CA1120788A - Underwater craft for acoustic inspection of pipelines for leaks - Google Patents
Underwater craft for acoustic inspection of pipelines for leaksInfo
- Publication number
- CA1120788A CA1120788A CA000296288A CA296288A CA1120788A CA 1120788 A CA1120788 A CA 1120788A CA 000296288 A CA000296288 A CA 000296288A CA 296288 A CA296288 A CA 296288A CA 1120788 A CA1120788 A CA 1120788A
- Authority
- CA
- Canada
- Prior art keywords
- craft
- hydrophones
- pipeline
- underwater
- underwater craft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/80—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using ultrasonic, sonic or infrasonic waves
- G01S3/801—Details
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
- B63C11/00—Equipment for dwelling or working underwater; Means for searching for underwater objects
- B63C11/34—Diving chambers with mechanical link, e.g. cable, to a base
- B63C11/36—Diving chambers with mechanical link, e.g. cable, to a base of closed type
- B63C11/40—Diving chambers with mechanical link, e.g. cable, to a base of closed type adapted to specific work
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
- G01M3/24—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations
- G01M3/243—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations for pipes
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Examining Or Testing Airtightness (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
A B S T R A C T
An underwater craft equipped for inspecting pipelines for leaks by acoustic means, characterized in that the craft is equipped with at least two directional hydrophones which are acoustically accessible from outside and which are aimed at the pipeline from various positions.
An underwater craft equipped for inspecting pipelines for leaks by acoustic means, characterized in that the craft is equipped with at least two directional hydrophones which are acoustically accessible from outside and which are aimed at the pipeline from various positions.
Description
The invention relates to an underwater craft equipped for inspect-ing pipelines for leaks by acoustic means.
A leak in a pipeline for gases or liquids, in particular a small leak, causes a hissing sound. This sound comprises both audible and ultra-sonic vibrations and it has long been known that acoustic means may be used in detecting and locating such leaks. In particular for pipelines for liquids - oil or oil products - use is made of listening and recording apparatus accommodated in a pig which is carried along by the stream of matter through the pipeline. However, this method cannot always be used.
In pipelines for the transport of gas it is far more difficult to detect the sound of a leak inside the pipeline than in a pipeline for liquids. Again, in the case of pipelines which are connected to producing fields offshore it is by no means easy to provide facilities for introducing and removing a pig.
Acoustic vibrations, both audible and ultrasonic, are very well propagated in water and thus the idea of using a craft as the basis for detection readily suggests itself. This craft may be a surface vessel, a submarine, or, alter~atively, a manned or unmanned underwater craft towed by a ship. The certainty of detecting a leak, however, constitutes a problem and the invention indicates how this can be improved.
The invention therefore provides an underwater craft equipped for inspecting a pipeline for leaks by acoustic means while the craft is moving along the pipeline, which craft is equipped with two or more directional hydrophones, said hydrophones being sound-receiving only and being acoustical-ly accessible from outside the craft, said hydrophones being adapted to re-ceive acoustical vibrations emanating directly from a leak and being adapted ;
in use to be aimed at the pipeline from various positions on the craft.
3'7 The acoustic equipment may be tuned into a frequency or frequency range that has been cho~en as being de~initely signi-ficant for a leak. In addition, acoustic generators which imitate the sound of a leak may have been installed at various places.
Hereinafter the term source will consi~stently be used to indicate both leaks and generators.
The underwater craft may be a submarine or a towed underwater cr~ft, called a fish. The craft follows the pipeline, either through guidance by a helmsman or automatically, for instance by means of steering gear magnetically coupled to the steel of the pipeline.
The hydrophones may be fitted outside the hull of the craft or inside, but ~till acoustically accessible, for;in~tance via an opening or via a suitable membrane. Directional sensitivity can be obtained by placing a hood around the vibration pick-up, which hood is coated both inside and outside with sound-reflecting material.
This will reduce the influence of interfering sounds and amplify the reception of source sounds.
