Noninvasive detection of corrosion, MIC, and foreign objects in fluid-filled containers using leaky guided ultrasonic waves

• US 6,367,328 B1
• Filed: 07/11/2000
• Issued: 04/09/2002
• Est. Priority Date: 07/12/1999
• Status: Expired due to Term

• Current Assignee: Digital Wave Corporation (Hexagon Composites ASA)
• Original Assignee: Digital Wave Corporation (Hexagon Composites ASA)
• Inventors: Huang, Wei, Gorman, Michael R., Ziola, Steven M.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US09/613,704
• Time in Patent Office: 637 Days
• Field of Search: 735/70, 735/97, 735/99, 73/52, 735/87, 735/90, 732/90.R, 736/20, 736/22, 736/24, 736/43, 736/44, 736/00, 735/98, 735/92
• US Class Current: 73/592
• CPC Class Codes: G01N 17/006 of metals
• CPC Class Codes: G01N 2291/011 Velocity or travel time
• CPC Class Codes: G01N 2291/015 Attenuation, scattering
• CPC Class Codes: G01N 2291/025 Change of phase or condition
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 2291/2634 cylindrical from outside
• CPC Class Codes: G01N 2291/2695 Bottles, containers
• CPC Class Codes: G01N 29/041 on the surface of the material, e.g. using Lamb, Rayleigh or shear waves
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/36 Detecting the response signal , e.g. electronic circuits specially adapted therefor

Abstract

Ultrasonic energy in the form of guided waves is launched into the wall of a fluid-filled container. The guided wave propagates around the circumference of the container from a transmitting transducer to a receiving transducer. Part of the guide wave energy leaks into the fluid in the form of bulk waves, reflects off the inner wall on the other side and enters back to the receiving transducer trailing the direct wave. Analysis of the received waves determines the presence of corrosion pitting and MIC nodules on the container inner wall, and fluid level. In addition, it determines whether foreign objects are inside the container. The guided waves are created with wideband transducers excited at certain frequencies that depend on the material and geometry of the part being measured. The leakage energy is maximized with a shaped tone burst pulse at the specified frequency. The energy and energy ratio of both the direct and leakage fields are measured and related to the container inner wall condition and the presence of any foreign objects in the fluid.

Claims

1. A method for detecting container features, or fluids or other materials inside a fluid filled container, by leaky guided wave ultrasound (LGWU), the method comprising:

(a.) placing a transmitting transducer and a receiving transducer at longitudinal or circumferential positions of a fluid-filled container;

(b.) generating guided waves using a shaped tone burst pulse at a specified frequency; and

,

(c.) measuring both a direct field and a leakage field, thereby providing an indication of existence of features, fluid or materials inside of the fluid filled container.

2. The method of claim 1, wherein the container comprises one or more of:

a pipe, a conduit, a tank, a barrel, a drum, a cylinder, and a plate.

3. The method of claim 1, wherein the container comprises one or more of:

a circular region, a conic region, and a cubic region.

4. The method of claim 1, wherein the container features, fluids or other materials comprise one or more of:

corrosion on the inner wall of the fluid-filled container, MIC on the inner wall of the fluid-filled container, ice on the inner wall of the fluid filled container, ice in the fluid in the fluid filled container, foreign material in the fluid in the fluid filled container, fluid level of the fluid in the fluid filled container, or fluid density of the fluid in the fluid filled container.

5. The method of claim 4, wherein said corrosion comprises pitting or loss of wall material on the container inner wall.

6. The method of claim 4, wherein said MIC comprises microbiologically-induced corrosion.

7. The method of claim 1 wherein said fluid or other material comprises one or more of:

a floating solid, a slimy fluid, or a material attached to the inner wall.

8. The method of claim 1, wherein said transducer comprises a water-coupled wideband transducer, a dry-coupled wideband transducer, or an air-coupled wideband transducer.

9. The method of claim 1, wherein said guided waves are waves excited at a selected frequency and angle to maximize the leakage field for selected container ODs and materials.

10. The method of claim 1, wherein said measuring includes recording and analyzing the direct field energy, the leakage field energy and the energy ratio of leakage field energy to direct field energy.

11. The method of claim 1, wherein the amplitude of a given phase point on the tone burst is selected or modulated.

12. The method of claim 1, wherein said direct field is part of the received signal due to guided wave propagation along the container.

13. The method of claim 1 wherein said leakage field is part of the received signal for a leaky bulk wave propagating inside the fluid.

14. An integrated system for detecting container features, or fluids or other materials inside a fluid filled container, by leaky guided wave ultrasound (LGWU), the system comprising:

(a.) a transmitting transducer and a receiving transducer placed at longitudinal or circumferential positions of a fluid-filled container;

(b.) a guided wave generator which produces a shaped tone burst pulse at a specified frequency; and

,

(c.) an energy field detection module for measuring both a direct field and a leakage field, which measurement provides an indication of container features or materials inside the fluid filled container.

15. The integrated system of claim 14, wherein the container comprises one or more of:

a pipe, a tank, a barrel, a drum, a cylinder, and a plate.

16. The integrated system of claim 14, wherein the container comprises one or more of:

a circular region, a conic region, and a cubic region.

17. The integrated system of claim 14, wherein the container features, fluids or other materials comprise one or more of:

corrosion on the inner wall of the fluid-filled container, MIC on the inner wall of the fluid-filled container, ice on the inner wall of the fluid filled container, ice in the fluid in the fluid filled container, foreign material in the fluid in the fluid filled container, fluid level of the fluid in the fluid filled container, or fluid density of the fluid in the fluid filled container.

18. The integrated system of claim 14, comprising a computer or computer readable medium comprising an instruction set for controlling the transmitting transducer, or the guided wave generator.

19. The integrated system of claim 14, the energy field detection module comprising a computer or computer readable medium comprising an instruction set for measuring the direct field and the leakage field.

20. The integrated system of claim 14, the energy field detection module comprising a computer or computer readable medium comprising an instruction set for measuring the direct field and the leakage field and an additional instruction set for reporting the results of the measurement to a user.

21. The integrated system of claim 20, said instruction set comprising instructions for recording and analyzing the direct field energy, the leakage field energy and the energy ratio of leakage field energy to direct field energy.

22. The integrated system of claim 14, wherein said transducer comprises a water-coupled wideband transducer, a dry-coupled wideband transducer, or an air-coupled wideband transducer.

23. The integrated system of claim 14, wherein the energy field detection module comprises an analog to digital converter, which converter converts direct or leakage field energy into digital format data.

24. The integrated system of claim 23, the detection module comprising a digital display, which digital display provides a user-viewable display of information in the digital format data.

25. The integrated system of claim 14, wherein the energy field detection module comprises an analog energy detector and an analog display.

26. The integrated system of claim 14, the detection module comprising means for measuring the direct and leakage field.

39. The device of claim 22, further comprising a transmitting transducer coupling system, a receiving transducer coupling system, a RF amplifier, a RF receiver gain and filter circuitry, a computer with a plug-in arbitrary function generator, a 2-channel A/D converter, and an analysis/display software.

40. The device of claim 39, wherein the arbitrary function generator generates a pulse of user-defined frequency and wherein:

the output of the arbitrary function generator is connected to a first channel input of the A/D converter and to an input of the RF amplifier;

the RF amplifier output is connected to the transmitting transducer;

the receiving transducer is connected to an input of the RF receiver gain and filter circuitry;

the output of the RF receiver is connected to a second channel input of the A/D converter; and

,

the data analysis/display software controls signal generation, acquisition and display functions.

27. A device for detecting container features, or fluids or other materials inside a fluid filled container, by leaky guided wave ultrasound (LGWU), the device comprising:

(a.) a transmitting transducer and a receiving-transducer configured to be placed at circumferential or longitudinal positions of a fluid-filled container;

(b.) a guided wave generator which produces a shaped tone burst pulse at a specified frequency; and

,

(c.) means for measuring both a direct field and a leakage field, thereby providing an indication of existence of corrosion and MIC on the container inner wall, foreign objects inside the fluid and fluid level.

28. The device of claim 27, wherein the container comprises one or more of:

a pipe, a tank, a barrel, a drum, a cylinder, and a plate.

29. The device of claim 27, wherein the container comprises one or more of:

a circular region, a conic region, and a cubic region.

30. The device of claim 27, wherein the container features, fluids or other materials comprise one or more of:

corrosion on the inner wall of the fluid-filled container, MIC on the inner wall of the fluid-filled container, ice on the inner wall of the fluid filled container, ice in the fluid in the fluid filled container, foreign material in the fluid in the fluid filled container, fluid level of the fluid in the fluid filled container, or fluid density of the fluid in the fluid filled container.

31. The device of claim 27, further comprising a computer or computer readable medium comprising an instruction set for measuring the direct field and the leakage field and an additional instruction set for reporting the results of the measurement to a user.

32. The device of claim 31, said instruction set comprising instructions for recording and analyzing the direct field energy, the leakage field energy and the energy ratio of leakage field energy to direct field energy, or a ratio of another suitable wave characteristic of the leakage field to the direct field.

33. The device of claim 32, wherein the other suitable wave characteristic is amplitude of a given phase point on the tone burst.

34. The device of claim 27, wherein said transducer comprises a water-coupled wideband transducer, a dry-coupled wideband transducer, or an air-coupled wideband transducer.

35. The device of claim 27, further comprising a computer with a plug-in arbitrary function generator and analysis/display software.

36. The device of claim 35 further comprising a 2-channel A/D converter.

37. The device of claim 35, wherein the arbitrary function generator generates a pulse at a user-defined frequency.

38. The device of claim 35, wherein the arbitrary function generator generates a pulse at a user-defined frequency and wherein an output of the arbitrary function generator is connected to a first channel input of the A/D converter.