JPH0225079B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for repairing the inner surface of an existing gas pipe, which is used when repairing the inner surface of an existing gas pipe that is mainly buried underground. .

[Conventional technology]

In recent years, various methods have been proposed for repairing existing gas pipes buried underground from the inside so as to restore 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, and in the case of conventional coal gas, tar components in the gas are removed by Deterioration of sealing performance was not a particular problem because it penetrated into the sealing material called "skin," but in the case of dry natural gas, the sealing material dries and contracts, creating voids and causing the seal to deteriorate. Since the sealing performance of the pipe joint deteriorates and causes gas leakage, it is necessary to ensure the sealing performance of the pipe joint and perform repairs to prevent the sealing performance from deteriorating 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. Therefore, there is a need for a construction method that repairs the inner surface of the joint of the pipe from outside the pipe while it is buried.

Therefore, we have a means for filling and moving resin between at least a pair of front and rear pigs that are pulled by a tow rope and slide in airtight contact with the inner surface of the pipe in the existing pipe. When the pipe is located between the front and rear pigs, a suction force is applied from the front of the outer circumference of one pig, and pressurized air is applied to the rear of the other pig to apply filling pressure to the resin. A method was first proposed in which the sealing material of the joint is impregnated with a low-viscosity resin, and the space between the joints is then filled with a high-viscosity resin putty.

[Problem to be solved by the invention]

However, when repairing the inner surface of a pipe joint like this is done on the main pipe, the suction or pressurizing force during this work may be applied to the branch pipes that branch out or the supply pipes to each household supply destination. This causes problems such as enlargement of corrosion holes in the supply pipe. In addition, in order to prevent the penetrant and putty agent applied to the pipe joint from clogging the communication branch of the supply pipe, pressure may be applied to the supply pipe.
This has the disadvantage of enlarging the corrosion hole in the supply pipe, as described above.

On the other hand, for supply pipes, corrosion holes are closed by inner coating and a reinforcing layer is provided. Therefore, it has been considered to apply a resin coating to the above-mentioned supply pipe in advance to ensure sufficient strength against suction force or pressurizing force before repairing the pipe joint portion of the main pipe or branch pipe.

However, any remaining coating agent blown into the supply tube will accumulate in the main tube and harden relatively quickly. This is because a fast-curing resin is used. Therefore, it is necessary to pass a pig into this main pipe as soon as possible to smooth out the resin that has accumulated inside, but if this resin happens to come to an unrepaired pipe joint, it will locally get into the gap. This will cause inconvenience in future repairs to the pipe joint.
In particular, this will prevent the resin from permeating into the sealing material.

The present invention has been made based on the above-mentioned circumstances, and by incorporating repair of the main pipe joint part and inner coating of the supply pipe or branch pipe into a series of work procedures, it is possible to repair the main pipe joint part. There is no problem such as expansion of corrosion holes in the supply pipe or branch pipe, there is no blocking of the branch communication part of the supply pipe with resin, and there is no possibility of residual resin entering the main pipe by coating the inner surface of the supply pipe or branch pipe. It is an object of the present invention to provide a method for repairing the inner surface of a pipe in which repair of a pipe joint part is not substantially hindered during break-in.

[Means to solve the problem]

In order to achieve this object, the present invention has been developed in which, in existing gas piping that branches and connects a large number of supply pipes for supplying gas from a main pipe or a branch pipe to each house, a pig is moved by a tow rope in the main pipe to connect the pipe joint. A low viscosity resin is infiltrated into the sealing material of the pipe, a high viscosity putty is filled between the pipe joints, and in the main pipe, negative pressure is applied to the front side of the pig and positive pressure is applied to the back side of the pig. At the same time, the supply pipe or branch pipe is communicated with the atmosphere to prevent low viscosity resin or putty from entering the supply pipe or branch pipe, and the inner surface of the supply pipe or branch pipe is coated with a sprayed resin from the tip side to the branch side. In the first step, a low viscosity resin is infiltrated into the sealing material of the pipe joint in the main pipe.
In the second stage, the inner surface of the supply pipe or branch pipe is coated with resin, and in the third stage, the resin accumulated in the main pipe in the second stage is smoothed out by passing it through a pig, and then the joint part of the main pipe is coated with resin. It is characterized by filling the gap with a putty agent.

[Effect]

With the above construction method, the branch part of the supply pipe or branch pipe will not be blocked by low-viscosity resin or putty, and even if there is a corrosion hole in the supply pipe or branch pipe, it will not be enlarged. , the branch pipe lining resin will not remain in the main pipe.

〔Example〕

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

In the figure, reference numeral 1 indicates an existing pipe that is a gas main pipe buried underground, and this existing pipe 1 is a cast iron pipe that is connected for a long time via a pipe joint 2 such as a water pipe type using a conventional piping method. It is something that exists. In repairing the pipe joint 2 of the existing pipe 1, the present invention divides the existing pipe 1 into units of length suitable for repair, and repairs the supply pipe (or branch pipe) 3 interposed within that section at the same time. become.

As is well known in the art, the pipe joint part 2 has a large-diameter part 2a provided at the end of one pipe that abuts against the other end 2b, and this abutted fitting part usually has a "hemp skin". Packed with sealing material 4 called
It has a connection structure in which the opening is sealed with a lead material 5. A large number of the supply pipes 3 are prepared, for example, in order to guide the gas supplied through the existing pipe 1 to the gas meter of each customer's house. A communicating portion 3a having a small diameter opening is provided at the end connected to the connecting portion.

Inside the existing pipe 1 to be repaired, the pigs 6 and 7 introduced from one opening during the repair of the pipe joint 2 are placed in such a way that they can slide in airtight contact with the inner surface of the existing pipe 1. The rear pig 7 in the direction of movement has a cylindrical external appearance, but the other front pig 6 has a cylindrical rear end, for example, with the intention of providing the function described later. The section is cut diagonally at the top and bottom positions to form a chevron shape when viewed from the side, and the circumferential surface is 90 degrees out of phase in the circumferential direction with respect to the cut surface 6a cut off in the chevron shape. Concave air vent grooves 8 are formed on both the left and right sides, one front end of which opens into the space in front of the pig 6, and a rear end that overlaps the chevron-shaped cut surface 6a in the axial direction of the pig 6. It extends to the relevant position.

Such front and rear pigs 6, 7 are connected to each other by a connecting rope 9 with a predetermined spacing apart,
Further, both the pigs 6 and 7 are connected to traction ropes 10 and 11, which also serve as length measurement, and extend forward and backward, respectively. Furthermore, a coating agent blowing device 14 is connected to the supply pipe 3 via a pipe line 13 branched from the compressor 12 . The blowing device 14 blows compressed air from the compressor 12 through a pressure regulating valve 15 at a rate of, for example, 0.5 kg/cm ^{2 .}
The pressure is reduced to a low level, and the supply pipe 3 is
Coating agent tank 16
This allows the coating agent sprayed into the blowing device 14 under the pressure of the compressor 12 to be conveyed into the supply pipe 3 on the air flow. The compressor 12 is also the pressure regulating valve 1.
5' to the rear of the existing pipe 1, for example, 0.5
It is designed to supply compressed air of Kg/ ^cm2 . Further, a vacuum pump 17 is connected to the front end of the existing pipe 1, and is designed to provide a suction force of, for example, -0.5 kg/cm ² . In addition, in the space facing the pigs 6 and 7, for example, a low viscosity resin (100 cps to
Penetrant A (1st stage) of 1000 cps) and putty agent B (3rd stage) of high viscosity resin (for example 100,000 cps to 300,000 cps) are filled, and then they are filled with pigs 6 and 7 in the following order. It is transferred within the existing pipe 1.

First, dust at the pipe joint 2 in the existing pipe 1 is removed by appropriate means. Next, in the first stage, with the penetrant A filled between the pigs 6 and 7,
This is moved within the existing pipe 1 in the direction of arrow X. This movement is performed 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.
The pigs 6, 7 are moved together with the penetrant A by the traction rope 10. During this movement process, the air remaining in the sealing material 4 of the pipe joint 2 is absorbed and eliminated by the negative pressure action. And due to the movement of pigs 6 and 7,
When the leading pig 6 moves to the position shown in Fig. 1 with respect to the position of the pipe fitting 2 shown in the piping diagram or measured in advance with a video camera, the movement of the pigs 6 and 8 starts at this position. is temporarily stopped or set to a low speed state, and in this state, pressurized air at a predetermined pressure (for example, +0.5 kg/cm ² ) is applied from the rear space of the rear pig 7. As a result, the pig 7 is pressurized in the direction of arrow Y, and pressure is applied to the penetrant A.
Due to the pressurizing action, the low-viscosity resin penetrant A is penetrated into the sealing material 4 through the space between the pipe joints 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 seal material 4, and if there is no air leak, the penetrant A Pressurized infiltration causes a phenomenon in which the air trapped in the sealing material 4 is trapped, but in this case, the leading pig 6 is
Since the air vent groove 8 is formed as described above, the residual air in the sealing material 4 is circulated from the gap in the pipe circumferential direction due to the extrusion action of the penetrant A by pressurized infiltration, and passes through the air vent groove 8. Since the penetrating agent A is released into the space in front of the pig 6, the replacement action between the air and the penetrating agent A is reliably performed, and the penetrating agent A is deeply penetrated into the entire area of the sealing material 4.

In this case, the communication portion 3a of the supply pipe 3 is open to the atmosphere. Therefore, a small amount of air can enter and exit, and therefore, when the front side of the pigs 6 and 7 are connected to the existing pipe 1, they receive only a smaller negative pressure than the existing pipe 1, and the back side is not pressurized. Even when the pipe is closed, it receives only a smaller positive pressure than the existing pipe 1. When the pigs 6 and 7 pass through the communication branch with the supply pipe 3,
The penetrating agent A may be left in the communicating branch. However, since the penetrating agent A used has a long curing time, it is not cured until the next stage of treatment.

When the impregnating action of penetrant A on one pipe fitting 2 is completed, the pigs 6 and 7 are moved within the existing pipe 1 again using negative pressure and pulling by a rope, and the next step is carried out in the same manner as described above. The action of impregnating the pipe joint part 2 with the penetrant A is performed in order.

Note that when towing with the towing rope 10, the rope 9
Because of the tension, the penetrant A is attracted centrally between the pigs 6, 7 and tends to move away from the inner wall of the existing pipe 1.

In this manner, after the impregnation action of the penetrant A in the first stage is completed, the coating treatment inside the supply pipe 3 is then carried out in the second stage. At this time, the communication part 3a
is communicated with the blowing device 14. At this time, the pigs 6 and 7 are retracted to the rearmost position or taken out to the outside. By the action of the compressor 12, compressed air with the coating agent dispersed in a mist is blown into the supply pipe 3 through the communication part 3a, and is discharged into the existing pipe 1 while adhering the coating agent to the inner wall of the pipe. Here, the remaining coating material is deposited. Also, when the vacuum pump 17 is activated,
Allows air to flow in a fixed direction.

The coating agent can be injected into a plurality of supply pipes 3 at the same time. Next, a pig is passed into the existing pipe 1 to level out the coating agent deposited in the pipe from the supply pipe 3. This is because the coating agent is relatively fast-curing, and the coating agent deposited on the portion facing the supply pipe 3 by the pig can be easily leveled and removed. Also,
Even if a part of the coating agent enters the gap in the pipe joint part 2, there will be no problem because this gap will be filled with a putty agent as described later.

Next, as the third step, as shown in Figure 3,
Fill the space between the pigs 6 and 7 with putty B, which is a high viscosity resin, and move it into the existing pipe 1 as described above.
Once moved to a predetermined relative position, the movement is temporarily stopped or at a low speed, and pressurized air is applied to the rear space of the pig 7 to apply filling pressure to the putty agent B.
As a result, the low-viscosity penetrant remaining between the pipe fittings 2 is sucked out in front of the pig 6 through the air vent groove 8 and removed by the filling pressure, and is replaced by the putty agent B. is fulfilled.

In this case, since the compressor pressure is applied to the supply pipe 3 even after the coating agent has been supplied, the putty agent will not enter the supply pipe 3 from the communication branch, and there is a risk of clogging it. Nor. In particular, when applying pressure to the existing pipe 1, if a pressure slightly higher than the applied pressure is applied to the supply pipe 3,
It is possible to completely prevent the putty agent from entering the supply pipe 3.
Moreover, at this time, the corrosion hole of the supply pipe 3 is filled in the coating layer C and maintains sufficient pressure resistance, so there is no problem of the corrosion hole expanding due to the pressure applied thereto.

〔Effect of the invention〕

As described in detail above, the present invention first provides a penetrating agent to the pipe joint part of the main pipe and impregnates it into the sealing material, and then blows the coating agent into the supply pipe.
After that, the coating agent that had accumulated on the main pipe was smoothed out with a pig, and the putty agent was put into the joint of the main pipe, so when applying pressurized air or negative pressure to the main pipe, the supply pipe It is possible to apply pressure to avoid blockage, and the coating inside the supply pipe is incorporated during this work, so repairs inside the supply pipe, main pipe, and branch pipes can be accomplished efficiently and without waste. be done.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the first stage, FIG. 2 is a vertical sectional side view of the second stage, and FIG. 3 is a vertical sectional side view of the third stage, showing an embodiment of the present invention. 1... Existing pipe, 2... Pipe joint part, 2a... Large diameter part, 2b... Pipe end, 3... Supply pipe, 3a... Communication part, 4... Seal material, 5... Lead material, 6,7...
Pig, 6a...Resection surface, 8...Air vent groove, 9...
...Connection rope, 10, 11...Tow rope, 12
...Compressor, 13...Pipe line, 14...Blowing equipment, 15, 15'...Pressure regulating valve, 16...
Tank, 17... Vacuum pump.

Claims (1)

[Scope of Claims] 1. In existing gas piping that branches and connects a large number of supply pipes for supplying gas from the main pipe or branch pipes to each house, in the main pipe, a pig is moved by a tow cable to seal the pipe joint. A low-viscosity resin is infiltrated into the pipe joint, and a high-viscosity putty is filled into the gap at the pipe joint.In addition, in the main pipe, negative pressure is applied to the front side of the pig and positive pressure is applied to the back side of the pig. Alternatively, the branch pipe is communicated with the atmosphere to prevent low-viscosity resin or putty from entering the supply pipe or branch pipe, and when coating the inner surface of the supply pipe or branch pipe with sprayed resin from the tip side to the branch side, the first In the first step, a low-viscosity resin is infiltrated into the sealing material of the pipe joint in the main pipe, in the second step the inner surface of the supply pipe or branch pipe is coated with resin, and in the third step, the resin that has been deposited inside the main pipe in the second step is coated with the resin. A method for repairing the inner surface of existing gas piping, which is characterized by leveling the resin by passing it through a pig, and then filling the gap between the joints of the main pipe with a putty.