Method and apparatus for determining pipewall thickness using one or more ultrasonic sensors

1. A method for measuring the thickness of a pipe wall, comprising the steps of:

emitting ultrasonic signals into the pipe wall at one or more frequencies below 1 MHz and receiving reflected ultrasonic signals, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall using the time delay.

2. The method of claim 1 , wherein the step of emitting ultrasonic signals is performed using one or more ultrasonic sensors, each mounted on a shoe which is in contact with the pipe wall.

3. The method of claim 2 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors that are the same type as the one or more ultrasonic sensors.

4. The method of claim 3 , wherein the one or more test ultrasonic sensors are mounted on test shoes, each of which is substantially similar to the shoe on which each sensor is mounted.

5. The method of claim 3 , wherein each of the one or more test ultrasonic sensors is mounted on a test shoe that has a thickness through which signals traverse that is large enough such that the first received reflected signal and the second received reflected signal are received with a time separation that permits the first received reflected signal and the second received reflected signal to be measured independent of one another.

6. The method of claim 2 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors operated at a frequency greater than 1 MHz.

7. A method for measuring the thickness of a pipe wall, comprising the steps of: :

emitting ultrasonic signals into the pipe wall at one or more frequencies below 1 MHz and receiving reflected ultrasonic signals, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall using the time delay;

wherein the step of correlating the received reflected signals to the model signals, includes iteratively comparing a waveform of the received reflected signals to a waveform of the model signals using different values of the time delay.

8. A method for measuring the thickness of a pipe wall, comprising the steps of:

emitting ultrasonic signals into the pipe wall at one or more frequencies below 1 MHz and receiving reflected ultrasonic signals, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall using the time delay;

wherein the step of correlating the received reflected signals to the model signals includes mathematically comparing a waveform of the received reflected signals to a waveform of the model signals.

9. An apparatus for measuring a thickness of a pipe wall, comprising:

one or more ultrasonic sensors, each operable to emit ultrasonic signals and receive reflected ultrasonic signals, and to provide a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

an ultrasonic sensor processor adapted to fire the one or more ultrasonic sensors at one or more selected frequencies below 1 MHz, and to accept the signals from the sensor;

a signal processor adapted to include a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal, and adapted to correlate the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals, and determine the thickness of the pipe wall using the time delay.

10. The apparatus of claim 9 , wherein each sensor is mounted on a shoe which is in contact with the pipe wall.

11. The apparatus of claim 10 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors that are the same type as the one or more ultrasonic sensors.

12. The apparatus of claim 10 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors operated at a frequency greater than 1 MHz.

13. An apparatus for measuring a thickness of a pipe wall, comprising:

one or more ultrasonic sensors, each operable to emit ultrasonic signals and receive reflected ultrasonic signals, and to provide a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

an ultrasonic sensor processor adapted to fire the one or more ultrasonic sensors at one or more selected frequencies below 1 MHz, and to accept the signals from the sensor; and

a signal processor adapted to include a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal, and adapted to correlate the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals, and determine the thickness of the pipe wall using the time delay;

wherein the signal processor is adapted to compare a waveform of the received reflected signals to a waveform of the model signals using different values of the time delay in the process of correlating the received reflected signals to the model signals.

14. A method for measuring a thickness of a pipe wall, comprising the steps of:

emitting ultrasonic signals into the pipe wall at a frequency corresponding to a wavelength that is equal to or greater than one third the thickness of the pipe wall, and receiving reflected ultrasonic signals, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall using the time delay.

15. The method of claim 14 , wherein each sensor is mounted on a shoe which is in contact with the pipe wall.

16. The method of claim 15 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors that are the same type as the one or more ultrasonic sensors.

17. The method of claim 16 , wherein the one or more test ultrasonic sensors are mounted on test shoes, each of which is substantially similar to the shoe on which each sensor is mounted.

18. The method of claim 16 , wherein each of the one or more test ultrasonic sensors is mounted on a test shoe that has a thickness through which signals traverse that is large enough such that the first received reflected signal and the second received reflected signal are received with a time separation that permits the first received reflected signal and the second received reflected signal to be measured independent of one another.

19. The method of claim 14 , wherein the frequency corresponds to a wavelength that is equal to or greater than about 0.1 inches.

20. A method for measuring a thickness of a pipe wall with a flow meter having an array of ultrasonic sensors, which meter is operable to measure characteristics of a fluid flow within the pipe, comprising the steps of:

emitting ultrasonic signals at one or more frequencies below 1 MHz using at least one of the sensors within the array and receiving reflected ultrasonic signals, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall based on the time delay using the processor.

21. The method of claim 20 , wherein the step of emitting ultrasonic signals is performed using one or more ultrasonic sensors, each mounted on a shoe which is in contact with the pipe wall.

22. The method of claim 21 , wherein the first model signal and the second model signal are modeled using data empirically collected using one or more test ultrasonic sensors that are the same type as the one or more ultrasonic sensors.

23. The method of claim 22 , wherein the one or more test ultrasonic sensors are mounted on test shoes, each of which is substantially similar to the shoe on which each sensor is mounted.

24. A method for measuring the thickness of a pipe wall, comprising the steps of:

emitting an ultrasonic signal into the pipe wall at a frequency and receiving reflected ultrasonic signals resulting from the emitted signal, wherein the frequency is such that the reflected ultrasonic signals are not localized in time, and providing a sensor signal representative of the received reflected signals, including a first received reflected signal and a second received reflected signal;

providing a first model signal representative of the first received reflected signal and a second model signal representative of the second received reflected signal;

correlating the received reflected signals to the model signals, including varying a time delay between the model signals, until the model signals separated by the time delay substantially agree with the received reflected signals; and

determining the thickness of the pipe wall using the time delay.