JP2977602B2 - Lining method of pipe inner surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a pipe inner surface lining method for a multi-purpose pipe such as a water pipe or a gas pipe in which a plurality of branch pipes are branched from a main pipe.

[Prior Art] Conventionally, a method of blowing a paint into a pipe by air flow and lining it has been widely used for rehabilitation of water pipes and gas pipes, and is described in, for example, Japanese Patent Application Laid-Open No. 2-68177.

In this technique, the viscosity and the air velocity of the paint are properly selected, and a very good lining can be obtained by using a paint having good dripping characteristics.

[Problems to be solved by the invention]

However, the only problem that is difficult to solve is that the thickness of the coating film on the back of the elbow tends to be small.

This is because, when the air current collides with the back of the elbow and the direction is changed, the action of spreading the coating film is strong, and it is difficult to secure a practically necessary coating film thickness in the range of the air flow velocity required by the air flow method.

As a method of solving this problem, a method of smoothing a coating film and correcting the thickness of the coating film through a forming pig while the coating material is not cured after coating by an air current method has been performed (Japanese Patent Application Laid-Open No. Sho 62-266178). And JP-A-63-274474.

However, pigs used in conventional methods have a high density,
When compressed strongly, the force pressing against the inner wall of the tube becomes too strong and the coating film is wiped off, so a ball-shaped pig slightly smaller than the inner diameter of the tube or one size smaller is used. In other words, there is a problem that if the pipe size is different, a sufficient effect cannot be obtained in a portion having a large size because the pig is adapted to the minimum size of the target pipe. In addition, since the pig is moved from the large-sized main pipeline to the small-sized branch pipeline, it is likely that the pig does not enter the branch pipeline at the branch portion and goes straight through the main pipeline.

As a solution to this problem, Japanese Patent Application Laid-Open No. 1-304086 proposes a method in which the pig is pushed from the opposite side of the main line with air to guide the pig to the branch line (see FIG. 4, where 1 is the main line and 1A is the branch). tube).

However, also in this case, the pig moves in the direction from the main pipe to the branch pipe, and even if the pig is pushed by the airflow from the opposite side of the main pipe at the branch, the pig and the paint stored in front of the pig have inertia force. Therefore, it is likely to move to the main pipe on the opposite side without entering the branch pipe. The pig moved to the opposite side because it was pushed by the airflow from the opposite side of the main pipeline, eventually pushed back and moved to the branch pipeline, but the paint pushed by the pig was hardened and left in the main pipeline so the inner surface Would depart from the purpose of shaping.

Further, Japanese Patent Application Laid-Open No. 1-304086 discloses a case of lining not by shaping of a coating film lined by an air flow method but by placing a paint in front of a pig and pushing with a gas from the back of the pig, and Is smaller than the main pipeline, the outer diameter is reduced by compression.

However, since the properties of the pig are not further defined, it is questionable whether the reduced pig will form the required coating thickness.

[Means for Solving the Problems] The present invention has the following configuration as means for solving the above problems.

That is, in the method of the present invention, in a manifold pipe in which a plurality of branch pipes are branched from the main pipe, paint is injected into the pipe from one end of the main pipe or one of the branch pipes, and gas is supplied to the pipe to thereby feed the pipe. Surface lining is performed, and then lining paint having a viscosity of 5000 cp to 20000 cp is injected from the end of each branch line, and has a diameter larger than the inner diameter of this branch line from the end of each branch line. In this lining method, a new coating film is formed by inserting an elastic foam (sponge) made of synthetic resin and having open cells and pressing the elastic foam with air pressure. In this case, it is important that the elastic foam be inserted after the paint is cured.

Here, in the elastic foam made of the synthetic resin, the load at the time of 70% deflection in the load-deflection characteristic is 60 kg or less, and the load at the compression rate of 70% is 6 times or less the load at the compression rate of 10%. in, measuring 2-fold following minimum inner diameter d ₁ of the diameter D of the tube, and when the maximum inner diameter of the tube and d _2, D is a 1.1 × d ₂ or more, is a 0.5D~3D length Cylindrical or 1.
A spherical shape of 1 × d ₂ or more and 2d ₁ or less is preferable.

Under these dimensional conditions, the relining of the coating film on the inner surface of the different diameter pipe can be performed while the elastic foam is appropriately deformed, so that the shaping effect is remarkable.

If the outer shape of the elastic foam is cylindrical, molding becomes easy, and it may be produced at low cost.

The material is a flexible polyurethane foam, vinyl foam, latex foam, or the like, but is not limited thereto.

When the synthetic resin foam has a density of about 10 to 70 kg / m ^3, it is preferable to exhibit the effects of the present invention.

Load-The load at the time of 70% deflection in the deflection characteristics is 60 kg.
When the following condition is satisfied, the stress generated in the radial direction of the elastic foam when the elastic foam is inserted into the pipe is small. Further, the load at a compression rate of 70% is 6 times or less the load at a compression rate of 10%, and the change in the load due to deformation is small in this range.

Therefore, when the above conditions are satisfied, when shaping the lining surface when the pipe diameter changes, from a thick pipe to a thin pipe, it can be deformed according to the pipe diameter, and the stress on the pipe wall becomes thinner. Also does not increase rapidly, so that a uniform lining surface can be formed over the entire pipe.

Here, the load-deflection characteristics are as follows: compression speed 50 mm / min, compression plate 200 mmφ, sample size 50 mm x 300 mm x 300 mm, A
It shall be measured according to STM D3574.

Furthermore, when the elastic foam is pressed from the end of the branch pipe by air pressure, the inlet of the main pipe is opened, and a small amount of backflow prevention air is sent from the other branch pipe end to push the elastic foam into the main pipe inlet. It is even better if you lead to

The present invention is based on the above-described configuration, but produces an excellent effect when using an elastic foam defined under further conditions.

[Action]

The present invention is to form a good coating film which complements the weaknesses of both by forming a new coating film on the coated coating film by an elastic foam having a different coating principle on the coated coating film. That is, while the elbow portion, which is a weak point of the airflow method, has a small film thickness, the elastic foam of the present invention is a foam having open cells, so that a large amount of lining paint can be contained inside, and the paint is When the lining paint is put into the hardened pipe from the pipe end and the elastic foam is run, the same state as when the inside of the pipe is painted with a so-called sponge brush is obtained.

In particular, in the elbow portion, when the elastic foam changes direction, it is strongly pressed against the tube wall, so that the paint contained in the elastic foam is pushed out excessively to form a thick coating film.

Further, when the elastic foam satisfies the above condition, the force of the elastic foam pressing against the wall surface becomes substantially constant.

Therefore, even if the tube diameter changes, a new uniform coating film can be formed in accordance with the amount of the injected paint.

 The above was confirmed by the following experiment.

That is, two elastic foams are prepared (one has open cells and can be impregnated with paint, and the other has discontinuous cells and can be impregnated with paint). When both were slid while pressing with the same compression force, the coating film could be retained in the former case, whereas the paint was wiped off in the latter case.

This is because the principle of shaping the coating film of the present invention is different from that of the prior art
This means that it is completely different from the case of the shaping pig proposed in JP-A-266178 and JP-A-63-274474.

That is, the conventional pig has no function of absorbing the paint, but simply adjusts the gap between the pig and the pipe wall to shape the coating, and is the same as a so-called rubber spatula that pushes and shapes the coating.

On the other hand, there is a method of painting with only a sponge, but there is a limit to the range of pipe diameters that can be covered with one sponge. Therefore, a more effective coating can be achieved by combining an air flow method with no change in the pipe diameter.

In particular, the phenomenon that the elbow section becomes thinner by the air flow method becomes more remarkable as the pipe diameter becomes smaller. Generally, the branch pipe is smaller than the main pipe,
The problem of the elbow is apt to occur in the branch pipe. Therefore, the method of relining with the elastic foam from the end of the branch pipe is very effective in repairing the weak point of the air flow method.

In addition, when the elastic foam is inserted from the end of the branch pipe and moved to the main pipe side, the branch pipe is usually connected to the side of the main pipe at the branch point with the main pipe, so that the elastic foam is used. Is forced to bend in either the left or right direction, and it is reliably transferred to the opening side of the main pipeline by only a slight air flow being formed from the upstream side (see FIG. 2, where 1 is the main pipe, 1A is a branch pipe). After that, it is only necessary to go straight on the main conduit, so that only a small amount of air for preventing backflow is introduced into the branch conduit on the way, and the elastic foam is reliably led to the opening of the main conduit.

In addition, the present inventor performed lining of the inner surface of the pipe, and thereafter, included a coating material in an elastic foam having a diameter larger than the inner diameter of the pipe from the end of each branch pipe and made of synthetic resin and having open cells. The lining method of shaping the lining surface by pressing the elastic foam with air pressure was proposed earlier. Good lining results can also be achieved by including the paint in the elastic foam, inserting it into the tube and pressing it pneumatically. However, when the elastic foam is impregnated with the paint and inserted, the entrance of the pipe may become dirty at the time of insertion, resulting in poor workability. In addition, the amount of paint that can be impregnated into the elastic foam is limited, and if the pipe is long, there is a possibility that the shaping paint may be insufficient. In addition, the elastic foam must be passed while the paint lined on the inner surface of the pipe does not solidify, but the time until this solidification is relatively short, and the curing of the paint progresses before shaping with the elastic foam. The shaping effect by the foam may not be expected.

Therefore, in the present invention, after the coating is performed by the airflow method and the coating film is cured, a new coating material is injected and coated with an elastic foam to form a double coating film on a necessary portion.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, FIG. 3 shows a load-deflection curve of the elastic material used in this example. This figure is 50mm x 300mm x 3
FIG. 5 is a diagram showing the amount of deflection when a compression plate having a diameter of 200φ is placed on a flexible urethane foam of 00 mm and a load is applied thereon at a compression speed of 50 mm / min, as a percentage.

From this figure, it can be seen that the load of this elastic material increases in proportion to the amount of deflection up to a deflection of 10%, but when it exceeds 10%, the load increase rate is very small up to a deflection of about 50%. %, The load gradually increases up to about 70%, and when it exceeds 70%, the load rapidly increases.

Next, an embodiment of the method of the present invention will be described. FIG. 1 shows a pipe assembled according to a water supply pipe of an apartment, in which 10D is JIS20A.
The part that connects to the faucet at the end has a JIS15A irregular elbow attached.

During lining, a required amount of paint is injected from the ends of the pipes 5 and 10A to 10D with a shape cup and painted toward the main pipe side. This method may be a method as disclosed in JP-A-2-68177.

Paint Zenkanro is completed, after paint curing, by injecting paint viscosity 5000cp the connection pipe used for injecting the coating material conduit 5 ends, are formed by flexible polyurethane foam density 20 kg / m ³ A cylinder having a diameter of 30 mm and a length of 50 mm is inserted into the connecting pipe used for injecting the paint at the end of the pipe 5, and the hose 25 is connected.

The polyurethane foam used satisfies the load-deflection characteristics such that the load at 70% deflection is 60 kg or less, and the load at 70% compression is 6 times or less the load at 10% compression.

The other end 2 of the main line is opened, and a small amount of backflow prevention air is introduced into the other portions 10A to 10D by opening the valves 23A to 23D. Next, when the valve 23 is slightly opened to send air to the line 5, the polyurethane foam advances in the tube and is discharged from the other end 2 of the main line.

Next, the same polyurethane foam is inserted into the connecting pipe at the end 11A of the branch pipe 10A, backflow preventing air is injected into the other branch pipes, and the polyurethane foam is fed in the same procedure and collected from the other end 2 of the main pipe. .

Thereafter, the paint is applied again with the paint and polyurethane foam in all the branch pipes in the same manner.

As a result, with the airflow method alone, there was a part where the coating thickness on the back of the elbow was 0.3 mm or less, but the thickness of the back of all elbows was 0 by passing the polyurethane foam.
3mm or more could be secured.

Also, the movement of the polyurethane foam to the other end 2 of the main pipeline was extremely smooth and no anxiety was felt.

Although a cylinder is used in this embodiment, the same effect can be expected even if it is spherical because it is easy to mold.

〔The invention's effect〕

According to the present invention, the lining surface of a manifold pipe having a branch pipe can be uniformly coated. In particular, the first lining can complement the lining of the elbow portion where the coating film tends to be uneven.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example in which the present invention is applied to a pipe assembled according to a water supply pipe of an apartment. FIG. 2 is a view showing a method of moving an elastic foam from a branch pipe to a main pipe. FIG. 3 is a view showing a load-deflection curve of the elastic foam of the present invention, and FIG. 4 is a view showing a method of moving the elastic foam from the main pipe to the branch pipe. (P) ... elastic foam, 1 ... main pipe 5,10A ~ 10A ... branch pipe.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B05D 1/00-7/26 B05C 7 / 04,7 / 08 F16L 55/00

Claims (4)

(57) [Claims] A lining of a pipe inner surface by injecting paint in a pipe from one end of the main pipe or one of the branch pipes and feeding gas in a multi-piece pipe in which a plurality of branch pipes branch from the main pipe. After the paint is cured, the paint is re-injected from the end of each branch pipe, and has a diameter larger than the inner diameter of this branch pipe from the end of each branch pipe. A lining method comprising: inserting an elastic foam having the following formula; and pressing the elastic foam with air pressure. 2. The elastic foam according to claim 1, wherein the load-deflection characteristic is such that the load at the time of 70% deflection is 60 kg or less and the compression ratio is 70%.
% When the load is less than or equal to 6 times the load when the compression ratio of 10%, measuring 2-fold following minimum inner diameter d ₁ of the diameter D of the tube, and when the maximum inner diameter of the tube and d _2, D 1.1 × d ₂ or more and length
Cylindrical is 0.5D～3D, or and the diameter 1.1 × d ₂ or more, the lining method according to claim 1, wherein the one formed into a spherical shape is 2d ₁ or less. 3. The lining method according to claim 2, wherein said elastic foam is made of a flexible polyurethane foam, vinyl foam or latex foam. 4. When the elastic foam is pushed by air pressure from the branch pipe side end, the inlet of the main pipe is opened, and a small amount of backflow preventing air is sent from the other branch pipe end, so that the elastic foam is pushed into the main pipe. The lining method according to claim 1, wherein the lining is guided to an entrance.