JPH102483A - Polyolefin pipe for waterline, water pipeline and laying method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oil odor from being infiltrated into a pipe without worsening workability and earthquake resistance. SOLUTION: The periphery of a pipe body 12 is coated with a thermally shrinking tube 14. At the time of jointing this polyolefin pipe 10 to another pipe, a spirally cut second part 18 is easily removed from a first part 16 of the thermally shrinking tube 14 to expose a joint margin A of the pipe body 12. Even though oil in soil reaches the periphery of the polyolefin pipe 10, the oil is shut out by the thermally shrinking tube 14, so that the pipe body 12 is prevented from coming in direct contact with oil. The pipe body 12 is therefore prevented from swelling, and the flexible property of the pipe body 12 is not impeded because of the thermally shrinking tube 14 forming the outer layer of the pipe body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin pipe for water service, a water pipe, and a method of laying the pipe. The present invention relates to a polyolefin pipe for water service, a water pipe, and a method of laying the same.

[0002]

2. Description of the Related Art Conventionally, polyolefin pipes made of a polyolefin-based synthetic resin having high flexibility in consideration of earthquake resistance and the like are applied to water distribution pipes buried underground.
Here, since the difference in solubility parameter between the polyolefin resin and a solvent based on petroleum (gasoline, kerosene, etc.) is small, when gasoline or kerosene touches the polyolefin tube, the polyolefin resin swells and the density of the tube decreases. Resulting in. Then, the odor of oil such as gasoline or kerosene is transferred to the tap water inside the polyolefin pipe, and when the tap water is used for drinking water, a complaint may be caused due to the odor or taste.

[0003]

In order to prevent such an oil odor from migrating, a steel pipe (a cast iron pipe) that does not penetrate the oil odor around the outer periphery of the polyolefin pipe only in an area where there is a risk of soil contamination by the oil. ) Or coated with PVC tubing. However, when a steel pipe is used, there is a problem that workability is poor because the pipe itself is heavy. On the other hand, when a PVC pipe is used, there is a problem that the strength of the PVC pipe is slightly inferior to that of the steel pipe, so that sufficient earthquake resistance cannot be secured. In addition, the flexibility of the polyolefin tube was sometimes hindered by these cladding tubes.

[0004] Therefore, a main object of the present invention is to provide a polyolefin pipe for water service which can prevent the transfer of oil odor without deteriorating workability and earthquake resistance. Another object of the present invention is to provide a water pipe and a method of laying the water pipe, which can prevent the transfer of oil odor without deteriorating workability and earthquake resistance.

[0005]

According to a first aspect of the present invention, a water-supply polyolefin pipe buried underground is covered with a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of the polyolefin pipe. A polyolefin pipe for water supply. A second invention is a water pipe which is buried underground using the polyolefin pipe for a water service of the first invention.

A third invention relates to a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of a polyolefin pipe in a water pipe line buried in the ground having a joint where polyolefin pipes are joined. It is a water pipe characterized by being coated with. A fourth invention is a method of laying a water pipe in which two polyolefin pipes are joined, and (a) covering a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of a polyolefin pipe having a predetermined size. , (B) the two polyolefin tubes are fused and joined,
(c) A method of laying a water pipe in which a heat-shrinkable tube is put on a joint portion and (d) the heat-shrinkable tube is shrunk to cover the joint portion.

[0007]

According to the first aspect of the present invention, oil in the soil is blocked by the heat-shrinkable tube covering the outer periphery of the polyolefin tube. Therefore, the oil does not touch the outer periphery of the polyolefin tube, and the tube does not swell. In addition, since the coating layer is only formed on the polyolefin pipe for water supply, it is lighter than the case where a steel pipe or the like which is a coating pipe is used,
Moreover, the property of the polyolefin resin being rich in flexibility is not impaired.

In the second invention, a water pipe is laid using a polyolefin pipe covered with a heat-shrinkable tube. This pipe is lighter in weight than the case of using a steel pipe (cast iron pipe) as a cladding pipe, and the flexible nature of the polyolefin resin is not hindered by the heat-shrinkable tube. Also, the oil in the soil is blocked by the heat-shrinkable tube, and the oil does not reach the outer periphery of the tube. Therefore, the polyolefin tube is not swollen by contact with the oil.

In the third aspect, the oil in the soil is blocked by the heat-shrinkable tube, and does not reach the inside of the polyolefin tube from the joint thereof. Also,
Since the gas permeability of the heat-shrinkable tube is smaller than that of the polyolefin tube, the heat-shrinkable tube can sufficiently prevent the transmission of oily odor. According to the fourth invention, the water pipe of the third invention can be easily laid.

