CA1123089A - Method for mounting acoustic waveguide rod - Google Patents
Method for mounting acoustic waveguide rodInfo
- Publication number
- CA1123089A CA1123089A CA324,795A CA324795A CA1123089A CA 1123089 A CA1123089 A CA 1123089A CA 324795 A CA324795 A CA 324795A CA 1123089 A CA1123089 A CA 1123089A
- Authority
- CA
- Canada
- Prior art keywords
- waveguide
- acoustic
- rods
- rod
- vibration detection
- 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
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Examining Or Testing Airtightness (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
METHOD FOR MOUNTING ACOUSTIC WAVEGUIDE ROD
ABSTRACT
A method for connecting a pipe wall or mechanical wall, which is an acoustic vibration detection point, with an electro-acoustic transducer through the medium of a metallic acoustic waveguide rod. The distal end of the waveguide rod is secured to a metallic conical or pyramidal solid waveguide member in a divergent form. The bottom of the conical or pyramidal waveguide member is joined to the acoustic vibration detection point. The proximal end of the waveguide rod is fixed to the electroacoustic transducer.
ABSTRACT
A method for connecting a pipe wall or mechanical wall, which is an acoustic vibration detection point, with an electro-acoustic transducer through the medium of a metallic acoustic waveguide rod. The distal end of the waveguide rod is secured to a metallic conical or pyramidal solid waveguide member in a divergent form. The bottom of the conical or pyramidal waveguide member is joined to the acoustic vibration detection point. The proximal end of the waveguide rod is fixed to the electroacoustic transducer.
Description
~Z3~1 This invention relates to a method for mounting an acoustic waveguide rod, or a rod-shaped metal member for guiding acoustic wave, to effectively propagate acoustic information obtained at any oE acoustic vibration detection points to an electroacoustic transducer.
General:Ly, in a leak detection-system such as, for example, a nuclear reactor coolant leak detector adapted to quickly and accurately detect any coolant leakage by making use of a leak sound resulted from the coolant leakage which accidentally occurs during the reactor operation, or in a normalcy monitor-ing system utilizing thephenomenon ofso-called acoustic emission for various kinds of electrical and mechanical devices, it is required to efficiently convert acoustic information obtained at a detection point into an electric signal.
In the case of a water-cooled type nuclear reactor, for example, the primary cooling water circulates in the primary cooling system usually in a high temperature and high pressure condition and in a highly radioactiva-ted state. Thus, pipes, containers, etc. which constitute pressure boundaries of the primary cooling system, are usually under a temperature above 200C when the reactor is in operation. In addition, there are numerous spots which require constant monitoring for normal-cy or leakage of the primary coollng water, and for instance the number of risers or inlet pipes used in a pressure tube type reactor totals more than several hundreds. Therefore, if a detector is provided in each of these pipes or tubes, there will be required a number of detectors as well as many
General:Ly, in a leak detection-system such as, for example, a nuclear reactor coolant leak detector adapted to quickly and accurately detect any coolant leakage by making use of a leak sound resulted from the coolant leakage which accidentally occurs during the reactor operation, or in a normalcy monitor-ing system utilizing thephenomenon ofso-called acoustic emission for various kinds of electrical and mechanical devices, it is required to efficiently convert acoustic information obtained at a detection point into an electric signal.
In the case of a water-cooled type nuclear reactor, for example, the primary cooling water circulates in the primary cooling system usually in a high temperature and high pressure condition and in a highly radioactiva-ted state. Thus, pipes, containers, etc. which constitute pressure boundaries of the primary cooling system, are usually under a temperature above 200C when the reactor is in operation. In addition, there are numerous spots which require constant monitoring for normal-cy or leakage of the primary coollng water, and for instance the number of risers or inlet pipes used in a pressure tube type reactor totals more than several hundreds. Therefore, if a detector is provided in each of these pipes or tubes, there will be required a number of detectors as well as many
- 2 -' '' ~ . ~ ' r~ ~ .
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( appurtenant electronic circuits, resulting in a complicated mechanism of the apparatus and the elevated equipment cost.
The detection system used under such circumstances needs to meet the following requirements:
' (1) Since the threshold temperature for use of a piezo-; electric type electroacoustic transducer (PZT) is around 1 60C, the system must be set at a place where the tem-f perature will not rise above said level.
(2) The system must be able to monitor several hundreds of detection points with a minimized number of means.
~Z3~)8~
( appurtenant electronic circuits, resulting in a complicated mechanism of the apparatus and the elevated equipment cost.
The detection system used under such circumstances needs to meet the following requirements:
' (1) Since the threshold temperature for use of a piezo-; electric type electroacoustic transducer (PZT) is around 1 60C, the system must be set at a place where the tem-f perature will not rise above said level.
(2) The system must be able to monitor several hundreds of detection points with a minimized number of means.
(3) It must be able to make detection at a location as much away from the highly radioactive region as possible.
In order to meet such requirements, there have been heretofore employed an acoustic waveguide rod of metal having a diameter of 1 to 5 mm. Such metallic waveguide rod is welded at its distal end to a pipe wall or machine wall which is to be an acoustic vibration detection point while the proximal end is fixed to an electroacoustic transducer. In case only a small number of waveguide rods are used, as shown in Fig. 1, it is difficult to join an electroacoustic transducer 1 and a plural number of waveguide rods, s~ that one master waveguide , rod 2a is enlarged in diameter as compared with other waveguide i rods 2b, 2c and the waveguide rods 2b, 2c are welded to a half-way point of the length of the master waveguide rod 2a. The distal ends of these waveguide rods 2a, 2b, 2c are welded to the wall faces of the respective pipes 3a, 3b, 3c which are , , . ....
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the detection points. The acoustic vibration from a source of acoustic emission or leak sound propagates through the pipe wall or machine wall to supply an energy ioto the wave-guide rod. Attenua-tion of wave motion of this type of wave-guide rod occurs principally at the welds 4 in the detection areas, the welded portions S of the waveguide rod and the joint of the master waveguide rod 2a and the electroacoustic transducer 1. The attenuation factor is 2 to 4 dB (100 to 1,000 KHz) at the welds 4 in the detection areas and 5 to 8 dB at -the welded portions 5 of the waveguide rod. The joint of the electro-acoustic transducer 1 involves no serlous problem of attenua-tion because it is possible to prevent wave attenuation by us-ing an acoustic couplant of silicone type.
When 10 to 20 detection points are to be monitored by a single electroacoustic transducer in a conventional system, it becomes impossible to weld all of waveguide rods to a master waveguide rod at one point. Thus, it is required from the viewpoint of mechanical strength to weld the respective waveguide rods 9a, 9b, .... 9x to a master waveguide rod 8 hav-ing a diameter of about 10 mm at the different points along its length as shown in Fig. 2, and hence many branching polnts are provided. This obstructs propagation of energy to the electroacoustic transducer 1 and increases the attenuation factor; If the waveguide rod diameter is greater than 10 mm, the frequency component of less than 100 KHz (environmental noise component such as sound of flow or pump rotation) is allowed to pass more than ~ther frequency components, that is, . ~.. .
:, .. - :
~ ` :, ' , the ratio of the fre~uency component of 100 to 1,000 KH~ to the frequency component of less -than 100 KHz becomes smaller than that of the waveguide rod with a diameter of less than 5 mm. This is derived from the frequency fractional expres-sion f ~ c/d, where f is high-pass cutoff frequency (Hz), c is wave velocity (cm/sec) in me-tal, and d is waveguide rod diameter ~cm). The large waveguide rod diameter also discommodes machining such as bending work required for mounting of the waveguide rod to a container or a pipe. Thus, according to such conventional waveguide rod mounting method as described above, the number of the waveguide rods that can be safely joined to one master waveguide rod is about five at most, in view of welding performance and attenuation factor.
An object of this invention, therefore, is to provide an improved acoustic waveguide rod mounting method which is free of the problems of the prior art such as mentioned above and which allows mounting of the waveguide rod with excellent wave propagation characteristic.
Another object of this invention is to provide an acoustic waveguide rod mounting method which allows propagation of wave motion to an electroacoustic transducer without causing attenua-tion of acoustic vibration at any detection polnt.
Still another object of this invention is to provide an acoustic waveguide mounting method which allows connection of a plurality of waveguide rods to a single electroacoustic transducer.
These and other objects are accomplished in accordance 0~ - 5 -~. . ..,, : :
...
: .
with this invention which involves a method for connecting a pipe wall or machine wall, whcih is an acoustic vibration detection point, with an electroacoustic transducer through the medium oF a me-tallic acoustic waveguide rod. The distal end of the waveguide rod is secured to a metallic conical or pyramidal solid waveguide member in a divergent form. The bottom of the conical or pyramidal waveguide member is joined to the acoustic vibration detection point. The proximal end of the waveguide rod is fixed to the electroacoustic transducer.
The effective joint of the bottom of the conical or pyra-midal waveguide member to the pipe wall can be obtained by welding a cylinder of metal to the pipe wall, and joining the bottom of the waveguide member to the surface of the cylinder.
The acoustic waveguide rod mounting method of this inven-tion is suitably applied to the case wherein a plurality of waveguide rods are connected to a single electroacoustic trans-:. .
ducer. In this case~ each of the distal ends of the waveguide ~ rods is secured to the acoustic vibratlon detection point of a the pipe wall by using the conical or~pyramidal wavegulde mem-~ ber. The proximal ends of the waveguide rods are bunched and arranged properly, and are united each other by solder. The electroacoustic transducer is then joined to the solder sur~ace.
Thus the method of this invention is not necessitated to provide a master waveguide rod to which the other waveguide rods are joined, so that the increse of the attenuation factor due to the welder points is prevented.
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Details of the invention, and of a preferred embodiment thereof, will be further understood with reference to the j drawings, in which:
Figures 1 and 2 are schematic drawings for illustrating conventional waveguide rod mounting methods;
Figure 3 is a drawing showing a waveguide rod mounting method according to this invention where only one waveguide rod is mounted;
Figure 4 shows another waveguide rod mounting method according to this invention where a plurality of waveguide rods are mounted;
Figure 5 is an enlarged sectional view of the portion where the waveguide rods are united in the method of Fig. 4;
Figure 6 is a graph showing comparatively the attenuation factor of the present invention and that of the prior art;
and ` Figure 7 is a frequency spectrum of the output from a waveguide rod mounted according to the method ofthis inven-tion.
'~ Referring now to Fig. 3, there is described an embodi-f rnent of the waveguide rod mount1ng method of th1s 1nvent1on where only one waveguide rod is mounted.
A rod-shaped waveguide 12 made of a metaI such as iron, copper, brass, stainless steel, aluminium,cadm1um, etc., has ltS distal end inserted into a hole formed centrally in a pyramidal or conical solid waveguide member 16 from the top thereof. Then, the inseFted end of the waveguide rod 12 ; - 7 -, : ::: ~
Z30~9 and the conical solid member 16 are joined together by casting silver solder or the like into the space therebetween to thereby form a divergent distal end. The bottom of the con-ical waveguide member 16 is joined to a wall surface 13 of a pressurized container or a pipe which forms an acoustic detec-tion point. This distal end arrangement can enlarge the joined area between the conical waveguide member 16 and the wall 13 of the pressuri~ed container or pipe, making it possible to pre-vent attenuation of the propagated wave at this joined portion.
The bottom of the conical waveguide 16 may be directly joined to the wall 13, but it is also possible to previously weld a cylinder 17 to the wall 13 and then ~join the bottom of the conical waveguide member 16 to the surface of the cylinder 17 by weld1ng, silver soldering or a suitable jig, as shown in the drawing.
Joint of the proximal end of the waveguide rod 12 to an electroacoustic transducer 11 can be effected with the inter-mediate of a metal disc 18 when only one waveguide rod is mounted; The disc may be substituted by a corical metal block.
In case a plural number of waveguide rods are used in combination, an arrangement such as shown in Figs. 4 and5may be employed. The distal end of each waveguide rod is joined to the wall surface in the same way as the embodiment of Fig. 3.
