Flexible EMAT Arrays for Monitoring Corrosion and Defect Propagation in Metal Components and Structures
First Claim
1. Arrays of Electromagnetic Acoustic Transducers (EMAT) consisting of coils of electrical conductors and magnets arranged in various configurations and designed for durability, conformability and attachment to curved surfaces of metal components including but not limited to piping, pressure vessels and tanks operating at elevated temperatures as well as temperatures below ambient for the purpose of monitoring the extent and severity of defects including but not limited to corrosion, voids and cracks.
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Abstract
The invention pertains to the design, arrangement and fabrication of arrays of electromagnetic acoustic transducers (EMATs) for detection and monitoring of defects in metal components while they are being used in service. Emphasis is placed on printed circuit sensor coil designs that are attached to and covered with thin, flexible and insulating substrates. This laminated construction with additional means for electrical and thermal insulation, radiation heat shielding and simple cooling provides for consistent and reliable EMAT performance in monitoring components at elevated temperatures. The arrays include circular spiral coils, elongated spiral (racetrack) coils and rectangular spiral coils. Also described are arrays of dual-rectangular (butterfly) coils, meander coils and trapezoidal coils. Various assembly designs for the attachment of bias magnets are described.
29 Citations
32 Claims
- 1. Arrays of Electromagnetic Acoustic Transducers (EMAT) consisting of coils of electrical conductors and magnets arranged in various configurations and designed for durability, conformability and attachment to curved surfaces of metal components including but not limited to piping, pressure vessels and tanks operating at elevated temperatures as well as temperatures below ambient for the purpose of monitoring the extent and severity of defects including but not limited to corrosion, voids and cracks.
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15. An array of cylindrical magnets, as illustrated in
FIG. 23 , that are installed in rings that are centered over the said spiral Coils and made of suitable material such as aluminum, brass and plastics that can withstand elevated temperatures and fastened to the magnets near the bottom of the magnet that is closest to the EMAT coil array and linked together with a hinge or flexible material attached to the rings of adjacent magnets in a line that conforms to the component under interrogation.
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16. An array of block magnets, as illustrated in
FIG. 24 , that are installed in brackets that are centered over the said racetrack, spiral Coils and made of suitable material such as aluminum, brass and plastics that can withstand elevated temperatures and fastened to the magnets near the bottom of the magnet that is closest to the EMAT coil array and linked together with a hinge attached to the brackets of adjacent magnets in a line that conforms to the component under interrogation.
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17. An array of cylindrical or block magnets that are encased in a mold with slots between the magnets, as illustrated in
FIG. 25 , so as to improve the flexibility of said array that is made of flexible material such as silicon rubber that can withstand elevated temperatures and are held in position so that the magnets are centered over the said spiral Coils and are arranged with their center axis in a line that conforms to the component under interrogation.
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24. A two pole magnet that has a rectangular-shaped crossection for use with a arrays of overlapping coils as illustrated in
FIG. 17 ,FIG. 18 ,FIG. 19 ,FIG. 20 , andFIG. 21 that is fabricated in a shape that conforms to the contour of the component under interrogation and provides magnetic fields at its poles that are approximately normal to the surface of said component and parallel to the axis of each said coil in the array.
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25. A two pole U-shaped magnet for use with a arrays of overlapping coils as illustrated in
FIG. 17 ,FIG. 18 ,FIG. 19 ,FIG. 20 , andFIG. 21 that is fabricated in a shape that conforms to the contour of the component under interrogation and provides magnetic fields at its poles that are approximately normal to the surface of said component under interrogation and parallel to the axis of each said coil in the array.
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26. A three pole E-shaped magnet for use with arrays of overlapping coils as illustrated in
FIG. 17 ,FIG. 18 ,FIG. 19 ,FIG. 20 , andFIG. 21 that is fabricated in a shape that conforms to the contour of the component under interrogation and provides a magnetic field at its poles that is approximately normal to the surface of said component under interrogation and parallel to the axis of each said coil in the array.
Specification