Patent US4800165A successfully refreshed from Google Patents.
US4800165A
Expired / Lapsed
US
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Method of detecting corrosion rate of member of steel material
Assignee: Nippon Steel Corp
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Filing: 1987-01-09
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Granted: 1989-01-24
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Expires: 2007-01-09
Abstract
Abstract A method of detecting the rate of corrosion of an existing steel structure installed in a corrosive environment is disclosed. The method includes treating a measurement surface of the member so that an AC impedance of the measurement surface, when electrochemically measured at a predetermined high frequency range of potential variation applied to the measured surface, takes a first valve within a predetermined range; and second value of the impedance is then electrochemically measured at a low frequency range of potential variation applied thereto. The difference between the first and second values is calculated to detect the corrosion-reaction resistance of the surface and the rate of corrosion is determined on the basis of the detected corrosion-reaction resistance and according to a pre-calculated relation between the rate of corrosion and the corrosion-reaction resistance.
Inventors
- 👤 Tomoki Oka
- 👤 Hiroshi Kihira
- 👤 Kazumi Matsuoka
- 👤 Satoshi Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:50
CPC Classifications
G; G01; G01N; G01N17/00; G01N17/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
196 words
A method of detecting the rate of corrosion of an existing steel structure installed in a corrosive environment, said steel structure having a surface section to which a probe is to be attached for detecting said corrosion rate, said method comprising the steps of: removing deposits from said surface section of said steel structure so that an AC impedance of said surface section, when electrochemically measured by application of potential variation thereto at a predetermined high frequency range, takes a first value within a range of 5 Ωcm 2 to 50 Ωcm 2 ; measuring the impedance of said measurement surface by application of potential variation at a predetermined low frequency range to obtain a second AC impedance value; calculating the difference between said first and second measured values to detect a corrosion-reaction resistance of said surface section; and determining the rate of corrosion of said surface section on the basis of said detected corrosion-reaction resistance of said surface section and according to a precalculation relation between the rate of corrosion and the corrosion-reaction resistance; whereby the corrosion rate can be determined directly on said surface section without the need for a separate corrodible testing means.
Claim 2
Independent Claim
196 words
A method of detecting the rate of corrosion of an existing steel structure installed in a corrosive environment, said steel structure having a surface section to which a probe is to be attached for detecting said corrosion rate, said method comprising the steps of: removing deposits from said surface section of said steel structure so that an AC impedance of said surface section, when electrochemically measured by application of potential variation thereto at a predetermined high frequency range, takes a first value within a range of 5 Ωcm 2 to 50 Ωcm 2 ; measuring the impedance of said measurement surface by application of potential variation at a predetermined low frequency range to obtain a second AC impedance value; calculating the difference between said first and second measured values to detect a corrosion-reaction resistance of said surface section; and determining the rate of corrosion of said surface section on the basis of said detected corrosion-reaction resistance of said surface section and according to a precalculation relation between the rate of corrosion and the corrosion-reaction resistance; whereby the corrosion rate can be determined directly on said surface section without the need for a separate corrodible testing means.
Claim 3
Dependent Claim
17 words
A method according to claim 1, wherein said high frequency range is 100 Hz to 1,000 Hz.
Claim 4
Dependent Claim
17 words
A method according to claim 2, wherein said low frequency range is 2 mHz to 10 mHz.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-24 | 1992-07-25 | 1993-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-24 | 1996-07-25 | 1997-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-24 | 2000-07-25 | 2001-01-24 | $7700.00 | Window Closed / Lapsed |