Method of detecting leak of fluid from a long pipeline

• US 3,930,556 A
• Filed: 06/05/1973
• Issued: 01/06/1976
• Est. Priority Date: 04/26/1971
• Status: Expired due to Term

• Current Assignee: Osaka Gas Kabushiki Kaisha
• Original Assignee: Osaka Gas Kabushiki Kaisha
• Inventors: Kusuda, Takazo, Nishiwaki, Niichi
• Primary Examiner(s): Farley, Richard A.
• Assistant Examiner(s): Moskowitz, N.
• Application Number:
  US05/367,337
• Time in Patent Office: 945 Days
• Field of Search: 181/.5 R, 340/242, 73/40, 73/69, 73/71.4, 73/40.5 A, 73/40.5 R, 73/194 A, 73/194 B
• US Class Current: 73/40.50A
• CPC Class Codes: F16L 2101/30 Inspecting, measuring or testing
• CPC Class Codes: G01H 3/12 by electric means G01H3/14 takes precedence
• CPC Class Codes: G01M 3/243 for pipes

Abstract

A system for systematical detecting a leak of fluid from a long pipe comprising a plurality of apparatuses like microphones set at relatively large intervals within a relatively long limited space, formed by utilizing the wall of the pipe like a space within the pipe and extending longitudinally of the pipe. The apparatuses intercept sonic waves caused by the leak of fluid from the pipe propagated in the limited space. The system further includes an apparatus for detecting that at least one first-mentioned apparatus has intercepted the sonic wave caused by the fluid leak.

Claims

1. A method of detecting a leak of fluid from a pipe of a long pipeline for transporting fluid comprising, in combination:

a. forming a long hollow space defined at least on its one side in cross section by a wall of said pipe for the transport of fluid, said hollow space extending longitudinally along said pipe;

b. providing a plurality of stationary first means for intercepting sonic walve propagated within said hollow space, individual ones of said first means being in longitudinally spaced apart relationship to each other along said pipe over a long distance, any two of said individual ones of said first means which are adjacent to one another being capable of separate interception of a sonic wave inside of said pipe caused by a leak which may occur between them;

c. providing second means for detecting signals from said plurality of first means indicating the interception of a sonic wave by said first means;

d. causing at least any two of said first means which are adjacent to one another to intercept a sonic wave propagated within said hollow space;

e. causing said second means to detect the signals from said plurality of first means indicating that a sonic wave caused by a leak has been intercepted by at least said two adjacent ones of said first means; and

f. analyzing the relative relation between the signals;

whereby the presence and position of a fluid leak from the pipe is detected.

2. A method as set forth in claim 1, including providing a plurality of said second means, corresponding on a one-to-one basis to said first means, and positioning all of said second means at one place.

3. A method as set forth in claim 2, wherein the step of forming said hollow space is the step of forming this space from interior space of said pipe.

4. A method as set forth in claim 2, wherein the step of forming said hollow space is the step of forming this space from space formed between said pipe and a wall surrounding said pipe.

5. A method as set forth in claim 2, including determining when intensity of a sonic wave intercepted by at least one of said first means exceeds a predetermined value as an indication of a leak.

6. A method as set forth in claim 5, wherein the determining step is effected by at least one of said first means which detect that the intensity of an intercepted sonic wave has exceeded the predetermined value.

7. A method as set forth in claim 5, including sending from said first means to said second means a wave signal converted from a sonic wave intercepted by said first means, and determining with said second means that the intensity of the wave signal has exceeded a predetermined value thus indicating that the intensity of the sonic wave has exceeded the predetermined value.

8. A method as set forth in claim 2, including selecting a sonic wave caused by a leak of fluid from said pipe by self-correlation analysis from among sonic waves intercepted by said first means, thus determining presence of the leak.

9. A method as set forth in claim 2, including intercepting by at least two of said first means a sonic wave propagated through said hollow space, subjecting a plurality of sonic waves intercepted by a plurality of said first means respectively to cross-correlation analysis. selecting a sonic wave caused by a leak by cross-correlation analysis from among the sonic waves thus intercepted, thus determining the presence of a leak.

10. A method as set forth in claim 1, including forming a pattern from frequency and intensity changes in the sonic wave intercepted by said first means during a time period, and comparing the pattern thus obtained with a standard pattern showing known changes over a period of time in frequency and intensity of a sonic wave upon the occurence of a leak of fluid from said pipe, thus determining the presence of a leak of fluid from said pipe.

11. A method as set forth in claim 2, further comprising causing at least a number of said plurality of said first means to produce a plurality of respective signals indicating that said first means have intercepted the sonic wave;

providing third means which include said second means at one place;

sending the signals produced by said first means to said third means, these signals being a plurality of wave signals converted from the sonic waves intercepted by each one of said first means; and

analyzing the relative relation between the wave signals sent to said third means so as to pinpoint the position of a leak point.

12. A method as set forth in claim 11, wherein the analyzing step is effected by comparison of relative intensity among a plurality of the wave signals produced by at least a number of said plurality of said first means.

13. A method as set forth in claim 12, including subjecting each of the wave signals to self-correlation analysis prior to the comparison step to select from among the wave signals a wave signal caused by a leak.

14. A method as set forth in claim 11, wherein the step of analyzing is effected by determining difference between times required for the sonic waves to be propagated respectively from the leak point to at least a number of said plurality of said first means respectively by a crosscorrelation analysis among the wave signals.

15. A method as set forth in claim 11, wherein the analyzing step includes automatically analyzing the relative relation among said signals;

and further comprising automatically computing the position of the leak point based on the analysis of the relative relation, and indicating the resulting value.

16. A method as set forth in claim 15, further comprising automatically stopping supply of the fluid to the leak point by closing means.