JPS6118076B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is useful for repairing leakage when internal fluid leakage occurs due to cracks or wear in piping such as gas pipes or water pipes, or for repairing leakage in the future even if no leakage occurs. The present invention relates to a method for coating the inner surface of piping for preventive maintenance against leakage.

In the conventional pipe leak repair method, it is known that the leak is repaired by applying a sealant to the inner surface of only a relatively narrow area including the leak point or its vicinity. According to the method, first of all, once a leak has occurred, the degree of deterioration of the pipe has progressed, and even after repair, leaks are likely to occur again in other parts. Not only does it have the disadvantage of increasing costs overall, as preventive maintenance cannot be carried out to prevent recurrence of leaks and repairs must be repeated.
Since countermeasures are taken only after a leak has occurred, this method has the disadvantage that it cannot be applied to prevent the risk of leakage. Since the coating process was performed only by drying and solidifying the sealant to form a film after applying it, it took a relatively long time for the sealant to dry and solidify, resulting in poor workability. Not only that, but during drying and solidification, the sealant applied to the upper inner surface of the pipe migrates to the lower inner surface due to its own weight.
Problems such as not being able to form a film with a uniform thickness all around the circumference, or difficulty in repairing leaks that occur at the upper part of the inner surface, or
There is a problem that air bubbles form inside the sealant while it dries and hardens, making it difficult to obtain the desired repair effect.Furthermore, if the film is made thicker to solve this problem, the resistance to fluid flow increases. The time required for drying and solidification is extended, which tends to cause new problems such as further deterioration of workability.

In view of these problems, the present invention has been developed to not only repair leaks but also to perform preventive maintenance against leaks that may occur in the future.Moreover, the inner surface of the pipe is coated in a state that eliminates the above problems. The purpose of the present invention is to propose a method that can be carried out reliably and efficiently as planned, while also being economically viable in terms of time and cost.

That is, the method for coating the inner surface of a pipe according to the present invention involves forming a continuous ring-shaped adhesive layer in the axial direction of the pipe on the inner surface of the pipe, and then inserting a thin cylindrical film into the inner surface of the ring-shaped adhesive layer. Since it is characterized by adhesion, it has the following effects.

In other words, since the cylindrical film is bonded to the inner surface of the ring-shaped adhesive layer that is formed on the inner surface of the pipe and continues in the direction of the pipe axis, it can be used even for pipes that have leaked or for pipes that have not leaked. Also, it is possible to coat the inner surface over the entire length and circumference, and leakage can be prevented for a long period of time.

Because a cylindrical film is bonded to the inner surface of the pipe, air bubbles may form inside the sealant and the coating effect may be insufficient, unlike the case when coating was done by drying and solidifying the sealant in the past. The problem of curling and uneven thickness in the circumferential direction did not occur; therefore, the thickness of the cylindrical film itself and the adhesive layer itself for bonding it to the inner surface of the pipe did not occur. Although it can be made very thin, it is possible to easily achieve a uniform and sufficiently reliable coating effect in the circumferential direction.

As mentioned above, since the cylindrical film and adhesive layer can be made very thin, a reliable coating effect can be obtained at low cost, and the resistance to internal fluid flow can be minimized, allowing fluid There is less obstruction to the flow.

Since the adhesive layer can be thin, the time required for adhesion of the cylindrical film by curing this layer is shortened, and even if the adhesive layer is not completely cured, the inside of the cylindrical film can be This allows fluid to flow throughout the building, reducing the time required for construction work.

Due to the synergy of the above-mentioned steps, it has become possible to achieve a reliable and good inner surface coating treatment of pipes with less time and cost, and thus in a manner that is economically viable.

Embodiments of the present invention will be described below based on the drawings.

We will discuss a case where a leak occurs in a gas distribution pipe buried underground.

After the leaking pipe 1 is disconnected from adjacent pipes at both ends of the pipe 1 and the gas flow is cut off, and the gas inside the leaking pipe 1 is purged, bubbles are removed from the opening at one end of the pipe 1. Generator 2
and the discharged foam receiving container 5 is connected to the opening at the other end.

The foam generator 2 consists of a liquid adhesive storage tank 2A and an air pressure feeding blower 2B.
The air supply pipe 3 taken out from the storage tank 2A is branched into two parts, one of which is connected to the pipe 1 through a valve 4a, and the other connected to the bottom of the storage tank 2A through a valve 4b. The upper part and the intermediate part of the valve 4a piping 1 are connected via a foam delivery pipe 3' with a valve 4c interposed therebetween.

When the blower 2B is operated with the valve 4a closed and the valves 4b and 4c open, the storage tank 2
Air is force-fed to the inner bottom of A, foaming the liquid adhesive, and then filling and injecting it into the pipe 1 through the delivery pipe 3'. When the foamy adhesive reaches the container 5, the blower 2B stop. In this state, pipe 1
The entire interior is filled with foam adhesive. Next, when the valves 4b and 4c were closed, the valve 4a was opened, and the blower 2B was operated again, the foam-like adhesive filled in the pipe 1 was interrupted in the axial direction of the pipe by the compressed air. It is continuously discharged to the container 5 side while forming a diaphragm and in contact with the entire inner circumference of the pipe 1. When the blower 2B is stopped when the amount of surplus adhesive discharged into the container 5 reaches a predetermined amount, the inner surface of the pipe 1 has a continuous adhesive along the entire length in the axial direction and a continuous adhesive in the entire circumferential direction. A relatively thin ring-shaped adhesive layer S having a uniform thickness is left attached over the circumference.

After forming the ring-shaped adhesive layer S on the inner surface of the pipe 1, the bubble generator 2 and the container 5 are separated, and a thin and sufficiently flexible tube such as polyethylene is placed inside the adhesive layer S. Insert the shaped film 6. This film 6 is inserted by an inversion method. That is, the film 6 is wound around the drum 7, and its leading end is folded back to the outside to be hermetically attached to the film outlet 7A of the drum 7, while communicating with the internal space of the drum 7. Air is forced into the folded end portion of the film 6 by the operation of the connected blower 8, and by this air pressure, the inner surface of the film 6 wound around the drum 7 is sequentially exposed to the outer surface. Insert the film 6 into the pipe 1 from the outlet 7A while inverting it as shown.
Insert it. Along with this insertion, the outer peripheral surface of the film 6 after being reversed is expanded and transferred radially outward by the air pressure applied to the folded portion, and is evenly applied to the adhesive layer S in the circumferential direction and the axial direction. They are closely bonded. film 6
When the film reaches the opening at the other end of the pipe 1, the blower 8 is stopped, the film 6 is cut, and the unnecessary part of the film 6 is wound back onto the drum 7, thereby completing the leakage repair.

As in this embodiment, when forming the ring-shaped adhesive layer S on the inner surface of the pipe 1, the adhesive is made into a foam and injected into the pipe 1, and then the excess adhesive is discharged by air blowing. In this case, the amount of adhesive required is smaller than when it is injected in liquid form, and it can be formed quickly and easily, and a thin and even layer can be formed over the entire length and circumference. However, in addition to this, adhesive is sprayed from a spray gun installed on a cart that moves inside the pipe 1 toward the entire circumference, and a ring-shaped adhesive that continues in the axial direction is applied to the inner surface of the pipe 1. A layer S may also be formed.

Further, in inserting the cylindrical film 6, a pig method may be used in addition to the above-mentioned inversion method. In this pigging method, a guide thread is inserted into the pipe 1 in advance, an adhesive layer S is formed, and then a film 6 is tied to the end of the guide thread and the film 6 is inserted by pulling the guide thread. be.

In addition, the method of the present invention may be applied not only to gas pipes, but also to water pipes, cable line pipes, etc., and can be used not only for repairing leaks, but also for new pipes with no leaks or those with some degree of corrosion. It is also a good idea to apply this method for preventive maintenance to pipes that are currently in use.

In addition, for large-diameter pipe 1, in order to reduce the amount of adhesive to be injected and filled, another flexible pipe having an outer diameter slightly smaller than the inner diameter of the pipe 1 is inserted in advance. It's good to keep it.

Furthermore, the adhesive may also serve as a sealant, and in this case, even better and more reliable coating effects can be obtained.

Adhesives include the following:

That is, butyl rubber, polysulfide rubber, natural rubber latex, vinyl acetate/ethylene copolymer latex,
Styrene butadiene polymer latex, acrylonitrile butadiene copolymer latex, methyl methacrylate butadiene copolymer latex, vinylpyridine copolymer latex, chloroprene latex, vinyl chloride polymer, vinyl acetate polymer, Vinylidene chloride copolymer, cis 1.4 polyisoprene, polyurethane,
Examples include polybutene, polyacrylate, polyethylene, and the like.

Note that all of these also serve as sealants.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the method for coating the inner surface of a pipe according to the present invention, and FIG. 1 is a side view schematically showing the whole, FIG. 2 is an enlarged side view of the main part taken longitudinally through the pipe, and FIG. The figure is an enlarged longitudinal sectional front view of the main part showing a state in which the cylindrical film is adhered to the inner surface of the pipe. 1... Piping, 6... Cylindrical film, S... Adhesive layer.

Claims (1)

[Claims] 1. A method for coating the inner surface of a pipe 1, comprising:
The inner surface of the pipe is characterized in that a ring-shaped adhesive layer S that is continuous in the axial direction of the pipe is formed on the inner surface of the pipe 1, and then a thin cylindrical film 6 is inserted and bonded to the inner surface of the ring-shaped adhesive layer S. coating treatment method. 2 The ring-shaped adhesive layer S is formed by blowing air from one end in the axial direction of the pipe 1 to the adhesive injected into the pipe 1 in the form of a foam, and discharging the excess adhesive. A method for coating the inner surface of a pipe according to claim 1. 3. The method for coating the inner surface of a pipe according to claim 1 or 2, wherein the adhesive forming the adhesive layer S also serves as a sealant.