Acoustic emission leak source location

• US 4,858,462 A
• Filed: 01/20/1989
• Issued: 08/22/1989
• Est. Priority Date: 01/20/1989
• Status: Expired due to Term

• Current Assignee: Babcock & Wilcox Power Generation Group Incorporated (Babcock International Group PLC)
• Original Assignee: Babcock & Wilcox Company (Babcock International Group PLC)
• Inventors: Evans, Robert S., Robertson, Michael O., Coulter, John E.
• Primary Examiner(s): Noland, Tom
• Assistant Examiner(s): ROSKOS, JOSEPH
• Application Number:
  US07/300,408
• Time in Patent Office: 214 Days
• Field of Search: 73/40.5 A, 73/592, 73/587
• US Class Current: 73/40.50A
• CPC Class Codes: G01M 3/243 for pipes

Abstract

A method and apparatus for locating a leak which produces a continuous acoustic emission having background noise and spikes, comprises continuously monitoring the acoustic emissions using spaced apart detectors which produce signals having background noise and spikes corresponding to those of the continuous acoustic emissions. The spikes of one signal are offset in time with respect to the spikes of the other signal, which corresponds to the difference in travel time of the acoustic signals to each of the detectors. By measuring the offset between the spikes, the relative position of the acoustic emission, and thus the relative position of the leak, can be determined with respect to the position of the detectors. To facilitate separating the spikes from the background noise, a floating detection threshold value is applied to the signals for eliminating the background noise.

Claims

1. A method of locating a leak which produces a continuous acoustic emission having background noise and spikes, comprising:

continuously monitoring acoustic emissions from at least two spaced locations using detectors at the spaced locations to form at least two continuous signals having background noise and spikes corresponding to the background noise and spikes of the acoustic emission, the spikes in the signals of the detectors being offset from each other in time by an amount corresponding to the difference in travel time for an acoustic emission to each of the spaced locations;

adjusting a detection threshold value for each detector to remove the background noise from the spikes in each signal, the detection threshold value being adjusted in a floating manner so as to correspond to an average level for the signals; and

measuring the offset in time between the spikes of the signals, in real time, to determine the relative position of the acoustic emissions with respect to the spaced locations.

2. A method according to claim 1 wherein the location of the leak along a linear conduit is to be measured, the method including mechanically attaching each detector to the conduit at spaced locations along the conduit.

3. An apparatus for locating a leak which produces a continuous acoustic emission having background noise and spikes, comprising:

at least two spaced apart acoustic emission detectors each for receiving acoustic emissions from a leak, each detector forming a signal having background noise and spikes corresponding to the background noise and spikes of the acoustic emission, the spikes being offset in time by an amount corresponding to the difference in travel time for the acoustic transmission to each of the detectors;

signal processing means connected to each detector for applying a floating adjustable detection threshold value to each signal for eliminating the background noise from each signal, said signal processing means adjusting the detection threshold value to match a floating average level value for each signal; and

computing means for computing the offset between spikes in the signals, in real time, for determining the relative position of the acoustic emission with respect to the detectors.

4. An apparatus according to claim 3 including, in combination, a conduit for receiving fluid which may leak through the conduit, said detectors being mechanically coupled with the conduit at spaced locations along the length of the conduit.

5. A method of locating a leak which produces a continuous acoustic emission having background noise and spikes, comprising:

continuously monitoring acoustic emissions from at least two spaced locations using detectors at the spaced locations to form at least two continuous signals having background noise and spikes corresponding to the background noise and spikes of the acoustic emission, the spikes in the signals of the detectors being offset from each other in time by an amount corresponding to the difference in travel time for an acoustic emission to each of the spaced locations;

adjusting a detection threshold value for each detector to remove the background noise from the spikes in each signal, the detection threshold being adjusted to equal a momentary average value for the signals; and

measuring the offset in time between the spikes of the signals, in real time, to determine the relative position of the acoustic emissions with respect to the spaced locations.