JPS62269034A - Detection of leak point in piping - Google Patents

Abstract

PURPOSE:To calculate the distance up to a lead point, by blocking a gas leakage inspecting section to seal inert gas therein and sucking said gas from one end of said section to form an air layer to a leak place and again introducing the inert gas under pressure to detect the air layer at the other end of the inspecting section. CONSTITUTION:The valves A-G of a leakage detecting section 1 containing a leak print P are closed and a line 2 is connected to said section 1 by utilizing an adaptor 4 and a blocking valve 12 is opened. Next, the valve A is opened and air is sent into the section 1 by a pump 3 and the valve 12 is closed to hermetically seal the air. Then, initial pressure and falling pressure after a definite time are measured by a pressure gauge 15 and the leak quantity is calculated from the leak place P. Subsequently, inert gas 14 is sent into the section 1 from an inert gas injection line 13 to substitute air. Next, the inert gas is sucked from the line 2 by the pump 3 to form an air layer X. The line 13 is again connected and the air layer X is pushed out to the side of the line 2 by the pressure of the inert gas and the concn. of oxygen is detected by an O2 sensor 6. If oxygen is detected, the distance up to the leak place P is calculated from the quantity of the inert gas sucked heretofore through a flowmeter 5.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to pipes that are buried underground or hidden with concrete, and which prevent leakage from the buried or hidden locations. The present invention relates to a method for detecting a leakage point, which is necessary when a leakage point occurs and the leakage point must be repaired.

[Prior art and its problems] For example, when a gas leak occurs from a gas pipe buried underground, this gas leaks to the surface through the soil. For this reason, the leakage point is usually found by excavating the place on the ground where the gas odor is strongest, but if the road surface is concrete or there is a structure above the gas leakage point, the gas leakage point can be found. Gas often leaks to the ground from unexpected directions, and in such cases, it is difficult to locate the leak point on the gas pipe even if the gas leak is detected on the ground using the odor or gas detector. Conventionally, even in such cases, the method of conducting trial digging in several locations and detecting the problem using an odor or gas detector, or cutting the piping system at certain sections, has been adopted. The method used is to locate leak points through airtightness inspections.

However, implementing the above method requires a lot of time and effort, and not only is it difficult to respond quickly in case of emergency, but also the piping system is completely hidden due to buildings on the gas pipe. In some cases, exploration itself may not be possible.

OBJECTS OF THE INVENTION] From this point of view, it is an object of the present invention to propose a method for detecting leakage points in piping that can accurately find leakage points in a short time with less effort.

[Configuration of the present invention] The configuration of the present invention is as follows.

The gas leakage inspection section is shut off and inert gas is filled in this inspection section, and then this inert gas is sucked from one end of the inspection section to fill a part of the inspection section with air sucked from the leakage point. A layer is created, and then an inert gas is again injected into the test section from one end to move the air layer to the other end. A method of detecting leak points in piping that measures the amount of inert gas pushed out from the pipe and divides this amount by the cross-sectional area of the pipe to find the distance from one end of the inspection section to the leak point.

A specific inspection example of the above method will be explained next.

a. First, valves are installed at both ends of a certain section of the piping that includes the gas leak point (hereinafter referred to as the "inspection section") to shut off the inspection section. However, if there is an existing cock, etc., it may be used. Furthermore, if there is a branch pipe within this inspection section, the valve at the end of this branch pipe should also be closed.

50 Next, connect the suction line to one end of the test section using an adapter.

The diameters and lengths of all the pipes in the C9 inspection section are individually input into the calculator.As a result, the total capacity of the pipes is calculated and stored in the calculator.

d. Next, pressurize air into the test section from the pneumatic feed line, check the amount of pressure drop after a certain period of time, and calculate the amount of leakage in the test section based on this data and the total capacity of the piping obtained in step C. , is automatically stored in the arithmetic unit.

e. Next, further air is forced into the inspection area to create an air atmosphere in the soil near the leakage location. The press-in amount is automatically set based on the leakage amount determined in step d. However, this method
This should not be done if the piping is exposed to the air, but should be done if the piping is underground or if the conditions near the leak point are likely to create an atmosphere of leaked gas.

f. Next, an inert gas is injected into the test section through the injection line to replace the test section with the inert gas.

g. Next, inert gas is suctioned from within the inspection section through the suction line, and air is sucked into the piping from the leak location to create an air layer within the piping.

The suction time is automatically set based on the leakage amount determined in step d.

h. Once an air layer is formed in the piping, inert gas is again pressurized into the inspection section, pushing out the inert gas from the suction line side at the other end, moving the air layer to the suction side, and removing the inert gas. Continue to detect the ugliness concentration using the 02 sensor.

i. If you detect ugliness in the inert gas, etc. that you are inhaling, check the inert gas, etc. that you have inhaled! 2 quantities are obtained, divided by the cross-sectional area of the pipe, the distance from the suction point to the leakage point is calculated by a calculator, and this is displayed on a display, for example on a liquid crystal display, or printed out.

j. If you can find the distance to the leak point,
The location on the piping is identified based on the drawings, the location is excavated to expose the leakage location, and necessary measures are taken.

[Example 1] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

Reference numeral 1 indicates an inspection section within the gas conduit that includes the leak point P, and valves A and G are attached to both ends of this section, respectively. Also, valves B, C, and
D, E, and F are attached.

Reference numeral 2 denotes a suction line having an adapter 4 at its tip for connecting to one end of the gas leakage test section 1, and a suction pump 3 attached to its rear end. In addition, the suction pump 3 of the example
It is also possible to forcefully feed air into the piping by switching a solenoid valve, and it also serves as an air pressure feeding line, but this air pressure feeding line may be provided separately.

Reference numeral 5 denotes a flow meter attached to the suction line 2 to measure the flow rate of gas flowing within the suction line 2.

02-t 6 is attached to the suction line 2 in order to measure the oxygen concentration in the gas flowing inside the suction line 2.
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12 is a cutoff valve attached to the suction line 2 to turn the suction line 2 ON and OFF. In addition, a plurality of solenoid valves are used for switching various circuits.

Reference numeral 13 is an inert gas injection line for injecting an inert gas (for example, Nz) into the gas leakage inspection section 1 from the pump 14, and is attached to the end of the inspection section 1 by an adapter.

Reference numeral 15 denotes a pressure gauge attached to the suction line 2 to detect the pressure within the leakage test section l via the suction line 2.

16 is based on the input from the flow meter 5 and the 02 sensor 6, and divides the amount of inert gas injected into the inspection section 1 from the start of suction to the time of OL detection by the cross-sectional area of the pipe. Calculates the distance from the suction point to the leak point in the pipe, calculates the amount of gas leakage, measures the pressure in the inspection section, and sends a control signal to the control valve to control the amount of pressurized air. It is a computing unit that can output data.

Reference numeral 17 denotes a display device for externally displaying the calculation results of the arithmetic unit 16. Reference numeral 18 indicates a keyboard for inputting various information to the computing unit 16.

Next, an example of the use of the two-legged embodiment will be described.

a. First, in leak test section 1, close valves A and G at both ends of the section including leakage point P, and close valve B.
, C, D, E, F close.

b. Next, connect the suction line 2 to one end of the test section 1 using the adapter 4. Note that the cutoff valve 12 is open at this time.

C9 Next, valve A is opened, and air is sent into inspection zone 1 by switching from the pump to the solenoid valve. Valve 12 is closed to seal this air, and the pressure gauge 13 measures the initial pressure after a certain period of time. Measure the pressure drop at and read the amount of leakage from the leakage point P.

d.Next, if leak inspection section 1 is hidden by underground or concrete, B, C1D, E, F, G
Open the valve and send air from the pump into inspection zone 1 to completely replace the inside of the piping with air. Then B, C, D
, E, F, and G valves are closed, and the pressure is further increased to cause air to flow out from the leakage point P to the vicinity, creating an air atmosphere near point P. Outflow amount is automatically set.

e. Next, inert gas is introduced into the leakage test section l from the inert gas injection line 13 to replace the inside of the section with inert gas.

f. Next, close the valve G, open the cutoff valve 12, suck the inert gas in the leakage test zone 1 from the suction line 2 using the suction pump 3, and create an air layer X in the leakage test zone 1. to make.

8. Once the air layer The oxygen concentration continues to be detected by the Oz sensor 6.

h, the air layer X moves to the 02 sensor 6, and the 02
When the sensor 6 detects the oxygen concentration, the calculator 6 automatically calculates the amount of inert gas sucked up to that point by the cross-sectional area of the pipe, and displays or prints out this data on the display 17. .

In addition, if there is no gas leak between A-0, the W1 element concentration will not increase, so it is determined that there is no leak between A-0, and then, for example, next between A-B, C-D, and E-F. By performing the same operations as above, the entire piping route can be checked.

From the results displayed or printed out as described above, the distance between the suction point and the leak point P can be determined, so all that is left to do is move while measuring on the line of leak inspection section 1 based on the piping drawing, and move to the specified position. If you excavate at this point, you will come across point P.

Although the embodiment has been described as a method for detecting a leakage point in a gas conduit, the present invention is also effective as a method for detecting a leakage point in a conduit other than gas, and is within the scope of the technology.

[Effects of the present invention] As described above, the present invention first seals an inert gas into a leaking pipe, then pushes this inert gas out of one end of the pipe, and removes the oxygen in the pushed out inert gas. The distance to the leak point can be calculated by dividing the amount of inert gas, etc. pushed out until the concentration begins to rise by the cross-sectional area of the pipe, so the following effects can be expected.

a. The location of the leak can be immediately identified regardless of the burial conditions.

b. Since there is no need to excavate each time, the effort required for the 2nd work is reduced.
The leakage is reduced and leaks in areas where excavation is impossible can be immediately detected.

C1 In case of leakage from indoor piping, it can be detected using existing valves, cocks, etc. without cutting the piping.

d. In combination with piping drawings, leakage locations can be accurately identified.

e. The device may be simple, does not require any special skill to transport or handle, and can be made into a device that can immediately calculate distances using a microcomputer or the like.

r. Since the inert gas injection line is connected to the terminal on the opposite side from the suction side, after sucking the air layer from the leak point into the inspection area, inject the inert gas into the pipe again and push it out with this injection pressure. Since this is possible, the suction pump only needs to be operated until an air layer is first created, and then the extrusion pressure makes it possible to move the air FX, that is, to extrude the inert gas, and the suction pump can be made into a small capacity one. It has the advantage of being able to extrude quickly and extruding quickly.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an apparatus for carrying out the method of the present invention, and FIG. 2 is a detailed explanatory diagram of the present invention. 1...Leakage inspection section, 2...Suction line, 3...Pump, 4...
··adapter. 5...Flowmeter, 6...02 sensor. 12...Shutoff valve, 13...Inert gas injection line. 14...N2 gas cylinder, 15...pressure gauge. 16... Arithmetic unit, 17... Display unit, 18
···keyboard. Figure 1 7ff

Claims (1)

[Claims] The gas leakage inspection section is shut off and inert gas is filled in this inspection section, and then this inert gas is sucked from one end of the inspection section to fill a part of the inspection section with air sucked from the leakage point. A layer is created, and then inert gas is again injected into the test section from one end to move the air layer to the other end, and then the air layer is moved into the test section until the sensor detects the air layer at the other end. A method of detecting leak points in piping that measures the amount of inert gas pushed out from the pipe and divides this amount by the cross-sectional area of the pipe to find the distance from one end of the inspection section to the leak point.