JPH0567412B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a hard tube lining construction method for the inner surface of a pipe, and more specifically, a hard tube lining construction method that can prevent the shrinkage tendency of tube lining in the length direction that occurs over time after lining formation. Regarding.

Conventional technology and its problems As a conventional method for lining the inner surface of a pipe, there is a so-called hard tube lining method in which a hard plastic tube inserted into the pipe is heated and pressurized from within the tube to expand in the radial direction of the tube and line the inner surface of the pipe. It has been proposed (for example, see Japanese Patent Application Laid-open No. 88281/1983), and is attracting attention because it provides shape-retaining, high-strength, and high-quality tube lining.

However, in such a hard tube lining construction method, stress from cooling shrinkage inevitably remains in the obtained tube lining, and this internal residual stress tends to shrink in the length direction over time, and the degree of shrinkage is , it varies depending on construction conditions and tube material, etc., but if the length of one work is 100m, it is 20~
It has been empirically confirmed that a shrinkage tendency of about 40 cm remains.

The hard tube lining formed inside the tube is
Normally, after the tube is cut at the end, it is clamped and fixed to the tube by applying an end ring and applying adhesive as necessary. It sometimes came off, and there were concerns about its functionality as a waterproof membrane against groundwater infiltration. This problem can be solved by firmly fixing the end of the lining tube to the tube, but a fairly rigid fixation is required to counteract the shrinkage tendency, and no suitable solution has yet been established.
Furthermore, even if it were possible to securely fix the tube, this would leave the lining tube with a tendency to shrink, so when the tube is cut during pipework, the end of the tube lining will shrink and dent inside the tube. This will cause trouble in the end treatment of the tube cut section. Furthermore, when the tube lining of the pipe opening is opened to install a branch pipe, stress is concentrated at the opening, causing cracks and the like.

The present invention has been made with the aim of eliminating such conventional problems.

Means for Solving the Problems As a result of extensive research in order to eliminate the above-mentioned conventional problems, the present inventors formed a hard tube lining inside a pipe according to a conventional method, and then applied the lining locally in the length direction. The inventors discovered that the tendency of shrinkage over time in the longitudinal direction can be eliminated when reheating the material, thereby completing the present invention.

That is, in the hard tube lining method in which a hard plastic tube inserted into a pipe is heated and pressurized from inside the tube to expand in the tube radial direction and line the inner surface of the tube, the lining is removed after the hard tube lining is formed. Eliminate internal residual stress by locally reheating in the length direction,
This invention relates to a hard tube lining construction method for the inner surface of a tube, which is characterized by stabilizing the longitudinal dimension of the tube lining.

Embodiment An embodiment of the construction method of the present invention will be described below based on the attached drawings.

Figure 1 shows the process of inserting the hard plastic tube 1 into the tube 2 in the construction method of the present invention, and the process of inserting the hard plastic tube 1 into the tube 2.
The figure shows the heating and pressurizing process of the tube 1, and each of these processes is carried out according to a conventional method.
In the heating and pressing step, steam, for example, is used as the heating and pressing medium. The tube 1 is made of thermoplastic material, such as polyvinyl chloride, polyethylene, or polypropylene.

The hard tube lining 1' formed in the tube 2 by applying the heat-pressure expansion method is air-cooled and solidified under pressure in the state shown in FIG. 2, and then the remaining end is cut off and removed.

FIG. 3 shows the state of the local reheating process of the hard tube lining 1' formed as described above. A heating device 3 is installed.

The heating device 3 includes a central shaft 4 and a pair of slide plugs 5, 5' fixed to both ends thereof, and a heating chamber 6 is formed between the slide plugs 5, 5'. The inside of the chamber 6 is connected to a heating fluid supply source (not shown) through a heating fluid (for example, steam) passage 7 formed in the stopcock 5 on the rear side with respect to the moving direction and a conduit 8 connected to the passage 7. have been contacted.

In the state shown in FIG. 3, a heating fluid such as steam is supplied into the chamber 6 of the heating device 3 to heat the local part 1'a of the tube lining facing into the chamber 6. Continue until uniform softening occurs in the direction, and stop after uniform softening. After heating the local area 1'a, the heating device 3 is moved within the pipe by an appropriate distance, for example, a distance equivalent to 3 to 30 times, preferably 10 to 20 times, the pipe diameter by pulling the rope 9. Then, local heating is performed again, and by repeating such local heating over the entire length of the tube, the stress that causes longitudinal shrinkage over time is almost completely eliminated from within the tube lining 1'. can. The reason why the stress can be relieved is that the local part 1'a, whose tensile strength has decreased due to softening, is slightly elongated in the directions of arrows 10 and 11 under the influence of the stress in the parts connected on both sides. It is presumed that elongation contributes to stress relief.

In the present invention, as schematically shown in FIG.
The portion can be repaired by applying heat and pressure using the heating device 3.

Effects According to the method of the present invention, after forming the hard tube lining by applying the heat and pressure expansion method,
By locally reheating the lining,
The internal stress that causes longitudinal shrinkage over time can be eliminated, eliminating all problems associated with shrinkage over time.

[Brief explanation of the drawing]

FIGS. 1 to 3 are schematic explanatory diagrams showing the implementation status of one of the construction methods of the present invention in the order of steps, and FIG. 4 is a schematic explanatory diagram showing the status of repair of an insufficiently expanded portion. In the figure, 1 is a hard plastic tube, 2
is a tube, and 3 is a heating device.

Claims (1)

[Claims] 1. In the hard tube lining method, in which a hard plastic tube inserted into a pipe is heated and pressurized from within the tube to expand in the tube radial direction and line the inner surface of the tube, after the hard tube lining is formed, the lining is A hard tube lining construction method for the inner surface of a tube that eliminates internal residual stress by locally reheating and stabilizes the lengthwise dimensions of the tube lining.