JPH0577683U - Synthetic resin pipe - Google Patents

Abstract

(57) [Summary] [Purpose] When construction work, etc., is carried out near the pipe position, a part of the construction machinery, etc. may come into contact with the pipe and the impact force may damage the pipe. Provided is a means capable of solving such a conventional problem without deteriorating the characteristics (excellent in earthquake resistance and pipe jointability) of a conventional pipe. [Structure] An outer layer 12 made of polyvinyl chloride is externally fitted to an inner layer 11 made of polyethylene while being peelably adhered to each other.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a synthetic resin pipe used as a pipe for transporting a fluid such as gas or water.

[0002]

[Prior Art]

 In recent years, as the synthetic resin pipe, a pipe made of polyethylene having excellent seismic resistance and pipe fusion property (bondability with a pipe joint or a pipe joint by fusion) is adopted.

[0003]

[Problems to be solved by the device]

 However, a synthetic resin pipe made entirely of polyethylene is excellent in earthquake resistance and pipe fusion resistance as described above, but has the drawback of weak impact resistance. There was a problem that it might be damaged. For example, when other work such as construction work is performed near the piping position, some of the construction machinery used for the work may come into contact with the pipe and the impact force may damage the pipe. The present invention has been made in view of such circumstances, and an object thereof is to provide a method capable of solving the above-mentioned problem of impact resistance without substantially impairing the properties peculiar to conventional polyethylene pipes. There is.

[0004]

[Means for Solving the Problems]

The synthetic resin pipe according to the present invention is characterized in that the outer layer made of polyvinyl chloride is externally fitted to the inner layer made of polyethylene while being peelably attached to each other. The inner layer is preferably made of medium density polyethylene (polyethylene having a density of 0.930 to 0.942 g / cm ³ measured by the JIS standard: K6760 test method).

[0005]

[Action]

 In the synthetic resin pipe having the above-mentioned characteristics, since the outer layer is made of polyvinyl chloride having good impact resistance, the external impact force on the pipe due to the contact with the pipe of construction machinery etc. If the impact force is smaller than the impact fracture limit value of polyvinyl chloride (the limit value is higher than the impact fracture limit value of polyethylene), the outer layer does not undergo impact fracture and Will endure. Further, since the boundary portions of the inner and outer layers are in close contact with each other so as to be separable from each other, even if the impact force exceeds the limit value and the outer layer may be impact-damaged, the impact The progress of rupture to the inside stops at the boundary between the inner and outer layers, and the entire pipe does not break. In addition, since the boundary portion of the inner and outer layers is in a state of being peelably adhered to each other, the outer layer is bonded to the inner layer having excellent pipe fusion property in order to fusion bond the pipe or the pipe joint. When the inner layer is exposed by peeling, the work of exposing the inner layer becomes easy. Moreover, since the inner layer is made of polyethylene, the synthetic resin pipe provided with the inner layer does not lose the characteristic of polyethylene (that is, the characteristic of being excellent in earthquake resistance and pipe fusion).

[0006]

[Effect of the device]

Thus, according to the present invention, even when the external impact force is applied to the synthetic resin pipe, the fact that the entire pipe is destroyed by the impact force is avoided by the existence of the outer layer and the boundary portion, and Since the inner layer of the synthetic resin pipe is made of polyethylene, it also has the characteristics of polyethylene, so that the problem of conventional impact resistance can be solved without impairing the conventional characteristics. . In addition, after the outer layer is peeled off to expose the inner layer, the inner layer exposing operation can be easily performed when the pipe or the pipe joint is fusion-bonded to the inner layer. When the inner layer is made of medium density polyethylene, the pressure resistance and the pipe fusion property of the synthetic resin pipe are improved. This is because medium-density polyethylene has better pressure resistance than low-density polyethylene (polyethylene having a density of 0.910 to 0.930 g / cm ³ measured by the JIS standard: K6760 test method). In addition, the pipe fusion property is better than that of high-density polyethylene (polyethylene having a density measured by the test method of JIS standard: K6760 of 0.942 g / cm ³ or more).

[0007]

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a gas pipe as an example of the synthetic resin pipe of the present invention. In the figure, 11 is an inner layer 11 made of a thermoplastic resin and excellent in seismic resistance and pipe fusion resistance. The inner layer 11 is made of polyvinyl chloride and has a thickness of 1 An outer layer 12 having a thickness of about 2 mm is externally fitted in the state of close contact described below, and the gas pipe is constituted by a combination of both layers 11 and 12. The boundary portion between the inner layer 11 and the outer layer 12 is in a close contact state (that is, not in a bonded state) in which they are simply abuttingly pressed by the surface pressure of each other, so that they can be separated from each other. ing. As the polyethylene constituting the inner layer 11, medium density polyethylene, that is, polyethylene having a density of 0.930 to 0.942 g / cm ³ measured by the test method of JIS standard: K6760 was adopted.

The gas pipe having such a configuration is buried in an appropriate position in the soil according to the demand, but even when other works such as construction work are carried out in the vicinity of the pipe position, the present invention can be applied. According to this, a part of the construction machine used for construction does not come into contact with the gas pipe and the impact force thereof does not damage the gas pipe. Because the outer layer 12 is composed of polyvinyl chloride having good impact resistance, even if the impact force is generated on the gas pipe, the impact force is the impact fracture limit of polyvinyl chloride. This is because as long as it is smaller than the value, the outer layer 12 can withstand the impact force without being destroyed by impact. Further, since the boundary portion between the inner and outer layers 11 and 12 is in a state of being adhered to each other in a peelable manner, the impact force may exceed the above-mentioned limit value and the outer layer 12 may be destroyed by impact. Even so, the impact fracture progresses to the inside at the boundary between the inner and outer layers 11 and 12, and the entire tube is not destroyed. In addition, since the boundary portions of the inner and outer layers 11 and 12 are in a state in which they are in close contact with each other in a peelable manner, for example, for the inner layer 11 made of the thermoplastic resin, a pipe joint containing an electric heating element (ie The inner layer 11 is made of a thermoplastic resin, and the contact portion abutted on the inner layer 11 generates a juule heat for fusing the abutting portion and the inner layer 11 to each other. When the outer layer 12 is peeled off and the inner layer 11 is exposed in order to fusion-bond the electric-heater-containing pipe joint in which the electric heating body is embedded, the inner layer 11 can be easily exposed. Furthermore, since the inner layer 11 is made of polyethylene, the synthetic resin pipe provided with the inner layer 11 does not impair the characteristic of polyethylene (that is, the characteristic of being excellent in earthquake resistance and pipe fusion property).

It should be noted that reference numerals are added to the claims of the utility model for convenience of comparison with the drawings, but the invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a synthetic resin pipe according to the present invention.

[Explanation of symbols]

 11 inner layer 12 outer layer

Claims (2)

[Scope of utility model registration request] 1. A synthetic resin pipe in which an outer layer (12) made of polyvinyl chloride is fitted onto an inner layer (11) made of polyethylene so as to be peelably adhered to each other. 2. The synthetic resin pipe according to claim 1, wherein the inner layer (11) is made of medium density polyethylene.