Method for detecting the presence or absence of corrosion of cathodically protected structures
First Claim
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1. A method for determining corrosion of a cathodically protected steel structure in a soil or concrete medium, said method comprising the steps of:
- superimposing a plurality of discrete sine wave frequencies at a predetermined voltage over an ambient cathodic protection voltage applied to said structure;
measuring the electrochemical impedance of said structure at each of said frequencies;
determining a real and an imaginary component of said impedance at each of said frequencies;
plotting said real component of said impedance versus said imaginary component of said impedance at each of said frequencies;
determining corrosion of said structure directly from said plot independent of a calculating step, a generally linear plot indicating the presence of corrosion and a generally semi-circular plot indicating the absence of corrosion.
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Abstract
A method for detecting the presence or absence of corrosion of cathodically protected steel structures in soil and concrete in which the cathodic protection circuit is subjected to an electrochemical impedance spectroscopic analysis and the presence of corrosion is indicated by the presence of a Warburg impedance.
32 Citations
2 Claims
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1. A method for determining corrosion of a cathodically protected steel structure in a soil or concrete medium, said method comprising the steps of:
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superimposing a plurality of discrete sine wave frequencies at a predetermined voltage over an ambient cathodic protection voltage applied to said structure; measuring the electrochemical impedance of said structure at each of said frequencies; determining a real and an imaginary component of said impedance at each of said frequencies; plotting said real component of said impedance versus said imaginary component of said impedance at each of said frequencies; determining corrosion of said structure directly from said plot independent of a calculating step, a generally linear plot indicating the presence of corrosion and a generally semi-circular plot indicating the absence of corrosion.
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2. A method for determining corrosion of a cathodically protected steel structure in a soil or concrete medium, said method comprising the steps of:
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superimposing a plurality of discrete sine wave frequencies at a predetermined current over an ambient cathodic protection current applied to said structure; measuring the electrochemical impedance of said structure at each of said frequencies; determining a real and an imaginary component of said impedance at each of said frequencies; plotting said real component of said impedance versus said imaginary component of said impedance at each of said frequencies; determining corrosion of said structure directly from said plot independent of a calculating step, a generally linear plot indicating the presence of corrosion and a generally semi-circular plot indicating the absence of corrosion.
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Specification
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Current AssigneeGas Technology Institute
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Original AssigneeGas Research Institute (GTI Energy)
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InventorsThompson, Neil G.
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Primary Examiner(s)NGUYEN, NAM X
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Application NumberUS07/766,966Time in Patent Office2,203 DaysField of Search204/153.11, 204/147, 204/196, 204/404, 324/700, 205/724, 205/734, 205/725US Class Current205/734CPC Class CodesG01N 17/02 Electrochemical measuring s...
