JP2000180288A - Buried pipe leakage inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid an event affecting traffic from occurring at every inspection and to provide a buried pipe leakage inspecting method easily. SOLUTION: This method is a leakage inspecting method for targeting such as a gas pipe buried underground. When a buried pipe 1 is laid down, a gas induction pipe 2 targeting a leaked gas is laid above the buried pipe 1 separated from the buried pipe 1. The gas induction pipe 2 is laid in each interval between pits 3, 4 and 5, each interval between pits 3, 4 and 5 for the underground pipe 1 is one block. Gas aspiration holes 2C are formed along the laid direction of the gas induction pipe 2 with a predetermined interval. Both ends of the gas induction pipe 2 in the laid direction are erected directed toward the pits and their terminal ends are to be inspection ends 2A and 2B for mounting a gas concentration detecting means from the ground. Gas leakage between the pits where the gas induction pipe 2 is laid is inspected by detecting gas concentration at the inspection ends 2A and 2B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a gas buried pipe for leaks, and more particularly to a method for specifying a position of a gas buried pipe where a leak has occurred from the ground.

[0002]

2. Description of the Related Art Gas pipes laid under roads are regulated (Ministerial ordinance) unless polyester pipes are used.
Requires periodic leak inspection. Conventionally, as a method of performing a leak inspection of a buried pipe, a leak location is detected, and the method is as follows. In other words, the detection holes are bored from the ground to the vicinity of the buried pipe at predetermined intervals along the laying direction of the buried pipe, and a detector equipped with a gas concentration sensor and a suction device is inserted into each of the detection holes, and the inside of each of the detection holes is inserted. The method of observing the gas concentration of the buried pipe and specifying the location of the buried pipe corresponding to the detection hole where the highest concentration is detected as the leak location is adopted. According to this method,
If a leak occurs for a long time and the leaked gas fills the whole area of the ground and the gas concentration in each detection hole increases, and even if it is not possible to detect the leak location, the gas in each detection hole is temporarily removed by the suction device. After suction, there is an advantage that the leak location can be accurately detected by newly detecting the gas concentration in each detection hole.

[0003]

However, there is the following problem in the method of boring the detection holes and detecting the gas concentration in each detection hole to detect the presence or absence of a leak and the leak location. When performing a leak inspection, it is necessary to form a detection hole by boring. Therefore, when a periodic leak inspection is performed, the traffic on the road is affected each time. Moreover, after the inspection, the detection holes must be repaired with a rubber packing material or a pavement material. Effort and time are required for forming and backfilling the detection hole, and a leak inspection cannot be easily performed.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional leak inspection method, an object of the present invention is to eliminate a situation that greatly affects traffic every time an inspection is performed and to easily detect a leak in a buried pipe. Is to provide.

[0005]

In order to achieve this object, an invention according to claim 1 is a leak inspection method for a buried pipe such as a gas pipe buried under a road surface. At the time of laying, a gas guide pipe for leaked gas is laid separately from the buried pipe above the buried pipe, and the gas guide pipe is formed between the pits with the pit for the gas conduit as one block. It is laid every time, a gas suction hole is formed at a predetermined interval along the laying direction, and both ends in the laying direction are raised toward the pit, and the terminal portion is an inspection end where gas concentration detecting means can be installed from the ground, By detecting gas concentration at the inspection end, gas leakage between pits where gas guide tubes are laid is inspected.

According to a second aspect of the present invention, in the leakage inspection method for a buried pipe according to the first aspect, the gas guide pipe is formed with a projection protruding toward a center portion inside. .

[0007] The invention described in claim 3 is claim 1 or 2.
In the leak inspection method for a buried pipe according to the above, the gas guide pipe is surrounded by a sheet near the upper surface of the buried gas pipe or the surface on the ground side, and the leak gas is easily made to enter the gas suction hole. I have.

[0008]

According to the first aspect of the present invention, the gas guide tube is buried when the gas conduit is laid. In particular, a gas guide tube is laid between pits provided for a gas conduit, and both ends in the laying direction are set up into each pit, and a terminal portion thereof is used as an inspection end. Thus, the leak location can be specified by detecting the gas concentration at the inspection end of the gas guide tube between each pit. Therefore, the gas leak location can be specified using each pit without laying a gas guide tube for detecting gas leakage at the same time as laying the gas conduit, without performing a boring operation after the laying.

According to the second aspect of the present invention, since the gas guide tube is prevented from being crushed by the projection formed on the gas guide tube buried underground, the gas taken in from the gas suction hole can be accurately detected. Can be detected.

According to the third aspect of the present invention, the gas can be easily taken in from the gas suction hole by preventing the gas from flowing toward the ground surface by the sheet member, so that the location of the gas leakage can be accurately specified.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a schematic diagram for explaining a structure used in a leak inspection method according to an embodiment of the present invention. In FIG. 1, a gas is provided near a gas conduit 1 buried under a road surface and above a gas conduit 1. A gas guide tube 2 smaller in size than the conduit 1 is laid. The gas guide pipe 2 is laid in units of one block between the pits such as the water pit 3, the valve pit 4, and the terminal pit 5 provided for the gas conduit 1. It is started up into the pit, and its terminal is
B. The inspection ends 2A and 2B are located upstream and downstream in the flow direction of the gas flowing inside the gas conduit 1.

As shown in FIG. 2, the gas guide tube 2 has an elliptical cross-sectional shape, and has a predetermined interval (indicated by a symbol L in FIG. In this embodiment, L = 5 m or less), and a gas suction hole (indicated by reference numeral 2C in FIG. 1) formed of a through hole is formed on the lower surface. 2, a plurality of projections 2D projecting toward the center are formed inside the gas guide hole 2 in the circumferential direction (the state shown in FIG. 2A) and the laying direction (the state shown in FIG. 2B). Have been. The protrusion height of the protrusion 2D is set to a height that can maintain a state in which the internal space is not closed even if the inside of the gas guide tube 2 is crushed. Projection 2
As shown in FIG. 2 (A), D is formed on opposing surfaces on the inner peripheral surface of the gas guide tube 2.
When the external force in the direction of squashing acts on the opposing surfaces of the projections 2D, the internal space is prevented from being closed.

On the outer surface of the gas suction hole 2C formed in the gas guide tube 2, a sealing material made of a material such as a highly functional separation membrane having air permeability and a property of impermeable to solids and liquids is attached. So that only gas can be taken in. In this case, the gas can be taken in by sucking the atmosphere around the gas conduit 1 underground by a suction type gas detector (not shown) connected to the inspection end.

In FIG. 1, when the gas guide pipe 2 is laid, a buried display sheet member 6 is arranged above the gas guide pipe 2 so as to display the laid position of the gas conduit 2.

This embodiment utilizes the above-described structure,
The leak inspection is performed according to the following procedure. (1) The pits 3, 4, and 5 of the laying section to be inspected are opened, and a suction type gas detector is connected to the inspection end of the gas guide tube 2 to evacuate the gas guide tube 2. Thereby, when a leak has occurred from the gas conduit 1, the leaked gas is taken in from the gas suction hole 2C of the gas guide tube 2. (2) Observing the gas concentration with the suction type gas detector with respect to the inspection ends 2A and 2B of the gas guide tube 2 exposed in each pit, respectively, so that the gas guide tubes of the laid section adjacent to each other with the pit interposed therebetween. 2 to detect the state of the gas taken into. Thus, in one pit, the laying section of the gas conduit 1 corresponding to the gas guide pipe 2 laid between the adjacent pits with respect to the flow direction of the gas flowing in the gas conduit 1 on the upstream side and the downstream side. Gas leak can be detected. (3) When gas leakage is not detected in the detection of the state of gas being taken into the gas guide pipes 2 located on the upstream and downstream sides of the pit in the gas flow direction with respect to the pit at one location Then, move to the next pit and repeat the above operation.

According to the present embodiment, only the gas guide pipe 2 for inspecting the leakage of the gas conduit is buried at the same time as the gas conduit is buried, and the drilling after the gas conduit is buried, that is, the so-called inspection hole boring work is not performed. I'm done. Moreover, even if the gas guide tube 2 is crushed by the soil pressure after the burial, the internal space of the gas guide tube 2 is maintained in a state where the middle of the laying section and the inspection end communicate with each other by the protrusion 2D. It is possible to secure a gas suction path for detecting leakage of gas.

In the above-described embodiment, an example has been described in which the sheet member 6 for indicating the embedding position is disposed above the gas guide tube 2, but the present invention is not limited to this structure. FIG. 3 shows an example in which the gas guide tube 2 is surrounded by an embedded display sheet member (indicated by reference numeral 6 'for convenience), and the so-called gas guide tube 2 is provided in a sandwich shape by the embedded display sheet member 6'. .
In FIG. 3, the periphery of the gas guide tube 2 is surrounded by a buried display sheet member 6 ′ formed in a net shape as a highly functional separation membrane as in the case shown in FIG. Some space can be formed between the embedded display sheet member 6 ′ and the outer peripheral surface of the gas conduit 2. In such a configuration, before the gas guide tube 2 is buried, the gas guide tube 2 is inserted into the buried display sheet 6 ', and then the gas guide tube 2 is buried along with the gas conduit 1 being buried. Buried. The buried gas guide tube 2
A space is formed in the peripheral portion surrounded by the buried display sheet member 6 ', and the state where the intrusion of earth and sand or water from around the buried portion is prevented is maintained. Accordingly, by detecting the gas leakage in the adjacent gas guide tubes 2 across the pits by connecting the suction type gas detectors to the inspection ends 2A and 2B of the gas guide tubes 2 exposed in the pits. With gas guide tube 2
Can be detected in the section where the gas is buried.

According to such a configuration, since the peripheral portion of the gas guide pipe 2 is surrounded by the buried display sheet member 6 ', sediment and water from the peripheral portion are not taken in.
Gas leaks can be accurately detected.

[0019]

According to the first aspect of the present invention, the gas guide tube is buried when the gas conduit is laid. In particular, a space between the gas guides is laid between pits provided for the gas conduits, and both ends in the laying direction are raised into the respective pits, and a terminal portion thereof is used as an inspection end. Thus, the leak location can be specified by detecting the gas concentration at the inspection end of the gas guide tube between each pit. As a result, it is possible to specify a gas leak location using each pit without laying a gas guide tube for detecting gas leakage at the same time as laying a gas conduit and performing boring work after laying. Since there is no interruption of traffic and the gas leakage detection structure can be constructed at the same time as the gas conduit is buried, it is possible to quickly detect gas leakage without performing boring and backfilling operations.

According to the second aspect of the present invention, since the gas guide tube is prevented from being crushed by the projection formed on the gas guide tube buried underground, the gas taken in from the gas suction hole can be prevented. Can be accurately detected.

According to the third aspect of the present invention, the gas can be easily taken in from the gas suction hole by preventing the gas from flowing toward the ground surface by the sheet member, so that the location of the gas leak can be accurately specified.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a structure for a leakage inspection method according to an embodiment of the present invention.

FIG. 2 is a view for explaining the configuration of a gas guide tube used in the structure for the leak inspection method shown in FIG. 1;
(A) is a sectional view, and (B) is a view in the laying direction.

FIG. 3 is a cross-sectional view for explaining a modified example regarding the configuration of the embedded display sheet member used in the structure shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas conduit 2 Gas guide pipe 2A, 2B Inspection end 2C Gas suction hole 2D Projection 3, 4, 5 Pits 6, 6 'Embedded display sheet

[Procedure amendment]

[Submission date] January 11, 1999 (1999.1.1)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Gas pipes laid under roads are regulated (Ministerial ordinance) unless polyethylene pipes are used.
Requires periodic leak inspection. Conventionally, as a method of performing a leak inspection of a buried pipe, a leak location is detected, and the method is as follows. In other words, the detection holes are bored from the ground to the vicinity of the buried pipe at predetermined intervals along the laying direction of the buried pipe, and a detector equipped with a gas concentration sensor and a suction device is inserted into each of the detection holes, and the inside of each of the detection holes is inserted. The method of observing the gas concentration of the buried pipe and specifying the location of the buried pipe corresponding to the detection hole where the highest concentration is detected as the leak location is adopted. According to this method,
If a leak occurs for a long time and the leaked gas fills the whole area of the ground and the gas concentration in each detection hole increases, and even if it is not possible to detect the leak location, the gas in each detection hole is temporarily removed by the suction device. After suction, there is an advantage that the leak location can be accurately detected by newly detecting the gas concentration in each detection hole.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroaki Kaneko 3-4-5 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Yotsugi Corporation Yokohama Office (72) Inventor Shoichi Iida 3-12 Muromachi, Hadano-shi, Kanagawa F-term (Reference) 2G067 AA14 BB07 CC04 DD17

Claims (3)

[Claims] 1. A leak inspection method for a buried pipe such as a gas pipe buried under a road surface, wherein when the buried pipe is laid, a leak gas is provided separately from the buried pipe above the buried pipe. The gas guide tube is laid between the pits with the pits for the gas conduit as one block, and gas suction holes are formed at predetermined intervals along the laying direction. Both ends in the laying direction are raised toward the pit, and the terminal is an inspection end where gas concentration detection means can be installed from the ground.A gas guide pipe is laid by detecting the gas concentration at the inspection end. A method for inspecting leakage of buried pipes, wherein the method inspects gas leakage between pits. 2. The method according to claim 1, wherein said gas guide tube has a protrusion protruding toward a central portion inside said gas guide tube. . 3. The method for inspecting a leak of a buried pipe according to claim 1, wherein the gas guide pipe is surrounded by a sheet member near an upper surface of the buried gas pipe or a surface on a ground side, and the leak gas is subjected to gas suction. A method for inspecting leakage of buried pipes, characterized by being easily inserted into holes.