JPS6154476B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a pipe joint part of an existing gas pipe buried underground, which is repaired to ensure sealing performance from the inner surface of the pipe while the pipe joint part is buried underground. This article relates to methods for treating branched pipes during repairs.

In recent years, various methods have been proposed for repairing existing pipes such as gas pipes, water pipes, etc. buried underground from the inside so as to regenerate the pipes from corrosion and the like while they are still buried. In particular, in the case of existing gas pipes buried underground, in which cast iron pipes are connected by water-type joints, there is a need to repair the sealing properties of the pipe joints. In other words, recently, city gas has replaced the coal gas that had been used for a long time as dry natural gas. Deterioration of sealing performance was not a particular problem because it penetrated the sealing material called "hemp skin," but in the case of dry natural gas, the sealing material dries and contracts, creating voids. Since the sealing performance deteriorates and causes gas leakage, it is necessary to ensure the sealing performance of the pipe joint and perform repairs to prevent seal deterioration in the future.

However, for existing gas pipes that have a medium diameter or small diameter, workers cannot enter the pipe and repair the inner surface of the pipe joint like they can for large diameter pipes, so it is difficult to carry out repair work. This is difficult, and a construction method that repairs the inner surface of pipe joints from the outside while underground is desired.

Therefore, we have a means for filling and moving resin between at least a pair of front and rear pigs that slide in airtight contact with the inner surface of the pipe in the existing pipe, and in this movement process, the pipe joint part is moved between the front and rear pigs. We previously proposed a method in which suction force is applied from part of the outer circumference of one pig when the pig is located at Here, first, a low-viscosity resin penetrant is impregnated into the sealing material under pressure through the gap in the joint, and then a high-viscosity resin putty is filled into the gap in the joint. In this case, when pressurizing the penetrant, air is removed from the gap in the joint by suction force, and the penetrant is replaced and impregnated into the sealing material through the gap. Further, when pressurizing the putty agent, excess penetrant is removed from the gap of the joint part by the filling pressure, and the gap is filled with the putty agent to replace it.

As a result, not only is it possible to repair the inner surface of the joint of the pipe from the outside even when it is buried, but the penetrating agent impregnated into the sealing material under pressure can cause the sealing material to dry and shrink, thereby blocking the micropores. The sealing effect is enhanced, and since the agent that penetrates into the gap in the first stage acts as a lubricant for the filling of the putty agent in the second stage, the surface of the gap at the pipe joint becomes uneven. Even on rough surfaces, the filling adhesion of the putty agent was good, and the dual airtightness of the penetrant and putty agent made it possible to achieve a repair with a high sealing effect.

In order to repair the pipe joint in the pipe in this way, negative pressure is applied in front of the first pig, which provides the suction force mentioned above, so that Negative pressure is applied to certain branch pipes (branch pipes to the main pipe, supply pipes to the branch pipes). When the pig passes over the branch pipe, the residual negative pressure inside the branch pipe draws the filling resin into the branch pipe, which later solidifies.
This causes the inconvenience of clogging the branch pipe.

In addition, if the resistance to moving the pig in the existing pipe is large, it is necessary to apply pressure from the rear of the pig by only pulling it with a towing rope and applying negative pressure to the leading pig. Even if there is no residual negative pressure in the branch pipe, resin will enter the branch pipe when the pig passes through it, and this will solidify later and block the branch pipe. An inconvenience will occur.

The present invention has been made based on the above circumstances, and when repairing the pipe joint as described above, the branch pipe has at least a resin-filled space between the pigs that is filled with the resin in the existing pipe of the branch pipe. By applying a pressure higher than the resin filling pressure while passing through the communication part, the resin is prevented from flowing into the branch pipe and the branch pipe is prevented from being blocked.This method is used in repairing the joint of an existing pipe. The present invention attempts to provide a method for treating branched pipes.

For this purpose, the present invention provides that, within the pipe of the existing pipe,
Resin is filled between at least a pair of front and rear pigs that slide in airtight contact with the inner surface of the pipe, and the resin is moved to the pipe joint by applying negative pressure to the front of the pig and positive pressure to the rear of the pig. At the same time as filling the branch pipe with resin, an air pressure exceeding the filling pressure applied to the resin is applied to the branch pipe that communicates with the existing pipe, at least while the resin filling space between the pigs passes through the part of the branch pipe that communicates with the existing pipe. It is characterized by being kept as

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In Figures 1 and 2, reference numeral 1 indicates an existing pipe that is a gas pipe buried underground, and this existing pipe 1
In this example, a long cast iron pipe is connected via a water pipe joint 2 using a conventional piping system.
This existing pipe 1 is divided into units of length suitable for repair, and a plurality of pipe joints 2 interposed within that section are repaired. Large diameter part 2a provided at the pipe end
Then, the other tube end 2b is brought into contact with each other, a sealing material 3 usually called "hemp skin" is packed into this butted fitting part, and the opening is sealed with a lead material 4. It is something.

Further, the existing pipe 1 is provided with a branch pipe 5 (for example, a supply pipe that branches into many branches in the middle of the pipe in order to guide the gas supplied through the existing pipe 1 to the gas meter of each customer's unit). In the embodiment, a small-diameter throttle 6 is provided at the end of the branch pipe 5 (the end connected to the gas meter on the ground).

Inside the existing pipe 1 to be repaired, a pair of front and rear pigs 7, 8 are introduced from one opening for repairing the pipe joint. Each of these pigs 7,8
The pig has elasticity so that it can slide in airtight contact with the inner surface of the existing pipe 1, and the rear pig 8 in the direction of movement has a cylindrical external shape.
The other front pig 7 has the rear end of the cylindrical body diagonally cut off at the top and bottom positions to form a chevron shape when viewed from the side, with the intention of providing the function described later. The cut off surface 7a
On the other hand, concave air vent grooves 9 are formed on both the left and right sides with a phase shift of 90 degrees in the circumferential direction. It extends in the axial direction of the pig 7 to a position where it overlaps the chevron-shaped cut surface 7a.

The front and rear pigs 7 and 8 are connected to each other by a connecting rope 10 at a predetermined distance from each other, and each of the pigs 7 and 8 is connected to a towing rope 11 which also serves as a length measurement and which extends forward and backward, respectively. 12 are connected. Then, in the space facing the pigs 7 and 8, a penetrating agent A made of, for example, a low viscosity resin (100 cps to 1000 cps) having hardenability such as epoxy resin is applied.
(first stage) and high viscosity resin (e.g. 100,000 cps ~
300,000 cps) and putty agent B (second stage) is filled, and penetrant A or putty agent B is filled with pigs 7 and 8.
are moved into the existing pipe 1 in the following order.

That is, in the first stage, as shown in Figure 1,
With the penetrant A filled between the pigs 7 and 8, it is moved in the direction of the arrow X within the existing pipe 1. In this movement, the pigs 7 and 8 are moved together with the penetrant A by the pulling rope 11 while applying a predetermined negative pressure (for example, -0.5 Kg/cm ² ) inside the existing pipe 1 on the front side in the moving direction. During this movement process, the air remaining in the sealing material 3 of the pipe joint portion 2 is sucked out due to the negative pressure action. On the other hand, pressurized air at a predetermined pressure (for example, +0.5 kg/cm ² ) is applied to the rear space of the rear pig 8. Therefore, a filling pressure is applied to the penetrating agent A. Then, by the movement of the pigs 7 and 8, the pipe joint 2 is determined based on the piping diagram and towing rope, or measured in advance using a video camera, magnetic sensor, etc.
When the leading pig 7 moves to the relative position shown in FIG.
8 is temporarily stopped or slowed down. At this stage, the pig 8 is already pressurized in the direction of the arrow Y, and pressure is applied to the penetrant A.
Due to the pressurizing action, the penetrating agent A, which is a low-viscosity resin, is penetrated into the sealing material 3 through the gap in the pipe joint portion 2 .

At this time, if there is an air leak in the pipe joint 2, the penetrant A penetrates by pushing out the residual air in the sealing material 3, and if there is no air leak, the penetrant A The residual air in the sealing material 3 is trapped due to pressurized infiltration. The residual air in the sealing material 3 is pushed out from the gap 13 by the pressurized infiltration of the infiltrating agent A, and is released from the gap 13 in the circumferential direction of the tube through the air vent groove 9 into the space in front of the pig 7, so that the air and infiltration are eliminated. The substitution effect of the agent A is reliably performed, and the penetrant A is deeply penetrated into the entire area of the sealing material 3.

When the impregnating action of penetrant A on one pipe joint 2 is completed, the pigs 7 and 8 are moved within the existing pipe 1 again by negative pressure in the front, pulling by the rope, and pressurization in the rear. Then, the next pipe joint portion 2 is impregnated with penetrant A in the same manner as described above.

After the impregnation action of the penetrating agent A in the first stage is completed in this way, in the second stage, as shown in FIG. 2, a high viscosity resin putty agent B is filled between the pigs 7 and 8. When this is moved into the existing pipe 1 as described above and moved to a predetermined related position, the movement is temporarily stopped or at a low speed, and the filling pressure and suction force applied to the putty agent B are used to move the material into the existing pipe 1. Joint part 2
The low-viscosity penetrant remaining in the gap 13 is removed to the front of the pig 7 via the air vent groove 9, and is replaced by the putty agent B.

Then, when the penetrating agent A and the putty agent B are positioned between the pigs 7 and 8 and the pigs 7 and 8 move within the existing pipe 1, for example in the state shown in FIG.
is previously subjected to negative pressure on the front side of the pig 7, but when the pig 7 crosses the communication point of the branch pipe 5, the pressure is applied to the rear space of the pig 8 via the throttle 6, for example, via the pressure regulating valve 14. Compressor 1 that supplies pressurized air
5. Supply pressurized air. The pressure of this pressurized air
P ₁ has a size such that at least the relationship P ₁ ≧P ₂ is maintained with respect to the filling pressure P ₂ applied to the resin between the pigs 7 and 8. In addition, the pressure P ₃ to the rear space of the pig 8 is P ₃
＞P ₁ ≧P ₂ approximately. Therefore, even if the branch communication part of the branch pipe 5 is opened between the pigs 7 and 8, the penetrating agent A or the putty agent B will not enter the branch pipe 5. 5, it is possible to completely avoid clogging with resin during this pipe joint repair work. Note that after the pig 8 passes through the branch communication section, the supply of pressurized air to the branch pipe 5 may be stopped.

In this embodiment, pressurized air may be continuously supplied to the branch pipe 5 from the beginning of the work. This is because the flow rate of air passing through the branch pipe 5 is significantly smaller than the amount of suction by the vacuum pump 16 due to the restriction 6.

The present invention has been described in detail above, and even if pressurized air is applied to a part of the branch pipe and the branch pipe opens between the pigs, the pressurized air will not resist the filling pressure of the resin. to prevent resin from entering the branch pipe.
This reliably avoids blockage of the branch pipe and allows the pipe joint to be repaired with peace of mind.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the working mode of the first stage showing an embodiment of the present invention, Fig. 2 is a longitudinal sectional view showing the working state of the second stage, and Fig. 3 is a longitudinal sectional view showing the working state of the second stage. FIG. 3 is a vertical cross-sectional view for explaining the influence. 1... Existing pipe, 2... Pipe joint part, 2a... Large diameter part, 2b... Pipe end, 3... Seal material, 4... Lead material, 5... Branch pipe, 6... Restriction, 7, 8...Pig, 7a...Resection surface, 9...Air vent groove, 10...
...Connection rope, 11, 12...Tow rope, 13
... Gap, 14 ... Pressure regulating valve, 15 ... Compressor, 16 ... Vacuum pump, A ... Penetrant, B ... Putty agent.

Claims (1)

[Claims] 1 Fill the inside of the existing pipe with resin between at least a pair of front and rear pigs that slide in airtight contact with the inner surface of the pipe, and apply negative pressure to the front of the pig and positive pressure to the rear of the pig at the pipe joint. At the same time, the pipe joint is filled with resin, and the branch pipe that communicates with the existing pipe is subjected to an air pressure that exceeds the filling pressure applied to the resin.At least, the resin filling space between the pigs is A branch pipe treatment method for repairing a pipe joint of an existing pipe, characterized in that the branch pipe is applied while passing through a communicating part.