US4301677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measuring device for use with tubular products
Assignee: Electric Power Research Institute
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Filing: 1979-10-04
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Granted: 1981-11-24
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Expires: 1999-10-04
Abstract
Abstract Apparatus for detecting variations in the internal dimensions of a pipe includes a plurality of cantilever members for engaging the internal surface and strain gauges mounted on the cantilever members which are responsive to the flexing of the cantilever members. A Wheatstone bridge is utilized to measure changes in resistance of the strain gauges and hence the amount of flexing of the cantilevers due to undulations in the internal surface. The apparatus is particularly useful in detecting and measuring dents in tubes of nuclear power plant steam generators caused by corrosion of steel support plates.
Inventors
- 👤 Frederick M. Fisher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:16
CPC Classifications
C; C07; C07D; C07D401/00; C07D401/02; C07D401/04; G; G01; G01B; G01B7/00; G01B7/28; G01B7/287; G01B7/12; G01B7/13
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
Apparatus for detecting denting in the internal surface of a tube due to corrosion of support plates comprising support means of suitable dimensions for moving through said tube, said support means including an outer housing and a plurality of spring means for engaging said internal surface and maintaining said outer housing generally in line with the center line of said tube; a plurality of flexible members extending from said support means, each of said flexible members having a surface portion for engaging said internal surface; transducer means mounted on each of said flexible members for sensing flex of said member; and eddy current detection means for detecting the presence of tube support structures.
Claim 2
Dependent Claim
113 words
Apparatus for detecting denting in the internal surface of a tube due to corrosion of support plates comprising support means of suitable dimensions for moving through said tube, said support means including an outer housing and a plurality of spring means for engaging said internal surface and maintaining said outer housing generally in line with the center line of said tube; a plurality of flexible members extending from said support means, each of said flexible members having a surface portion for engaging said internal surface; transducer means mounted on each of said flexible members for sensing flex of said member; and eddy current detection means for detecting the presence of tube support structures.
Claim 3
Dependent Claim
26 words
Apparatus as defined by claim 1 wherein said housing includes a plurality of openings and said surface portions of said flexible members extend through said openings.
Claim 4
Dependent Claim
46 words
Apparatus as defined by claims 1 or 2 wherein each of said flexible members comprises a cantilever having an extended end and a supported end, said surface portion being near said extended end and said transducer means being mounted to said member near said supported end.
Claim 5
Dependent Claim
14 words
Apparatus as defined by claim 3 wherein said transducer means comprises a strain gauge.
Claim 6
Dependent Claim
27 words
Apparatus as defined by claim 4 wherein said transducer means further includes Wheatstone bridge means for detecting changes in said strain gauge as said cantilever is flexed.
Claim 7
Dependent Claim
17 words
Apparatus as defined by claim 5 and including means for moving said support means through said tube.
Claim 8
Dependent Claim
39 words
Apparatus as defined by claim 1 wherein said transducer means comprises a strain gauge which has an electrical resistance which changes in response to flexing of said member and Wheatstone bridge means for detecting changes in said electrical resistance.
References Cited (Backward Citations)
US2656613A
Cited
US3010212A
Cited
US2915830A
Cited
US3024651A
Cited
US3628029A
Cited
US4235020A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-23 | 1985-05-25 | 1985-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-23 | 1989-05-25 | 1989-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-23 | 1993-05-25 | 1993-11-24 | $7700.00 | Window Closed / Lapsed |