LINEAR STRUCTURE INSPECTION APPARATUS AND METHOD
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Accused Products
Abstract
An apparatus is provided for sensing anomalies in a long electrically conductive object to be inspected. The object may be a pipeline, or other hollow tube. The apparatus may have a magnetic field generator, and an array of sensors spaced about the field generator. As relative motion in the longitudinal direction occurs between the apparatus and the object to be inspected, the moving magnetic field, or flux, passed from the field generator into the object to be inspected may tend to cause eddy currents to flow in the object. The sensors may be spaced both axially and circumferentially to permit variation in magnetic flux, or eddy current divergence, to be sensed as a function of either or both of axial position relative to the wave front of the magnetic field (or, effectively equivalently any other known datum such as the radial plane of the midpoint of the field generator), and circumferential position about the periphery of the apparatus as measured from an angular datum. Post processing calculation may then tend to permit inferences to be drawn about the location, size, size, shape, and perhaps nature, of anomalies in the object. The sensors, and possibly the entire field generator, may be maintained at a standoff distance from the object to be inspected, as by a sealed housing such as may protect the sensors and reduce the need for and cost of maintenance. The field generator may include two primary poles of like nature held in a non-touching back to back orientation, and may include secondary magnetic circuits placed to bias the flux of the primary magnetic circuit into a more focussed shape with respect to the object to be inspected.
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Citations
66 Claims
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1-46. -46. (canceled)
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47. An apparatus for detecting anomalies in an electrically conductive structure, the electrically conductive structure having a ratio of length to girth in excess of 20:
- 1, the apparatus being movable in the lengthwise direction relative to the structure, said apparatus comprising;
a magnetic field generator, said magnetic field generator including a first primary magnetic circuit oriented to pass a magnetic flux into the structure along a wave front extending predominantly cross-wise to the lengthwise direction when said apparatus is moved in the lengthwise direction; and a magnetic flux sensing array, said magnetic flux sensing array including flux sensors spaced sectorally adjacent to the magnetic field generator, the array extending in a direction predominantly aligned with the wave front and positioned to monitor flux drag between said magnetic field generator and said structure. - View Dependent Claims (48, 49, 50, 51, 52, 53)
- 1, the apparatus being movable in the lengthwise direction relative to the structure, said apparatus comprising;
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54. An intelligent pipeline pig for insertion in a pipeline having a cylindrical pipe wall, said intelligent pipeline pig having:
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a body and flux sensors mounted within said body, said sensors being operable from within said body to monitor properties of said pipeline while said intelligent pipeline pig is within said pipeline and said sensors are enclosed within said body; a magnetic flux field generator operable to pass magnetic flux across a gap into the pipeline pipe wall; and said sensors being mounted to monitor flux drag in said gap. - View Dependent Claims (55, 56, 57, 58, 59, 60)
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61. A pipeline pig for insertion in a pipeline, the pipeline having an electrically conductive pipe wall, said pipeline pig having a longitudinal axis defining an axial direction, and a periphery radially distant from said longitudinal axis, said pig including a magnetic field generator for passing magnetic flux into said pipe wall, said pig having an array of magnetic flux sensors mounted about said magnetic field generator, said flux sensors being operable to permit independent monitoring of magnetic flux at a plurality of sectors about said magnetic field generator;
- said magnetic flux generator including a first magnetic circuit and a second magnetic circuit, said first and second magnetic circuits being segregated from each other, and one of
(a) each of said first and second magnetic circuits having a respective first pole oriented cross-wise to said axis, said first poles of said first and second magnetic circuits being placed next adjacent to each other;
said first poles of said first and second magnetic circuits being mutually repulsive; and
said sensors being operable to sense axial variation in magnetic flux relative to said first poles of said first and second magnetic circuits; and(b) said flux sensors include at least a first set of sensors and a second set of sensors, said first set of sensors being mounted about said magnetic field generator in a first orientation relative to said magnetic field generator, and said second set of sensors being mounted about said magnetic field generator in a second orientation relative thereto, and combined readings of sensors in said first and second sets of sensors permitting radial and axial components of magnetic flux to be sensed in at least two of said plurality of sectors. - View Dependent Claims (62, 63, 64, 65, 66)
- said magnetic flux generator including a first magnetic circuit and a second magnetic circuit, said first and second magnetic circuits being segregated from each other, and one of
Specification