That is, the distal ends of the respective wavegu1de rods~12a, 12b, 12c, ... 12x are secured to the corresponding conical wave-guide members 16a, 16b, 16c, ... 16x. The cylinders 17a, 17b, .
17c, ... 17x are previously welded to the desired pipe walls or machine walls 13a, 13b, 13c, ... 13x which are the acoustic - ~ - 8 -- ,: , , -, ~ - :
.
~Z3~;)85~
vibration detection points, and the conical waveguide members 16a, 16b, 16c, ... 16x are joined to the surfaces of the respective cylinders.
The proximal ends of the respective waveguide rods 12a, 12b, 12c ... 12x are arranged properly and passed through respective holes in a perforated bunching plate 19. The thus bunched proximal end portions of the waveguide rods which have been passed through the bunching plate are then united by a round tube 20 which comprises a small diameter portion 20a and a large diameter portion 20b, these portions 20a and 20b being connected by a step portion 20c; The end of the small diameter portion 20a abuts on the bunching plate 19 and fixed thereto.
The round tube 20 is so designed that the top end of the large diameter portion 20b is extended higher by a length of about 3 to 5 mm than the proximal end eaces of the waveguide rods 12a, 12b, 12c, ... 12x. Then silver solder is cast into the round tube 20 from the top opening thereof. This silver solder fills the spaces 21 between the respective waveguide rods within the round tube to form a metal region 22 of 3-5 mm thick reaching to the top end of the round tube 20. The face of the metal region 22 to be joined to the electroacoustic transducer 11 is subjected to fine fishining of approximately 6S and then coated with an acoustic couplant. This acoustic couplant may be a conventional silicone grease. According to this arrangement, th.e acoustic signal obtained at any acoustic vibration detection point is propagated to the electroacoustic 9 _ :' `: , 3L~Z3~9 transudcer lt without decay by the waveguide rods, so that a master waveguide rod is unnecessitated.
Fig. 6 is a graph showing comparatively the attenuation factor given in a conventional master waveguide rod system and that noted in the waveguide rod bunching system of this inven-tion. In the graph, a mark X indicated by (a) is the attenua-tion factor which is given when three waveguide rods having 4 mm diameter are combined conventionally by welding two of these three rods to the remaining one master rod, and the respective distal ends of the rods are contacted to a pipe wall via a conical solid waveguide member, and a signal is applied to the master rod. In this case, the attenuation fac-tor (a) is about 8 dB. The point (b) shows the attenuation factor of about 2 dB, which is observed in the bunching sys-tem of this invention using the same number of waveguide rods having the same diameter. This point (b) agrees, within the experimental errors, with the attenuation factor curve (c) obtained when a single waveguide rod is used. This ascertains that substantially no attenuation takes place at the bunched portion.
Fig. 7 is the frequency spec-trum of output from a wave-guide rod (~ mm in diameter and 5 m in length) mounted accord-ing to the method of this invention in a conditlon where high tempera-ture and high pressure water was released into the atmosphere. This spectral diagram indicates posltive pro-pagation of acoustic vibration with frequency of up to about 1,000 KHz.
''~ , .
~Z3~ 39 Thus, when waveguide rods are mounted according to the method of this invention, the acoustic vibration at any detection point is efficiently propagated to an electroacoustic transducer, and it becomes possible to Join a plurality of fine waveguide rods to a single electroacoustic transducer w:ithout causin~ attenuation of the acoustic signal. It will be understood that the method of this invention can meet all of the aforesaid three requirements which are necessary in the acoustic vibration detection system under high temperature, high pressllre, high radioactiv-ty and comp icated piplng state.
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, . ::: ...
In order to meet such requirements, there have been heretofore employed an acoustic waveguide rod of metal having a diameter of 1 to 5 mm. Such metallic waveguide rod is welded at its distal end to a pipe wall or machine wall which is to be an acoustic vibration detection point while the proximal end is fixed to an electroacoustic transducer. In case only a small number of waveguide rods are used, as shown in Fig. 1, it is difficult to join an electroacoustic transducer 1 and a plural number of waveguide rods, s~ that one master waveguide , rod 2a is enlarged in diameter as compared with other waveguide i rods 2b, 2c and the waveguide rods 2b, 2c are welded to a half-way point of the length of the master waveguide rod 2a. The distal ends of these waveguide rods 2a, 2b, 2c are welded to the wall faces of the respective pipes 3a, 3b, 3c which are , , . ....
:
:
~;, 3~
the detection points. The acoustic vibration from a source of acoustic emission or leak sound propagates through the pipe wall or machine wall to supply an energy ioto the wave-guide rod. Attenua-tion of wave motion of this type of wave-guide rod occurs principally at the welds 4 in the detection areas, the welded portions S of the waveguide rod and the joint of the master waveguide rod 2a and the electroacoustic transducer 1. The attenuation factor is 2 to 4 dB (100 to 1,000 KHz) at the welds 4 in the detection areas and 5 to 8 dB at -the welded portions 5 of the waveguide rod. The joint of the electro-acoustic transducer 1 involves no serlous problem of attenua-tion because it is possible to prevent wave attenuation by us-ing an acoustic couplant of silicone type.
When 10 to 20 detection points are to be monitored by a single electroacoustic transducer in a conventional system, it becomes impossible to weld all of waveguide rods to a master waveguide rod at one point. Thus, it is required from the viewpoint of mechanical strength to weld the respective waveguide rods 9a, 9b, .... 9x to a master waveguide rod 8 hav-ing a diameter of about 10 mm at the different points along its length as shown in Fig. 2, and hence many branching polnts are provided. This obstructs propagation of energy to the electroacoustic transducer 1 and increases the attenuation factor; If the waveguide rod diameter is greater than 10 mm, the frequency component of less than 100 KHz (environmental noise component such as sound of flow or pump rotation) is allowed to pass more than ~ther frequency components, that is, . ~.. .
:, .. - :
~ ` :, ' , the ratio of the fre~uency component of 100 to 1,000 KH~ to the frequency component of less -than 100 KHz becomes smaller than that of the waveguide rod with a diameter of less than 5 mm. This is derived from the frequency fractional expres-sion f ~ c/d, where f is high-pass cutoff frequency (Hz), c is wave velocity (cm/sec) in me-tal, and d is waveguide rod diameter ~cm). The large waveguide rod diameter also discommodes machining such as bending work required for mounting of the waveguide rod to a container or a pipe. Thus, according to such conventional waveguide rod mounting method as described above, the number of the waveguide rods that can be safely joined to one master waveguide rod is about five at most, in view of welding performance and attenuation factor.
An object of this invention, therefore, is to provide an improved acoustic waveguide rod mounting method which is free of the problems of the prior art such as mentioned above and which allows mounting of the waveguide rod with excellent wave propagation characteristic.
Another object of this invention is to provide an acoustic waveguide rod mounting method which allows propagation of wave motion to an electroacoustic transducer without causing attenua-tion of acoustic vibration at any detection polnt.
Still another object of this invention is to provide an acoustic waveguide mounting method which allows connection of a plurality of waveguide rods to a single electroacoustic transducer.
These and other objects are accomplished in accordance 0~ - 5 -~. . ..,, : :
...
: .
with this invention which involves a method for connecting a pipe wall or machine wall, whcih is an acoustic vibration detection point, with an electroacoustic transducer through the medium oF a me-tallic acoustic waveguide rod. The distal end of the waveguide rod is secured to a metallic conical or pyramidal solid waveguide member in a divergent form. The bottom of the conical or pyramidal waveguide member is joined to the acoustic vibration detection point. The proximal end of the waveguide rod is fixed to the electroacoustic transducer.
The effective joint of the bottom of the conical or pyra-midal waveguide member to the pipe wall can be obtained by welding a cylinder of metal to the pipe wall, and joining the bottom of the waveguide member to the surface of the cylinder.
The acoustic waveguide rod mounting method of this inven-tion is suitably applied to the case wherein a plurality of waveguide rods are connected to a single electroacoustic trans-:. .
ducer. In this case~ each of the distal ends of the waveguide ~ rods is secured to the acoustic vibratlon detection point of a the pipe wall by using the conical or~pyramidal wavegulde mem-~ ber. The proximal ends of the waveguide rods are bunched and arranged properly, and are united each other by solder. The electroacoustic transducer is then joined to the solder sur~ace.
Thus the method of this invention is not necessitated to provide a master waveguide rod to which the other waveguide rods are joined, so that the increse of the attenuation factor due to the welder points is prevented.
- . . . ~ .-, ":
~:~3~
Details of the invention, and of a preferred embodiment thereof, will be further understood with reference to the j drawings, in which:
Figures 1 and 2 are schematic drawings for illustrating conventional waveguide rod mounting methods;
Figure 3 is a drawing showing a waveguide rod mounting method according to this invention where only one waveguide rod is mounted;
Figure 4 shows another waveguide rod mounting method according to this invention where a plurality of waveguide rods are mounted;
Figure 5 is an enlarged sectional view of the portion where the waveguide rods are united in the method of Fig. 4;
Figure 6 is a graph showing comparatively the attenuation factor of the present invention and that of the prior art;
and ` Figure 7 is a frequency spectrum of the output from a waveguide rod mounted according to the method ofthis inven-tion.
'~ Referring now to Fig. 3, there is described an embodi-f rnent of the waveguide rod mount1ng method of th1s 1nvent1on where only one waveguide rod is mounted.
A rod-shaped waveguide 12 made of a metaI such as iron, copper, brass, stainless steel, aluminium,cadm1um, etc., has ltS distal end inserted into a hole formed centrally in a pyramidal or conical solid waveguide member 16 from the top thereof. Then, the inseFted end of the waveguide rod 12 ; - 7 -, : ::: ~
Z30~9 and the conical solid member 16 are joined together by casting silver solder or the like into the space therebetween to thereby form a divergent distal end. The bottom of the con-ical waveguide member 16 is joined to a wall surface 13 of a pressurized container or a pipe which forms an acoustic detec-tion point. This distal end arrangement can enlarge the joined area between the conical waveguide member 16 and the wall 13 of the pressuri~ed container or pipe, making it possible to pre-vent attenuation of the propagated wave at this joined portion.
The bottom of the conical waveguide 16 may be directly joined to the wall 13, but it is also possible to previously weld a cylinder 17 to the wall 13 and then ~join the bottom of the conical waveguide member 16 to the surface of the cylinder 17 by weld1ng, silver soldering or a suitable jig, as shown in the drawing.
Joint of the proximal end of the waveguide rod 12 to an electroacoustic transducer 11 can be effected with the inter-mediate of a metal disc 18 when only one waveguide rod is mounted; The disc may be substituted by a corical metal block.
In case a plural number of waveguide rods are used in combination, an arrangement such as shown in Figs. 4 and5may be employed. The distal end of each waveguide rod is joined to the wall surface in the same way as the embodiment of Fig. 3.
That is, the distal ends of the respective wavegu1de rods~12a, 12b, 12c, ... 12x are secured to the corresponding conical wave-guide members 16a, 16b, 16c, ... 16x. The cylinders 17a, 17b, .
17c, ... 17x are previously welded to the desired pipe walls or machine walls 13a, 13b, 13c, ... 13x which are the acoustic - ~ - 8 -- ,: , , -, ~ - :
.
~Z3~;)85~
vibration detection points, and the conical waveguide members 16a, 16b, 16c, ... 16x are joined to the surfaces of the respective cylinders.
The proximal ends of the respective waveguide rods 12a, 12b, 12c ... 12x are arranged properly and passed through respective holes in a perforated bunching plate 19. The thus bunched proximal end portions of the waveguide rods which have been passed through the bunching plate are then united by a round tube 20 which comprises a small diameter portion 20a and a large diameter portion 20b, these portions 20a and 20b being connected by a step portion 20c; The end of the small diameter portion 20a abuts on the bunching plate 19 and fixed thereto.
The round tube 20 is so designed that the top end of the large diameter portion 20b is extended higher by a length of about 3 to 5 mm than the proximal end eaces of the waveguide rods 12a, 12b, 12c, ... 12x. Then silver solder is cast into the round tube 20 from the top opening thereof. This silver solder fills the spaces 21 between the respective waveguide rods within the round tube to form a metal region 22 of 3-5 mm thick reaching to the top end of the round tube 20. The face of the metal region 22 to be joined to the electroacoustic transducer 11 is subjected to fine fishining of approximately 6S and then coated with an acoustic couplant. This acoustic couplant may be a conventional silicone grease. According to this arrangement, th.e acoustic signal obtained at any acoustic vibration detection point is propagated to the electroacoustic 9 _ :' `: , 3L~Z3~9 transudcer lt without decay by the waveguide rods, so that a master waveguide rod is unnecessitated.
Fig. 6 is a graph showing comparatively the attenuation factor given in a conventional master waveguide rod system and that noted in the waveguide rod bunching system of this inven-tion. In the graph, a mark X indicated by (a) is the attenua-tion factor which is given when three waveguide rods having 4 mm diameter are combined conventionally by welding two of these three rods to the remaining one master rod, and the respective distal ends of the rods are contacted to a pipe wall via a conical solid waveguide member, and a signal is applied to the master rod. In this case, the attenuation fac-tor (a) is about 8 dB. The point (b) shows the attenuation factor of about 2 dB, which is observed in the bunching sys-tem of this invention using the same number of waveguide rods having the same diameter. This point (b) agrees, within the experimental errors, with the attenuation factor curve (c) obtained when a single waveguide rod is used. This ascertains that substantially no attenuation takes place at the bunched portion.
Fig. 7 is the frequency spec-trum of output from a wave-guide rod (~ mm in diameter and 5 m in length) mounted accord-ing to the method of this invention in a conditlon where high tempera-ture and high pressure water was released into the atmosphere. This spectral diagram indicates posltive pro-pagation of acoustic vibration with frequency of up to about 1,000 KHz.
''~ , .
~Z3~ 39 Thus, when waveguide rods are mounted according to the method of this invention, the acoustic vibration at any detection point is efficiently propagated to an electroacoustic transducer, and it becomes possible to Join a plurality of fine waveguide rods to a single electroacoustic transducer w:ithout causin~ attenuation of the acoustic signal. It will be understood that the method of this invention can meet all of the aforesaid three requirements which are necessary in the acoustic vibration detection system under high temperature, high pressllre, high radioactiv-ty and comp icated piplng state.
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- ~ . ~ ~ .......... . . ..
, . ::: ...
Claims (6)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for connecting a pipe wall or machine wall, which is an acoustic vibration detection point, with an electroacoustic transducer through the medium of a metallic acoustic waveguide rod comprising:
securing the distal end of said waveguide rod to a metallic conical or pyramidal solid waveguide member in a divergent form;
joining the bottom of said waveguide member to said acoustic vibration detection point; and fixing the proximal end of said rod to the electroacoustic transducer.
securing the distal end of said waveguide rod to a metallic conical or pyramidal solid waveguide member in a divergent form;
joining the bottom of said waveguide member to said acoustic vibration detection point; and fixing the proximal end of said rod to the electroacoustic transducer.
2. The method according to claim 1, wherein a cylinder is welded to the pipe wall or machine wall which is an acoustic vibration detection point, and the bottom of said conical or pyramidal waveguide member is joined to the surface of said cylinder.
3. The method according to claim 1, wherein the proximal end of said waveguide rod is joined to one surface of a metallic disc and the other surface of said disc is joined to said electroacosutic transducer.
4. A method for connecting a plurality of pipe walls or machine walls, which are acoustic vibration detection points, to an electroacoustic transducer through the medium of a plurality of metallic acoustic waveguide rods comprising:
mounting each of the distal ends of said waveguide rods to a metallic conical or pyramidal solid waveguide member in a divergent form;
joining the bottom of each said waveguide member to each of the acoustic vibration detection points; and bunching the proximal ends of said waveguide rods in order and joining them to each other by solder, and then mounting an electroacoustic transducer to the solder surface.
mounting each of the distal ends of said waveguide rods to a metallic conical or pyramidal solid waveguide member in a divergent form;
joining the bottom of each said waveguide member to each of the acoustic vibration detection points; and bunching the proximal ends of said waveguide rods in order and joining them to each other by solder, and then mounting an electroacoustic transducer to the solder surface.
5. The method according to claim 4, wherein a cylinder is welded to each of the pipe or machine wall which are the acoustic vibration detection points, and the bottom of each said conical or pyramidal waveguide member is joined to the surface of said cylinder.
6. The method according to claim 4, wherein the proximal ends of said waveguide rods are passed through the respective holes in a perforated bunching plate, and the thus bunched proximal end portions of said waveguide rods which have been passed through said bunching plate are further united by a round tube, the lower end thereof abutting on said bunching plate while the upper end thereof projecting slightly higher than the proximal end faces of said waveguide rods, then silver solder is cast into said round tube to fill the spaces between said respective waveguide rods to form a metal region reaching to the upper end of said round tube, and the surface of said metal region is joined to an electroacoustic transducer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP53-62547 | 1978-05-25 | ||
| JP53062547A JPS586141B2 (en) | 1978-05-25 | 1978-05-25 | How to install an acoustic waveguide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1123089A true CA1123089A (en) | 1982-05-04 |
Family
ID=13203363
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA324,795A Expired CA1123089A (en) | 1978-05-25 | 1979-04-03 | Method for mounting acoustic waveguide rod |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS586141B2 (en) |
| CA (1) | CA1123089A (en) |
| IT (1) | IT1112898B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2552780A (en) * | 2016-07-29 | 2018-02-14 | Fish Guidance Systems Ltd | An acoustic device for forming a wall of sound in a fluid |
| CN108799846A (en) * | 2018-07-06 | 2018-11-13 | 中国核动力研究设计院 | A kind of nuclear power station pressure pipeline acoustic emission detection device and method |
| CN114754710A (en) * | 2022-04-12 | 2022-07-15 | 西安热工研究院有限公司 | Method for measuring corrosion of inner wall of fire facing side of water wall tube on fire back side |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5455298B2 (en) * | 2007-11-06 | 2014-03-26 | オークマ株式会社 | Bearing condition diagnosis device |
| US8800373B2 (en) * | 2011-02-14 | 2014-08-12 | Rosemount Inc. | Acoustic transducer assembly for a pressure vessel |
| JP5409878B2 (en) * | 2012-11-02 | 2014-02-05 | オークマ株式会社 | Bearing condition diagnosis device |
| JP7305854B2 (en) * | 2018-09-06 | 2023-07-10 | 株式会社東芝 | Detection system and detection method |
-
1978
- 1978-05-25 JP JP53062547A patent/JPS586141B2/en not_active Expired
-
1979
- 1979-04-03 CA CA324,795A patent/CA1123089A/en not_active Expired
- 1979-05-21 IT IT22852/79A patent/IT1112898B/en active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2552780A (en) * | 2016-07-29 | 2018-02-14 | Fish Guidance Systems Ltd | An acoustic device for forming a wall of sound in a fluid |
| GB2552780B (en) * | 2016-07-29 | 2018-11-28 | Fish Guidance Systems Ltd | An acoustic device for forming a wall of sound underwater |
| US10388267B2 (en) | 2016-07-29 | 2019-08-20 | Fish Guidance Systems Limited | Acoustic device for forming a wall of sound underwater |
| CN108799846A (en) * | 2018-07-06 | 2018-11-13 | 中国核动力研究设计院 | A kind of nuclear power station pressure pipeline acoustic emission detection device and method |
| CN114754710A (en) * | 2022-04-12 | 2022-07-15 | 西安热工研究院有限公司 | Method for measuring corrosion of inner wall of fire facing side of water wall tube on fire back side |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS586141B2 (en) | 1983-02-03 |
| IT1112898B (en) | 1986-01-20 |
| IT7922852A0 (en) | 1979-05-21 |
| JPS54154371A (en) | 1979-12-05 |
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