florida Atlantic University, Degree grantor
Hartt, William H., Thesis advisor
College of Engineering and Computer Science
Department of Ocean and Mechanical Engineering
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Issuance: monographic
Date Issued: 1994
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 219 p.
Language(s): English
Summary: Laboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface area ratio and permitted the desired initial current density to be realized. In the initial polarization stage the change in potential versus current density data with time was found to be linear with a slope equal to the product of the total circuit resistance and cathode surface area and with the vertical intercept corresponding to the anode open circuit potential. Lower temperature or increased flow resulted in reduced polarization and a relatively high current density, but data for experiments employing a particular resistance conformed to straight lines with the same slope R[ext] x A[c] (external resistance times cathode surface area). Some experiments exhibited concave behavior at longer test duration. An explanation for the linear interdependence of potential and current density and the following concave behavior is presented. The laboratory experiments were compared with offshore structure survey results. It is projected that the potential-current density behavior of galvanic cathodic protection (CP) systems of different geometries can be quantitatively interrelated through this slope parameter. Implications of the data are discussed within the context of cathodic protection design, rapid polarization and system performance for offshore structures.
Identifier: 12362 (digitool), FADT12362 (IID), fau:9263 (fedora)
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): College of Engineering and Computer Science
Thesis (Ph.D.)--Florida Atlantic University, 1994.
Subject(s): Steel--Cathodic protection
Seawater
Offshore structures
Held by: Florida Atlantic University Libraries
Persistent Link to This Record: http://purl.flvc.org/fcla/dt/12362
Sublocation: Digital Library
Use and Reproduction: Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.