[0010]

According to the present invention, even when a light-weight and flexible polyolefin tube is used, oil does not come into contact with the outer periphery of the tube and the polyolefin resin does not swell, so that workability and earthquake resistance are improved. The transfer of oil odor can be prevented without deteriorating the properties. The above object of the present invention,
Other objects, features and advantages will become more apparent from the following detailed description of embodiments, which proceeds with reference to the accompanying drawings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A water supply polyolefin pipe 10 of this embodiment shown in FIGS. 1 and 2 is used as a water pipe laid underground or is likely to be soil-contaminated by oil at a gas station or an oil tank vehicle plant. And includes a tube body 12.

The tube main body 12 is a fixed length tube made of a polyolefin resin having high flexibility such as polyethylene. As the dimensions of the tube body 12, the outer diameter D is 20 mm or more and the total length is set to about 5 m. For example, when the outer diameter is 90 mm, the wall thickness is set to about 8.5 mm. The entire outer periphery of the tube body 12 is covered with the heat-shrinkable tube 14. Further, a joint margin A with a port of another tube is formed from both ends of the tube main body 12 to a position of a predetermined length. And the second portion 18 are formed.

The diameter of the heat-shrinkable tube 14 before being coated is set to be larger than the outer diameter of the tube main body 12 as shown in FIG. And is brought into close contact with the outer periphery of the tube body 12. Further, as shown in FIGS. 4A and 4B, the second portion 18 covering the joining margin A of the heat-shrinkable tube 14 is cut in a spiral shape, and the second portion 18 is cut when the water pipe is laid. The joint margin A of the tube main body 12 can be easily separated from the first portion 16.

Here, the heat-shrinkable tube 14 is made of a resin material having a gas permeability smaller than that of the polyolefin resin.
As such a material, for example, hard vinyl chloride, nylon (6,66), vinylidene chloride, PET (polyethylene terephthalate) and the like can be used. The gas permeability of polyethylene as an example of a polyolefin resin and hard vinyl chloride as an example of a coating layer are shown in Table 1 below.
Shown in

[0015]

[Table 1]

The joining margin A of the pipe body 12 is
For example, when the outer diameter D of the tube body 12 is 90 mm, the joint allowance A is set to 60 mm, and when the outer diameter D is 125 mm, the joint allowance A is set to about 80 mm. When the water polyolefin pipe 10 thus formed is connected to another pipe to form a water pipe,
As shown in FIG. 5, another water supply polyolefin pipe 20 having a receiving port is used.

The polyolefin pipe 20 for water supply includes a pipe body 1
2 includes a pipe body 20a made of the same polyolefin resin as described above, and a receiving port 22 having an inner diameter slightly larger than the outer diameter of the pipe body 12 and a length slightly shorter than the joining margin A of the polyolefin pipe 10 is formed at one end. The above-described heat-shrinkable tube 14 is covered up to the open end of the receiving port 22 on the outer periphery of the tube 20. A heating wire (not shown) is built in the inner peripheral surface of the receiving port 22, and a terminal communicating with the heating wire is provided on the outer circumference of the receiving port 22. On the other hand, a joining margin A is formed at the other end of the tube 20 similarly to the above-mentioned polyolefin tube 10, and the outer periphery thereof is covered with the second portion 18.

Referring to FIG. 6, when connecting polyolefin pipes 10 and 20, first, heat shrink tube 24 is put on pipe 20 from receiving port 22 side. Heat shrink tube 24
Is made of the same material as the above-mentioned heat-shrinkable tube 14, and is formed in a cylindrical shape having a larger diameter than the receiving port 22 and a predetermined length.
Next, one end of the polyolefin pipe 10 is connected to the receiving port 22 of the pipe 20.
Insert inside. Subsequently, in this state, a power supply is connected to a terminal (not shown) of the receptacle 22, the heating wire is heated to heat and melt the inner peripheral surface of the receptacle 22, and the tubes 10 and 20 are fused. Then, the heat-shrinkable tube 2 previously covered on the receiving port 22 side
4 is moved to cover the joint between the polyolefin pipe 10 and the pipe 20. Finally, heat is applied to the heat-shrinkable tube 24 by warm air or the like to reduce the diameter, and the heat-shrinkable tube 24 is brought into close contact with the joint to completely cover (FIG. 7).

Referring to FIG. 8, when laying a water pipe in soil-contaminated area B with oil, first, a groove for laying a water pipe is excavated, and then polyolefin pipes 10 and 20 are laid. This is laid in the groove while being sequentially joined by using. At this time, the joint portion is also covered with the heat-shrinkable tube 24 as described above, and finally, the groove is backfilled with soil. Even if oil in the soil around the polyolefin pipe 10 or 20 reaches the outer periphery of the polyolefin pipe 10 or 20 in the water pipe laid underground in this way, this oil is a heat-shrinkable tube as a coating layer. Blocked by 14 and 24. Therefore, since the oil does not directly contact the pipe main bodies 12 and 20a, the pipe main bodies 12 and 20a are not swollen by the oil. Even if a bending force acts on the polyolefin pipe 10 or 20 due to ground displacement such as an earthquake, the pipe main body 12 or 20a flexibly deforms following the ground displacement. That is, the flexibility of the tube body 12 or 20a is not impaired by the heat-shrinkable tubes 14 or 24.