The use of at least two hydrophones promotes reliability in operation. By installing them at various places on the craft, certain - ~I L6~r~ R~N560 advantages may be achieved. If ~G~hydrophones are ~c~beii-~ in one row parallel to the longitudinal axis of the craft at its underside, the signal from a source is detected by all these hydrophones. In addition to the increased reliability in operation mentioned hereinbefore 25 other advantages may be achieved. All hydrophones may be aimed ~;
roughly at the same point of the pipeline. This increases the sensitivity of detection by increasing the signal-to-noise ratio, ~ Y'~ ~ 4 . _ _ so that sounds are detected with more certainty. Moreover, the detectability limit islshifted to include weaker source~. If in the processing of the signals a correlation technique is applied the signal from a source is detected as a sharp and high peak, which increases the advantages mentioned ev~n further.
Another possibility is that the directions of the hydro-phones arranged in a row are parallel to each other. In thi~ case a larger area of the pipeline is covered. A source will he observed for a longer period of time. An advantage is that sounds origin-ating from an impact or a tap can be recognized as such and areconsequently not erroneously recorded as originating from a source.
Another possibility is that at least one pair of hydrophones is presentJ the two hydrophones of a pair being installed opposite each other in a plane perpendicular to the longitudinal axis of the craft, projecting outside the craft to the left and to the right, respectively, and aimed at the pipeline. The hydrophones forming a pair may be positioned on booms. A considerable advantage of this configuration is that a much larger area o~ the circum-ference of the pipeline can be monitored directly, the "dark side"is considerably decreased. The distance between the hydrophones may be 3-5 times the diameter of the pipeline. There may be for instance 2-5 pairs of hydrophones arranged in two rows on either side of the craft spaced along the length, each row being parallel to the longitudinal axis of the craft. These hydrophones may again 0 6 i~ D .~ ~ t 6 ~ 7' î~
be aimed at the pipeline and parallel to each other or roughly aimed at the same cross-section of the pipeline. The respective ,, '7~
advantages of the two ways Or positioning are analogous to those described hereinbefore.
An attractive combination of the various possibilities I~R~S'I;I~G ~
- mentioned is installati~ of three rows of hydrophones parallel to the longitudinal axis of the craft, one row centrally at the underside of the craft, one row projecting to the left and one row to the right. In this way advantages already described separately hereinbefore are combined.
The craft may be equipped with two fins slanting downwards9 and carrying the hydrophones that form pairs. This has great con-structional advantages. Any degree of projection of the hydrophones can be realized in a robust design and the stability of the craft is increased.
The equipment for processing the signals received may be composed of combinations, known in themselves, of selective amplifiers, detectors, integrators, comparators and indicating/recording apparatus. Correlators for two or more channels may be present as well.
The invention will now be further explained with reference to some ~igures.
Figs. 1, 2, 3 and 4 show some variants of an underwater craft equipped with hydrophones. Figs. 5 and 6 show a hood con-struction for hydrophones.
In Fig. 1 numeral 1 shows an underwater craft, in this case a manned submarine. The craft may be 6 m long and 1.5 m wide. In this example the submarine is at about 3 metres' distance from a pipeline 2 having a diameter of 0.75 m. Affixed to the bottom of the submarine are two directional hydrophones 3 and 4, one near the stem and one near the stern of the submarine. Both hydrophones are directed perpendicularly downwards and the submarine will manoeuvre in such a way that the two hydrophones are adapted to be aimed at pipeline 2. Broken lines 5 indicate the main direction of sensitivity.
Figure 2 shows a submarine 10 over a pipeline 11, the sub-marine being equipped with three hydrophones 12, 13 and 14 installed in one row. These hydrophones are adapted to be aimed at one point of the pipeline as indicated by broken line 15.
Figure 3 shows a submarine 20 in cross-section over a pipe-line 21. Hydrophones 24 and 25 are attached to booms 22 and 23 pro-jecting laterally. This pair of hydrophones is adapted to be aimed at one and the same cross-section of pipeline 21, as indicated by broken lines 26 and 27. A large area of the circumference of the pipeline is thus brought within the more optimum directional sensi-tivity of the hydrophones.
Figure 4 shows a bottom view of submarine 30. This sub- ;
marine is equipped with fins 31 and 32. Near the edges of these fins hydrophones 33 and 3~ are located, each time four in a row parallel to the longitudinal axis of the submarine. A third row of hydro-phones 35 is affixed to the bottom of the submarine along the `~
centre line. Each pair of hydrophones 33 and 34, one opposite the other li.e. in this case four pairs)~ is adapted to be aimed at one and the same cross-section of the pipeline under inves~igation. So, ;~
in this case four pairs aimed at four different cross-sections.
