JPH01105092A - Branch pipe working method and branch pipe shielding device - Google Patents

Abstract

PURPOSE: To release the block of a branch pipe smoothly by a process where the internal pressure of the branch pipe in the downstream side of the block member is made substantially equal to the internal pressure of the branch pipe in the upstream side of the block member. CONSTITUTION: When the block of a branch pipe B is to be released, the internal pressure in the upstream and downstream sides of the block member 5B is made substantially equal. Thus, when the clamping of a resilient ring-shaped member 5f by pressing plates 5c, 5d is released, there exists substantially no force derived by the pressure difference of the internal pressure of the branch pipe B pressing the pressing plates 5c in the downstream side of the resilient ring-shaped member 5f and the inner peripheral wall of the branch pipe B. In this way, it is easy for the resilient ring-shaped member 5f to deform by compensation from the reduced diameter condition generating the gap between it and the inner peripheral wall of the branch pipe B.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to, for example, a water-stop device installed in the middle of a branch pipe for a terminal device such as a fire hydrant or an air valve connected to a water main. The present invention relates to a branch pipe work method for replacing a gate valve while preventing water leakage from a branch pipe while supplying water through a water main, and a branch pipe blocking device used in the method.

More specifically, the method includes: (1) blocking the branch pipe with a gate valve interposed in the middle of the branch pipe connected to the main pipe for fluid transport; and (2) blocking the branch pipe. a step of removing the terminal device attached to the end; 3) a step of attaching a cover body to the end 4E of the branch pipe to close the end opening of the branch pipe; , <5> Slidingly operate an operating shaft that freely slides through the lid body in the axial direction in a sealed state, and an obturator provided on the inner end side of the operating shaft is installed in a portion upstream of the gate valve. 6) By moving a pair of press plates attached to the inner end of the operating shaft toward each other in the axial direction, the elastic ring-shaped body interposed between the press plates is moved in the axial direction. (7) removing the gate valve; (8) maintenance completed or new; Step of attaching the gate valve, <9> To the elastic ring-shaped body by the pressing plate -
releasing the clamping pressure to unblock the branch pipe by the obturator; <10> moving the obturator until it is housed in the lid body; <11> blocking the branch pipe with the gate valve. Thereafter, the present invention relates to a method for working with twin branch pipes, comprising the following steps: (12) opening the gate valve after installing the terminal device;

On the other hand, the device is connected to the main pipe for i-body shafting, and the downstream end of the gate valve is closed so as to close the end opening of the branch pipe with the gate valve interposed in the middle. or a lid body that can be attached to the end of a pipe portion connected thereto, and a cylindrical first body that passes through the lid body so as to be slidable in the axial direction in a sealed state.
an operating shaft, and a second operating shaft that slidably passes through the first operating shaft.
An operating shaft is provided, and separate pressing plates are attached to the inner ends of the first operating shaft and the second operating shaft, and between the pair of pressing plates, pinching pressure is applied from the axial direction by the pair of pressing plates. A branch pipe shield is provided with an elastic ring-shaped body that is elastically deformed to an enlarged diameter state in close contact with the inner peripheral wall of the branch pipe to close the gap between the inner peripheral wall and the outer peripheral portion of the pair of pressing plates. Concerning closing devices.

[Conventional technology]

When performing work on a branch pipe, such as replacing a gate valve installed in a branch pipe, conventionally, after installing a new gate valve in step 9, described above, the branch pipe is blocked with a blocker. This was done by loosening the clamping force from the axial direction on the elastic ring-shaped body of the obturator and causing it to elastically restore deformation to a reduced diameter state that creates a gap between it and the inner circumferential wall of the branch pipe (Ref. ).

[Problem that the invention seeks to solve]

However, the conventional method described above has the following problems.

In other words, when a maintained or new gate valve is installed, the differential pressure between the fluid pressure on the upstream side and the atmospheric pressure on the downstream side causes the elastic ring to move against the inner circumferential wall of the branch pipe and Because the force acts as a force pressing against the pressure plate on the downstream side, even if the pressure on the elastic ring-shaped body by the pressure plate is released, the elastic ring-shaped body will continue to press against the pressure plate on the downstream side and the branch pipe due to the differential pressure. The main pipe is pressed against the inner circumferential wall of the pipe and held in close contact with the main pipe, making it difficult to unblock the branch pipe smoothly, which can significantly reduce work efficiency, especially when fluid is being transported into the main pipe at high pressure. It was coming.

In view of the above-mentioned circumstances, it is an object of the first invention to provide a branch pipe work method that can smoothly unblock a branch pipe. An object of the present invention is to provide a branch pipe blocking device useful for use in a pipe work method.

[Means for solving problems]

The feature of the method for working on branch pipes according to the first invention is that the step of unblocking the branch pipe by the obturator after maintenance has been completed or a new gate valve has been installed is carried out on the downstream side of the obturator. a step of making the internal pressure of the branch pipe approximately equal to the internal pressure of the branch pipe upstream of the obturator; and a step of releasing the clamping pressure on the elastic ring-shaped body by the pressing plate. It is in.

[For production]

In other words, according to the branch pipe working method of the first invention, when unoccluding the branch pipe, the internal pressures on the upstream side and the downstream side of the obturator are almost the same, so that the elastic ring by the pressing plate When the clamping pressure on the ring-shaped body is released, the force caused by the pressure difference in the internal pressure of the branch pipe that presses the elastic ring-shaped body against the pressure plate on the downstream side thereof and the inner circumferential wall of the branch pipe is almost eliminated. , the elastic ring-shaped body is easily elastically restored to a reduced diameter state in which a gap is created between the elastic ring-shaped body and the inner circumferential wall of the branch pipe.

〔Effect of the invention〕

As a result, even if fluid is being transported into the main pipe under high pressure, by releasing the pressure on the elastic ring, branch pipes can be smoothly unblocked, allowing maintenance and replacement of gate valves. This makes it possible to improve the efficiency of branch pipe work.

[Means for solving problems]

A characteristic configuration of the branch pipe blocking device according to the second invention includes a pair of pressing plates for elastically deforming the elastic ring-shaped body into an enlarged diameter state in close contact with the inner circumferential wall of the branch pipe by applying pressure from the axial direction. When the clamping force applied to the elastic ring-shaped body by the pair of pressing plates becomes less than a predetermined level, fluid is released into the contact portion between the inner circumferential wall of the downstream pipe or the branch pipe and the elastic ring-shaped body. The present invention is characterized in that a flow path is formed that opens to allow passage from the upstream side of the elastic ring-shaped body to the downstream side.

[For production]

In other words, if the branch pipe delay closing device of the second invention is used, the squeezing force applied to the elastic ring-shaped body by the pair of pressing plates becomes less than a predetermined value, so that the flow path is opened and the fluid flows to the upstream side of the elastic ring-shaped body. Since the internal pressure of the branch pipe on both sides of the elastic ring-shaped body is almost the same, the elastic ring-shaped body has less hindrance in the diameter-reduced state where a gap is created between the inner peripheral wall of the branch pipe and the elastic ring-shaped body. Restore and transform.

Moreover, the equal ratio of the upstream side and the downstream side of the elastic ring-shaped body to smoothly unblock the branch pipe described above is the same as that of the pair of pressing plates originally provided in this type of device. This can be done by providing a flow path at the contact area between the inner circumferential wall of the downstream pipe or the branch pipe and the elastic ring-shaped body, so some modifications are made to these components. This can be done simply by relaxing the clamping force on the elastic ring-shaped body.

〔Effect of the invention〕

As a result, when performing maintenance or replacement of a gate valve, etc. installed in a branch pipe, by using the branch pipe delay closing device according to the second invention, it is possible to confirm that the maintenance work has been completed or to install a new gate valve, etc. Since the branch pipe can be unblocked smoothly by making the internal pressures on both sides of the elastic ring-shaped body substantially the same, the work efficiency can be improved.

Moreover, the configuration for this can be obtained by making some modifications to the parts originally included in this type of device. It is advantageous in terms of cost since it is not necessary to install large-scale equipment such as equipment, etc., and an increase in work space can be avoided. Furthermore, in order to unblock the branch pipe, there is no need for any special operation to make the internal pressure on both sides of the elastic ring almost the same other than the operation of loosening the clamping force on the elastic ring. Work can be done with the same operational feel and without the fear of forgetting an operation.

Therefore, as a whole, it has been possible to provide a branch pipe delay closing device that is excellent in terms of both operation and cost, which is used when performing work on branch pipes while continuing fluid transport.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

First, prior to explaining the branch pipe working method according to the first invention, a branch pipe delay closing device according to the second invention used therein will be explained.

As shown in Figure 3, this branch pipe delay closing device is branch-connected to the underground water main (A), and an air valve (1) is connected to the end of the branch, and an air valve (1) is connected to the middle part. Said water stop valve (
2), the pipe portion (3) on the upstream side of the water stop valve (2) of the branch pipe (B) is replaced with the water stop valve (2).
) is a device for shutting off water in a state that allows replacement of the water stopper (5) and a fixing means (6).

The branch pipe (B) has a manhole cover (B,) which is connected to the flanged T-shaped pipe of the water main (A) by a flange at the large diameter part on one end, and a manhole cover (B,) with a small diameter of Bυ. The valve box (B
and a short pipe (B,) for installing an air valve which is connected by a flange to the other end of this valve box (B2), and the upstream pipe part (3) to be water-stopped is Human hole lid (BL
) is a small diameter pipe part.

As shown in FIG. 1(0) and FIG. 2, the lid body (4) is configured to close the opening at the other end of the water stop valve (2) from which the short pipe (B3) is removed. The water stop valve (2) can be connected to the other end with a flange, and the water stop valve (5) can be housed therein.

As shown in FIGS. 1(N) and 2, the water stopper (5) has an operating shaft that extends freely through the axial center of the lid (4) in a watertight manner in the axial direction. (5A) and this operating axis (
5A) and an obturator (5B) attached to the inner end side.

The operating shaft (5A) includes a cylindrical first operating shaft (5a), and a second operating shaft (5a) that penetrates the first operating shaft (5a) in a watertight manner.
It consists of an operating shaft (5b).

The obturator (5B) has a first pressing plate (5) attached to the inner end of the first operating shaft (5a) of the operating shafts (5^).
c) and the second operating shaft (5b) of the operating shafts (5^).
) is slidably fitted onto the inner end of the second pressure plate (
5d), and by sliding the second operating shaft (5b) in the axial direction of the outer end with respect to the first operating shaft (5a), the second pressing plate (5d) is A pressing operation tool (5e) is moved closer to the first pressing plate (5a), and both pressing plates (5d) are moved closer to each other as the second pressing plate (5d) is moved closer.
5c) and (5d) from the axial direction, and the outer periphery of the reocclusion plate (5c) and (5d) and the upstream pipe portion (
3) and an elastic ring-shaped body (5f) that elastically expands in diameter so as to close the gap with the inner circumferential wall.

Both of the pressing plates (5c) and (5d) are formed to have a smaller diameter than the minimum inner diameter of the branch pipe (B) so that they can move in the axial direction within the branch pipe (B), and are elastic. Similarly, the ring-shaped body (5f) is formed to have a smaller diameter than the minimum inner diameter of the branch pipe (B) in the natural state where the pinching pressure is released. In addition, the second pressing plate (5d) has
A protrusion (5g) for preventing falling off is formed to engage and hold the elastic ring-shaped body (5f).

As shown in FIGS. 4 and 5, the elastic ring-shaped body (5f) has a plurality of notches (5x) formed along the circumferential direction on its first pressing plate (5C) side. ing. This notch (5x) forms an elastic ring-shaped body (5f) in the pinched state.
) is closed by elastic deformation, and is opened when the clamping force is below a predetermined level to form a flow path (F) that communicates both sides of this elastic ring-shaped body (5f'), which will be explained later. When replacing the water stop valve (2), replace the new water stop valve (2).
) is attached, and when the branch pipe (B) is unoccluded by the obturator (5B), it is released when the clamping force by the pair of press plates (5c) and (5d) becomes less than a predetermined level. The fluid is passed from the upstream side to the downstream side of the elastic ring-shaped body (5f), thereby making the internal pressures on both sides of the elastic ring-shaped body (5f) almost equal, and causing the elastic ring-shaped body (5f) to move naturally. This is to allow the branch pipe (B) to be smoothly and elastically restored and deformed to release the blockage of the branch pipe (B) without any trouble.

As shown in FIG. 1 (N) and FIG. 2, the fixing means (6) has the manhole cover (
An operation for the fixator (6a) in which a detachable fixator (6A) is attached to the large diameter portion of the second operating shaft (5b) and the outer end of the second operating shaft (5b) is used as the operating part (6a). Part (6
B) is incorporated into a water stopper (5).

The fixator (6A) is arranged such that the second operating shaft (5b) is connected to the first operating shaft between the other end of the second operating shaft (5b) and the second pressing plate (5d) of the obturator (5B). When the pressing operation tool (5e) is in the sliding position relative to the shaft (5a) and comes into contact with the second pressing plate (5d), it is bent into a dogleg shape and a projection (6b) formed at the middle part of the bend is bent. ) protrudes outward so as to engage with the large diameter portion of the manhole cover (131) from the axial direction, and the second operation shaft (5b) presses against the first operation shaft (5a). (5e) is in the sliding position at a predetermined distance from the second pressing plate (5d), the protrusion (6b) is positioned in a nearly straight line so that the protrusion (6b) It is constructed by interposing a plurality of links (6c) located inwardly at intervals in the circumferential direction.

In other words, the fixator (6A) is connected to the water stop edge (2) of the water stop device (5) by engaging the protrusion (6b) formed on the link (6C) with the large diameter portion of the manhole cover (B,). ) side, and the water pressure acting on the water stopper (5) causes the water stopper (5) to move towards the side.
5) from moving toward the water main (A) side, the water stopper (5) and its blocker (5B) are prevented from moving toward the water main (A) side.
It is fixed so as to be located in the small diameter pipe portion (3) of the pipe.

The second operating shaft (5b) serves as an operating tool (6B) for the fixator (6A).

Further, the branch pipe delay closing device is screwed to the outer end side of the second operating shaft (5b) of the operating shafts (5^), so that the outer end of the first operating shaft (5a) is connected to the inner end. A pinching operation nut (7) that presses the first operating shaft (5a) to the side, a first presser fitting (8) that is removably fitted near the outer end of the first operating shaft (5a), and a second operating shaft (5b). ) is removably attached to the outer end of the second presser metal fitting (9).
).

When the first presser metal fitting (8) is attached to the first operation shaft (5a), a first hook (8a) attached thereto is engaged with a protrusion (4a) formed on the lid body (4). This prevents the first operation shaft (5a) from moving outward with respect to the lid (4), and this first holding fitting (8)
The means for fixing the first operating shaft (5a) to the first operating shaft (5a) is
This is means for engaging the set bolt (11) with the circumferential groove (10) formed in (a).

When the second presser metal fitting (9) is attached to the second operating shaft (5b), a second hook (8b) attached to the first presser metal fitting (8) engages with it, so that the second presser metal fitting (9) can perform the second operation. This prevents the shaft (5b) from sliding outward with respect to the first operating shaft (5a).

In addition, the second operating shaft (5b) of the operating shafts (5A)
) is formed into a different diameter portion (12) for preventing rotation of the second operation shaft (5b), and the nut (7) for pinching operation is connected to the water stopper (5b). ) from the lid body (4) toward the inner end side.
) is formed to a size that fits within the external shape. The lid body (4) also has a water stop check port (14) that is opened and closed by a stopper (13) and releases water inside the lid body (4) in the open state.
) is formed.

Next, the branch pipe working method of the first invention will be explained step by step, taking as an example the replacement work of the water stop valve (2) using the above-mentioned branch pipe delay closing device.

<1> Close the water stop valve (2) to shut off the branch pipe (B).

<2> As shown in FIG. 1(A), remove the air valve (1), which is an example of a terminal device, from the water stop valve (2), together with the short pipe (B,).

3> As shown in Figure 1 (O), attach the lid (4) holding the water stopper (5) to the water stop valve (2) and connect it to the branch pipe (B).
Close the end opening. In this case, the water stopper (5) is attached to the first and second presser fittings (8), (9) and the second
The hook (8b) prevents the second operating shaft (5b) from sliding outward with respect to the first operating shaft (5a), and the fixator (6) is in a reduced diameter state.

<4> Open the water stop valve (2).

<5. (＞As shown in Figure 1 (G), the operation axis (5Δ)
By pressing the first operating shaft (5a), the obturator (5B) and fixator (6A) are moved to the inside of the manhole cover (B1) upstream of the water stop valve (2), and the 1 hook (8a).

<5-11> As shown in Figure 1 (d), the second hook (
8b) from the second presser metal fitting (9), remove the second presser metal fitting (9) from the second operating shaft (5b), and by applying water pressure and pulling the second operating shaft (5b), the fixator (
6A) bend the link (6c).

5-C> Figure 1 (As shown in the ladle, place the first hook (8a)
), pull up the first operation shaft (5a), and remove the water stopper (5a).
) by moving it laterally, the obturator (5
At the same time, the projection (6b) of the bent link (6c)
is engaged with the manhole cover (81) to fix the water stopper (5).

<6> As shown in Fig. 1 (f), the second operating shaft (5b)
While not rotating, screw together the nib 1-(7) for pinching operation to move the first press plate (5c) to the second press plate (5c).
d) side and clamp it to elastically deform the elastic ring-shaped body (5f) to an enlarged diameter state, and press it into close contact with the inner circumferential wall of the branch port to stop water. Thereafter, the stopper (13) is opened to allow water to be discharged from the water stop confirmation port (14), the water stop is confirmed by the water stop being released, and the first presser metal fitting (8) is removed.

7> As shown in Figure 1 (G), disconnect the water stop valve (2) from the manhole cover (B1), and push the water stop valve (5) along with the cover body (4) outward from the water stop valve (5). Take it out.

The above is the water stop valve (2) removal work, which is the first half of the branch pipe work, and the water stop valve (2), which is the second half of the branch pipe work.
Replacement and subsequent installation are the reverse of the above operations. In other words, 8> Attach a new water stop valve (2) to the lid (4), attach it to the water stop device (5), and replace the water stop valve (
After connecting 2) to the manhole cover (B,), connect the water stopper (5).
Attach the first presser metal fitting (8) to the operating shaft (5A).

The state after this step is the same as that shown in FIG.

<9-i> The internal pressure of the branch pipe (B) on the downstream side of the obturator (5B) is made approximately equal to the internal pressure of the branch pipe (B) on the upstream side of the obturator (5B). Specifically, in this step, the screwing of the nut (7) for pinching operation is slightly loosened, and the elastic ring-shaped body (5f) is formed by the pair of pressing plates (5c) and (5d).
By reducing the clamping force to a predetermined level or less, fluid is passed from the upstream side of the elastic ring-shaped body (5f) to the downstream side of the elastic ring-shaped body (5f) through the notch (5x) formed in the elastic ring-shaped body (5f). This is done by filling the inside of the branch pipe (B) on the downstream side of the shaped body (5) with fluid. By performing this step, the difference in internal pressure between the branch pipes (B) on both sides of the obturator (5B) is almost eliminated, and the elastic ring-shaped body (5
First pressing plate (5c) and branch pipe (It) for f)
Since the pressing force against the inner circumferential wall side is almost eliminated, the following <9-
The blockage of the branch pipe (B) can be smoothly released only by loosening the clamping force on the elastic ring-shaped body (5f) in step 0).

<9-111> This is carried out simultaneously with the step <9-i> above, but the nut (7) for the clamping operation is further loosened and the elastic ring-shaped body (5f) is pressed against the elastic ring-shaped body (5f) in its thickness direction. Release the clamping force on the The state after this step is the same as that shown in FIG. 1(N).

<10-a> Push down the first operating shaft (5a) and turn off the water stopper (
5) inward, the protrusion (6b) of the bent link (6c) is released from the manhole cover (Bl), and the obturator (5B) is moved to the manhole cover (B1). )
Pull it out from the small diameter pipe part (3) and attach it to the first hook (8a
) is engaged with the protrusion (4a) formed on the lid (4). The state after this step is the same as that shown in FIG. 1(d).

<1O-RO> By pushing down the second operating shaft (5b),
Extend the link (6c) of the fixator (6A), attach the second presser metal fitting (9) to the second operation shaft (5b), and
Engage the second hook (8b) with the presser metal fitting (9). The state after this step is the same as that shown in FIG. 1(c).

<10-c> Remove the first hook (8a) and remove the first operating shaft (
5a) and the obturator (5B) and fixator (6Δ
) is moved until it is accommodated in the lid body (4) downstream of the water stop valve (2).

<11> After shutting off the branch pipe (B) with the water stop valve (2) (this state is the same as the state shown in Figure 1 (0))
, disconnect the lid (4) from the water stop valve (2) and remove the lid (4) together with the water stop valve (5). The state after this step is the same as that shown in FIG. 1(A).

<12> Connect the short pipe (B3) to which the terminal device air valve (1) is attached to the water stop valve (2), and open the water stop valve (2). The state after this step is the same as that shown in FIG. In addition, at this time, the air valve (1) may be the original one, or may be a maintained or new one.

With this, the work to replace the water stop valve (2), which is an example of work on a branch pipe, is completed.

[Another example]

Hereinafter, other embodiments of the present invention will be separately listed as a branch pipe delay closing device and a branch pipe working method.

<A> Branch pipe delay closing device <A-1> In the above embodiment, the fixing device (6A) is shown as one that fixes the position by engaging the link (6c) with the manhole cover (B1). Its retaining configuration can be changed as appropriate, and as the fixator (6^), the branch pipe (B)
The position may be fixed by tension or friction on the inner circumferential surface.

<A-2> In the above embodiment, the second operating shaft (5b) of the operating shaft (5A) is used as the operating tool (6B) of the fixture (6A), but the second operating shaft (5b) is used as the operating tool (6B). It may also be one that passes through the inside of the second operating shaft (5b).

<A-3> In the above embodiment, the position of the obturator (5B) is fixed by the fixator (6A), but the fixator (6A) may be omitted.

<^-4> In the above embodiment, the elastic ring-shaped body (5f)
The notch (5 The structure can be changed as appropriate, and some examples are listed below.

(A-4-1> As shown in Figure 6, an elastic ring-shaped body (
A notch (5x) of 5f) is formed in a portion that abuts the inner circumferential wall of the branch pipe (B).

(A-4-2> As shown in Figure 7, an elastic ring-shaped body (
A notch (5f) (5x) is formed from a portion that contacts the first pressing plate (5C) to a portion that contacts the inner circumferential wall of the branch pipe (B).

<^-4-3> As shown in Figure 8, an elastic ring-shaped body (
A notch (5x) of 5r) is formed over the entire circumference in a cross-sectional view.

(A-4-4> As shown in Figure 9, an elastic ring-shaped body (
A small hole (5xx) is formed in 5f) so that the upper and lower sides thereof communicate with each other.

(A-4-5> As shown in Figure 10, the first pressing plate (
5C) with a groove (5y) formed, and an elastic ring-shaped body (5f)
When the clamping force on the elastic ring-shaped body (
5f) is removed from the groove (5y), and the groove (5y) is removed.
5y) to form a flow path (F).

(A-4-6> Notch (5) for forming flow path (F)
The number of small holes (5xx), or grooves (5y) is arbitrary, and the shape thereof can be changed as appropriate.

<A-5> In the above embodiment, the water stop valve (2) installed in the water supply branch pipe (B) was applied to stop water for replacement, but the branch pipe delayed closing of the second invention The device has branch pipes for various fluids (
It can be applied not only to late closing for replacing the valve (2) installed in the valve (B), but also to the case where the branch pipe (B) is configured internally.

<B) Method for working with branch pipes <8-1> In the previous example, the closing device (5B) is released when the clamping force against the elastic ring-shaped body (5f) becomes less than a predetermined level, and the fluid is transferred to the elastic ring-shaped body. The internal pressure of the branch pipe (B) on the upstream side and the downstream side of the obturator (5B) can be made almost equal by passing the body (5f) from the upstream side to the downstream side. In order to realize the step 9-4>, instead of that, the obturator (5B) having various configurations of the above-mentioned <A-4> may be used, or the first
As shown in FIG.
), this small hole (5
A closure (5) configured to allow passage of fluid through the closure (5)
B) may also be used.

(B-2>Although not shown, instead of the method described in the previous embodiment or the above (B-1>), a bypass flow path that communicates the upstream side and the downstream side of the obturator (5B) is provided. Branch pipe (B)
A cock is provided separately for opening and closing the bypass flow path, and when the branch pipe (B) is unoccluded by the obturator (5B), this cock is opened.
) may be made so that the internal pressures of these sections can be made approximately equal by passing the fluid from the upstream side to the downstream side.

<8-3> Furthermore, the same fluid as the fluid transported in the main pipe (A), or air, etc. that does not pose any problem when mixed with it, is added to the inside of the branch pipe (B) on the downstream side of the obturator (5B). A fluid injection device is provided to pressurize other fluids, and an obturator (
In unblocking the branch pipe (B) due to 5B),
The fluid injection device is operated to make the internal pressure of the branch pipe (B) downstream of the obturator (5B) almost equal to the internal pressure of the branch pipe (B) upstream of the obturator (5B). You may also do so.

The operation of the fluid press-in device may be configured to be performed manually, or may be configured to be performed automatically in conjunction with a decrease in the clamping force on the elastic ring-shaped body (5f). good.

<l5-4> Branch pipe downstream of the obturator (5B) (
The internal pressure of the IS) is controlled by the branch pipe (IS) upstream of the obturator (5B).
The step of making the internal pressure approximately equal to the internal pressure of B) and the step of releasing the clamping force on the elastic ring-shaped body (5f) in the thickness direction are performed simultaneously as explained in the previous example. Alternatively, either one may be performed sequentially.

<B-5> The specific configuration of the branch pipe slow-closing device used in this method can be changed as appropriate, and is similar to the above-mentioned <A-1> to <A-3>.
Although not shown, only one of the pair of press plates (5c) and (5d) may be movable.

<8-6> The terminal device may be a fire hydrant or the like in addition to the air valve (1) described in the previous embodiment, and can be changed as appropriate.

<8-7> In addition to the replacement work of the gate valve (2) explained in the previous example, the branch pipe work performed by this method includes the maintenance work of the gate valve (2), and the work of replacing the gate valve (2).
In addition to step 2), there is work such as interposing other devices into the branch pipe (B).

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the branch pipe working method and branch pipe slow closing device according to the present invention, FIGS. 3 is a sectional view of the target pipe, FIG. 4 is an enlarged sectional view of the main part, and FIG. 5 is a plan view of the elastic ring-shaped body. 6th
10 to 10 are sectional views of main parts showing another embodiment of a branch pipe delay closing device, and FIG. 11 is a sectional view of main parts of a branch pipe slow closing device showing another embodiment of a method for working with branch pipes. be. (A)... Main pipe, (B)... Branch pipe, (
1)...Terminal device, (2)...Gate valve, (4)...Lid, (5A)...Operation shaft, (5B) ... Obturator, (5a) ...
・First operation axis, (5b)...Second operation axis, <5
C), (5d)...Press plate, (5r)...
...Elastic ring-shaped body, (F) ...Flow path.

Claims (1)

[Claims] 1. <1> A gate valve (2) interposed in the middle of a branch pipe (B) branched and connected to a main pipe (A) for fluid transportation allows the branch pipe (B) to <2> step of blocking the terminal device (1) attached to the end of the branch pipe (B);
), <3> a step of attaching a lid (4) to the end of the branch pipe (B) to close the end opening of the branch pipe (B), <4> a step of removing the gate valve (2). ), <5> Sliding operation of the operating shaft (5A) that slidably passes through the lid (4) in the axial direction in a sealed state to open the operating shaft (
The obturator (5B) provided on the inner end side of the gate valve (5A)
2) moving the pair of press plates (5c) and (5d) of the obturator (5B) to the inner end side of the operating shaft (5A) to the shaft center. By approaching and moving in the direction, the elastic ring-shaped body (5f) interposed between the pressing plates (5c) and (5d) is compressed from the axial direction and tightly attached to the inner circumferential wall of the branch pipe (B). (7) removing the gate valve (2); (8) replacing the maintenance work or the new gate valve (
2) attaching step, <9> releasing the clamping pressure on the elastic ring-shaped body (5f) by the pressing plates (5c) and (5d) to release the blockage of the branch pipe (B) by the obturator (5B); <10> Moving the obturator (5B) until it is accommodated in the lid (4); <11> After blocking the branch pipe (B) with the gate valve (2), A method for working with branch pipes, comprising the steps of: removing the lid (4); <12> opening the gate valve (2) after installing the terminal device (1); The process includes <9-i> connecting a branch pipe (B) downstream of the obturator (5B);
) to approximately equal the internal pressure of the branch pipe (B) upstream of the obturator (5B), and <9-B> elasticity by the pressing plates (5c) and (5d). A method for working with branch pipes, which includes the step of releasing the clamping pressure on the ring-shaped body (5f). 2. The gate valve (2) is connected to the main pipe (A) for fluid transport so as to close the end opening of the branch pipe (B) with the gate valve (2) interposed therebetween. ) or the end of the pipe section connected thereto (4)
and a cylindrical first operating shaft (5a) that slidably passes through the lid (4) in the axial direction in a sealed state; A second operating axis (5b) is provided, and the first operating axis (5a) and the second operating axis (
Separate pressure plates (5c) and (5d) are attached to the inner end side of 5b), and the pair of pressure plates (5c) and (5d) are
d), due to the pinching pressure from the axial direction by the pair of press plates (5c) and (5d), the inner peripheral wall of the branch pipe (B) is elastically deformed to an enlarged diameter state in close contact with the inner peripheral wall of the branch pipe (B). In the branch pipe blocking device in which an elastic ring-shaped body (5f) is interposed between the outer periphery of the pair of press plates (5c) and (5d), ), (5d) located on the downstream side or at the contact portion between the inner circumferential wall of the branch pipe (B) and the elastic ring-shaped body (5f), the pair of pressing plates (5c), ( The elastic ring-shaped body (5 d)
A branch pipe blocking device forming a flow path (F) that opens so that the fluid passes from the upstream side to the downstream side of the elastic ring-shaped body (5f) when the clamping force against f) becomes less than a predetermined value. .