The degree of the effect of preventing the oil odor from penetrating into the pipe main bodies 12 and 20a depends on the wall thickness and material of the pipe main bodies 12 and 20a and the heat shrink tubes 14 and 24, as well as the ambient temperature, Burial depth, degree of soil contamination,
It also depends on environmental factors such as tap water residence time. Therefore, when laying water pipes, investigate the conditions under which grievances due to unpleasant odor of tap water do not occur in the laying environment,
It is necessary to work to satisfy the conditions.

In general, the amount of toluene mixed in tap water is 24-170 μg / l (0.024-0.170 ppm).
About 20 to 1800 μg / l (0.
It is known that complaints due to unpleasant odors occur at about 020 to 1.800 ppm). In addition, the amount of mixed toluene was 7
It is known that human health is affected when the amount of xylene is about 500 μg / l (0.500 ppm) or about 00 μg / l (0.700 ppm). Therefore, the content of toluene is 24 μg / l (0.024 ppm).
Hereinafter, the amount of xylene mixed is 20 μg / l (0.0
It is desirable to set various conditions so as to be 20 ppm) or less. However, with regard to off-flavors, there is a large variation in the permissible range between regions, and if too strict standards are set, the actual situation may not be met. Therefore, it may be considered acceptable if the amount of oil mixed is 0.1 ppm or less.

According to this embodiment, the polyolefin tube 1
Numeral 0 indicates that the heat shrinkable tube 14 is coated on the pipe main body 12, which is lighter in weight than the case where a conventional coated pipe such as a steel pipe is used, so that the workability is good. Further, even if a bending force acts on the polyolefin pipe 10, the pipe body 12 is flexibly deformed following the displacement of the ground without being swollen by oil, so that the inside of the pipe body 12 is not deteriorated without deteriorating the earthquake resistance. The odor of the oil can be prevented from migrating. Furthermore, since the second portion 18 of the heat-shrinkable tube 14 that covers the joining margin A can be easily removed immediately before the installation of the polyolefin pipe 10, the oxidation of the joining margin A can be prevented. Therefore, the step of removing the oxidized portion of the joining margin A can be omitted, and the workability can be improved.

In the above-described embodiment, the first heat shrink tube 14 is heated before the first heat shrink tube 14 is brought into close contact with the tube body 12.
Although the case where the portion 16 and the second portion 18 are separated is shown, the second portion 18 covering the joining margin A may be cut off after the heat-shrinkable tube 14 contracts. However, the pipe body 12
Care must be taken not to damage the surface of the Also,
The joining margin A of the tube body 12 may be secured without covering the heat shrinkable tube 14 from the beginning.

In the above-described embodiment, the case where the polyolefin pipe 10 is inserted into the polyolefin pipe 20 having a socket and joined is shown.
May be joined using a socket tube, and the joined portion may be covered with a heat-shrinkable tube.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is an illustrative view showing one embodiment of the present invention;

FIG. 3 is an illustrative view showing a state where a heat-shrinkable tube is arranged on an outer periphery of a tube main body.

FIG. 4 is a perspective view showing a state where a first portion and a second portion of the heat-shrinkable tube are separated.

FIG. 5 is an illustrative view showing a polyolefin pipe for water supply having a receiving port at one end.

FIG. 6 is an illustrative view showing a method of laying a water pipe connecting two polyolefin pipes;

FIG. 7 is an illustrative view showing a method of laying a water pipe connecting two polyolefin pipes;

FIG. 8 is an illustrative view showing a state where the water pipe shown in FIG. 7 is buried;

[Explanation of symbols]

 10, 20 ... polyolefin pipe for water supply 12, 20a ... pipe body 14, 24 ... heat shrinkable tube 16 ... first part 18 ... second part 22 ... socket A ... joining margin D ... outer diameter of pipe body

Claims (5)

[Claims] 1. A water-supply polyolefin pipe buried underground, which is covered with a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of the polyolefin pipe. 2. The heat-shrinkable tube includes a first portion that is covered except for a joining margin, and a second portion that is separated from the first portion and covers the joining margin. 2. The water supply polyolefin pipe according to claim 1, wherein the pipe is easily removable at the time of laying. 3. A water pipe buried underground using the water polyolefin pipe according to claim 1. 4. A water pipe line having a joint where polyolefin pipes are joined and buried underground, wherein said joint is covered with a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of said polyolefin pipe. A water pipeline characterized by the following. 5. A method of laying a water pipe in which two polyolefin pipes are joined, comprising: (a) placing a heat-shrinkable tube made of a synthetic resin having a gas permeability smaller than that of the polyolefin pipe having a predetermined size on one side. (B) a fusion splicing of the two polyolefin tubes, (c) covering the joint with the heat-shrinkable tube, and (d) shrinking the heat-shrinkable tube to cover the joint. How to lay.