JPH0943166A - Electromagnetic wave exciting method for leakage position detection of tube utilizing electromagnetic wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a method for exciting an electromagnetic wave to apply the detection of the leakage position of a tube utilizing the wave. SOLUTION: In the method for detecting the leakage position of a tube 4 having the steps of exciting and propagating an electromagnetic wave to the tube such as a gas tube 4, and receiving the leaked wave, a probe 4 or a loop is projected to the inside of a cover 11 for blocking the opening 10 of a tee 9 installed on the extension of the tube 4 to be detected at the lateral side, the probe 4 or loop is connected to an electromagnetic wave oscillator via a coaxial cable, the probe 5 or loop is disposed in the tee 9 in the state that the cover 11 is mounted, and the wave is excited. Accordingly, in order to excite the wave to the tube 4, it is not necessary to cut the one end of the tube 4 and to stop supplying of gas. The leakage of the wave from the tee 9 for constituting an exciter 2 can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave exciting method for detecting a leaked portion of a pipe such as a gas pipe using the electromagnetic wave.

[0002]

2. Description of the Related Art For example, a detection method using electromagnetic waves has been proposed as one of methods for detecting a leaked portion such as a corrosion hole formed in a gas pipe. This method excites electromagnetic waves in a metal gas tube and propagates it in the same manner as a circular waveguide,
By receiving the electromagnetic waves leaking from the leaking point,
This is a method of detecting a leaked point. FIG. 7 schematically shows a configuration to which this method is applied. Reference numeral 1 is an oscillating device,
Reference numeral 2 is an excitation unit, 3 is a coaxial cable, and the excitation unit 2 is configured as a coaxial-to-circular waveguide converter in which a probe 5 is protruded in the gas pipe 4. Reference numeral 6 is an antenna, and 7 is a receiving device. A worker searches for electromagnetic waves leaking from a leaking point 8 while moving the antenna 6.

[0003]

In the above conventional method, one end of the gas pipe must be cut in order to excite the electromagnetic wave to the gas pipe, and therefore the gas supply must be stopped. Moreover, the conventional method is not perfect in preventing the leakage of electromagnetic waves from the excitation unit. The present invention
The purpose is to solve such a problem.

[0004]

In order to solve the above-mentioned problems, first of all, in the present invention, there is provided a method for detecting a leaking portion of a pipe by exciting and propagating the electromagnetic wave in the pipe and receiving the leaking electromagnetic wave. , The probe is configured to project inside the lid that closes the opening on the side of the tee that is installed on the extension of the target tube, and the probe and the electromagnetic wave oscillation device are connected by a coaxial cable and the lid is attached. It is proposed that the probe be positioned in the tee to excite electromagnetic waves in this state.

Next, according to the present invention, in a method of exciting and propagating an electromagnetic wave in a pipe and detecting a leaking electromagnetic wave, the leaked portion of the pipe is detected, which is installed as an extension of the target pipe. While forming a loop inside the lid that closes the opening on the side of the tee, connect the probe and the electromagnetic wave oscillation device with a coaxial cable, position the loop inside the tee with the lid attached, and It is suggested that the structure be set to excite. Also in this configuration,
The loop proposes to orient its axial direction axially of the tee or tangentially to the inner circumference.

Next, in the present invention, it is proposed that the lid is screwed and fixed to the opening of the tee, and a shield material is interposed between the ends of the lid and the opening of the tee or the screwed portion.

In the above means, when the lid is attached to the opening on the side of the tee, the probe or loop is in a protruding state in the tee, so that the probe or loop can excite electromagnetic waves into the tube through the tee. .

The shield material interposed between the ends of the lid and the lateral opening of the tee or in the screwed portion prevents leakage of electromagnetic waves from the opening of the tee.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows an embodiment of the overall configuration when the method of the present invention is applied to the detection of a leaked portion of a gas pipe, and the same reference numerals are given to the same components as those shown in FIG. The description is omitted. Reference numeral 9 is a tee previously installed in the gas pipe 4, and the opening 10 on the side of the tee 9 has a structure in which a lid 11 is attached by a screw to close it. In the present invention, the excitation unit 2 is configured by using this lid 11.

That is, FIGS. 2 to 6 specifically show an embodiment of the excitation unit 2. The same components as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. To do. First, in FIG. 2, reference numeral 12 is a support, 13 is a lock nut, and these are connected by a screw portion 14. The threaded portion 14a of the lock nut 13 is inserted inward from the mounting hole 15 formed in the center of the lid 11, and is screwed into the threaded portion 14b of the support body 12 arranged inside to tighten the mounting portion 15 of the lid 11. Around the lock nut 13
The brim portion 15 and the support body 12 are sandwiched to be in a fixed state. Prior to such screwing, the tip of the coaxial cable 3 is inserted into the lock nut 13, the center lead 16 is projected, and the braid of the shield wire 17 is expanded along the clamp 18. A washer 19 and a gasket 20 are interposed on the tip side of the above, and the expanded shielded wire 17 is brought into pressure contact with the inner wall of the support 12 by the above-mentioned tightening to be in a mounted state. On the other hand, a linear probe 5 is joined to the tip end side of the center lead 16, and the probe 5 is supported by the insulator 21 at the center position of the support 12. In such a configuration, the screw portion 22a of the lid 11 can be closed by screwing the screw portion 22a of the lid 11 to the screw portion 22b of the opening 10 on the lateral side of the tee 9 to close the opening 10. Located in tee 9.

At this time, if an O-ring-shaped shield material 24 made of conductive rubber, soft metal, or the like is interposed between the end of the opening 10 and the inside of the lid 11, the lid 11 is screwed into the screw portion 22a.
When tightened by screwing 22b, the shield member 24 is pressed against the end of the opening 10 and the inside of the lid 11 to form a shield portion against electromagnetic waves, so that the leakage of electromagnetic waves from the excitation portion 2 is prevented. Can be perfect. In addition to this, the shield part can be configured by interposing a shield material in the screw part of the screw parts 22a and 22b. For example,
After winding a thread made of soft metal around the outer periphery of the screw portion 22b of the opening 10 of the tee 9 or applying a conductive compound, the screw portion 22a of the lid 11 is attached to the screw portion 22b.
By screwing in and filling the gap between the threaded portions 22a and 22b with a deformed thread or conductive compound,
The shield part can be configured.

In the above structure, when an electromagnetic wave is supplied from the oscillating device 1 to the exciter 2 through the coaxial cable 3, the electromagnetic wave in the mode corresponding to the electric field generated by the probe 5 is tee 9.
It is excited inside and propagates from the tee 9 to the gas pipe 4. In this way, the gas pipe 4 can propagate the electromagnetic wave in the same mode as the circular waveguide. In the case of FIG. 2, the gas pipe 4
An electromagnetic field of TM ₀₁ mode is formed in and propagates. If the gas pipe 4 has a leak point 8 such as a through hole, the electromagnetic wave propagating through the gas pipe 4 leaks to the outside from the leak point 8. Therefore, the leaked electromagnetic wave is received by the antenna 6, and the leak point 8 is leaked. Can be detected.

FIG. 3 is a modified example of FIG. 2, and the configuration of the probe 5 is different from that of FIG. That is, the probe 5 of FIG. 3 is not a linear shape as shown in FIG.
It has a V-shape and the tip is directed in the axial direction of the tee 9. Since other configurations are similar to those of FIG. 2, the same reference numerals are given and description thereof is omitted.

FIG. 4 replaces the probe of FIG. 2 with a loop 23.
Is projected to the inside of the lid 11, and the loop 23 is configured by connecting a conductive wire between the tip of the center lead 16 and the tip of the support 12. The other components are the same as those in FIG. 2, and therefore, the same reference numerals are given and the description thereof is omitted.
In this embodiment, the loop 23 has its axial direction oriented in the tangential direction of the inner circumference of the tee 9. In this configuration, the gas pipe 4 has an electromagnetic field in the TM ₀₁ mode similar to that in FIG. Are formed and propagated.

FIG. 5 is a modification of FIG. 4, and this configuration is
Only the direction in which the axis of the loop 23 is oriented differs from the configuration of FIG. Therefore, like the above, the same reference numerals are given and the description thereof is omitted. In this embodiment, the loop 23 has its axial direction directed to the axial direction of the tee 9, and in this configuration, an electromagnetic field of TE ₀₁ mode is formed and propagates in the gas pipe 4.

FIG. 6 is a modified example of FIG. 2, and in this configuration, unlike the configuration so far, the lid 11 is screwed inside the opening 10 and attached. That is, reference numeral 25 is a support body corresponding to the support body 12 of FIG. 1, and this support body 12 is formed by screwing a threaded portion 26a formed on the outer periphery to a threaded portion 26b formed inside the opening of the tee 9. With the configuration to be attached, the collar portion 27 is provided on one end side. Since other configurations are similar to those of FIG. 2, the same reference numerals are given and description thereof is omitted.

The support mechanism of the coaxial cable 3 with respect to the lid 11, the configuration of the probe 5 and the loop 23 at the tip of the coaxial cable 3, the support mechanism, etc. are conventionally used in a coaxial-waveguide converter or the like. Other mechanisms are available. Further, in the above-mentioned embodiments, the inspection target is the gas pipe. However, in the present invention, an appropriate metallic pipe can be the inspection target in addition to the gas pipe.

[0018]

As described above, according to the present invention, since electromagnetic waves are excited from the tee installed on the extension of the pipe to the pipe, it is not necessary to cut one end of the pipe to perform the excitation.
Therefore, there is an effect that it is not necessary to stop the supply of gas. Further, the present invention has an effect that it is possible to surely prevent the leakage of the electromagnetic wave from the tee that constitutes the excitation unit.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of leak point detection performed by applying the method of the present invention.

FIG. 2 is a cross-sectional view showing a first embodiment of an exciting unit according to the present invention.

FIG. 3 is a cross-sectional view showing a second embodiment of an exciting unit according to the present invention.

FIG. 4 is a cross-sectional view showing a third embodiment of an exciting unit according to the present invention.

FIG. 5 is a cross-sectional view showing a fourth embodiment of an exciting unit according to the present invention.

FIG. 6 is a cross-sectional view showing a fifth embodiment of an exciting unit in the present invention.

FIG. 7 is a schematic diagram showing an overall configuration of conventional leak detection of a pipe using electromagnetic waves.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2 Excitation part 3 Coaxial cable 4 Tube 5 Probe 6 Antenna 7 Receiver 8 Leakage point 9 Tee 10 Opening 11 Lid 12 Support 13 Lock nut 14a, 14b Screw part 15 Collar 16 Center lead 17 Shield wire 18 Clamp 19 Washer 20 Gasket 21 Insulator 22a, 22b Screw part 23 Loop 24 (O-ring shield member) 25 Supports 26a, 26b Screw part 27 Collar part

Claims (6)

[Claims] 1. A method for detecting a leaking portion of a pipe by exciting and propagating the electromagnetic wave to the pipe and receiving the leaking electromagnetic wave, the method comprising: The probe is configured to protrude inside the lid that closes the opening, the probe and the electromagnetic wave oscillation device are connected by a coaxial cable, and the probe is positioned inside the tee with the lid attached to excite the electromagnetic wave. Excitation Method of Electromagnetic Waves for Detecting Leakage Locations in Pipes Using Electromagnetic Waves 2. A method for detecting a leaking portion of a pipe by exciting and propagating the electromagnetic wave to the pipe and receiving the leaking electromagnetic wave, the method being provided on a side of a tee installed on an extension of the target pipe. The loop is configured to project inside the lid that closes the opening, and the probe and the electromagnetic wave oscillation device are connected by a coaxial cable, and the loop is positioned inside the tee with the lid attached to excite the electromagnetic wave. Excitation Method of Electromagnetic Waves for Detecting Leakage Locations in Pipes Using Electromagnetic Waves 3. A method for exciting an electromagnetic wave in detecting a leaked portion of a pipe using the electromagnetic wave according to claim 2, wherein the axial direction of the loop is oriented in the axial direction of the tee. 4. The method of exciting an electromagnetic wave in detecting a leaked portion of a pipe using the electromagnetic wave according to claim 2, wherein the loop has its axial direction oriented in the tangential direction of the inner circumference of the tee. 5. The O-ring-shaped shield material is interposed between the lid and the end of the opening of the tee, and the lid is fixed by screwing into the opening of the tee. Electromagnetic Wave Excitation Method for Detecting Leakage Locations in Pipes Using Various Electromagnetic Waves 6. The leaking portion of the pipe using electromagnetic waves according to claim 1, wherein the lid is configured to be screwed into and fixed to the opening of the tee, and a shield material is interposed in the screwed portion. Electromagnetic wave excitation method for detection