US3737764A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Eddy-current test apparatus for detection of flaws in a metal seal placed within an electrically conductive tube
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1971-09-27
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Granted: 1973-06-05
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Expires: 1991-09-27
Abstract
Abstract A method and apparatus for eddy-current detection of flaws such as bubbles and different characteristics of a metal seal within an electrically conductive tube. The method consists in recording separately on the one hand the variations in potential which are directly related to variations in amplitude of the eddy currents as a function of the cross-section of the tube and on the other hand the variations in the frequency of said currents also as a function of said cross-section while also recording simultaneously with these two variations the variations in said potential as a function of said frequency, the frequency of the eddy currents being determined as a function of the nature and shape of the tube and of the seal.
Inventors
- 👤 J Dufayet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:48
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9046
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
260 words
An apparatus for eddy current detection of flaws in a metal seal within an electrically conductive tube comprising a Hartley oscillator, the tank coil of said oscillator surrounding an electrically conductive displaceable tube containing the metal seal, said coil acting as both a generator for setting up eddy currents in said tube and also as an eddy-current detection coil, means for relatively displacing the tube with respect to said tank coil, a two-channel recorder having a voltage channel and a frequency channel connected to the oscillating circuit of said Hartley oscillator, said voltage channel recording the curve of variations in potential of the Hartley oscillator, which varies with the tube cross section, as a function of the displacement of the tube and said frequency channel recording the curve of variations in frequency of the oscillations, which also varies with the cross section of the tube, as a function of the displacement of the tube, a second recorder connected to the oscillator circuit and having a voltage input and a frequency input for generating a curve of variations in said potential as a function of said variations in frequency while said tube is being displaced, a differential amplifier connected between said oscillating circuit and the voltage channel of said two channel recorder and the voltage input of said second recorder and a frequency-voltage converter connected between said oscillating circuit and the frequency channel of said two channel recorder and the frequency input of said second recorder, the three curves thus obtained simultaneously indicating defects of the metal seal within the tube.
Claim 2
Independent Claim
260 words
An apparatus for eddy current detection of flaws in a metal seal within an electrically conductive tube comprising a Hartley oscillator, the tank coil of said oscillator surrounding an electrically conductive displaceable tube containing the metal seal, said coil acting as both a generator for setting up eddy currents in said tube and also as an eddy-current detection coil, means for relatively displacing the tube with respect to said tank coil, a two-channel recorder having a voltage channel and a frequency channel connected to the oscillating circuit of said Hartley oscillator, said voltage channel recording the curve of variations in potential of the Hartley oscillator, which varies with the tube cross section, as a function of the displacement of the tube and said frequency channel recording the curve of variations in frequency of the oscillations, which also varies with the cross section of the tube, as a function of the displacement of the tube, a second recorder connected to the oscillator circuit and having a voltage input and a frequency input for generating a curve of variations in said potential as a function of said variations in frequency while said tube is being displaced, a differential amplifier connected between said oscillating circuit and the voltage channel of said two channel recorder and the voltage input of said second recorder and a frequency-voltage converter connected between said oscillating circuit and the frequency channel of said two channel recorder and the frequency input of said second recorder, the three curves thus obtained simultaneously indicating defects of the metal seal within the tube.
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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |