Pipe testing apparatus and method using electrical or electromagnetic pulses transmitted into the pipe

• US 6,194,902 B1
• Filed: 02/27/1997
• Issued: 02/27/2001
• Est. Priority Date: 02/27/1996
• Status: Expired due to Term

• Current Assignee: WaveTrue, Inc.
• Original Assignee: Profile Technologies, Inc.
• Inventors: Burnett, Gale D., Kuo, John T.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/807,645
• Time in Patent Office: 1,461 Days
• Field of Search: 324/637, 324/639, 324/532, 324/535
• US Class Current: 324/637
• CPC Class Codes: G01N 17/00 Investigating resistance of materials to the weather, to corrosion, or to light

Abstract

A method and system for detecting corrosion on a pipe or a pipeline. An electrical or electromagnetic pulse is transmitted into a pipe or pipeline to travel as a propagating electromagnetic wave along the pipeline to a receiving location. Both the distance traveled from the transmitting and receiving location, and also the time interval for such travel are measured. Velocity of the wave is detected as a means of ascertaining whether corrosion is present. Various embodiments, using both multi-channel and single cables, are used to transmit the detected waves, and the waves are received at a plurality of spaced locations along the length of the pipe or pipeline. For an insulated pipeline, the signals can be received by a directional antenna, and the pulses can be transmitted into the pipeline by means of either an antenna placed directly adjacent to the pipeline or a magnet electrical contact member in direct contact with the pipeline.

Claims

1. A method of identifying corrosion on an electromagnetically permeable elongate member, such as a pipe, said method comprising:

a. transmitting an electrical or electromagnetic pulse into said elongate member at a transmitting location of the elongate member and at a transmitting time, to cause said pulse to travel as a propagating electromagnetic wave to a receiving location over a travel distance and during a travel time interval;

b. receiving at a receiving time said electromagnetic wave at said receiving location on said elongate member;

c. ascertaining a delay in said electromagnetic wave traveling over said travel distance to ascertain presence of corrosion on said elongate member.

2. The method as recited in claim 1, wherein said pulse wave or waves has a sufficiently high frequency, so that the electromagnetic wave travels over the outside surface of the elongate member at a very thin skin depth where corrosion on an exterior surface of the elongate member may be present.

3. The method as recited in claim 1, wherein a receiving means is operatively positioned at said receiving location to receive said electromagnetic wave, and said receiving means comprises an antenna responsive to electromagnetic radiation.

4. The method as recited in claim 1, wherein said receiving means comprises a plurality of receivers which are operatively positioned at spaced receiving locations along a lengthwise axis of said elongate member, said method further comprising:

a. ascertaining distances between said spaced receiving locations;

b. ascertaining times of travel of said electromagnetic wave between said receiving locations;

c. ascertaining, from said distances and said times of travel, velocity of said electromagnetic wave or waves between said receiving locations to identify presence of corrosion.

5. The method as recited in claim 4, said method further comprising ascertaining an area or areas between two receiving locations where the velocity of the electromagnetic wave or waves is lower, to identify presence and location of corrosion.

6. The method as recited in claim 5, wherein there is provided a multi-channel cable, comprising a plurality of channels, and each of said receivers is operatively connected to a related one of said channels, with said multi-channel cable directing signals received from said receivers to a data receiving location.

7. The method as recited in claim 6, wherein said multi-channel cable is a fibre optic multi-channel cable.

8. The method as received in claim 6, wherein said multi-channel cable is an electrically conductive multi-channel cable.

9. The method as recited in claim 6, wherein said pulse is transmitted to said elongate member by directing a pulse from a pulse generator to a transmitter at said transmitting location, with the transmitter in turn transmitting an electric or electromagnetic pulse into the elongate member at the transmitting location, and said multi-channel cable transmits the received signals to a data acquisition/signal analyzer means.

10. The method as recited in claim 9, wherein said pulse generator transmits a triggering signal to a data acquisitions/signal analyzer.

11. The method as recited in claim 10, wherein said pulse is transmitted into a first end of a section of the elongate member which is under test, and is received at a second end location of said section of the elongate member for forward profiling of said section, said method further comprising transmitting a second pulse or set of pulses from the second end of the section of the elongate member under test for reverse profiling toward the first end of the section of the elongate member, where the signal is received and delivered to a data receiving location.

12. The method as recited in claim 1, wherein a transmitter is positioned at said transmitting location to transmit the pulse into the elongate member, and a receiver is positioned sequentially at a plurality of spaced receiving locations along said elongate member, and pulses are transmitted into said elongate member for each receiving location at which the receiver is placed, and signals received by the receiver at the receiving locations are transmitted to a data receiving location.

13. The method as recited in claim 1, wherein said elongate member is a pipe having an insulating layer, said method further comprising providing a receiver which is an antenna responsive to electromagnetic radiation, and said receiver is placed adjacent to an outer surface of the insulating layer of the pipe to receive the electromagnetic wave.

14. The method as recited in claim 13, wherein there is a transmitter to transmit the pulse into the pipe, and a portion of the insulation is removed at the transmitting location, and the transmitter is placed adjacent to the pipe at the transmitting location.

15. The method as recited in claim 14, wherein the transmitter comprises an electrical contact member which is placed into direct contact with the pipe, and an electric current is transmitted to the transmitter.

16. The method as recited in claim 14, wherein the transmitter is a directional antenna, which is positioned adjacent to the pipe, and an electric pulse is transmitted to the antenna, which in turn transmits an electromagnetic pulse into the pipe.

17. The method as recited in claim 14, wherein there is a receiving means positioned adjacent to said pipe, said receiving means comprising a plurality of antennas which are placed adjacent to the insulation of the pipe at a plurality of receiving locations.

18. The method as recited in claim 1, wherein there is provided at the transmitting location a plurality of transmitters which are spaced circumferentially from one another, and a plurality of electric or electromagnetic pulses are transmitted from said transmitters into said elongate member, either sequentially, simultaneously, or both simultaneously and sequentially toward a receiving location or locations.

19. The method as recited in claim 18, wherein there is a plurality of receivers at the receiving location, which are spaced circumferentially from one another, said method further comprising transmitting pulses as electromagnetic waves from selected transmitters at said transmitting location to the receives at said receiving location in selected patterns.

20. The method as recited in claim 1, wherein there is a plurality of receivers at said receiving location, said method further comprising transmitting a pulse toward said receiving location, and one of said receivers, or a plurality of said receivers is operated to receive the electromagnetic wave generated by the pulse and transmit a received signal to a data collecting location.

40. The method as recited in claim 1, wherein two pulses are transmitted into said elongate member in timed relationship to travel as waves toward one another to intersect at an intersecting location on said elongate member, said method further comprising receiving said intersecting waves with a receiver at a receiving location which is at said intersecting location or proximate to said intersecting location, for identification of corrosion and/or location of corrosion.

41. The method as recited in claim 40, further comprising coordinating timing of transmission of said pulses and said receiving location in a manner that said receiving location and said intersecting location coincide.

42. The method as recited in claim 41, wherein timing of said two pulses is adjusted to match the intersecting location with the receiving location where the receiving location is known, as a means of ascertaining location of the intersecting location.

43. The method as recited in claim 40, where a plurality of pairs said two pulses are transmitted in varying timed relationship so that each of some of said pairs of pulses intersect at a plurality of differing intersecting locations, and the timing of the pulses of said plurality are coordinated with a plurality of receiving locations so that intersecting waves are received to identify corrosion and/or location of corrosion.

44. The method as recited in claim 43, wherein timing of the transmission of the pulses is adjusted to cause said intersecting locations to be coordinated with said receiving locations.

45. The method as recited in claim 43, wherein wave forms received from intersecting waves by a receiver or receivers at said receiving locations are analyzed to identify corrosion.

46. The method as recited in claim 1, wherein there is a plurality of receivers at the receiving location, which are spaced circumferentially from one another, said method further comprising receiving transmitted pulses at one or more of said receivers of said plurality.

47. The method as recited in claim 1, further comprising transmitting said pulse at a first circumferential location on said elongate member to a receiving location which is spaced circumferentially on said elongate member from the circumferential location at which the pulse was transmitted into the elongate member.

48. The method as recited in claim 1, wherein the pulse transmitted into said elongate member travels as a wave form having earlier and later arrivals at said receiving location so that the wave form that arrives at the receiving location comprises a plurality of wave form arrivals said method further comprising analyzing the wave form received at the receiving location relative to phase shift, dispersion, or continuation, and/or a combination of two or more of phase shift, dispersion and continuation.

49. The method as recited in claim 1, wherein said pulse is transmitted from a pulse generator to travel to said transmitting location of the elongate member, and said pulse is received at the receiving location which is at or closely adjacent to said transmitting location and timing of the arrival at the receiving location is utilizing in ascertaining time of travel of other pulses as waves to other receiving location in said elongate member.

50. The method as recited in claim 1, wherein said pulse is transmitted into said elongate member by means of a transmitter, and said transmitter is also used as a receiver to receive a pulse in the form of a wave transmitted into said elongate member from a transmitting location spaced from said transmitter.

51. The method as recited in claim 1, wherein there is provided a reference elongate member having properties similar to said elongate member on which corrosion is to be identified, and a pulse or pulses are transmitted into said reference elongate member and received from elongate member, with ascertainment of travel time relative to distance on said reference elongate member to provide a reference against which comparable travel time in the elongate member that is being tested for corrosion can be compared.

52. The method as recited in claim 1, wherein said elongate member is a pipe having a layer of insulation said pipe, and an antenna is positioned outside of said insulating layer to receive the wave.

53. The method as recited in claim 52, where there is also a metallic shield surrounding said layer of insulation, and said antenna to receive the wave is positioned outside of said metallic shield.

54. The method as recited in claim 1, wherein a cable or cables are utilized to transmit and/or receive pulses and/or receive pulses, and said cable or cables radiation of shielded cables.

55. The method as recited in claim 54, wherein said pulse is transmitted as an electrical pulse through a radiation shielded cable to the transmitting location, and the electromagnetic wave received at the receiving location is transmitted through a radiation shielded cable.

56. The method as recited in claim 1, wherein said pulse that is transmitted to said transmitting location is a square wave pulse.

57. The method as recited in claim 1, wherein the pulse transmitted into the elongate member has a length that is between one nanosecond and one millisecond.

58. The method as recited in claim 1, wherein said pulse is transmitted to elongate member has a pulse length which is less than one nanosecond.

59. The method as recited in claim 1, wherein the pulse that is transmitted to the elongated member has a pulse length greater than one millisecond.

60. The method as recited in claim 1, wherein said pulse has a voltage between about 100 millivolts and 4 volts.

61. The method as recited in claim 1, wherein the voltage of the pulse that is transmitted to the elongate member has a voltage of 4 volts or greater.

62. The method as recited in claim 1, wherein voltage of the pulse transmitted to the elongate member has a voltage level of 100 millivolts or less.

63. The method as recited in claim 1, wherein there is a transmitter to transmit the pulse and a receiver to receive the pulse and said transmitter and receiver are moved sequentially along the elongate member to differing transmission transmitting and receiving locations so as to ascertain corrosion at differing locations at said elongate member.

64. The method as recited in claim 63, wherein said transmitter is an antenna and said receiver is an antenna, and said transmitting and receiving antennas are moved along said elongate member to ascertain corrosion at different segments of said elongate member.

65. The method as recited in claim 1, wherein said wave is received by a receiving antenna which is a high pass receiving antenna.

66. The method as recited in claim 1, wherein said elongate member is a pipe, and the pulse transmitted into the pipe travels a shortest route to the receiving location, and also the wave travels along a plurality of heliocoidal paths along said pipe to said receiving location, where one or more of said heliocoidal said paths passes through an area of corrosion, and one or more others of said paths does not pass through said area of corrosion, whereby there are earlier and later arrivals of the wave form, some of which are more affected by the corrosion than others, said method comprising analyzing said wave form to detect deviations from a reference wave form, which deviations result from modifications of wave form components traveling on different heliocoidal paths.

67. The method as recited in claim 6 where in said multichannel cable has first and second ends, both of which are attached to a receiving apparatus, said method further comprising transmitting pulses in a first direction along said elongate member for forward profiling of said elongate member and transmitting pulses in an opposite direction for reverse profiling of said elongate member.

21. A system for identifying corrosion on an electromagnetically permeable elongate member, such as a pipe, said system comprising:

a. a transmitter means to transmit an electric or electromagnetic pulse wave(s) into said elongate member at a transmitting location of the elongate member and at a transmitting time, to cause said pulse to travel as a propagating electromagnetic wave to a receiving location over a travel distance and during a travel time interval;

b. a receiving means to receive said electromagnetic wave at said receiving location on said elongate member;

c. means to ascertain a time interval of travel of said electromagnetic pulse or wave(s) from said transmitting location to said receiving location

whereby a delay in said electromagnetic wave traveling over said travel distance can ascertain presence of corrosion on said elongate member.