~Iydrophones 35 are also aimed at that pipeline vertically downwards.
Figure 5 shows a cross-section of a hood for a hydrophone.
The hood - ,~, . . ~:
consists of a basis 40 of strong material, for instance a metal or a strong construction of reinforced polymeric material. The outside is covered with a layer 41 of sound-reflecting material and the inside with a layer 42 of the same material. Such a layer may con-sist of a thin metal film applied to a layer of ~ound-insulating material. Vibration-sensitive element 43 is located in a central position. This may consist of a number of piezoelectric crystals.
If the apex angle of the hood is 90 all the sound waves entering in the direction of the centre line will impinge on the crystals in the same phase and thus be converted into a strong electric signal. The directional sensitivity is then at its maximum in a beam coinciding with the centre line of the hood, and having a base equal to the bottom view of the hood.
Fig. 6 shows such a bottom view. The hood is provided with one or more vents 44.
.
A leak in a pipeline for gases or liquids, in particular a small leak, causes a hissing sound. This sound comprises both audible and ultra-sonic vibrations and it has long been known that acoustic means may be used in detecting and locating such leaks. In particular for pipelines for liquids - oil or oil products - use is made of listening and recording apparatus accommodated in a pig which is carried along by the stream of matter through the pipeline. However, this method cannot always be used.
In pipelines for the transport of gas it is far more difficult to detect the sound of a leak inside the pipeline than in a pipeline for liquids. Again, in the case of pipelines which are connected to producing fields offshore it is by no means easy to provide facilities for introducing and removing a pig.
Acoustic vibrations, both audible and ultrasonic, are very well propagated in water and thus the idea of using a craft as the basis for detection readily suggests itself. This craft may be a surface vessel, a submarine, or, alter~atively, a manned or unmanned underwater craft towed by a ship. The certainty of detecting a leak, however, constitutes a problem and the invention indicates how this can be improved.
The invention therefore provides an underwater craft equipped for inspecting a pipeline for leaks by acoustic means while the craft is moving along the pipeline, which craft is equipped with two or more directional hydrophones, said hydrophones being sound-receiving only and being acoustical-ly accessible from outside the craft, said hydrophones being adapted to re-ceive acoustical vibrations emanating directly from a leak and being adapted ;
in use to be aimed at the pipeline from various positions on the craft.
3'7 The acoustic equipment may be tuned into a frequency or frequency range that has been cho~en as being de~initely signi-ficant for a leak. In addition, acoustic generators which imitate the sound of a leak may have been installed at various places.
Hereinafter the term source will consi~stently be used to indicate both leaks and generators.
The underwater craft may be a submarine or a towed underwater cr~ft, called a fish. The craft follows the pipeline, either through guidance by a helmsman or automatically, for instance by means of steering gear magnetically coupled to the steel of the pipeline.
The hydrophones may be fitted outside the hull of the craft or inside, but ~till acoustically accessible, for;in~tance via an opening or via a suitable membrane. Directional sensitivity can be obtained by placing a hood around the vibration pick-up, which hood is coated both inside and outside with sound-reflecting material.
This will reduce the influence of interfering sounds and amplify the reception of source sounds.
The use of at least two hydrophones promotes reliability in operation. By installing them at various places on the craft, certain - ~I L6~r~ R~N560 advantages may be achieved. If ~G~hydrophones are ~c~beii-~ in one row parallel to the longitudinal axis of the craft at its underside, the signal from a source is detected by all these hydrophones. In addition to the increased reliability in operation mentioned hereinbefore 25 other advantages may be achieved. All hydrophones may be aimed ~;
roughly at the same point of the pipeline. This increases the sensitivity of detection by increasing the signal-to-noise ratio, ~ Y'~ ~ 4 . _ _ so that sounds are detected with more certainty. Moreover, the detectability limit islshifted to include weaker source~. If in the processing of the signals a correlation technique is applied the signal from a source is detected as a sharp and high peak, which increases the advantages mentioned ev~n further.
Another possibility is that the directions of the hydro-phones arranged in a row are parallel to each other. In thi~ case a larger area of the pipeline is covered. A source will he observed for a longer period of time. An advantage is that sounds origin-ating from an impact or a tap can be recognized as such and areconsequently not erroneously recorded as originating from a source.
Another possibility is that at least one pair of hydrophones is presentJ the two hydrophones of a pair being installed opposite each other in a plane perpendicular to the longitudinal axis of the craft, projecting outside the craft to the left and to the right, respectively, and aimed at the pipeline. The hydrophones forming a pair may be positioned on booms. A considerable advantage of this configuration is that a much larger area o~ the circum-ference of the pipeline can be monitored directly, the "dark side"is considerably decreased. The distance between the hydrophones may be 3-5 times the diameter of the pipeline. There may be for instance 2-5 pairs of hydrophones arranged in two rows on either side of the craft spaced along the length, each row being parallel to the longitudinal axis of the craft. These hydrophones may again 0 6 i~ D .~ ~ t 6 ~ 7' î~
be aimed at the pipeline and parallel to each other or roughly aimed at the same cross-section of the pipeline. The respective ,, '7~
advantages of the two ways Or positioning are analogous to those described hereinbefore.
An attractive combination of the various possibilities I~R~S'I;I~G ~
- mentioned is installati~ of three rows of hydrophones parallel to the longitudinal axis of the craft, one row centrally at the underside of the craft, one row projecting to the left and one row to the right. In this way advantages already described separately hereinbefore are combined.
The craft may be equipped with two fins slanting downwards9 and carrying the hydrophones that form pairs. This has great con-structional advantages. Any degree of projection of the hydrophones can be realized in a robust design and the stability of the craft is increased.
The equipment for processing the signals received may be composed of combinations, known in themselves, of selective amplifiers, detectors, integrators, comparators and indicating/recording apparatus. Correlators for two or more channels may be present as well.
The invention will now be further explained with reference to some ~igures.
Figs. 1, 2, 3 and 4 show some variants of an underwater craft equipped with hydrophones. Figs. 5 and 6 show a hood con-struction for hydrophones.
In Fig. 1 numeral 1 shows an underwater craft, in this case a manned submarine. The craft may be 6 m long and 1.5 m wide. In this example the submarine is at about 3 metres' distance from a pipeline 2 having a diameter of 0.75 m. Affixed to the bottom of the submarine are two directional hydrophones 3 and 4, one near the stem and one near the stern of the submarine. Both hydrophones are directed perpendicularly downwards and the submarine will manoeuvre in such a way that the two hydrophones are adapted to be aimed at pipeline 2. Broken lines 5 indicate the main direction of sensitivity.
Figure 2 shows a submarine 10 over a pipeline 11, the sub-marine being equipped with three hydrophones 12, 13 and 14 installed in one row. These hydrophones are adapted to be aimed at one point of the pipeline as indicated by broken line 15.
Figure 3 shows a submarine 20 in cross-section over a pipe-line 21. Hydrophones 24 and 25 are attached to booms 22 and 23 pro-jecting laterally. This pair of hydrophones is adapted to be aimed at one and the same cross-section of pipeline 21, as indicated by broken lines 26 and 27. A large area of the circumference of the pipeline is thus brought within the more optimum directional sensi-tivity of the hydrophones.
Figure 4 shows a bottom view of submarine 30. This sub- ;
marine is equipped with fins 31 and 32. Near the edges of these fins hydrophones 33 and 3~ are located, each time four in a row parallel to the longitudinal axis of the submarine. A third row of hydro-phones 35 is affixed to the bottom of the submarine along the `~
centre line. Each pair of hydrophones 33 and 34, one opposite the other li.e. in this case four pairs)~ is adapted to be aimed at one and the same cross-section of the pipeline under inves~igation. So, ;~
in this case four pairs aimed at four different cross-sections.
~Iydrophones 35 are also aimed at that pipeline vertically downwards.
Figure 5 shows a cross-section of a hood for a hydrophone.
The hood - ,~, . . ~:
consists of a basis 40 of strong material, for instance a metal or a strong construction of reinforced polymeric material. The outside is covered with a layer 41 of sound-reflecting material and the inside with a layer 42 of the same material. Such a layer may con-sist of a thin metal film applied to a layer of ~ound-insulating material. Vibration-sensitive element 43 is located in a central position. This may consist of a number of piezoelectric crystals.
