JPH0933377A - Method for inspecting pipe by electromagnetic wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the erroneous detection by an external noise in an inspection method for detecting a leakage position such as corroded hole generated in a pipe such as gas pipe by use of electromagnetic waves. SOLUTION: In the method of inspecting a leakage position 26 of a pipe 14 to be inspected by exciting an electromagnetic wave to ward the pipe 14 by a transmitting device 11, propagating it in the pipe, and receiving the leaked electromagnetic wave with a receiving device 21, the receipt is performed also in the state where the excitation of the electromagnetic wave is temporarily turned off, and the received signal in OFF is compared with the received signal in ON, thereby, the electromagnetic wave by leakage is discriminated. When a certain electromagnetic wave is received by a receiving device, whether it contains one leaked from a leakage position, or consists of only an external noise, can be easily and surely discriminated, and the erroneous detection of the leakage position can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for detecting leak points such as corrosion holes formed in a gas pipe by using electromagnetic waves.

[0002]

2. Description of the Related Art As one of methods for detecting a leaked portion such as a corrosion hole formed in a gas pipe, a detection method using electromagnetic waves has been proposed. In this method, an electromagnetic wave is excited in a metal gas pipe, propagated in a manner similar to that of a circular waveguide, and the electromagnetic wave leaking from the leaked part is received to detect the leaked part. FIG. 5 schematically shows a conventional configuration to which this method is applied. Reference numeral 1 is a transmitting device,
Reference numeral 2 is an excitation unit, 3 is a coaxial cable, and the excitation unit 2 is attached by cutting one end of the gas pipe 4, and the probe 5 is installed in the gas pipe 4.
Is configured as a coaxial-to-circular waveguide converter. Reference numeral 6 is an antenna, and 7 is a receiving device. In the above configuration, the transmitter 1 side continuously excites the electromagnetic wave with the exciter 2, and in this state, the worker on the receiver 7 side moves the antenna 6 and searches for the electromagnetic wave leaking from the leakage point 8. .

[0003]

In addition to the electromagnetic wave leaking from the leaking point 8, various external noises enter the antenna 6, so that when the receiving device 7 receives a certain electromagnetic wave, It is necessary to discriminate whether it includes the one leaking from the leaking point 8 or only the external noise, but in general, the discrimination is relatively difficult. The present invention aims to solve such problems.

[0004]

In order to solve the above-mentioned problems, in the present invention, an electromagnetic wave is excited by a transmitting device into a pipe to be inspected to propagate in the pipe, and a leaking electromagnetic wave is received by a receiving device. In the method of inspecting the leaked part of the pipe by the method, the electromagnetic wave caused by the leakage is identified by receiving even when the excitation of the electromagnetic wave is temporarily turned off and comparing the received signal at the time of OFF with the received signal at the time of ON. Suggest to do.

In the present invention, in the above structure,
An ON-OFF control unit for exciting electromagnetic waves is configured on the transmitting device side, a remote control switch for the ON-OFF control unit is configured on the receiving device, and the ON-OFF control unit is operated on the receiving device side. I suggest that.

Further, according to the present invention, in the above-mentioned structure, an ON-OFF control means for exciting an electromagnetic wave is formed on the side of the transmitting device, and ON-OFF control is performed by itself.
It is proposed to transmit a signal synchronized with the N-OFF operation to the receiving device side so that the receiving device side can detect the ON-OFF state.

[0007]

[Operation] When the receiving device is receiving a certain electromagnetic wave,
Turn off the excitation of electromagnetic waves to the pipe to be inspected by the transmitter.
Then, if the received electromagnetic wave is the electromagnetic wave leaked from the leak point of the pipe to be inspected, the electromagnetic wave is not received, but in the case of external noise, there is no change. Therefore, if the received electromagnetic waves include electromagnetic waves leaked from leaking points, the reception level decreases when excitation of the electromagnetic waves is turned off. Therefore, compare the received signal when it is off with the received signal when it is on. By doing so, it is possible to identify electromagnetic waves due to leakage.

The excitation ON / OFF on the transmitter side is performed by an operation on the receiver side, or by transmitting a signal in synchronization with the ON / OFF operation of the excitation performed on the transmitter side to the receiver side. The excitation ON-OFF state can be known on the receiving device side, and thus the above-described comparison can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 schematically shows the overall configuration of a first embodiment in which the method of the present invention is applied to the detection of a leak location in a gas pipe. Reference numeral 11 is a transmitting device, 12 is an exciting unit, and 13 is a coaxial cable that connects the transmitting device and the exciting unit 12. In this embodiment, the excitation unit 12 does not cut the gas pipe 14,
The probe 18 and the loop (not shown) are attached to the lid 17 of the opening 16 on the side of the tee 15 which is installed in advance so as to project into the tee 15. An example of a specific configuration of the excitation unit 12 will be described later with reference to FIG.

The transmitter 11 includes an oscillator, an amplifier, etc.
In addition to the basic components necessary for exciting the electromagnetic wave, an excitation ON-OFF control means 19 and a receiving means 20 for receiving an operation signal of the ON-OFF control means 19 are provided.
The ON-OFF control means 19 has an appropriate configuration such as ON-OFF of the oscillator and ON-OFF of the waveguide.

Reference numeral 21 is a receiving device, and 22 is a receiving device 21.
Is an antenna connected with the coaxial cable 23. In the receiving device 11, in addition to a basic configuration such as a detector, an amplifier, a signal processing device, and a reception level display device necessary for receiving electromagnetic waves, the ON-OFF control means 19 of the transmitting device 11 is turned ON.
A remote operation switch for OFF operation is provided, and the remote operation switch is composed of an operation switch 24 and a switch state transmission means 25. The transmitting means 25 and the receiving means 20 are shown as wireless communication means in the figure, but it goes without saying that they may be wired communication means.

In the above structure, the worker on the transmitter 11 side attaches the exciter 12 to the tee 15 provided on the extension of the gas pipe 14 which is the object of detection of the leakage point, and the exciter 12 and the transmitter 11 are installed. To connect them to the operating state. The worker on the side of the receiver 21 operates the operation switch 24 of the receiver 21.
Is operated to send an ON command from the transmission means 25 to the ON-OFF control means 19 via the reception means 20 of the transmission device 11, and the excitation of the electromagnetic wave in the excitation unit 12 is turned ON. Then, in this state, the worker moves the antenna 22 while looking at the display of the reception level on the display device of the reception device 21 to search for electromagnetic waves.

When a high reception level is detected in the search, the operation switch 24 is operated to send an OFF command to the ON-OFF control means 19 of the transmitter 11 to excite the electromagnetic wave in the exciter 12. Turn off. At this time, when the electromagnetic wave received at the time of ON includes the electromagnetic wave leaked from the leak point 26 of the gas pipe 14, the reception level is lowered as shown in FIG. On the other hand, when the electromagnetic wave received at the time of ON does not include the electromagnetic wave leaked from the leak point 26 of the gas pipe 14 and only the external noise is received, FIG.
As shown in (a), the reception level does not change even if the excitation is turned off. Therefore, by comparing the reception level at the time of OFF and the reception level at the time of ON, the electromagnetic wave due to the leakage can be identified, and the leakage point 26 can be detected by the electromagnetic wave due to the leakage. OFF and O
A worker may compare the reception levels at N hours,
Automation is also possible.

FIG. 2 schematically shows the overall construction of a second embodiment in which the method of the present invention is applied to the detection of a leak location in a gas pipe, and the same reference numerals are given to the same components as in FIG. Is attached and the description is omitted. In this embodiment, the transmitter 11
Can turn on and off the excitation of electromagnetic waves by itself.
An OFF control means 27 is provided and ON / OFF thereof
A transmission means 28 for transmitting a signal synchronized with the operation is provided. On the other hand, the receiving device is provided with receiving means 29 for receiving a signal in synchronization with the ON-OFF operation and displaying the operation state.

In the configuration of FIG. 2, on the transmitting device 11 side, the excitation is turned on at preset time intervals in the storage means or the like.
-OFF, and on the receiving device 21 side, the transmitting device 11
ON-OF of excitation by receiving the synchronization signal transmitted from the side
F status is displayed. Therefore, the worker on the receiving device 21 side
Similar to the case of FIG. 1, from the ON-OFF state of the excitation and the reception level, when a location with a high reception level is detected in the exploration, the electromagnetic wave leaked from the leakage location 26 of the gas pipe 14 to the received electromagnetic wave. Can be detected by comparing the reception level when the excitation is OFF and the reception level when the excitation is ON.

FIG. 4 specifically shows an embodiment of the exciting section 12. The same components as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. First, in FIG. 4, reference numeral 30 is a support, 31 is a lock nut, and these are connected by a screw portion 32. The screw portion 32a of the lock nut 31 is inserted inward from the mounting hole 33 formed in the center of the lid 17, and is screwed into and screwed with the screw portion 32b of the support body 30 disposed inside, so that the mounting hole 33 of the lid 17 is secured. The periphery of is held between the collar portion 34 of the lock nut 31 and the support body 30 to be in a fixed state. Prior to such screwing, the tip of the coaxial cable 13 is inserted into the lock nut 31, the center lead 35 is projected, and the braid of the shield wire 36 is clamped 37.
The washer 38 and the gasket 39 are provided on the tip side of the lock nut 31 in the above-mentioned screwing, and the expanded shield wire 36 is pressed against the inner wall of the support body 30 to be in the attached state by the above-mentioned tightening. . On the other hand, a linear probe 18 is joined to the tip side of the center lead 35, and the probe 18 is supported at the center position of the support 30 by an insulator 40. In such a configuration, the screw portion 41a of the lid 17 can be closed by screwing the screw portion 41a of the lid 17 into the screw portion 41b of the opening portion 16 on the side of the tee 15 and tightening the screw portion 41b. Located in tee 15.

In the above structure, when the transmitter 11 supplies the electromagnetic wave to the exciter 12 through the coaxial cable 13, the electromagnetic wave in the mode corresponding to the electric field generated by the probe 18 is excited in the tee 15, and the tee 15 causes the gas pipe 14 to flow.
Propagate to. Thus, the gas pipe 14 can propagate electromagnetic waves in the same mode as the circular waveguide. In the case of the figure, an electromagnetic field of TM ₀₁ mode is formed and propagates in the gas pipe 14. When the gas pipe 14 has a leaked portion 26 such as a corrosion hole, the electromagnetic wave propagating through the gas pipe 14 leaks to the outside from the leaked portion 26. Therefore, the leaked electromagnetic wave is received through the antenna 22 as described above. By receiving the data at 21, the leak point 26 can be detected.

In the above embodiment, the electromagnetic wave is excited to the gas pipe 14 by the exciting portion 12 attached to the opening 16 on the side of the tee 15.
It is also possible to perform it by an exciter which is cut and attached to No. 4.

Further, in the above embodiments, the object of inspection is a gas pipe, but the present invention can be applied to an appropriate metal pipe in addition to the gas pipe.

[0020]

As described above, according to the present invention, in an inspection method for detecting leak points such as corrosion holes formed in a gas pipe by using an electromagnetic wave, a receiving device receives an electromagnetic wave. In this case, it is possible to easily and surely identify whether it includes the one leaked from the leaking point or only the external noise, and thus to prevent the false detection of the leaking point. is there.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the overall configuration of a first embodiment in which the method of the present invention is applied to detection of a leak location in a gas pipe.

FIG. 2 is a schematic diagram of an overall configuration of a second embodiment in which the method of the present invention is applied to detection of a leak location in a gas pipe.

FIG. 3 is an explanatory diagram showing the operation of the present invention.

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

FIG. 5 is a schematic diagram showing an overall configuration of a conventional leak location detection of a gas pipe using electromagnetic waves.

[Explanation of symbols]

 1,11 Transmitter 2,12 Exciter 3,13,23 Coaxial cable 4,14 Gas pipe 5,18 Probe 6,22 Antenna 7,21 Receiver 8,26 Leakage point 15 Tee 16 Opening 17 Lid 19,27 ON-OFF control means 20,29 Receiving means 24 Operation switch 25,28 Transmission means 30 Support 31 Lock nuts 32a, 32b Screw part 33 Mounting hole 34 Collar part 35 Center lead 36 Shield wire 37 Clamp 38 Washer 39 Gasket 40 Insulator 41a, 41b screw part

Claims (3)

[Claims] 1. A method for inspecting a leaked portion of a pipe by exciting the electromagnetic wave to a pipe to be inspected by a transmitting device to propagate the inside of the pipe and receiving a leaking electromagnetic wave by a receiving device. A method of inspecting a pipe by electromagnetic waves, characterized in that electromagnetic waves due to leakage are identified by performing reception even when the signal is turned off and comparing the received signal when turned off with the received signal when turned on. 2. An electromagnetic wave excitation ON-O is provided on the transmitter side.
The FF control means is configured and the receiving device is turned ON-OF.
The method for inspecting a pipe by electromagnetic waves according to claim 1, wherein the remote control switch of the F control means is configured so that the ON-OFF control means is operated on the receiving device side. 3. On the transmitter side, ON-O for exciting electromagnetic waves
The FF control means is configured to perform ON-OFF control by itself and to transmit a signal synchronized with the ON-OFF operation to the receiving device side so that the receiving device side can detect the ON-OFF state. The method for inspecting a pipe by electromagnetic waves according to claim 1, characterized in that