22. The system as recited in claim 21, wherein said transmitter is characterized in that it transmits a pulse that has a sufficiently high frequency, so that the electromagnetic wave travels over the outside surface of the elongate member at a very thin skin depth where corrosion on an exterior surface of the elongate member may be present.

23. The system as recited in claim 22, wherein said receiving means comprises an antenna responsive to electromagnetic radiation.

24. The system as recited in claim 21, wherein said receiving means comprises a plurality of receivers which are operatively positioned at spaced receiving locations along a lengthwise axis of said elongate member, said system further comprising means to ascertain intervals of time of travel of said electromagnetic wave between said transmitting locations and said receiving locations.

25. A system as recited in claim 24, said system further comprising means to ascertain intervals of travel time between various pairs of receivers to identify where the velocity of the electromagnetic wave or waves is lower, to identify presence and location of corrosion.

26. The system as recited in claim 25, wherein there is a multi-channel cable, comprising a plurality of channels, and each of said receivers is operatively connected to a related one of said channels, with said multi-channel having an operative connection to a data receiver to direct signals received from said receivers to the data receiver.

27. The system as recited in claim 26, wherein said multi-channel cable is a fibre optic multi-channel cable.

28. The system as recited in claim 26, wherein said multi-channel cable is an electrically conductive multi-channel cable.

29. The system as recited in claim 26, wherein there is a pulse generator to transmit the pulse to the transmitter at said transmitting location, with the transmitter in turn transmitting an electric or electromagnetic pulse or wave(s) into the elongate member at the transmitting location, and a data acquisition/signal analyzer means connected to said multi-channel cable to receive signals from the multi-channel cable.

30. The system as recited in claim 29, wherein said pulse generator transmits a trigger signal to the data acquisition/signal analyzer means.

31. The system as recited in claim 30, wherein there is a first transmitter at a first end of a section of the elongate member which is under test, and a first receiver at a second end location of said section of the elongate member for forward profiling of said section, said system further comprising a second transmitter at the second end location to transmit a second pulse or set of pulses from the second end of the section of the elongate member under test for reverse profiling toward the first end of the section of the elongate member, a second receiver to receive the electromagnetic wave at a second receiving location at the first end of the section.

32. The system as recited in claim 21, wherein the receiving means is a portable receiver adapted to be positioned sequentially at a plurality of spaced receiving locations along said elongate member, whereby pulses are transmitted into said elongate member for each receiving location at which the portable receiver is placed, a data receiver operatively connected to the portable receiver in a manner to permit the receiver to be moved to the receiving locations.

33. The system as recited in claim 21, wherein the transmitter comprises an electrical contact member which is placed into direct contact with the pipe, and an electric pulse is transmitted to the transmitter.

34. The system as recited in claim 21, wherein the transmitter is a directional antenna, which is positioned adjacent to the elongate member and an electric pulse is transmitted to the antenna, which in turn transmits an electromagnetic pulse or waves (S) into the elongate member.

35. The system as recited in claim 21, wherein said elongate member is a pipe having a layer of insulation, and said receiving means is positioned adjacent to said pipe, said receiving means comprising a plurality of antennas which are placed adjacent to the insulation of the pipe at a plurality of receiving locations.

36. The system as recited in claims 35, wherein the transmitter is a directional antenna, which is positioned adjacent to the pipe, whereby an electric pulse can be transmitted to the antenna, which in turn transmits an electromagnetic pulse into the pipe.

37. The method as recited in claim 35, wherein said transmitter means comprises a plurality of transmitters which are arranged in a pattern spaced circumferentially from one another, whereby a plurality of electric or electromagnetic pulses or wave(s) can be transmitted from said transmitters into said elongate member, either sequentially, simultaneously, or both simultaneously and sequentially toward a receiving location or locations.

38. The system as recited in claim 37, wherein said receiving means comprises a plurality of receivers which are arranged to be spaced circumferentially from one another, whereby pulses can be transmitted from selected transmitters at said transmitting location to said receivers in selected patterns.

39. The system s recited in claim 21, wherein said receiving means comprises a plurality of receivers spaced circumferentially from one another.