If the apex angle of the hood is 90 all the sound waves entering in the direction of the centre line will impinge on the crystals in the same phase and thus be converted into a strong electric signal. The directional sensitivity is then at its maximum in a beam coinciding with the centre line of the hood, and having a base equal to the bottom view of the hood.
Fig. 6 shows such a bottom view. The hood is provided with one or more vents 44.
.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An underwater craft equipped for inspecting a pipeline for leaks by acoustic means while the craft is moving along the pipeline, which craft is equipped with two or more directional hydrophones, said hydrophones being sound-receiving only and being acoustically accessible from outside the craft, said hydrophones being adapted to receive acoustical vibrations emanating directly from a leak and being adapted in use to be aimed at the pipeline from various positions on the craft.
2. The underwater craft as claimed in claim 1, wherein at least 2 of said sound-receiving hydrophones are aligned parallel to the longitudinal axis of the craft and at its underside.
3. The underwater craft as claimed in claim 1, wherein at least one pair of hydrophones is present, the two hydrophones of a pair being arranged opposite each other in a plane perpendicular to the longitudinal axis of the craft, projecting outside the craft to the left and to the right, respective-ly, and adapted to be aimed at the pipeline.
4. The underwater craft as claimed in claim 3, wherein the distance between two hydrophones of a pair is 3-5 times the diameter of the pipeline.
5. The underwater craft as claimed in claim 3, wherein at least 2 pairs of hydrophones are present, arranged in two rows on either side of the craft spaced along the length, each row being parallel to the longitudinal axis of the craft.
6. The underwater craft as claimed in claim 4, wherein at least 2 pairs of hydrophones are present, arranged in two rows on either side of the craft spaced along the length, each row being parallel to the longitudinal axis of the craft.
7. The underwater craft as claimed in claim 3, wherein the craft is equipped with two fins slanting downwards and carrying the hydrophones that form pairs.
8. The underwater craft as claimed in claim 4, wherein the craft is equipped with two fins slanting downwards and carrying the hydrophones that form pairs.
9. The underwater craft as claimed in claim 5, wherein the craft is equipped with two fins slanting downwards and carrying the hydrophones that form pairs.
10. The underwater craft as claimed in any one of the claims 1-3, wherein all hydrophones are adapted to be directed at the same point or at the same cross-section of the pipeline.
11. The underwater craft as claimed in any one of the claims 1-3, wherein the directions of the hydrophones arranged in a row are parallel to each other.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7702753 | 1977-03-15 | ||
| NL7702753A NL7702753A (en) | 1977-03-15 | 1977-03-15 | UNDERWATER VEHICLE FOR ACOUSTIC INSPECTION OF PIPELINES FOR LEAKS. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1120788A true CA1120788A (en) | 1982-03-30 |
Family
ID=19828167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000296288A Expired CA1120788A (en) | 1977-03-15 | 1978-02-06 | Underwater craft for acoustic inspection of pipelines for leaks |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS53114181A (en) |
| AU (1) | AU514412B2 (en) |
| CA (1) | CA1120788A (en) |
| FR (1) | FR2383828A1 (en) |
| GB (1) | GB1552589A (en) |
| IT (1) | IT1107116B (en) |
| NL (1) | NL7702753A (en) |
| NO (1) | NO780868L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10577923B2 (en) | 2015-03-20 | 2020-03-03 | Halliburton Energy Services, Inc. | Leak detection via doppler shift differences in moving hydrophones |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4212258A (en) * | 1978-05-12 | 1980-07-15 | International Submarine Services, S.A. | Underwater apparatus for acoustically inspecting a submerged object |
