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US4019133A
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Corrosion detecting and monitoring apparatus
Assignee: Gulf Research and Development Co
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Filing: 1975-12-29
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Granted: 1977-04-19
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Expires: 1995-12-29
Abstract
Abstract A corrosion detector for determining the corrosivity of a fluid and the ability of a metal to withstand the corrosive tendencies includes a tubular test specimen and a reference specimen. The two specimens are of the same composition and configuration over the length of the test specimen over which measurements are made. Means are provided for maintaining the two specimens at a temperature within less than 1° F. of each other. The corrosive fluid is passed through the test specimen. An alternating current is passed through the test specimen and reference specimen and the change in resistance of the test specimen relative to the reference specimen is measured in a phase sensitive Wheatstone bridge circuit to determine the extent of corrosion.
Inventors
- 👤 Robert E. Manley
- 👤 John D. McCoy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:54
CPC Classifications
G; G01; G01N; G01N17/00; G01N27/00; G01N27/02; G01N27/04; G01N27/041; G01R; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
176 words
Apparatus for measuring the rate of corrosion of a ferromagnetic metal by a flowing fluid comprising a tubular test specimen of the ferromagnetic metal, means for flowing the fluid through the test specimen, a tubular reference specimen of the ferromagnetic metal adjacent to the test specimen, said reference specimen being of substantially the same length, diameter and wall thickness as the test specimen, electrical insulation separating the test specimen and the reference specimen, a housing enclosing the test specimen and the reference specimen, thermal insulation within the housing around the test specimen and the reference specimen adapted to maintain the temperature of the specimens within 1° F. of one another, an alternating current source connected to the test specimen and the reference specimen to pass a current therethrough, and electrical leads attached to the outer surface of the test specimen and to the reference specimen connecting the specimens in a Wheatstone bridge circuit for measuring the resistance of the test specimen relative to the reference specimen to indicate the extent of corrosion of the test specimen.
Claim 2
Dependent Claim
176 words
Apparatus for measuring the rate of corrosion of a ferromagnetic metal by a flowing fluid comprising a tubular test specimen of the ferromagnetic metal, means for flowing the fluid through the test specimen, a tubular reference specimen of the ferromagnetic metal adjacent to the test specimen, said reference specimen being of substantially the same length, diameter and wall thickness as the test specimen, electrical insulation separating the test specimen and the reference specimen, a housing enclosing the test specimen and the reference specimen, thermal insulation within the housing around the test specimen and the reference specimen adapted to maintain the temperature of the specimens within 1° F. of one another, an alternating current source connected to the test specimen and the reference specimen to pass a current therethrough, and electrical leads attached to the outer surface of the test specimen and to the reference specimen connecting the specimens in a Wheatstone bridge circuit for measuring the resistance of the test specimen relative to the reference specimen to indicate the extent of corrosion of the test specimen.
Claim 3
Dependent Claim
39 words
Apparatus as set forth in claim 1 characterized by electrically insulating couplings connecting the ends of the test specimen to the means for passing the fluid through the test specimen to electrically insulate the test specimen from said means.
Claim 4
Dependent Claim
46 words
Apparatus as set forth in claim 2 characterized by the insulating couplings being outside of the housing, and temperature control means within the housing adapted to adjust the temperature in the test specimen to the temperature at which knowledge of the rate of corrosion is desired.
Claim 5
Dependent Claim
18 words
Apparatus as set forth in claim 2 characterized by the Wheatstone bridge circuit being a phase sensitive circuit.
Claim 6
Dependent Claim
30 words
Apparatus as set forth in claim 2 including a temperature recorder constructed and arranged to indicate the rate of change of temperature of the fluid flowing through the test specimen.
Claim 7
Dependent Claim
38 words
Apparatus as set forth in claim 2 characterized by temperature control means in the means for passing the fluid through the test specimen adapted to maintain the fluid delivered to the test specimen at a substantially constant temperature.
Claim 8
Dependent Claim
31 words
Apparatus as set forth in claim 2 characterized by the thermal insulation being adapted to maintain the temperatures of the test specimen and reference specimen within 0.1° F. of one another.
Claim 9
Dependent Claim
27 words
Apparatus as set forth in claim 2 characterized by the test specimen being curved and the reference specimen having substantially the same shape as the test specimen.
Claim 10
Dependent Claim
109 words
In apparatus for measuring the rate of corrosion of a test specimen by a flowing fluid wherein the resistance of a test specimen is periodically compared in an alternating current Wheatstone bridge circuit with the resistance of a reference specimen, the improvement comprising a tubular test specimen through which the fluid flows, a tubular reference specimen of the same diameter and composition as the test specimen adjacent the test specimen, means for flowing the fluid through the test specimen, electrical insulation between the test specimen and the reference specimen, and means for maintaining the temperatures of the test specimen and the reference specimen within 0.5° F. of one another.
Claim 11
Dependent Claim
109 words
In apparatus for measuring the rate of corrosion of a test specimen by a flowing fluid wherein the resistance of a test specimen is periodically compared in an alternating current Wheatstone bridge circuit with the resistance of a reference specimen, the improvement comprising a tubular test specimen through which the fluid flows, a tubular reference specimen of the same diameter and composition as the test specimen adjacent the test specimen, means for flowing the fluid through the test specimen, electrical insulation between the test specimen and the reference specimen, and means for maintaining the temperatures of the test specimen and the reference specimen within 0.5° F. of one another.
Claim 12
Dependent Claim
176 words
Apparatus for indicating the rate of corrosion of a metal by a flowing fluid comprising a tubular test specimen of the metal; means for flowing the fluid through the test specimen; means around the test specimen for adjusting the temperature of the fluid flowing through the test specimen; a reference specimen of the metal adjacent to the test specimen; electrical insulation separating the test specimen and the reference specimen; a housing enclosing the test specimen, reference specimen and means for adjusting the temperature; thermal insulation within the housing around the test specimen and the reference specimen adapted to maintain the temperature of the specimens within 1° F. of one another; an alternating current source connected to the test specimen and the reference specimen to pass a current therethrough; and electrical leads attached to the outer surface of the test specimen and to the reference specimen connecting the specimens in a Wheatstone bridge circuit for measuring the resistance of the test specimen relative to the reference specimen to indicate the extent of corrosion of the test specimen.
Claim 13
Dependent Claim
176 words
Apparatus for indicating the rate of corrosion of a metal by a flowing fluid comprising a tubular test specimen of the metal; means for flowing the fluid through the test specimen; means around the test specimen for adjusting the temperature of the fluid flowing through the test specimen; a reference specimen of the metal adjacent to the test specimen; electrical insulation separating the test specimen and the reference specimen; a housing enclosing the test specimen, reference specimen and means for adjusting the temperature; thermal insulation within the housing around the test specimen and the reference specimen adapted to maintain the temperature of the specimens within 1° F. of one another; an alternating current source connected to the test specimen and the reference specimen to pass a current therethrough; and electrical leads attached to the outer surface of the test specimen and to the reference specimen connecting the specimens in a Wheatstone bridge circuit for measuring the resistance of the test specimen relative to the reference specimen to indicate the extent of corrosion of the test specimen.
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) | 1980-04-18 | 1980-10-18 | 1981-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-18 | 1984-10-18 | 1985-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-18 | 1988-10-18 | 1989-04-19 | $7700.00 | Window Closed / Lapsed |