JPH03175018A - Method for forming hard tubular lining over internal surface of tube - Google Patents

Abstract

PURPOSE:To stabilize longitudinal dimension of a tube lining by, after forming hard tubular lining, locally reheating the lining in a longitudinal direction of the lining to eliminate internal residual stress. CONSTITUTION:Hard tubular lining 1' formed inside a tube 2 by hot pressure expansion method is air-cooled under pressure and solidified and then excessive ends are cut and removed. An axially movable heating device 3 is provided within the lining 1'. The device 3 includes a center shaft 4 and a pair of slide plugs 5, 5' fixed to the opposite ends of the shaft and the interior of a heating chamber 6 defined between the plugs 5, 5' is connected to a heating fluid supply source through a passage 7 of heating fluid, e.g. steam, formed in the plug 5 on the rear side and a pipe 8. Steam is supplied into the chamber 6 of the device 3 to heat a section 1'a of the lining so that the lining is uniformly softened in a thickness direction. In this manner, local heating is applied repeatedly over the entire length of the tube to eliminate stress which causes contraction with the passage of time in a longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hard tube lining method for the inner surface of a tube, specifically a hard tube lining method that can prevent the shrinkage tendency of the tube lining in the length direction that occurs over time after the lining is formed. Regarding.

Prior art and its problems As a conventional method for lining the inner surface of a pipe, 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.
A so-called hard tube lining construction method has been proposed (see, for example, Japanese Unexamined Patent Publication No. 58-88281), and is attracting attention because it provides shape-retaining, high-strength, and high-quality tube linings.

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

The rigid tube lining formed inside the tube is usually cut at the tube end and then clamped and fixed to the tube by applying an end ring and applying adhesive as necessary. Due to shrinkage, the end of the tube liner sometimes came off from the terminal ring, and there were concerns about its functionality as a waterproof membrane against underground water 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 countermeasure has yet been established. Furthermore, even if it were possible to securely fix the lining, the shrinkage tendency remains within the lining tube, so when the pipe is cut during pipe work, the end of the tube lining may shrink and dent inside the pipe. 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 The present inventors have conducted intensive research to eliminate the above-mentioned conventional problems. After forming a hard tube lining inside a pipe according to a conventional method, the lining is locally applied in the longitudinal direction. The inventors discovered that the tendency of shrinkage over time in the length direction can be eliminated when reheating the material, thereby completing the present invention.

That is, the present invention provides a hard tube lining method in which 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 line the inner surface of the pipe, after forming the hard tube lining. This relates to a hard tube lining construction method for the inner surface of a tube, which is characterized by locally reheating the tube in the length direction to eliminate internal residual stress and stabilize the lengthwise dimension of the tube lining.

EXAMPLE An example of the construction method of the present invention will be described below based on the accompanying drawings.

Figure 1 shows the process of inserting the hard plastic tube (1) into the pipe (2) in the method of the present invention, and Figure 2 shows the process of heating and pressurizing the tube (1). Each step is carried out according to a conventional method, and in the heating and pressing step, for example, steam is used as the heating and pressing medium. The tube (1) is thermoplastic, and is made of, for example, polyvinyl chloride, polyethylene, or polypropylene.

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

FIG. 3 shows the state of the local reheating process of the hard tube lining (1') formed as described above, and in this process, the inside of the lining (1') is A movable heating device (3) is installed.

The heating device (3) is equipped with a central shaft (4) and a pair of stopcocks (5) (5') fixed to both ends of the central shaft (4).
) A heating chamber (6) is formed between the two. Inside the chamber (6), heating fluid is supplied through a heating fluid (e.g. 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). source (not shown).

In the state shown in Fig. 3, the chamber (6) of the heating device (3) is
) by supplying a heating fluid, e.g. steam, into the chamber (
6) Part of the tube lining facing inside (1'
a) is heated, and the heating is continued until the local part (2'a) is uniformly softened in the thickness direction, and is stopped after uniformly softening. After heating the local area (1'a), the heating device (3) is moved to an appropriate distance, for example, 3 to 30 times the pipe diameter, preferably 10 to 20 times, by pulling the rope (9). The tube lining (1') moves a corresponding distance within the tube, and then performs local heating again. By repeating this local heating over the entire length of the tube, the tube lining (1') It can be almost completely erased from within. The reason why stress can be relieved is that the local area (1'a) whose tensile strength has decreased due to softening is affected by the stress in the parts connected on both sides of the local area (1'a), and the arrow mark (10)
and (11), and it is presumed that this elongation contributes to stress relief.

In the present invention, as schematically shown in FIG.
If this occurs, the under-expanded portion (1'b) can be repaired by applying heat and pressure using the heating device (3).

Effects According to the construction method of the present invention, after forming a hard tube lining by applying the heating and pressurizing expansion method, by locally reheating the lining, the internal structure that causes shrinkage in the longitudinal direction over time can be removed. It can eliminate stress and eliminate all problems associated with shrinkage over time.

[Brief explanation of drawings]

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. (that's all)

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 inside the tube to expand in the pipe radial direction and line the inner surface of the pipe, after forming the hard tube lining, the lining is lengthened. A hard tube lining construction method for the inner surface of a tube, which eliminates internal residual stress by locally reheating in the direction of the tube, thereby stabilizing the lengthwise dimension of the tube lining.