JPH08261865A - Method and apparatus for leak inspection of gas pipe - Google Patents

Abstract

PURPOSE: To enhance the detection sensitivity of gas leakage when a nail or the like is driven into a gas pipe. CONSTITUTION: A flow passage changeover valve 27 is set in such a way that a pipe 22 communicates with a pipe 26. In this state, a pump 22 is operated, and a pressure inside a gas pipe 10 is raised up to a prescribed pressure. The flow passage changeover valve 27 is changed over in such a way that a pipe 29 communicates with the pipe 26. While an average pressure inside the gas pipe 10 is held at the prescribed pressure, the pressure change which is generated by the pump 22 is given to the gas pipe 10. After that, the pump 22 is stopped, and the pressure inside the gas pipe 10 is monitored by a pressure gage 24. When the pressure is lowered, it is judged that gas leakage has been generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas pipe leakage inspection method and apparatus for inspecting a gas pipe for the presence or absence of gas leakage.

[0002]

2. Description of the Related Art As shown in FIG. 2, in the conventional inspection for gas leakage in a gas pipe, after completion of construction of the gas pipe 101, after closing the end of the gas pipe 101 with a valve 102 on the downstream side of the gas pipe 101. A gas such as air is sent into the gas pipe 101 by the pressurizing pump 103 to pressurize it, then the valve 104 on the upstream side of the gas pipe 101 is closed, and a pressure gauge 105 provided in the middle of the gas pipe 101 pressurizes the gas for a predetermined time. Was monitored and it was judged that there was a gas leak when the pressure dropped.

By the way, as the gas pipe 101 installed in the wall of the building, for example, a flexible pipe 101a which is a flexible steel pipe as shown in FIG. 3 is used, and the flexible pipe 101a is flexible. Tube 101a
A cover cover 111 made of vinyl or the like is attached for the purpose of surface protection and improvement of appearance.

[0004]

However, as shown in FIG. 3, since the flexible pipe 101a is installed inside the wall 112 of the building, shelves, electric appliances, etc. are installed on the wall 112 in the subsequent construction of the building. At the time of mounting, the nail 113 or the like may be driven into the flexible tube 101a in the wall 112. In this case, if the gap between the flexible tube 101a and the nail 113 or the like is small, the amount of gas leakage is so small that it is difficult to determine whether or not there is a gas leakage in the conventional gas leakage inspection.

The present invention has been made in view of the above problems, and an object thereof is a gas pipe leakage inspection method capable of improving detection sensitivity of gas leakage when a nail or the like is driven into the gas pipe. And to provide a device.

[0006]

A gas pipe leakage inspection method according to claim 1, wherein the pressure inside the gas pipe is increased to a predetermined pressure, and then the pressure is changed in the gas pipe, and the pressure change is stopped. After that, the pressure in the pipe is monitored, and if there is a pressure drop, it is determined that there is a gas leak.

In this gas pipe leakage inspection method, the pressure variation in the gas pipe changes the gap between the gas pipe and the nail or the like to increase the amount of gas leakage and improve the gas leakage detection sensitivity. .

A gas pipe leakage inspection device according to claim 2 is
After increasing the pressure in the gas pipe to a predetermined pressure by the pressure increasing means for increasing the pressure in the gas pipe to a predetermined pressure,
A pressure fluctuation applying means for applying a pressure fluctuation in the gas pipe, and a pressure for monitoring the pressure in the gas piping in order to detect a pressure drop due to a gas leak after stopping the pressure fluctuation by the pressure fluctuation applying means. And a monitoring means.

In this gas pipe leakage inspection device, after the pressure inside the gas pipe is increased to a predetermined pressure by the pressure increasing means, the pressure variation applying means causes the pressure variation in the gas piping, and the pressure variation is stopped. After that, the pressure in the gas pipe is monitored by the pressure monitoring means, and the pressure drop due to the gas leakage is detected. By giving a pressure fluctuation in the gas pipe, the gap between the gas pipe and the nail or the like changes, the amount of gas leakage increases, and the detection sensitivity of gas leakage is improved.

The gas pipe leakage inspection device according to claim 3 is
The gas pipe leakage inspection apparatus according to claim 2 further comprises pressure fluctuation frequency control means for controlling the frequency of pressure fluctuations given by the pressure fluctuation applying means.

In this gas pipe leakage inspection apparatus, the pressure fluctuation frequency control means controls the frequency of pressure fluctuations to resonate the gas piping, thereby making it possible to change the gap between the gas piping and the nail or the like to a greater extent. The detection sensitivity of gas leakage is further improved.

The gas pipe leakage inspection device according to claim 4 is
The gas pipe leakage inspection apparatus according to claim 2 or 3, further comprising a pressure fluctuation width adjusting means for adjusting the width of the pressure fluctuation applied by the pressure fluctuation applying means, so that the width of the pressure fluctuation can be adjusted.

A gas pipe leakage inspection device according to claim 5 is
The gas pipe leakage inspection device according to any one of claims 2 to 4, further comprising flow rate detection means for detecting a flow rate associated with gas leakage in the gas pipe, so that the gas leakage amount can be detected.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the structure of a gas pipe leakage inspection apparatus according to an embodiment of the present invention. The gas pipe 10 in which the gas pipe leakage inspection apparatus according to the present embodiment is used is, for example, a flexible pipe which is a steel pipe having flexibility as shown in FIG. 3, and this flexible pipe includes surface protection for the flexible pipe. In order to improve the appearance, a cover cover 11 made of vinyl or the like is attached. This gas pipe 10 is installed, for example, inside a wall of a building, a valve 12 arranged inside the building is provided on the downstream side of the gas pipe 10, and outside the building on the upstream side of the gas pipe 10. Valve 1
3 is provided.

The gas pipe leakage inspection apparatus according to this embodiment is
A pipe 21 connected to the upstream side of the valve 13 is provided. Tube 2
A discharge port of a pump 22 as a pressure increasing means and a pressure fluctuation applying means is connected to the upstream end of 1. In the middle of the pipe 21, a pressure fluctuation range adjusting valve 23 as a pressure fluctuation range controlling means, a pressure gauge 24 as a pressure monitoring means, and a flow meter 25 as a flow rate detecting means are provided in this order from the pump 22 side. ing. A pipe 26 is connected to the suction port of the pump 22, and an outlet of a flow path switching valve 27 is connected to the upstream end of the pipe 26. A pipe 28 is connected to one inlet of the flow path switching valve 27. One end of a pipe 29 is connected to the other inlet of the flow path switching valve 27, and the other end of the pipe 29 is connected to the middle of the pipe 21 between the pressure fluctuation width adjusting valve 23 and the pump 22. As the pump 22, a pump whose discharge pressure changes, such as a reciprocating pump using a piston or a diaphragm, is used. A pressure fluctuation frequency control device 30 that controls the frequency of pressure fluctuations by controlling the frequency of reciprocation of the pump 22 is connected to the pump 22.

Next, a gas pipe leakage inspection method using the gas pipe leakage inspection device according to this embodiment will be described. First, after the construction of the gas pipe 10, as shown in FIG.
The pipe 21 is connected to the upstream side of 3, the valve 12 is closed, and the valve 13 is opened. Further, the flow path switching valve 27 is set so that the pipe 28 and the pipe 26 communicate with each other. In this state, the pump 22 is operated to send a gas such as air sucked through the pipes 28 and 26 to the gas pipe 10 through the pipe 21, and while watching the pressure gauge 24, the inside of the gas pipe 10 is predetermined. Boost to pressure.
Next, the flow path switching valve 27 is switched so that the pipe 29 and the pipe 26 communicate with each other. As a result, the gas is circulated by the pump 22 between the part of the pipe 21, the pipe 29, and the pipe 26, and the pressure generated by the pump 22 is maintained while the average pressure in the gas pipe 10 is maintained at a predetermined pressure. Fluctuations are applied to the gas pipe 10. At this time, the frequency of pressure fluctuation is controlled by the pressure fluctuation frequency control device 30, and the width of pressure fluctuation is adjusted by the pressure fluctuation width adjusting valve 23. After that, the pump 22 is stopped to stop the pressure fluctuation in the gas pipe 10, and the gas pipe 10 is operated by the pressure gauge 24.
Monitor the pressure inside. Then, if the pressure is lower than the predetermined pressure at the time of the first pressurization, it is determined that there is gas leakage. Moreover, the amount of gas leakage is measured by the flow meter 25.

As described above, according to this embodiment, when a nail or the like is driven into the gas pipe 10, the pressure between the gas pipe 10 is changed to change the clearance between the gas pipe 10 and the nail or the like. As a result, the amount of gas leakage increases, and the gas leakage detection sensitivity is improved. Further, by controlling the frequency of the pressure fluctuation and causing the gas pipe 10 to resonate, the gap between the gas pipe 10 and the nail or the like can be changed more greatly, and the gas leak detection sensitivity is further improved. Further, according to this embodiment, the gas leak amount can be measured by the flow meter 25.

[0019]

As described above, the gas pipe leakage inspection method according to claim 1 or any one of claims 2 to 5
According to the gas pipe leakage inspection device described in (1), by changing the pressure in the gas pipe, the gap between the gas pipe and the nail or the like can be changed to increase the amount of gas leakage. There is an effect that it is possible to improve the detection sensitivity of the gas leakage in the case of driving.

According to the gas pipe leakage inspection device of the third aspect, in addition to the above effect, the frequency of the pressure fluctuation is controlled to resonate the gas pipe, so that the gap between the gas pipe and the nail or the like is further improved. It is possible to make a big change,
There is an effect that the detection sensitivity of gas leakage can be further improved.

According to the gas pipe leakage inspection device of the fifth aspect, in addition to the above-mentioned effects, there is an effect that the gas leakage amount can be detected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a gas pipe leakage inspection device according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a conventional method for inspecting gas leakage in a gas pipe.

FIG. 3 is a cross-sectional view showing a state where a nail is driven into the gas pipe.

[Explanation of symbols]

 10 Gas Pipes 12, 13 Valves 21, 26, 28, 29 Pipes 22 Pumps 23 Pressure Fluctuation Width Adjustment Valves 24 Pressure Gauges 25 Flow Meters 27 Flow Path Switching Valves 30 Pressure Fluctuation Frequency Control Devices

Claims (5)

[Claims] 1. The pressure in the gas pipe is increased to a predetermined pressure, and thereafter, the pressure in the gas pipe is changed, and after the pressure change is stopped, the pressure in the pipe is monitored and there is a pressure drop. A gas pipe leakage inspection method characterized by determining that there is a gas leak. 2. A pressure increasing means for increasing the pressure in the gas pipe to a predetermined pressure, and a pressure fluctuation applying means for increasing the pressure in the gas pipe by the pressure increasing means to change the pressure in the gas pipe. A gas pipe leakage inspection, comprising: a pressure monitoring device for monitoring the pressure in the gas pipe to detect the pressure drop due to the gas leakage after stopping the pressure fluctuation by the pressure fluctuation applying device. apparatus. 3. The gas pipe leakage inspection apparatus according to claim 2, further comprising pressure fluctuation frequency control means for controlling the frequency of pressure fluctuations given by the pressure fluctuation applying means. 4. The gas pipe leakage inspection device according to claim 2, further comprising a pressure fluctuation width adjusting means for adjusting a width of pressure fluctuation given by the pressure fluctuation applying means. 5. The gas pipe leakage inspection apparatus according to claim 2, further comprising a flow rate detection unit that detects a flow rate associated with a gas leak in the gas pipe.