ID-OD discrimination sensor concept for a magnetic flux leakage inspection tool
First Claim
1. An instrument pig for determining the characteristics of a ferromagnetic pipeline through which it passes, comprising:
- a pig body coaxially supported and moving within the pipeline in response to fluid flow;
first and second coaxial circumferential, spaced apart magnets of opposed polarities supported to said pig body and providing substantially complete magnetic saturation of an area of the pipeline between the magnets;
first instruments supported by the pig body between said magnets and arranged to generate signals that are responsive to flux leakage servicing to provide first information as to anomalies in the pipeline interior and/or exterior surface;
second instruments employing pulsed and sensing coil pairs supported by the pig body between said magnets and arranged to generate signals that are responsive to eddy currents induced in the pipeline interior surface servicing to provide second information as to anomalies in the pipeline interior surface;
signal processing circuitry combining said first and second signals to indicate the magnitude and interior or exterior location of the pipeline anomalies; and
wherein said second instruments are energized only in response to signals generated by said signal processing circuitry.
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Accused Products
Abstract
An instrument pig and method of operation thereof for determining the characteristics of a ferromagnetic pipeline through which it passes, including a pig body, first and second coaxial circumferential, spaced apart magnets of opposed polarities supported to the pig body and providing substantially complete magnetic saturation of an area of the pipeline between the magnets, first instruments between the magnets and arranged to generate signals that are responsive to flux leakage servicing to provide first information as to anomalies in the pipeline interior and/or exterior surfaces, second instruments supported by the pig body between said magnets and arranged to generate signals that are responsive to eddy currents induced in the pipeline interior surface servicing to provide second information as to anomalies in the pipeline interior surface, signal processing circuitry combining the first and second signals and wherein the second instruments are energized only in response to signals generated by said signal processing circuitry.
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Citations
16 Claims
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1. An instrument pig for determining the characteristics of a ferromagnetic pipeline through which it passes, comprising:
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a pig body coaxially supported and moving within the pipeline in response to fluid flow;
first and second coaxial circumferential, spaced apart magnets of opposed polarities supported to said pig body and providing substantially complete magnetic saturation of an area of the pipeline between the magnets;
first instruments supported by the pig body between said magnets and arranged to generate signals that are responsive to flux leakage servicing to provide first information as to anomalies in the pipeline interior and/or exterior surface;
second instruments employing pulsed and sensing coil pairs supported by the pig body between said magnets and arranged to generate signals that are responsive to eddy currents induced in the pipeline interior surface servicing to provide second information as to anomalies in the pipeline interior surface;
signal processing circuitry combining said first and second signals to indicate the magnitude and interior or exterior location of the pipeline anomalies; and
wherein said second instruments are energized only in response to signals generated by said signal processing circuitry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of determining the characteristics of the interior and exterior surfaces of a metal pipeline comprising the steps of:
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(a) moving an axially supported pig body through a pipeline;
(b) by means of magnets carried by the pig body magnetically saturating a circumferentially zone of the pipeline that moves with the pig;
(c) continuously measuring changes of reluctance in the moving circumferential zone to provide indications of the presence and size of anomalies in the pipeline interior or exterior surfaces;
(d) electrically energizing a plurality of pulse coils to induce eddy currents in the internal surface of said moving circumferential zone of the pipeline;
(e) by means of a plurality of sensing coils each paired with a said pulsed coil measuring said eddy currents to determine the presence or absence of anomalies in the pipeline interior surface;
(f) comparing the results of steps (c) and (e) in signal processing circuitry to determine whether the anomaly detected in step (c) is on the exterior or interior surface of the pipeline;
(g) recording the results of steps (c) and (f) to provide information as to the occurrence, size and exterior/interior locations of pipeline wall anomalies; and
(h) energizing said plurality of pulse coils in step (d) only in response to signals generated by said signal processing circuitry. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification