JPS61294324A - Detecting method for leakage place of piping - Google Patents

Abstract

PURPOSE:To calculate the distance from a suction place to a leakage place of inactive gas by dividing the quantity of the inactive gas which is sucked by the time the oxygen density in the inactive gas starts to rise by a sectional area of the piping. CONSTITUTION:It is assumed that there is the gas leakage place at a point P in a gas conduit 1. In this case, since the point P is unknown, respective valves B-G of the branch pipes of the gas conduit 1 are opened and the inactive gas is sealed from a line 2 into the whole piping by opening a valve A. Further, the valves A-G are closed and a valve 3 is closed and the inactive gas or the like which is sealed from the inside of the piping is sucked by a pump 4 and at the same time, the quantity of suction and the oxygen density are continued to be measured by a flowmeter 7 and an oximeter 6 respectively. When the inactive gas is sucked, since air is sucked from the point P of the leakage place into the pipe in the section, it is soon detected by the oximeter 6. When the detection is started, the quantity of the inactive gas sucked hitherto is read by the flowmeter 7 and the quantity of suction is divided by the sectional area of the gas conduit 1. As a result, the distance to the point P is given.

Description

[Detailed Description of the Invention] Field of Industrial Application The present invention is applicable to piping that is buried underground or hidden in concrete, and leakage occurs from the buried or hidden location. However, the present invention relates to a method for detecting a leakage point, which is necessary when the leakage point needs to be repaired.

ΦPrior art and its problems For example, when a gas leak occurs from a gas pipe buried underground, this gas leaks to the ground via -F. For this reason, if you excavate in the place where the gas odor is strongest on the ground, you will normally find the leakage point, but if the road surface is concrete or there is a structure above the gas leakage point, the gas will be released. Gas often leaks to the ground from unexpected directions, and in such cases, it is difficult to locate the leak on the gas pipe even if the gas leak is detected on the ground using the odor or gas detector. This is often the case.

Conventionally, even in such cases, the method of conducting trial digging in several places and detecting the leak using an odor or gas detector, or by cutting the piping system in certain sections and performing an airtightness test to locate the leak point. This method is adopted.

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

- Purpose of the present invention From this point of view, it is an object of the present invention to propose a method for detecting leak points in piping, which can accurately discover leak points in a short time with little effort.

・Structure of the present invention As a technical means to achieve the above object, the present invention seals an inert gas etc. into a leaking pipe, and then sucks in the inert gas etc. from one end and at the same time sucks the leaking pipe. Continuously measure the oxygen concentration in the inert gas, etc., and divide the amount of inert gas, etc. sucked in until the oxygen concentration starts to rise by the cross-sectional area of the pipe. We propose a method for detecting leak points in piping that calculates the distance from the suction point to the leak point.

In this way, inert gas, etc. is once sealed inside the piping, and the oxygen concentration in the inert gas, etc. is measured while being sucked, and the inert gas, etc. sucked in is measured until the oxygen concentration starts to rise. By dividing the amount by the pipe cross-sectional area, the distance from the suction point to the leak point on the pipe can be immediately calculated. Therefore, since the piping route is known, for example, in the case of buried piping, measuring the distance from the ground and excavating it will ensure that the leakage point is reached.

In addition, if the amount of leakage is small, the suction time will be longer, so in this case, by suctioning from one end to some extent,
The suction time can be shortened by creating an air layer in the piping from the leakage point and then opening the valve furthest from the primary suction point.

At this time, a layer of air moves inside the pipe.

- The embodiment diagram is a detailed explanatory diagram of the present invention, and it is assumed that there is a gas leak point at point P in the gas conduit l. In this case, point P is unknown, so first, each valve B, C of the branch pipe of gas pipe 1
, D, E, F, and G, open valve A, and fill the entire pipe with inert gas (for example, Nz) from line 2, and then , close the G valve, then close the valve 3, and use the pump 4 to suck in the inert gas sealed in the pipe from inside the pipe.At the same time, the flow meter 7
Continue to measure the amount of suction and the oxygen concentration using the oxygen meter 6.

When the inert gas or the like is sucked in this way, air is sucked into the pipe from the leak point P within one section, and this air is eventually detected by the oxygen meter 6. When the oxygen meter 6 begins to detect the amount of oxygen, the flow meter 7 reads the amount of inert gas, etc. that has been suctioned so far, and this suction amount is divided by the cross-sectional area of the gas conduit l. As a result, the distance from the measurement location to point P can be determined.

Although the above embodiment is a method for detecting a leakage point in a gas conduit, it goes without saying that the present invention can be applied to other methods for detecting a leakage point in a fluid pipe.

Effects of the Present Invention As described above, the present invention seals -U inert gas etc. into the leaking pipe, firstly sucks this inert gas etc. from one end of the pipe, and then extracts the inert gas to be sucked. Measure the amount of inert gas, etc. sucked in when the oxygen concentration in the pipe starts to rise, and calculate the distance to the leak point by dividing 1.1 of this inert gas, etc. by the cross-sectional area of the pipe. I decided to do this, so
You can expect the following effects.

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

b. Since there is no need to excavate each time, the work effort is reduced.
Time is saved and leaks in areas where excavation is not possible are immediately identified.

c. If there is a leak from the N pipe, it can be detected using existing valves, cocks, etc. without cutting the pipe.

d. In combination with piping drawings, leak points 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.

[Brief explanation of drawings]

The figure is an explanatory diagram of the present invention. l...Piping, 2...Insertion line for inert gas, etc. 3...Valve, 4...
Pump, 5... Suction line for inert gas, etc., 6
...Oxygen meter, 7...Flowmeter procedure amendment cap) October 2, 1985 Michibe Uga, Commissioner of the Patent Office 1, Indication of Case Patent Application 1988 τ137281, Invention Name of Method for Detecting Leak Points in Piping 3, Relationship with the Amendment Case Applicant Tokyo Gas Co., Ltd. 1-5-20 Kaigan, Minato-ku, Tokyo Representative Hiroshi Watanabe 4, Agent 5 Subject of amendment ( 1) Description and Claims column (2) Detailed Description of the Specification Invention column 7. □,,';'Patent Office゛・, B. Contents of amendment (1) Regarding this matter, the section of the specification and claims will be amended as shown in the attached sheet. (2) Details -) 13th from the top of page 4 - 20th line 1 of the same page
Delete 1 interval. 7. List of Attached Documents (1) Attachment 1 Attachment Fill in inert gas, etc. in the leaking pipe, then suck in the inert gas, etc. from one end, and remove the inert gas that is sucked in at the same time. Continuously measure the oxygen concentration in active gas, etc., and divide the amount of inert gas, etc. sucked in until the oxygen concentration starts to rise by the cross-sectional area of the piping. A method for detecting leak points in piping to determine the distance to the leak point.

Claims (2)

[Claims] (1) Fill the leaking pipe with inert gas, etc., then suck the sealed inert gas, etc. from one end, and at the same time as the suction, continuously measure the oxygen concentration in the inert gas, etc. Leakage in piping: calculate the distance from the suction point of inert gas, etc. to the leakage point by dividing the amount of inert gas, etc. sucked in until the oxygen concentration starts to rise by the cross-sectional area of the piping. How to detect the location. (2) In the above suction means, an air layer is created in the pipe from the leakage point by suctioning a certain amount from one end, and then the suction time is shortened by opening the valve at the farthest distance from the suction point. A method for detecting a leakage point in a pipe according to claim 1, wherein the distance is determined.