Electromagnetic analysis of concrete tensioning wires
First Claim
1. An inspection apparatus for detecting discontinuities in tensioning wires of a concrete pipe, comprising:
- (i) driver means to induce a current in a metallic pre-stressing reinforcement of a concrete pipe;
(ii) detector means to produce an output responsive to magnetic flux, the detector means spacedly disposed from said driver coil and adapted to be disposed proximal to a surface of the pipe and not displaced axially along the pipe from said driver means more than one pipe diameter from a plane orthogonal to the axis of the pipe and common to said driver means;
(iii) displacement sensor means to output the distance of the inspection apparatus from a known location;
(iv) means for causing the inspection apparatus to move along the concrete pipe; and
(v) means for storing outputs corresponding to detector means and the displacement sensor means.
1 Assignment
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Accused Products
Abstract
Discloses methods to perform magnetic testing of tensioning elements in a pre-stressed concrete cylindcr, such as a pipe or water reservoir and testing apparatus. The apparatus includes magnetic flux production means and detector means disposed proximal to a surface of the cylinder in a plane in common with the magnetic flux production means that is orthogonal to an axis of the cylinder. The apparatus operates over a range of low frequency signals, for example, between 20 and 300 hertz or a pulse. Output of the inspection apparatus includes a signal and distance plot showing the results of testing a cylinder at one or more frequencies. In accordance with another method of analysis, a characteristic of the phase of the output over distance is plotted, including the phase or representations of the in-phase or quadrature components of the received signal in relation to the driving signal.
29 Citations
88 Claims
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1. An inspection apparatus for detecting discontinuities in tensioning wires of a concrete pipe, comprising:
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(i) driver means to induce a current in a metallic pre-stressing reinforcement of a concrete pipe;
(ii) detector means to produce an output responsive to magnetic flux, the detector means spacedly disposed from said driver coil and adapted to be disposed proximal to a surface of the pipe and not displaced axially along the pipe from said driver means more than one pipe diameter from a plane orthogonal to the axis of the pipe and common to said driver means;
(iii) displacement sensor means to output the distance of the inspection apparatus from a known location;
(iv) means for causing the inspection apparatus to move along the concrete pipe; and
(v) means for storing outputs corresponding to detector means and the displacement sensor means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of detecting discontinuities in tensioning wires of a concrete pipe comprising:
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(i) providing a driving signal to a driver having an axis oriented orthogonal to an axis of a concrete pipe and proximal to an inside surface thereof to generate an induced current in pre-stressing elements extending substantially circumferentially of the pipe;
(ii) providing a detector for producing an output responsive to a magnetic flux, the detector located in close proximity to an interior wall of a pipe and axially displaced not more than one pipe diameter of a plane orthogonal to the axis of the pipe and common to the driver, (iii) moving the detector along the wall of the pipe; and
(iv) recording the output and the location of the detector as it moves.
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16. A method of testing the tensioning wires of a pre-stressed concrete pipe along a length thereof using apparatus including magnetic flux production means spacedly disposed from magnetic flux detector means, said magnetic flux detector means adapted to be disposed proximal to a surface of a pipe, the magnetic flux production means producing a magnetic field in response to a driving signal and the detector means producing a detector signal in response to magnetic flux and locating means to indicate a location along said pipe and control means operatively connected to said locating means, to said magnetic flux production means and to said magnetic flux detector means, the method comprising performing the steps of:
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(i) providing a driving signal of at least one frequency;
(ii) receiving a detector signal; and
(iii) recording the detector signal in relation to the frequency of the driving signal and the location indication over a range of locations traversed along a length of pipe. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A method of testing tensioning wires of a pre-stressed concrete pipe along a length thereof using apparatus including magnetic flux production means and magnetic flux detector means each disposed proximal to a surface of a pipe to be tested in a spaced relationship to the other and axially disposed within one pipe diameter to the other, the magnetic flux production means producing a magnetic field in response to a driving signal and the detector means producing a detector signal in response to magnetic flux, location indication means and control means operatively connected to said location indication means, to said magnetic flux means and to said detector means, the method comprising:
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(i) providing a driving signal of at least one frequency;
(ii) receiving a detector signal;
(iii) producing an output representative of the detector signal corresponding to the in-phase and quadrature components of the detector signal in relation to the fundamental frequency of the driving signal; and
(iv) recording the output representative of the detector signal in relation to the fundamental frequency and the location;
whereby at least one fundamental frequency is recorded over a range of locations traversed along a length of pipe. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. An inspection apparatus for detecting discontinuities in tensioning wire of a concrete cylinder, comprising:
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(i) a driver coil adapted to be oriented with an axis orthogonal to an axis of a concrete cylinder to induce a current in a tensioning wire of a concrete cylinder in response to a driving signal;
(ii) means for producing a driving signal;
(iii) detector apparatus to produce an output responsive to a magnetic flux, said detector apparatus has an axis orthogonal to the axis of said driver coil and spacedly disposed there from, said detector coil adapted to be oriented proximal to a surface of said concrete cylinder and substantially in a plane orthogonal to an axis of the concrete pipe in common with the driver coil; and
(iv) filter means for producing an output signal representative of differences between the driving signal and the output produced by said detector apparatus. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A method of detecting discontinuities tensioning wires a concrete cylinder comprising:
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(i) providing a driving signal to a driver coil means having an axis oriented orthogonal to an axis of a concrete cylinder to generate induced current in pre-stressing elements extending substantially circumferentially around the cylinder;
(ii) providing a detector proximal to a surface of the concrete cylinder and spacedly disposed from said driver means along said axis of said driver coil means, the detector to produce an output responsive to a magnetic flux;
(iii) filtering the output of the detector relative to the driving signal; and
(iv) recording the filtered output and the location of the detector.