| GB2083989A (en) * | 1980-09-10 | 1982-03-31 | Plessey Co Ltd | Ultrasonic reflectors |
| JPS5810623A (en) * | 1981-07-14 | 1983-01-21 | Toshiba Corp | Water leakage detector |
| JPS60105931A (en) * | 1983-11-14 | 1985-06-11 | Tokyo Gas Co Ltd | Leakage detecting apparatus for gas piping and gas appliance |
| GB2521681B (en) * | 2013-12-31 | 2017-08-16 | Sonardyne Int Ltd | Underwater leak detection apparatus, underwater leak detection system and method of detecting an underwater leak of a fluid |
-
1977
- 1977-03-15 NL NL7702753A patent/NL7702753A/en not_active Application Discontinuation
-
1978
- 1978-02-06 CA CA000296288A patent/CA1120788A/en not_active Expired
- 1978-03-13 IT IT67547/78A patent/IT1107116B/en active
- 1978-03-13 FR FR7807136A patent/FR2383828A1/en active Granted
- 1978-03-13 JP JP2782778A patent/JPS53114181A/en active Pending
- 1978-03-13 NO NO780868A patent/NO780868L/en unknown
- 1978-03-13 GB GB9813/78A patent/GB1552589A/en not_active Expired
- 1978-03-14 AU AU34101/78A patent/AU514412B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10577923B2 (en) | 2015-03-20 | 2020-03-03 | Halliburton Energy Services, Inc. | Leak detection via doppler shift differences in moving hydrophones |
Also Published As
| Publication number | Publication date |
|---|---|
| IT7867547A0 (en) | 1978-03-13 |
| AU3410178A (en) | 1979-09-20 |
| GB1552589A (en) | 1979-09-12 |
| IT1107116B (en) | 1985-11-18 |
| NL7702753A (en) | 1978-09-19 |
| FR2383828B1 (en) | 1981-01-09 |
| AU514412B2 (en) | 1981-02-05 |
| FR2383828A1 (en) | 1978-10-13 |
| NO780868L (en) | 1978-09-18 |
| JPS53114181A (en) | 1978-10-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4996879A (en) | Subsea pipeline leak detection | |
| Watkins et al. | Sound source location by arrival-times on a non-rigid three-dimensional hydrophone array | |
| Ainslie | Principles of sonar performance modelling | |
| US8125850B2 (en) | Method for identifying gas leaks using a stationary seabed placed steered beamformed acoustic antenna with active narrow beam transmitter interrogation capability | |
| CA2276361C (en) | Acoustic positioning of seismic ocean bottom cable | |
| US3992923A (en) | Underwater pipelines | |
| CA1120788A (en) | Underwater craft for acoustic inspection of pipelines for leaks | |
| AU654124B2 (en) | Electrooptical sensor system for marine seismic data acquisition | |
| US4709356A (en) | Seismic array positioning | |
| US7679999B2 (en) | Marine acoustic sensor assembly | |
| US3992924A (en) | Underwater pipelines | |
| RU103616U1 (en) | DEVICE FOR DETERMINING THE LOCATION OF A PRODUCT LEAK FROM UNDERWATER PIPELINES | |
| US20240219223A1 (en) | Prediction Of Far-Field Radiated Acoustic Fields In A Fluid Using Near-Field Acoustic Measurements | |
| RU94019575A (en) | METHOD OF STUDYING PIPELINATION DEFECTS AND DEVICE FOR ITS IMPLEMENTATION | |
| Nielsen et al. | Hull-mounted hydrophones for passive acoustic detection and tracking of sperm whales (Physeter macrocephalus) | |
| KR102436066B1 (en) | Monitoring system for underwater object by using of floating measuring apparatus for radiated noise | |
| Bjørnø | Developments in sonar technologies and their applications | |
| RU40474U1 (en) | DEVICE FOR DETERMINING THE LOCATION OF A PRODUCT LEAK FROM UNDERWATER PIPELINES | |
| RU2141740C1 (en) | Device for measurement of pressure levels of hydroacoustic fields of vessel | |
| Cai et al. | Passive acoustic detection of a small remotely operated vehicle | |
| Schinault | Development of a prototype towed coherent hydrophone array system | |
| Gaggero et al. | Processing strategies for evaluating the ship radiated noise using an underwater vertical array | |
| EP1089092A1 (en) | Method and apparatus for measuring physical parameters from the phase and amplitude histories of an acoustic signal | |
| RU2183303C1 (en) | Method for diagnosis of technical condition of pipe-line sea section | |
| RU2141739C1 (en) | Device for measurement of pressure levels of hydroacoustic fields of vessel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |