JPH0533118B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is applicable to water supply and sewage, chemical industry, paper manufacturing, iron manufacturing,
In various fields of industrial society, such as smelting and refining, it is mainly concerned with a method of lining the inner surface of existing pipelines as they are, and in particular, it is known as a method for lining the inner surface of existing pipelines as they are, especially for cleaning or transporting different types of liquids separately. The technical feature is that by combining the pig with the liner described below and hydraulically transporting these, it is possible to easily line pipelines with the required thickness with resin even for large-diameter and long-distance pipelines. That is.

[Conventional technology and its problems]

Conventionally, a method has been known in which an object called a pig is used as a coating method to apply a thin layer of paint, adhesive, etc. to the inner surface of a relatively long pipeline. Attach multiple pigs at a predetermined interval to one end of the wire that has been passed through the wire, inject paint between these pigs, and
A method of pulling and coating the wire.

(2) A method in which two or more pigs are used, an adhesive or the like is interposed between the pigs, and the pigs are pumped using gas or liquid.

In the case of (1), the pig used is about 2 mm smaller than the inner diameter of the pipe, but in the case of (2), in which fluid is used for pumping, the pig is the same as or smaller than the inner diameter of the pipe. Large diameter pigs were used.

However, the method (1) of pulling the pig using a wire is difficult to apply in practice to long pipelines or pipes with many bends, and it is difficult to apply the method (2) of using fluid pressure. However, in the case where the pig is pumped with a gaseous compressible fluid, the pig tends to run intermittently or in waves, and stable running cannot be achieved unless the speed of the pig is increased to a certain extent, so the resin is limited to a low viscosity. In addition, in the case where hydraulic power is used as the pumping source, the viscosity of the adhesive and running speed are lower than in the former because the following pig is larger than the inner diameter of the pipe, but in any case, The thickness of the coating was several tens of microns per process, and pinholes were likely to occur, making it impossible to expect a highly accurate all-over coating.

Furthermore, in construction methods that use resins in the low viscosity range, if threaded fittings such as sockets or elbows are used for piping and the pipe expands in the diametrical direction, the inner surface of the stepped portion However, it was not possible to complete the coating, and the application was limited to fully welded pipelines.

[Means for solving problems]

Therefore, the present invention provides a bullet-shaped pig with approximately the same diameter as the pipe inner diameter from the pipeline and one end side, and 1 to 4 points from the pig.
One or more liners with a small diameter of mm are sequentially loaded at regular intervals to impart thixotropic properties between the pig and each liner, and have a viscosity of 2,000 to 400,000 cps (20
After filling the required amount of cold-curing resin in water (°C) to line the pipeline, the last liner is moved through the pipeline at a slow speed of less than 10 cm per second by water pressure, and then By lining the inner surface with resin with a film thickness of 0.5 to 2 mm during the process, it is now possible to perform the inner lining work of particularly large-diameter and long-distance pipelines with high precision, which was previously considered difficult. All of the problems described above have been resolved.

[Effect]

In the lining method of the present invention, the resin injected between the pig and the connecting liner exhibits thixotropic properties as the liner progresses, and in particular the fluidity of the resin sandwiched between the outer periphery of the liner and the inner surface of the pipe is improved. At the same time, it rapidly increases the viscosity of the resin in the area where the liner passes and the clamping pressure is released, thereby effectively performing lining.

〔Example〕

As an example of the method of the present invention, weld-connected straight pipes whose lining work is relatively easy will be omitted, and examples will be focused on pipes using threaded pipe vertical pipes that create steps in the pipe line. to describe. However, for ease of explanation, each example was carried out using the following piping specifications.

That is, in Fig. 1, steel pipe 1 with an inner diameter of 80.7 mm
The pipe is connected using two sockets 2 and three elbows 3 and has a total length of 10 m including one rising point.

(Part 1) The purpose of this embodiment is to form a lining with uneven thickness at the top and bottom, which is effective for pipe lines where the bottom part of the pipe is severely worn or corroded. After removing the gauge pipe a to which the pressure gauge, flow meter, thermometer, etc. were attached and cleaning the inside of the pipe by an appropriate means, a bullet-shaped polyurethane pig 4 with a diameter of 80 mm and a length of 150 mm and an elastic material were inserted through its opening. having a diameter of 78mm,
1 each of 5 bullet-shaped liners with a length of 150 mm and a specific gravity of 0.15
After injecting 4.5 kg of a two-component mixed water-curable epoxy resin 6 with thixotropic properties according to the specifications below between them, the gauge pipe a was attached, and the water pressure was applied from the rear of the liner 5. The pipe was fed at an average speed of 7 cm per second until the pig 4 and liner 5 were discharged from the end of the pipe.

(Specifications of the epoxy resin used) Base resin Viscosity 3000cps (20℃) Curing agent Viscosity 3000cps (20℃) Immediately after mixing Viscosity 3000cps (20℃) Mixing ratio Base resin: Curing agent = 2:1 And after curing the resin 6 in water, Three straight pipes were cut out from the longitudinal part, each pipe was divided into three equal parts, and the thickness of the lining 7 was measured.

In the above example, the specific gravity of the liner 5 was set to 0.15, so it is assumed that the liner receives the buoyant force and propels the pumped water in a floating state within the pipe, and as expected, the ceiling section at each of the above measurement points The average thickness was 0.7 mm, and the thickness at the bottom was 1.3 mm.

In addition, when using the resin 6 with such a low viscosity, the liner 5 has a hollow interior, and by filling the cavity with an arbitrary cooling material, the resin 6 between the inner wall of the pipe and the liner 5 can be cooled. Good results were achieved in increasing the viscosity of perilla and improving workability, such as the advancement of the liner within the pipe and the prevention of so-called sagging.

However, in the bullet-shaped liner 5 of the above example, abrasion phenomenon due to the rear end of the liner 5 was partially observed at the elbow portion 3.

(Part 2) This embodiment aims to apply an even and relatively thick lining to the entire circumference of the inner surface of the pipe, and as shown in Fig. 3, a pig of the same shape as the previous one is used. Two elastic spherical liners 5' with a specific gravity of 1.0 and a diameter of 76 mm are inserted at regular intervals in the rear direction of 4, and 2.3 kg of epoxy resin 6 with thixotropic properties given the following specifications is applied to each space in the same manner as in the above example. injected into the pipes at 1.5 per second by hydraulic force.
By propelling the tube at a speed of 1.5 cm, a lining 7 having an average thickness of 2.0 mm was obtained over the entire circumference of the inner surface of the tube.

(Specifications of the epoxy resin used) Base resin Viscosity 400,000 cps (20℃) Curing agent Viscosity 160,000 cps (20℃) Immediately after mixing Viscosity 300,000 cps (20℃) Mixing ratio Base resin: Curing agent = 2:1 Note that the above two examples show Although it is possible to freely change the combination of the bullet-shaped liner 5 and the spherical liner 5', especially by arranging the spherical liner 5' at the rearmost position, the abrasion phenomenon at the elbow 3 part can be effectively eliminated. It is possible.

[Principle consideration of the present invention]

The present invention utilizes a complex phenomenon based on the basic principle of the pig for compartmentalized transportation of different liquids mentioned at the beginning and the physicochemical properties of epoxy resin.
The basic model is shown in Figure 4.

In other words, taking as an example the case where the cross sections of the liner and pipe are concentric, in the laminar region of the pumped water, the distribution of flow velocity is approximately as indicated by the arrow, and the rapidly decreasing portion of the arrow indicates the part of the annular flow that flows through the gap between the liner and the inner surface of the pipe, and the dash-dotted line indicates the interface between them, but the pressure gradient in the gap becomes larger as the thickness of the gap becomes narrower. , the difference with the center of the tube becomes even wider.

In short, it is known that the magnitude of the pressure gradient can be calculated theoretically as a function of the amount of void between the inner surface of the pipe and the liner, the flow rate of the pumped water, and the inner diameter of the pipe.

Therefore, the lining method of the present invention disclosed in each of the above embodiments is applicable to the pig 4 and the liners 5, 5'.
By propelling the resin 6 with an incompressible fluid such as water, the resin 6 interposed between them flows internally under the pressure of the succeeding liner, activating thixotropic properties and increasing fluidity. The resin sandwiched between the outer periphery and the inner surface of the tube is sheared by the elasticity and rigidity of the liner 5 and is repeatedly pressed strongly against the inner surface of the tube, so that the liner 5 cannot be propelled under such dynamic phenomena. Therefore, the viscosity of the resin left behind on the inner surface of the tube increases rapidly as the last liner passes through, and it is reliably cured in water without causing any sag.

Furthermore, according to the present invention, the resin 6 between the pig 4 and the liner 5 is pressurized so that the resin 6 between the pig 4 and the liner 5 can be applied to stepped portions where a screw-in type pipe vertical arm is used at a pipeline connection portion, a bent portion, etc. , the desired lining can be secured.

In addition, in the technology of the present invention, the leading pig moves forward at a slow speed and the water pressure is relatively low, so that unlike conventional cleaning pigs, resin will not leak out to the front surface due to distortion. Also, the following liner is somewhat smaller than the pipe diameter, but since the pressure that is smaller by the amount of pressure loss is transmitted from the rear end to the front to the pig side, the following liner constantly pushes the pig, and the pig The resin 6 between the liners is always kept full of the pipe.

〔Effect of the invention〕

As described above, in the pipe lining method of the present invention, the thixotropic underwater cold-curing resin interposed between the pig and the liner is sequentially applied to the inner surface of the pipe by the action of the liner, which is propelled at a slow speed by water pressure. Since it is applied, the work is smooth regardless of the thickness of the lining, and by changing the diameter and specific gravity of the liner as appropriate,
In addition to demonstrating the exceptional effect of being able to freely set the lining thickness and uneven wall thickness on the top and bottom depending on the application, it is also particularly effective for large diameter, long distance, or pipelines with steps inside the pipe, which were previously considered difficult. Thick wall lining can be constructed extremely easily and efficiently, etc.
Many excellent effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side view of a pipeline in an embodiment of the method of the present invention, Fig. 2 is a partial enlarged view showing a part of the pipeline cut away, and Fig. 3 is a partially enlarged view of a pipeline in another embodiment. FIG. 4 is a schematic diagram showing changes in flow velocity in the laminar region within the pipe. In addition, in the figure, 1...steel pipe, 2...socket, 3...
...Elbow, 4...Pig, 5,5'...Liner,
6...Epoxy resin.

Claims (1)

[Claims] 1. A bullet-shaped pig 4 having approximately the same diameter as the inner diameter of the pipe,
One or more liners 5, 5' having a diameter 1 to 4 mm smaller than this are sequentially inserted, and an underwater cold-curing resin having an appropriate viscosity and thixotropic property is inserted between the pig 4 and the liners 5, 5'. A pipeline lining method in which a required amount of 6 is interposed, and the final liner is pumped by hydraulic power at a slow speed of 10 cm or less per second. 2. The pipeline lining method according to claim 1, wherein the liner has a specific gravity of 0.15 to 1.2. 3. The pipeline lining method according to claim 1 or 2, wherein the liner is capable of storing a cooling material. 4 Claim 1 in which the liner is bullet-shaped
The method for lining a pipeline according to any one of the items 1 to 3. 5 Claims 1 to 5 in which the liner is spherical
The method for lining a pipeline according to any one of item 3. 6. The method for lining a pipeline according to any one of claims 1 to 3, wherein the liner is a combination of a bullet shape and a spherical shape.