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48. A method of testing the tensioning wires of a pre-stressed concrete cylinder along a length thereof using apparatus including magnetic flux production means and magnetic flux detector means each proximal to a surface of a cylinder and in a spaced relationship to each other, the magnetic flux production means to produce a magnetic field in response to a driving signal and the detector means to produce a detector signal in response to magnetic flux and locating means to indicate a location along said cylinder and control means operatively connected to said locating means, to said magnetic flux means and to said detector means, the method comprising performing the steps of:
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(i) providing a driving signal of at least one frequency;
(ii) receiving a detector signal;
(iii) filtering the received detector signal relative to the driving signal;
(iv) receiving a location indication; and
(v) recording the filtered detector signal, the frequency of the driving signal and the location indication over a range of locations traversed along a length of cylinder. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55)
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56. A method of testing the tensioning wires of a pre-stressed concrete cylinder along a length thereof using apparatus including magnetic flux production means and magnetic flux detector means each disposed proximal to a surface of the cylinder in a spaced relationship to the other and axially disposed not more than one cylinder diameter from the other, the magnetic flux production means for producing a magnetic field in response to a driving signal and the detector means for producing a detector signal in response to magnetic flux, location indication means and control means operatively connected to said location indication means, to said magnetic flux means and to said detector means, the method comprising:
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(i) providing a driving signal of at least one frequency;
(ii) receiving a detector signal;
(iii) producing an output representative of the detector signal corresponding to the in-phase and quadrature components of the detector signal in relation to the fundamental frequency of the driving signal; and
(iv) recording the output representative of the detector signal in relation to the fundamental frequency, the fundamental frequency and the location;
whereby at least one fundamental frequency is recorded over a range of locations traversed along a length of cylinder. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63)
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64. A method of testing the tension wires of a pre-stressed concrete cylinder along a length thereof using apparatus including magnetic flux production means and magnetic flux detector means each disposed proximal to a surface of the cylinder, the magnetic flux production means for producing a magnetic field in response to a driving signal and the detector means for producing a detector signal in response to magnetic flux, location indication means and control means operatively connected to said location indication means, to said magnetic flux means and to said detector means, the method comprising:
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(i) providing a driving signal of at least one frequency;
(ii) positioning the detector means in relation to the magnetic flux production means, each said detector means and the magnetic flux production means axially disposed not more than one cylinder diameter to the other;
(iii) receiving a detector signal;
(iv) producing an output representative of the detector signal corresponding to the in-phase and quadrature components of the detector signal in relation to the fundamental frequency of the driving signal; and
(v) recording the location of the detector means and output representative of the detector signal in relation to the fundamental frequency, the fundamental frequency and the location of a deter;
whereby at least one fundamental frequency is recorded over a range of locations traversed by said detector means along a length of a pre-stressed concrete cylinder. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71)
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72. Apparatus for detecting discontinuities in a spirally wound metallic pre-stressing reinforcements embedded the wall of a concrete pipe or substantially cylindrical fluid containment structure having a longitudinal axis, comprising:
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(i) a detector oriented to lie along the wall surface of said concrete pipe or structure to be monitored, said detector being capable of detecting magnetic flux flowing in a direction parallel to the longitudinal axis of the pipe or structure, means for causing the detector to move along the surface of such pipe or structure;
(ii) means for determining at least one of the location of the detector or the distance it has moved from a known original location;
(iii) means for recording the magnetic flux recorded by the detector and recording it in association with the location of the detector when such flux was detected or the distance that the detector has moved from an original known location when such flux was detected. - View Dependent Claims (73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83)
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84. A method of detecting discontinuities in spirally wound metallic pre-stressing elements of a concrete pipe having such elements which comprises:
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(i) providing a detector coil which has its axis parallel to the axis of the pipe, and which is of a diameter less than one quarter of the diameter of the pipe, (ii) placing the detector coil in close proximity to the interior wall of the pipe, (iii) generating a periodically varying induced current in the pre-stressing elements, (iv) moving the detector coil along the wall of the pipe and (v) recording the distance moved or the location of the detector coil, and the induced voltage or current sensed by the detector coil as it moves. - View Dependent Claims (85, 86, 87, 88)
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Specification