JPH09203482A - Construction method for city gas pipe line and device used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a construction work and to enhance the working efficiency, and to dispense with the interruption of the construction work and to carry out the construction for the pipe line in a no-blow condition. SOLUTION: A pipe line 10 is blocked by a first no-blow jig 20, upstream of a constructing section of the pipe line 10, a change-over valve 70 is located in the pipe line through the intermediary of a second no-blow jig 30. In such a case that the pipe line construction is carried out while gas of the same kind as that flowing the pip line 10 charged into a gas bomb 80 through the change-over valve 70 is adjusted to a pressure of gas flowing the pipe line 10, and is then fed, the gas bomb 80 is communicated with the pipe line through the change-over valve 70, and after the completion of the construction work, the communication between the gas bomb 80 and the pipe line 10 is shut off by the change-over valve 70, and the upstream side and downstream side of the change-over valve 70, corresponding to the downstream and upstream sides of the constructing section of the pipe line communicate with each other. Then, the first and second no-blow jigs are removed so as to communicate the upstream side with the downstream side of the constructing section through the change-over valve 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a city gas pipeline, and more particularly to an uninterrupted flow that does not interrupt the flow of gas when, for example, partially replacing a city gas pipeline. In this condition, the gas does not spout to the outside.
The present invention relates to a method for constructing a city gas pipeline that enables various types of construction work to be performed in a blown state, and an apparatus used for the method.

[0002]

2. Description of the Related Art Regarding the above-mentioned construction method, for example, the prior art disclosed in Japanese Patent Laid-Open No. 63-297894 is known. In the case of this type of prior art, as a general method, as shown in FIG. 8, upstream and downstream pipelines sandwiching the pipeline construction section are perforated by a no-blowing jig, and inserted into the pipeline from here. In the state in which the pipeline is blocked by the backs a and b thus made, the upstream pipe and the downstream hole are brought into communication with each other by the bypass pipe c. After the completion of construction, the backs a and b are pulled out in a no-blowing state, the bypass pipe c between both holes is removed, and at the same time both holes are closed, so that the partial replacement work of the pipeline is not interrupted. The work is done efficiently in the flowing state and in the no-blowing state.

[0003]

However, in the case of the above-mentioned prior art, since the bypass device is provided, there are the following problems. . Work efficiency will decrease due to temporary construction of the bypass pipe c. . Maintenance and storage space for bypass pipe c is required. . A branch joint and a bypass pipe line for mounting the bypass pipe c are required, and the number of parts is increased. . The strength of the conduit will decrease due to the temporary drilling work for the bypass pipe c. . When supplying or stopping the gas by the bypass pipe c, the airtight test work in accordance with the business law shall be accompanied. . . A temporary interruption of gas occurs due to the provision of the bypass pipe c, and PR for the gas is required for the downstream demand destination.

In view of the above-mentioned problems, the present invention provides a construction method and a method thereof, which enables construction of various works for city gas pipelines without a bypass device in an uninterrupted flow state or a no-blowing state. The purpose is to provide a device for use.

[0005]

In order to achieve the above object, the present invention uses a conventionally well-known no blow jig for the inside of the upstream and downstream pipes sandwiching the construction section of the city gas pipeline. After shutting off with a gas cylinder, install a switching valve in the pipe near the shut-off position on the downstream side, using the same blower jig as well as with a gas cylinder filled with the same gas as the gas flowing through the pipe. Equipped with. Further, in the switching valve body, a first communication port that communicates the upstream side and the downstream side of the valve body, and a second communication port that communicates only with the downstream side, in a portion inserted into the pipe.
A passage for communicating the second communication port with the gas cylinder is provided, and during the construction of the pipeline, the second means is provided by the switching means of the valve body.
The communication port of the is connected to the gas cylinder, the common gas sealed in the gas cylinder is supplied to the downstream side of the valve body, and after the construction is completed, the communication with the gas cylinder is cut off by the switching operation of the valve body, and the first communication port It is characterized in that the upstream side and the downstream side of the valve body are brought into communication with each other via the pipe, and the pipe blocking means on the upstream side and the downstream side sandwiching the construction section are removed to return the pipe line to the communication state.

The present invention also relates to the above switching valve body,
The second communication port communicates with the gas cylinder at the first rotation position where the valve body is rotated, and the communication with the gas cylinder is blocked at the second rotation position, and the first communication port is upstream of the valve body. One of the other characteristics is that the switching valve body is constructed so that it can remain in the pipeline even after completion of the construction by displacing the side and the downstream side so as to communicate with each other.

Further, according to the present invention, the gas pressure of the co-gas flowing out of the cylinder is set to the gas pressure of the gas flowing through the pipeline through the plurality of pressure reducing portions, and the pressure-reduced gas is heated. It is characterized in that it is introduced into the exchange section to correct the temperature drop caused by adiabatic expansion due to depressurization, and then is circulated to the depressurization section at the next stage or the above-mentioned pipeline.

The present invention further comprises a plurality of stages of pressure reducing portions arranged between the input side and the output side, and an atmosphere contact type heat exchange portion is arranged between the pressure reducing portions. On the gas discharge side of the heat exchange unit, an emergency shutoff unit capable of shutting off the gas supply to the depressurization unit for the gas introduced into the heat exchange unit by the discharge pressure equal to or higher than a predetermined pressure is provided. The gas discharge part is characterized by being provided with a gas pressure adjusting means provided with a fuse plug for interrupting the supply of gas to the connection part side in an emergency.

In addition, the present invention is characterized in that the plurality of stages of pressure reducing units are pressure reducing valves having the input side as a primary side and the output side as a secondary side. .

[0010]

According to the construction method as described above, the upstream and downstream pipelines that sandwich the pipeline construction section are shut off, but during the construction period, the common gas sealed in the gas cylinder switches the switching valve body. By supplying the gas to the downstream side of the construction section, it is possible to perform the construction in the uninterrupted flow state without interrupting the gas flow in the pipeline to the downstream side of the construction section even without the bypass device.

Further, in the case of the uninterrupted flow treatment, means for shutting off the upstream and downstream pipes sandwiching the construction section and means for installing a switching valve element in the pipeline near the shutoff position on the downstream side are involved. Since a no-blowing jig known in the related art can be easily applied to the pipe line blocking means and the switching valve body setting means, it is possible to maintain a no-blowing state in which gas is not ejected to the outside.

As a result, it is possible to easily implement the pipeline work under the undisturbed flow condition and the no blow condition, and the bypass device which is indispensable in the conventional construction method can be omitted, resulting in a large construction cost. It is possible to reduce the work efficiency.

Further, the co-gas supplied from the gas cylinder into the pipe must be under the same use conditions as the gas used in the pipe. Therefore, in the present invention, the co-gas supplied from the gas cylinder is adjusted to the above working pressure in the process of being supplied by the gas pressure adjusting means. Moreover, since the gas pressure adjusting means can correct the temperature decrease of the gas generated at the time of pressure reduction, it is possible to secure the necessary amount of gas in the pipe while preventing thermal damage to the pipe due to the temperature decrease. it can. Furthermore, the structure of the heat exchange section used for gas temperature calibration is an atmosphere contact type structure that does not use a power source or heating source, so that the cause of ignition is eliminated and a simple gas supply can be performed safely. You can

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a method for constructing a city gas pipeline according to the present invention, in which no blow jigs 20 and 30 are mounted on the upstream side and the downstream side of the pipeline 10 across the construction section. There is.

That is, in the upstream no-blow jig 20 as the first no-blow jig, the saddle 22 mounted on the pipe line 10 by fastening the flange portion 21 with a bolt-nut (not shown), and A shutter device 23 having a shutter plate 23a attached to the upper part of the saddle 22, a bag 24 that is inserted into the conduit 10 to close the inside of the conduit, and a valve 25 that supplies air when expanding the bag 24. It is composed of.

On the other hand, in the downstream no-blow jig 30 as the second no-blow jig, the flange portion 41 is a bolt.
A saddle 40 fastened by a nut 42, and a shutter device 50 mounted on the saddle 40,
An adapter 60 that allows a gas from a gas cylinder 80 in which a co-gas of the same type as the gas in the pipe is sealed to flow into the pipe, a first communication port 75 described below that communicates only with the downstream side, and the upstream side and the downstream side communicate with each other. And a switching valve body 70 having a second communication port 76 which will be described later.

The co-gas of the same kind as the gas in the pipe from the gas cylinder 80 is decompressed by the gas pressure regulator 83 as the gas pressure adjusting means so as to have the same pressure as the gas flowing in the pipe, and the supply pipe 81 and the adapter. It is adapted to be supplied to the downstream side of the pipeline 10 via the 60, sandwiching the construction section.

FIG. 2 shows details of the downstream no-blow jig 30. A shutter device 50 is attached to an upper portion of a pedestal 43 having a hollow 44 provided in an upper portion of the saddle 40. .

A hollow body 52 of the shutter device 50 is provided with a hollow 52 having substantially the same diameter as the hollow 44 of the pedestal 43, and a shutter plate 54 having an edge portion housed in a recess 53 provides the hollow 52. The hollow 52 is closed.
Then, by pulling with the handle 55, the shutter plate 54 is pulled out from the cylindrical body 51, and the hollow 52 is opened.

On the upper part of the cylinder 51 of the shutter device 50, a cylinder 61 having a hollow 62 having a diameter substantially the same as the hollow 44 of the pedestal 43 of the adapter 60 is attached. Retracting portion 63 provided on one side of the cylindrical body 61
A supply pipe 81 from the gas cylinder 80 is connected to the gas cylinder 80, and the valve 64 is opened to open the gas cylinder 80.
The gas from the is introduced into the pipe.

The switching valve body 70 is inserted into the hollow 62 of the cylindrical body 61, the hollow 52 of the cylindrical body 51, and the hollow 44 of the pedestal 43, and the switching valve body 70 should be inserted. By these hollow 62, hollow 52 and hollow 4
4 is closed. The switching valve body 70 is provided with a cylinder body 71 in which openings 72, 73, 74 are formed. Inside the cylindrical body 71, as shown in FIGS. 3 to 5, a first communication port 75, which will be described later, which communicates only with the downstream side, and a second communication, which will be described later, that brings the upstream side and the downstream side into communication with each other. A valve body 77 having a mouth 76 is rotatably inserted therein, and is rotated by a valve body switching jig 90 as a valve body switching means shown in FIG. Also, the direction of the second communication port 76 can be changed.

Next, a method of constructing the city gas pipeline will be described with reference to FIG. First, as shown in FIG.
Saddle 2 on the upstream side and the downstream side of the pipeline 10 across the construction section
Install 0 and 30. That is, as described above, when the saddles 20 and 30 are attached, the flange portions 21 and 41 are fastened with bolts and nuts.

Next, as shown in FIG. 2B, shutter devices 23 and 50 are attached to the upper portions of the saddles 20 and 30, respectively, and a drill 102 is attached to the tip of the shaft 101 from the upper portions of the shutter devices 23 and 50. The drilling jig 100 thus prepared is mounted and a hole 11 is made in the conduit 10.
When opening the hole 11, each shutter device 23, 5
0 shutter plates 23a and 54 are closed and the drill 102 of the drilling jig 100 is mounted on the shutter devices 23 and 50, and at the same time, the shutter devices 23 and
The upper portion of 50 is closed by a closing member (not shown), and the shutter plates 23a and 54 are pulled out, so that the drill 102 can be lowered to the side of the pipeline 10 without causing gas leakage.

After opening the hole 11, at the same time when the drill 102 is pulled up, the shutter plates 23a and 54 are pushed into the shutter devices 23 and 50 to close the inside of the shutter devices 23 and 50. 1
1 is closed.

On the upstream side of the pipeline 10, the bag 2 inserted inside the pipeline 10 as shown in FIG.
4, the valve 25 is opened, air is supplied, and the back 24 is inflated to close the upstream side.

On the other hand, on the downstream side of the pipeline 10, as shown in FIG. 3C, the gas from the gas cylinder 80 is piped into the upper portion of the shutter device 50 with the shutter plate 54 of the shutter device 50 closed. The adapter 60 for allowing the gas to flow into the gas cylinder 80 is attached, and the supply pipe 81 of the gas cylinder 80 is connected to the lead-in portion 63.

Next, the switching valve body 70 is mounted from the upper portion of the adapter 60. The shutter valve 54 is opened by inserting the switching valve body 70 into the adapter 60, and then the adapter 60.
By opening the shutter plate 54 at the time when the inside is closed by the switching valve body 70, the switching valve body 70 can be lowered into the inside of the conduit 10 in a no-blowing state without gas leakage. At this time, the shutter device 50 is removed and the switching valve body 70 keeps the hole 11 closed.

However, the upstream side of the pipeline 10 is the back 24 first.
If it is blocked by, there is no gas flow to the downstream side, and therefore the switching valve body 70 should be lowered to the inside of the pipeline 10 with the shutter plate 54 opened first. You can

At this time, when the switching valve body 70 is attached, as described above, the first communication port 75 communicating only on the downstream side of the switching valve body 70 is rotated by the valve body switching jig 90 described above. It will be directed to the downstream side.

In this state, the valve 82 of the gas cylinder 80
By opening the valve 64 of the adapter 60 as well as opening the valve, the gas from the gas cylinder 80 switches the valve element 7
It passes through the first communication port 75 of 0 and flows into the downstream side of the switching valve body 70.

At this time, the gas pressure from the gas cylinder 80 is adjusted by the gas pressure regulator 83 so that the gas pressure from the gas cylinder 80 becomes the same as the gas pressure flowing in the pipe. Since the same type of co-gas as the gas in the pipe is supplied, it is possible to supply the specified gas to each customer even during the construction period. Under this condition, the pipelines in the construction section will be constructed.

After the construction of the pipeline 10 is completed, on the upstream side of the pipeline 10 where the construction section is sandwiched, air is evacuated from the bag 24 and withdrawn from the pipeline 10, and the shutter plate 23a is pushed in to remove the pipeline 10. The hole 11 is closed.

On the other hand, on the downstream side of the pipeline 10 across the construction section, the valve 82 of the gas cylinder 80 and the adapter 6 are provided.
The valve 64 of 0 is closed to stop the supply of the co-gas of the same kind as the gas from the gas cylinder 80 into the pipe.

In this state, the switching valve body 70 is rotated by the valve body switching jig 90 so that the second communication port 76 is connected to the conduit 10.
The original gas supply is restarted by directing the gas toward the upstream side and the downstream side.

Then, when carrying out backfilling work for the evacuation,
On the upstream side of the pipeline 10 across the construction section, the shutter device 23 is removed, and a plug (not shown) is screwed into the saddle 22 to close the hole 11 of the pipeline 10,
Perform backfilling of the pit. In addition, in the case of a pit, when it is not necessary to backfill like a common groove, the lid is closed to close the pit.

On the other hand, on the downstream side of the pipeline 10 across the construction section, as described above, the shutter device 50 is already removed, and the remaining saddle 40 and the switching valve body 7 are removed.
0 refills the pit while leaving it in the conduit 10 as it is. Also in this case, as described above, when the backfilling is not required, the lid is closed to close the stand.

As a result, on the downstream side of the pipeline 10 where the construction section is sandwiched, the hole 11 of the pipeline 10 is closed by the switching valve body 70 itself, so that the pipeline is not screwed into the saddle 40. It is possible to maintain 10 closed states.

As described above, in the present embodiment, the conduit 10 is
The pipe on the upstream side of the construction section is cut off using the no-blowing jig 20, and the switching valve body 70 is installed on the downstream side via the no-blowing jig 30. First communication port 75 communicating only with the downstream side of
Is in communication with the gas cylinder 80, and the same type of gas as the gas in the pipe enclosed in the gas cylinder 80 is supplied to the downstream side of the switching valve body 70, and after the construction is completed, switching is performed by the valve body switching jig 90. The valve body 70 is switched so as to disconnect the communication state with the gas cylinder 80, and is connected to the upstream side of the switching valve body 70 via the second communication port 76 that makes the upstream side and the downstream side of the switching valve body 70 in the communication state. After making the communication with the downstream side, by removing the shutter devices 23, 50,
I tried to complete the construction.

Therefore, during the construction period, the common gas sealed in the gas cylinder 80 is delivered to the downstream side of the switching valve body 70 without the need for a bypass configuration in which a bypass pipe is temporarily installed as in the conventional case. Since it can be supplied promptly, the work can be done in a short period in a no-blowing state without interrupting the gas flow to the downstream side of the work section.

Further, since the bypass form in which the bypass pipe is temporarily installed is not required, the work efficiency is improved because the temporary construction work of the bypass pipe is unnecessary, and the maintenance and storage space of the bypass pipe are also unnecessary. Furthermore, the number of parts is reduced because a branch joint for attaching the bypass pipe is not required, and it is not necessary to supply or stop the gas by temporarily installing the bypass pipe, and the airtightness test according to the business law accompanying it is not necessary. There is no need for construction, and there is no temporary interruption of gas supply when temporarily installing a bypass pipe, so there is no need to publicize it to customers.

Further, after the construction is completed, the saddle 40 and the switching valve body 70 are left in the pipeline 10 in the downstream side of the construction section of the pipeline 10.
It is also possible to maintain the pipe line 10 in the no-blowing state without performing the sealing work of the hole 11 of 0.

Furthermore, since the gas pressure of the co-gas flowing out from the gas cylinder is adjusted to the same pressure as the gas pressure in the pipeline on the downstream side of the switching valve body by the gas pressure adjusting means, each customer can The specified gas can be supplied to.

Next, an apparatus used in the above construction method will be described. FIG. 7 shows a gas cylinder 8 used in the above method.
It is a figure which shows the internal structure of the gas pressure regulator 83 (refer FIG. 1) which comprises the gas pressure regulation means for adjusting the gas pressure from 0 to the working pressure in a pipe | tube. Gas pressure regulator 83 shown in FIG.
Is characterized by including at least a plurality of pressure reducing units and a heat exchange unit arranged between the pressure reducing units. In the configuration shown in FIG. 7, two gas cylinders 80 are prepared,
The case where two supply paths are set is targeted, and the pipeline 10 via the switching valve body 70 is illustrated as a target pipeline corresponding to the pipeline in the civilian land of the general customer. In the present embodiment, the gas supply unit 111 shown in FIG. 7 has a pressure of 200 kg / cm ^{2 and} a pressure of 50 L (liter).
Used a cylinder filled with 10 Nm ³ / tube of city gas and a gas cylinder 80,80 ′ filled with 2 Lm ³ / tube of city gas in a 10 L (liter) container under a pressure of 200 kg / cm ^2. 2 systems are set (in FIG. 7, 50 L and 10 L, which are the numbers indicating the capacities of a plurality of cylinders, are attached to the plurality of cylinders). The pipes from each system are gathered at appropriate places and connected to the primary side pressure reducing unit 112. A check valve 111a is arranged in the piping of each system to prevent gas from flowing backward from an unused gas cylinder to a supplied cylinder. Further, the gas pressure in each system can be monitored by the pressure gauge 111b, and replacement work with a new cylinder and abnormality detection can be performed when the gas in the cylinder is completely supplied. When exchanging the cylinders 80, 80 ', it is necessary to shut off the gas in the system in which the cylinders 80, 80' that need to be replaced are shut off. Therefore, a manually operable on-off valve 111c is installed in the system.

In the gas supply path of the gas supplied from the gas supply section 111 in FIG. 7, when the gas supply section 111 side is the input side and the coupler 150 forming the connection with the pipe of the supply destination is the output side, In the meantime, the primary side decompression unit decompression unit 112 and the secondary side decompression unit 113 are installed along the gas supply direction. Primary-side and secondary-side pressure reducing units 112, 11
No. 3 uses regulator valves 112a and 113a, and in the primary pressure reducing unit 112, 200 Kg / cm ² which is the filling pressure of the city gas corresponding to the common gas filling the cylinders 80 and 80 'is set. 5.0 kg / cm ²
In the secondary pressure reducing section 113, the gas pressure reduced in the primary pressure reducing section 112 is reduced to 240 mmAq, which is equivalent to the pipe internal pressure at a supply destination such as a general household. Is set. In FIG. 7, the numbers attached to the primary and secondary pressure reducing portions 112 and 113 and the numbers attached to the valves described later indicate the input pressure and the output (pressure reducing) pressure, respectively.

The primary pressure reducing section 112 is provided with a relief mechanism when the pressure of the pressure-reduced gas reaches or exceeds a predetermined pressure. As the relief mechanism, a relief valve 112b composed of an angle valve arranged on the output side of the primary side pressure reducing section 112 is used, and the relief valve 112b is
5 Kg / c, which is the pressure reduced by the primary pressure reducing unit 112
When a pressure of 8 kg / cm ² , which is higher than m ² , is reached, an overpressure gas can be released to the atmosphere.

A predetermined pressure (5 Kg is applied by the primary pressure reducing unit 112.
/ Cm ² ), the secondary side decompression section 113 is arranged on the side to which the decompressed gas is supplied.
A heat exchange section 114 is arranged in front of 13. The heat exchange unit 114 is configured by connecting finned tubes that can be brought into contact with the atmosphere and that do not require a power source or heat source for heating to a predetermined length and are connected in series. The temperature of the gas whose temperature has dropped due to expansion is calibrated to the ambient temperature of the operating environment. In the configuration shown in FIG. 7, a part of the finned tube is folded back and molded to prevent the height from increasing.

The gas discharge section of the heat exchange section 114 includes:
The emergency shutoff unit 115 is connected. Emergency shutoff unit 11
5 is provided with a check valve 116, a balance valve 117, and a shutoff valve 118 which are arranged in a pipe line communicating with the gas discharge part of the heat exchange part 114. The balance valve 117 causes the shut-off valve 118 to act on the shut-off valve 118 when the pressure of the gas discharged from the heat exchange section 114 after being depressurized by the primary-side depressurizing section 112 reaches or exceeds a specified value.
The pipe opening / closing member (not shown) provided in FIG. 8 can be operated to close the pipe. Usually, the gas pressure reduced by the primary pressure reducing unit 112 is 5 kg /
7 cmg / cm ^{2 which} is higher than the gas discharge pressure in the primary side depressurization unit 112 is maintained as a specified pressure while maintaining the state in which the line opening / closing member of the shutoff valve 118 is not operated when cm ² is loaded.
When the pressure acts, the gas having the pressure is supplied to the shutoff valve 118 to operate the conduit opening / closing member. The specified pressure set in the balance valve 117 is the pressure resistance in the pipe line from the gas output part (discharge part) of the primary pressure reducing part 112 to the gas input part of the secondary pressure reducing part 113 via the heat exchange part 114. (9.9 K / cm ² ) is taken into consideration, and the secondary side pressure reduction is performed from the gas discharge part (output side) of the primary side pressure reduction part 112 including the destruction of the finned tube that constitutes the heat exchange part 114. This is to prevent breakage of the pipeline extending to the gas input portion of the portion 113. The shutoff valve 118 is used for the primary pressure reducing unit 1.
On the gas input side of the secondary pressure reducing unit 113 that acts on the balance valve 117, the switching valve is arranged in the upstream pipe line 12 and includes a pipe opening / closing member (not shown) inside. When the gas pressure in (1) reaches a specified value or more, the conduit opening / closing member is operated to close the gas supply path to the primary side pressure reducing section 112 to shut off the gas.

A part of the pipe leading to the shutoff valve 118 is branched to the emergency shutoff unit 115, and the warning member 119 and the atmosphere discharge unit 120 are connected to the branched pipeline. Although details of the warning member 119 are not shown, in the case of the present embodiment,
It has a window portion provided at the end of the pipeline, and a warning indicator is fitted inside the window portion. Normally, that is, when the pressure of the gas input to the secondary pressure reducing unit 113 is equal to or lower than the specified pressure, the warning indicator exposes the white film to the outside through the window and is input to the secondary pressure reducing unit 113. When the pressure of the gas reaches a specified pressure or higher, the gas having the pressure causes a red sphere to protrude from the white film to be exposed through the window.

The atmosphere discharge part 120 is composed of an on-off valve,
After the gas supply to the input side of the primary pressure reducing unit 112 is cut off, the gas acting on the balance valve 117 and the cutoff valve 118 is released when releasing the gas cutoff state to the primary pressure reducing unit 112. Release to the atmosphere.

On the other hand, the piping of the gas discharged from the heat exchange section 114 is branched into a path toward the secondary pressure reducing section 113 in addition to the path toward the emergency shutoff section 115 described above. The secondary side depressurization unit 113 is a regulator valve 113a capable of releasing a predetermined pressure (5 Kg / cm ² ) depressurized by the primary side depressurization unit 112 as a specified pressure and shutting off the pipeline at a pressure higher than that. It is configured. The secondary-side pressure reducing unit 113 is provided to reduce the pressure of the gas reduced by the primary-side pressure reducing unit 112 to the supply pressure at a supply destination such as a general household, and the side on which the reduced pressure gas is discharged is provided. A relief valve 121 for maintaining the pressure of the depressurized gas is arranged. The relief valve 121 has a pressure (420 m) at which the discharge pressure of the gas depressurized by the secondary pressure reducing unit 113 is higher than a predetermined depressurizing pressure of 240 mmAq.
When the pressure reaches (mAq), excess gas is released to the atmosphere, and when the pressure reaches a pressure higher than that value and, conversely, a pressure lower than 150 mmAq, the gas is shut off. The relief valve 121 has a function of releasing and shutting off to the atmosphere to prevent the pressure reducing function from being obtained when the secondary side pressure reducing unit 113 is damaged, thereby preventing the gas pressure from rising abnormally. This is for stopping the supply when an abnormal decrease in the pressure in 80 'or an abnormal situation in the pipeline of the supply path occurs.

A fuse plug 122 is connected to the gas discharge portion of the secondary side pressure reducing portion 113. Fuse stopper 122
Is equipped with an on-off valve that is provided to prevent a secondary disaster from occurring if the raw gas blows out as it is in the event of an emergency when the connection part comes out, or is disconnected. The pressure of the gas discharged from 113 is 6 m ³ /
The gas outlet side pipe line can be cut off when the time reaches h. The fuse stopper 122 is provided with an opening / closing valve 122a corresponding to an outlet valve.
Is closed when the output side pipeline is closed by the fuse plug 122, and is closed again after the gas is released to the atmosphere at the atmospheric release section in the supply path reaching the output side.

The gas pressure regulator 83 having the above structure can be carried by being mounted on a truck or the like together with the gas cylinders 80, 80 ', and can be transported to the switching valve body 70 (see FIG. 1). Connected).

When supplying gas, the gas pressure regulator 83
Then, the pressure in the cylinders 80, 80 'was confirmed by the pressure gauge 111b provided in the gas supply unit 111, and if the pressure was usable, one of the on-off valves 111c was opened and further indicated by reference numeral 122a in FIG. The on-off valve corresponding to the outlet valve is opened. When the on-off valve 111c is opened, gas is supplied from the selected cylinder 80 (80 ') to the input side of the gas pressure regulator 83.

In the gas pressure regulator 83, the cylinder 80 (8
The gas discharged from 0 ') is supplied to the primary pressure reducing unit 112, and the pressure in the cylinder 80 (80') is 200K.
The pressure is reduced from g / cm ² to 5 Kg / cm ² . Although the temperature of the depressurized gas has dropped due to adiabatic expansion that occurs during depressurization, it passes through the heat exchange section 114, is calibrated to the ambient temperature of the environment in which it is used, and is supplied toward the secondary side depressurization section 113.

Since the heat exchange section 114 has an atmosphere contact structure which does not require a power source or a heat source for increasing the temperature of the gas whose temperature is decreasing, it does not have a factor to ignite the supplied gas. Therefore, it is possible to ensure safety in handling the gas. Heat exchange section 114
The gas that passes through is prevented from passing through the pipeline with the temperature lowered by adiabatic expansion due to the temperature correction, which prevents the damage of the equipment due to the temperature decrease and supplies the necessary gas. The quantity is secured.

On the other hand, the pressure of the gas depressurized by the primary depressurization unit 112 becomes higher than 5 Kg / cm ² and becomes 7 K.
When g / cm ² is reached, the emergency cutoff unit 115 closes the input side pipe line connected to the primary pressure reduction unit 112 to cut off gas. That is, the pressure of the gas supplied from the primary pressure reducing unit 112 to the secondary pressure reducing unit 113 is 5
When it is Kg / cm ² or more, the secondary side decompression unit 113
When the pressure of the gas input to reaches the specified value or more, the emergency shutoff unit 115 is activated. In the emergency shutoff unit 115, when a gas pressure higher than a specified pressure acts on the balance valve 117, the equilibrium state up to that point is broken and the conduit opening / closing member of the shutoff valve 118 is actuated, whereby the gas to the primary pressure reducing unit 112 is discharged. The input side line of is closed. Further, at this time, since the warning indicator in the warning member 119 exposes the red sphere through the window, it can be easily confirmed from the outside that the emergency shutoff unit 115 is operating. In this way, in the pipeline until the gas discharged from the primary pressure reducing unit 112 is input to the secondary pressure reducing unit 113,
When a pressure that affects the pressure resistance of the components of the pipeline is generated, the gas supply is cut off in the pipeline, so the pipeline from the primary pressure reducing section to the secondary pressure reducing section is damaged in advance. This can be avoided, and the state can be easily confirmed from the outside.

The gas depressurized to a predetermined pressure of 5 Kg / cm ² in the primary depressurization unit 112 is supplied to the secondary depressurization unit 113 only when it is at the specified depressurization pressure, and the working pressure at the supply destination is increased. The pressure is reduced to a certain 240 mmAq. In the secondary pressure reducing unit 113, the input gas pressure is 5 Kg / c.
When the pressure becomes higher than m ² , the gas at that pressure
15 and when the pressure of the gas depressurized by the secondary depressurization unit 113 reaches 420 mmAq, excess pressure is released to the atmosphere via the relief valve 121. Further, when the pressure of the depressurized gas becomes higher than 420 mmAq and lower than 150 mmAq, the relief valve 121 is closed and the atmospheric release of the gas is stopped.
As a result, the depressurized gas has the fuse plug 12 only when the depressurized pressure is maintained at the prescribed depressurized pressure.
2 will be supplied.

The gas whose final pressure is set at the supply destination by the secondary pressure reducing unit 113 is supplied to the supply destination through the fuse plug 122. When the flow rate of the gas depressurized by the secondary depressurization unit 113 has reached a predetermined value (6 m ³ / h) or more, the gas outlet side pipeline is closed by the fuse plug 122 to cut off the gas supply. To be done. As a result, in the event of an emergency such as disconnection of the connecting portion, the secondary side pressure reducing portion 1
It is possible to prevent the raw gas supplied from 13 from being blown out so as not to cause a secondary disaster which may occur when the raw gas is jetted out.

The gas pressure regulator 83 shown in FIG.
Although the two pressure reducing sections, the primary side and the secondary side, are provided, it goes without saying that the number of pressure reducing steps is not limited to this. For example,
By increasing the number of pressure reduction stages, the gas with a pressure obtained in the middle of the pressure reduction stage flows through a pipeline that corresponds to the construction section, for example, a gas with a higher pressure than the service pipes that are piped to the general customer mentioned above. It is also possible to supply it to a medium-pressure conduit that is open.

[0060]

As described above, according to the method for constructing a city gas pipeline of the present invention, during construction, it is not necessary to temporarily install a bypass pipe as in the conventional case. , The co-gas enclosed in the gas cylinder can be promptly supplied to the downstream side of the switching valve, and the short-term pipe can be installed in the no-blowing state without interrupting the gas flow to the downstream side of the construction section. It can be carried out.

After the construction is completed, the second no-blow jig excluding the shutter device and the switching valve body are left in the pipe line, so that the pipe can be closed without the need to seal the hole formed in the pipe line. It is possible to maintain the no-blow condition of the road.

Further, since the gas pressure of the co-gas flowing out from the gas cylinder is adjusted to the same pressure as the gas pressure in the pipeline on the downstream side of the switching valve body by the gas pressure adjusting means, it is possible to meet each demand destination. It is possible to supply the specified gas. Therefore, the work can be simplified, the work efficiency can be improved, the interruption of the gas supply can be eliminated, and the pipeline work can be performed in the no-blow state.

On the other hand, according to the city gas pipeline construction apparatus of the present invention, the switching valve is constructed by reducing the gas pressure supplied to the downstream side of the switching valve body from the pressure of the gas sealed in the gas cylinder. Gas pressure can be adjusted in the conduit downstream of the body. Moreover, since the temperature drop of the gas generated during depressurization can be corrected to the ambient temperature by the heat exchange section, the piping system and various valves equipped in the gas pressure adjusting means can be prevented from being thermally damaged while being protected from the pipeline. It is possible to supply gas with the same pressure as the gas inside to the pipeline in the construction section. Moreover, since the structure of the heat exchange section does not use a power source, a heat source, or the like, it is possible to supply the gas in a safe state without causing ignition of the supplied gas.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a method for constructing a city gas pipeline of the present invention.

FIG. 2 is a cross-sectional view showing details of a no-blow jig on the downstream side of the construction section of the pipeline of FIG.

3 is a cross-sectional view taken along the line AA showing the switching valve body of FIG.

FIG. 4 is a sectional view taken along line BB showing the switching valve body of FIG.

5 is a cross-sectional view taken along line CC of the switching valve body of FIG.

FIG. 6 is a diagram for explaining a method of constructing the city gas pipeline of FIG.

FIG. 7 is a diagram for explaining the configuration of an apparatus used for the construction shown in FIG.

FIG. 8 is a diagram for explaining a conventional method of constructing a city gas pipeline.

[Explanation of symbols]

 10 Pipes 20, 30 No blow jig 23a, 54 Shutter plate 23, 50 Shutter device 24 Back 40 Saddle 60 Adapter 70 Switching valve body 75 First communication port 76 Second communication port 80, 80 'Gas cylinder 83 Gas pressure adjustment Device 112 Primary pressure reducing unit 113 Secondary pressure reducing unit 114 Heat exchange unit 115 Emergency shutoff unit 117 Balance valve 118 Shutoff valve 119 Warning member 122 Fuse plug

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[Procedure amendment]

[Submission date] December 13, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

[Fig. 2]

[Figure 3]

FIG. 4

[Figure 5]

FIG. 6

FIG. 7

[Figure 8]

Claims (6)

[Claims] 1. The upstream side of the construction section of the city gas pipeline,
After shutting the inside of the pipe on the downstream side with a conventionally known no-blowing jig, the switching valve body also installed with the no-blowing jig on the pipe line near the shut-off position on the downstream side, and the inside of the pipe line A gas cylinder filled with a co-gas of the same kind as the gas for flowing the gas, the switching valve body having a first communication port for communicating the upstream side and the downstream side of the valve body with a portion inserted into the pipe. , A second communication port that communicates only with the downstream side, and a passage that connects the second communication port with the gas cylinder. During the construction of the pipeline, the second communication port is connected by the valve body switching means. Supply the common gas enclosed in the gas cylinder to the downstream side of the valve body with the mouth in communication with the gas cylinder, and after the completion of construction, disconnect the communication with the gas cylinder by switching the valve body and through the first communication port. The upstream side and the downstream side of the valve body to communicate with each other, and Construction method for city gas pipe, characterized in that to return the free upstream and downstream Remove the tube blocking means conduit in communication with. 2. The switching valve body has a second communication port communicating with a gas cylinder through a passage in a first rotation position where the valve body is rotated, and a second communication port communicates with the gas cylinder in a second rotation position. The communication is cut off, and the first communication port is displaced so that the upstream side and the downstream side of the valve body communicate with each other, and the switching valve body is constructed so that it can remain in the pipeline even after the completion of construction. The method for constructing a city gas pipeline according to claim 1. 3. The gas outlet path of the gas cylinder includes:
The means for adjusting the gas pressure of the co-gas flowing out of the cylinder to the same pressure as the gas pressure of the gas flowing through the pipe line on the downstream side of the switching valve body. Construction method for city gas pipelines in Japan. 4. The gas pressure of the co-gas flowing out of the cylinder is set to the gas pressure of the gas flowing through the pipeline through a plurality of depressurization units, and the depressurized gas is introduced into the heat exchange unit. 4. The method for constructing a city gas pipeline according to claim 3, wherein the temperature reduction caused by the adiabatic expansion due to the pressure reduction is corrected and then the gas is circulated to the next-stage decompression section or the pipeline. 5. The apparatus used in the method for constructing a city gas pipeline according to claim 4, comprising a plurality of pressure reducing sections arranged between the input side and the output side. An atmosphere contact type heat exchange part is arranged between the parts, and a decompression part for the gas introduced into the heat exchange part by a discharge pressure higher than a predetermined pressure is provided on the gas discharge side of the heat exchange part. Is equipped with an emergency shutoff unit capable of shutting off the gas supply, and the gas discharge unit of the final stage depressurization unit is provided with gas pressure adjusting means provided with a fuse plug for shutting off the gas supply to the connection unit side in an emergency. Equipment for city gas pipeline construction characterized by 6. The city according to claim 5, wherein the plurality of stages of pressure reducing units are configured by pressure reducing valves having the input side as a primary side and the output side as a secondary side. Equipment for gas pipeline construction.