US3883797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for checking the continuity of metallic pipes using an oscillator whose frequency changes at discontinuities
Assignee: Individual
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Filing: 1974-06-20
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Granted: 1975-05-13
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Expires: 1994-06-20
Abstract
Abstract The apparatus according to the invention may be used in the oilrecovery and gas industry. The apparatus comprises means for inducing an alternating magnetic field in the pipe being checked and a converter for converting a change in the magnetic field into an electric signal, said means and said converter comprising two transformers mounted in a fixed position relative to each other and electrically coupled therebetween, and an electronic amplifier circuit with positive feedback formed by the transformer windings. The magnetic circuits of the both transformers are completed by the body of the pipe being checked. Upon the occurence of a discontinuity in the pipe being checked the magnetic flux values of the both transformers are changed so that the frequency of the output signal of the converter is also changed to obtain the information on the discontinuity of the metal of the pipe.
Inventors
- 👤 Abram Lvovich Abrukin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:59
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9046
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
239 words
An apparatus for checking-up the continuity of metallic pipes comprising: means for inducing magnetic field in the pipe being checked, said field being changed upon the occurence of a discontinuity in said pipe, and a converter for converting a change in the magnetic field into an electric signal carrying the information on the discontinuity of said pipe, said means and said converter comprising two transformers with open magnetic circuits mounted in a fixed position relative to each other, the magnetic circuits of said transformers being completed during the checking-up by the body of the pipe being checked, and an electronic amplifier circuit with positive feedback formed by the windings of said transformers, the primary windings of said transformers being matchingly interconnected and coupled to the output of said electronic amplifier circuit, and the secondary windings of said transformers having different number of turns being oppositely connected in series and coupled to the input of said electronic amplifier circuit, the ratio between the number of turns of said primary windings and the difference in the number of turns of said secondary windings complying with the condition K Beta > 1 wherein K is gain of said electronic amplifier circuit, and Beta is resultant transformation ratio of the system of the interconnected transformers, whereby, upon the occurence of a discontinuity in the pipe being checked, the frequency of the electric signal at the output of said electronic amplifier circuit is changed.
Claim 2
Independent Claim
239 words
An apparatus for checking-up the continuity of metallic pipes comprising: means for inducing magnetic field in the pipe being checked, said field being changed upon the occurence of a discontinuity in said pipe, and a converter for converting a change in the magnetic field into an electric signal carrying the information on the discontinuity of said pipe, said means and said converter comprising two transformers with open magnetic circuits mounted in a fixed position relative to each other, the magnetic circuits of said transformers being completed during the checking-up by the body of the pipe being checked, and an electronic amplifier circuit with positive feedback formed by the windings of said transformers, the primary windings of said transformers being matchingly interconnected and coupled to the output of said electronic amplifier circuit, and the secondary windings of said transformers having different number of turns being oppositely connected in series and coupled to the input of said electronic amplifier circuit, the ratio between the number of turns of said primary windings and the difference in the number of turns of said secondary windings complying with the condition K Beta > 1 wherein K is gain of said electronic amplifier circuit, and Beta is resultant transformation ratio of the system of the interconnected transformers, whereby, upon the occurence of a discontinuity in the pipe being checked, the frequency of the electric signal at the output of said electronic amplifier circuit is changed.
Claim 3
Dependent Claim
20 words
An apparatus according to claim 1, wherein the windings of said transformers are surrounded by screens of nonmagnetic stainless steel.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |