JPH0278528A - Technique of hard tube lining on inside of pipe - Google Patents

Abstract

PURPOSE:To enable the title technique to form efficiently hard tube lining without generating trouble from a view point of execution by a method wherein a large number of through holes, which are pierced through in an axial direction and arranged in a row at intervals in a circumferential direction, are formed in a thick part of a tube and a heating fluid is circulated within the through holes. CONSTITUTION:A large number of through holes 1a, which are pierced through in an axial direction and arranged in a row at intervals in a circumferential direction, are formed in a thick part of a hard plastic tube 1, the hard plastic tube 1 is inserted into an object pipe (a) for lining and a front and rear plugs 2, 3 are plugged into both and parts of the tube 1. Steam is fed within through holes 1a... of the thick part of the tube 1 through a conduit 9 and passage 6 and the tube 1 is heated from the thick part. After an internal and external surface temperatures of the tube 1 are attained to at least the softening point, pressurized air is fed within the tube 1 through a conduit 11 and passage 7 while continuing heating operation and the hard tube 1 is lined to the pipe (a) by expanding the hard tube 1.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is directed to a hard tube lining method for the inner surface of pipes, specifically for the inner surface of relatively large diameter pipes such as water mains, city gas mains, sewage mains, etc. The present invention relates to a method for forming a hard tube lining using a relatively thick hard plastic tube.

BACKGROUND ART Conventionally, as a pipe inner lining construction method, a hard plastic tube inserted into a pipe is heated and pressurized from inside the tube to expand fat in the pipe radial direction, and the inner surface of the pipe is lined.
A so-called hard tube lining construction method has been proposed (see, for example, Japanese Patent Publication No. 88281/1983).

The hard tube lining formed by the method described above is hard and self-maintains its inner lining state, and is therefore superior in quality to soft tube linings that rely on the adhesive force of an adhesive to maintain their inner lining state.

In the hard tube lining method, the hard plastic tube inserted into the pipe is heated and softened during the entire pressurized expansion process in order to make it possible to expand under pressure.

As a means of heating and softening conventional hard plastic tubes,
A method of supplying a heating fluid such as steam into a tube has been proposed. This heating and softening means using heating fluid has the advantage that heating and softening can be performed more simply in terms of equipment and operation than heating means that uses a heating jig with a built-in electric heater.

The heat softening means using a heating fluid does not pose any particular problem when the hard plastic tube has a relatively thin wall thickness. However, for relatively large diameter pipes such as water mains, for example 200 to 80
A problem arises when the method is applied to heat softening a tube having a relatively thick wall, for example, about 5 to 20 mm, such as the inner lining of a tube with a diameter of 0 mm. That is, when comparing the heat-softening state of the inner circumferential portion that is in direct contact with the heating fluid and the heat-softening state of the outer circumferential portion that is not in direct contact, the outer circumferential portion is considerably worse than the inner circumferential portion. This is because plastic does not have very good thermal conductivity, and heat dissipates at the outer circumferential surface. Non-uniformity in the heating and softening state between the inner circumferential portion and the outer circumferential portion may lead to insufficient expansion or rupture during pressurized expansion, causing trouble.

In this case, in order to compensate for the insufficient heating of the outer periphery of the tube, it is possible to heat the tube from the outside in addition to heating from inside the tube. It doesn't do much to make it bigger.

DISCLOSURE OF THE INVENTION The main object of the present invention is to heat and soften a thick-walled hard plastic tube to be inserted into a pipe so that the inner and outer circumferences are almost uniform, and to heat and expand the fat to prevent insufficient expansion or The object of the present invention is to provide a hard tube lining method for the inner surface of a tube that can be carried out sufficiently reliably without fear of bursting or the like.

Other features of the invention will become clear from the description below.

The present invention is a construction method in which a hard or semi-hard plastic tube inserted into a pipe is expanded under heat and pressure to line the inner surface of the pipe. This invention provides a hard tube lining method for the inner surface of a tube, which has a large number of through holes arranged in parallel at intervals, and in which a heated fluid flows through the through holes during the heating process. .

The construction method of the present invention is applied to the inner lining of pipes having a relatively large diameter, for example, a diameter of about 200 to 800 mm, such as water mains, city gas mains, sewage mains, etc. As the lining material, a hard or semi-hard plastic tube with a relatively thick wall, for example, about 5 to 20 mm, is used.

Hard or semi-rigid plastic tubes need to be softened by heating (1) They need to be thermoplastic, and in consideration of heating with a heating fluid, they must be made of a material with a relatively low softening point, such as 60 to 100°C. Preferably 70
Those having a softening point of about 95° C. are used. Examples of such low softening point plastics include polyvinyl chloride, polyethylene, and polypropylene.

Hard plastic tubes must be inserted into the pipe to be lined, so the outer diameter (
diameter), and usually has an outer diameter equivalent to about 50 to 90% of the inner diameter of the tube.

The cross-sectional shape of the tube is preferably similar to the cross-section of the tube, and is usually circular.

A large number of through holes are formed in the thick portion of the hard plastic tube, passing through them in the axial direction and arranged in parallel at intervals in the circumferential direction. It is preferable that the through holes are arranged in parallel on a concentric circle passing through the center of the thick part.

The cross-sectional shape of the through hole is arbitrary, and examples thereof include a circle, a triangle, and a quadrangle. In the case of triangles, they can be arranged in parallel by changing their directions.

The total opening area of the through holes is 2 of the total cross-sectional area of the tube.
It is preferable that it occupies a range of about 0 to 50%; if it is larger than this, it is not very preferable in terms of the strength of the tube, and if it is smaller than this, it is not very preferable in terms of tube heating. Further, the diameter of the through hole is appropriately selected from within a range of about 40 to 70% of the thickness of the tube, taking into consideration the adverse effect on the strength of the tube.

Also, if the distance between the through holes is too large, it will cause heating problems.
Also, if it is too small, there is a risk of unfavorable results in terms of strength, so it is preferable that it is smaller than the wall thickness of the tube.
Usually, it is appropriately selected from a range of 50 to 100% of the tube wall thickness.

Such a hard plastic tube with through holes is disclosed in, for example, Japanese Patent Publication No. 7052/1982, No.
, 18333/1987 and the like.

During construction, the hard plastic tube with through holes is inserted over its entire length into the pipe to be lined, making use of the difference in diameter.

The tube is then heated by a heating fluid flowing through the through hole.

Various heating fluids such as steam and heated air can be used as the heating fluid, but steam in particular has a large heat capacity and becomes pure water when condensed, so there is a risk of contaminating the tube or causing pollution if it is discharged as is. There is no such thing, so it is suitable.

If the pressure of the heated fluid flowing through the through hole is too high,
Since there is a risk that the tube may partially expand in the through hole portion, the pressure of the heating fluid is preferably within a range of about 0 to 2.0 kg/cm 2 (gauge pressure).

The heating fluid flowing through the through-hole heats the tube from the thick part, making it easier for heat to reach the entire thick part.
In addition, the loss of heat energy dissipated to the outside is reduced,
Heating will be performed efficiently. Therefore, even though the tube has a thick wall, the entire wall thickness becomes uniformly heated and softened in a relatively short time.

In the process of heating and softening the tube, in order to maintain the shape of the tube, the inside of the tube can be maintained at a pressure that does not cause expansion, for example, 0 to 0.5 kg/cm2 (gauge pressure). In this case, a heating fluid such as heated air preheated to about 50 to 100° C. may be used as the shape-retaining fluid, and in addition to heating from inside the through hole, heating may be performed from inside the tube.

After the heating and softening process of the tube is completed, pressurized fluid is supplied into the tube while heating from the inside of the through hole is preferably continued. The type of pressurized fluid is not particularly limited, and pressurized air is usually used. The pressurized air supplied into the tube pressurizes the tube from the inside and causes it to expand, forming a hard tube lining on the inner surface of the tube.

The pressure of the pressurized air may be within a range that can inflate the tube, and usually a pressure of about 0.5 to 2.0 kg/cm2 (gauge pressure) is sufficient. Pressurized air is 50-10
It may be used after being heated to a temperature of about 0°C.

Since such pressure expansion of the tube is carried out after uniform heating and softening, troubles such as insufficient expansion and rupture will not occur.

After completing the pressurized expansion of the tube, all operations are completed by cooling and solidifying the tube while keeping the inside of the tube in a pressurized state. In the cooling process,
A cooling fluid such as water, air, etc. may be passed through the through hole of the tube.

According to the construction method of the present invention, a relatively thick hard plastic tube can be used to efficiently form a relatively thick hard tube lining on the inner surface of the tube without causing any trouble during construction.

EXAMPLE Below, one implementation of the construction method of the present invention will be explained based on the accompanying drawings.

Figures 1 to 3 show an example of the construction method of the present invention using a thick hard plastic tube (1) in which a large number of through holes (1a) having a circular cross section are formed. As shown in FIG. 2, the hard tube (1) has a smaller diameter and a relatively larger wall thickness than the tube to be lined (a).

During construction, the hard tube (1) is inserted over its entire length into the pipe to be lined (a) using the diameter difference, and then the front collar (2) and rear collar are inserted at both ends of the tube (1). A frame (3) is applied. The front collar (2) and the rear frame (3) have annular grooves (4) and (5) on their inner surfaces, and these grooves (4)
), (5) the end of the tube (1) is inserted and fixed. The grooves (4) and (5) have small diameter grooves (4a) and (5a) in their deep parts, and these grooves (4a) and (5a)
Inside the tube (1), through holes (1a) in the thick part are opened at both ends thereof.

Furthermore, the front collar (2) has a small diameter groove (
a passageway (6) for supplying a heating fluid, for example steam, into the through hole (1a)... through the tube (1a);
) for supplying pressurized fluid, e.g. pressurized air, into the passage (
7), and the supply port of the former passage (6) is equipped with a valve (8).
) to the boiler (not shown) through a conduit (9) with a valve (10), and the supply port of the latter passage (7) is connected to a conduit (11) with a valve (10).
) are each connected to a compressor (not shown).

The rear frame (3) has the through hole (1a)...a smaller diameter groove (
passage (12) for discharging steam through 5a);
and a passage (13) for discharging pressurized air from inside the tube (1), and a conduit (16) with valves (14), (15) is provided at the outlet of each passage (12), (13). ), (1
7) are prepared for each.

During construction, steam is supplied to the tube (1
), the steam flows through the through holes (1a), heating the tube (1) from the thick part, while heating the tube (1) from the thick part. Exhaust system, i.e. small diameter groove (
5a), is discharged to the outside through the passage (12) and the discharge pipe (16).

Such heating operation using steam is usually performed under normal pressure, but in some cases, it may be performed under low pressure that does not involve expansion of the through hole (1a), for example, 0.5 kg/cm.
The heating may be carried out under a pressure of about 100% (gauge pressure).Also, while continuing steam heating from the through hole (1a), heating from inside the tube (1) is carried out using a pressurized air supply system. May be used together.

Since the tube (1) is heated from the inside of the through hole (1a), that is, from the inside of the thick wall, the heating in the thickness direction is approximately uniform throughout, regardless of the thickness.

After the inner and outer surface temperatures of the tube (1) reach the softening point or higher (but not exceeding the melting point) by the above heating operation, pressurized air is preferably used while continuing the heating operation from inside the through hole (1a). Pressurized air preheated to about 80 to 100°C is supplied into the tube (1) through the supply system, that is, the conduit (11) and the passage (7), and the pressure inside the tube (1) is controlled by the expansion. Necessary pressure, e.g. 0.5-2. 0kg/co+
” (gauge pressure), the hard tube (1)
is expanded and lined in tube (a) in the conventional manner.

This lining condition is shown in FIGS. 1 and 3. As mentioned above, the hard tube (1) is heated so that the temperature in the thickness direction is uniform, so regardless of the thickness, the hard tube (1) is expanded and lined uniformly over its entire length without the risk of bursting. Ru.

As shown in Fig. 1, after completing the heating, pressurizing and expansion operation, the steam heating is stopped and the compressed air is used to cool and solidify the hard tube lining (1' ) is obtained.

When examining the surface smoothness of the hard tube lining (1') obtained in the examples shown in Figures 1 to 3, it was found that the through holes (1a) were exaggerated as shown in the enlarged cross-sectional view of Figure 4. Slight unevenness was observed, with the formed portion being a concave portion (18a) and the non-forming portion being a convex portion (18b). The surface smoothness of the hard tube lining (1') can be improved by using a hard plastic tube (19) with a cross-sectional structure as shown in FIG.

The hard tube (19) shown in FIG.
The structure is different from the rigid tube (1) shown in FIGS. 1 to 3 in that the tubes 9a) have a triangular cross section and are arranged in parallel in alternately opposite directions. Partition wall (19b) forming the oblique side of the triangular through hole (19a)
(19b) and the bottom wall (19C) forming the bottom part,
The wall thickness is approximately the same, no matter which cross section you take in the diametrical direction.
The structure is such that the proportions occupied by the void portion and the non-void portion are approximately equal. Therefore, during pressurized expansion, the entire 360° circumferential surface exhibits a similar resistance to the expansion pressure applied from the inside, and the entire surface is expanded without excess or deficiency, resulting in a surface with good surface smoothness. An inner lining is obtained.

In order to further clarify the characteristics of the method of the present invention, various experimental examples conducted according to the method of the present invention are listed below.

[Experiment example 1] (I) Experimental conditions■ Pipe diameter (inner diameter) to be lined...250mmφ length
......50m■ Hard plastic tube material...Polyvinyl chloride Diameter (outer diameter)
...200mm Wall thickness ...10mm Softening point ...72℃ [Phase] Through-hole cross-sectional shape ...Circular diameter ......φ6mm mutual interval··
...9mm Number of tubes ...66 Total opening area ...28% (relative to tube cross-sectional area) Formation position ...center of thick wall ■ Type of heated fluid Type: Steam supply amount: 100 kg/hour supply pressure
-・-0,3~0. 5kg/cm2 (gauge pressure) Supply time: 5 minutes Heating conditions: Only in the through hole■ Pressurized fluid type: Heated air temperature:・20℃ Supply pressure: 0.5 kg/cm2 (gauge pressure) Pressure expansion time: Approx. 3 minutes Cooling time: Approx. 30 minutes Under the above experimental conditions When the method of the present invention was carried out according to the embodiment shown in FIG. 1, a lining of good quality similar to the hard tube lining (1') shown in FIG. 3 was obtained without any trouble. The atmosphere during installation of the tube (a) was maintained at room temperature (18° C.).

[Experiment Example 2 The material of the hard plastic tube is polyethylene,
The experiment was carried out under the same experimental conditions as in Experimental Example 1 except that polypropylene was used, and the same good results as in Experimental Example 1 were obtained.

[Experimental Example 3] The experiment was carried out under the same experimental conditions as Experimental Example 1, except that the hard plastic tube with the cross-sectional area shown in Fig. 5 was used, and a hard tube lining with a smooth surface was obtained. . The conditions for the through hole are as follows.

Cross-sectional shape: Length of one side of equilateral triangle: 12mm Thickness of interval: 2.5mm Total opening area ・
...38% (relative to tube cross-sectional area)

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view schematically showing one implementation state of the construction method of the present invention, Fig. 2 is a longitudinal cross-sectional view showing the situation before the expansion operation in Fig. 1, and Fig. 3 is the situation after the same expansion operation. FIG. 4 is a vertical cross-sectional view showing an enlarged view of the inside lining, and FIG. 5 is a vertical cross-sectional view showing another preferred example of the hard plastic tube used in the construction method of the present invention. . In the figure, (1) is the hard tube, (1a) is the through hole, (2) is the front collar, (3) is the rear frame, (4), (5) is the annular groove, (6), (7) is a passage. (that's all)

Claims (1)

[Claims] (1) In the method of heating and pressurizing and expanding a hard or semi-hard plastic tube inserted into a pipe to line the inner surface of the pipe, the tube is thick-walled, and the tube is passed through the thick part of the pipe in the axial direction. A hard tube lining method for the inner surface of a tube, characterized in that the tube has a large number of through holes arranged in parallel at intervals in the circumferential direction, and a heating fluid is caused to flow through the through holes during a heating process.