JPS6098285A - Synthetic resin pipe for gas piping - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention is designed to peel off a protective layer made of a thin synthetic resin pipe on the outer surface of a gas pipe main body made of a thick synthetic resin pipe by interfacial destruction without causing structural damage to one or more layers. The present invention relates to a synthetic resin pipe for gas piping, which is characterized by being tightly attached to a gas pipe, and its purpose is to prevent the occurrence of cracks due to damage caused during transportation or construction.

This type of synthetic resin pipe for gas piping has superior corrosion resistance and chemical resistance compared to conventionally commonly used steel pipes, and is also lightweight and can be fusion-bonded, making it easier to construct and more economical. On the other hand, it is susceptible to scratches due to impacts during transportation such as loading and unloading, and impacts from debris and shovels during backfilling, and furthermore, these scratches can progress due to loads such as earth pressure and wheel pressure after construction, resulting in large cracks. It had drawbacks such as overgrowth and causing gas leaks.

Therefore, in order to eliminate such drawbacks, the synthetic resin pipe for gas piping is further covered with a relatively large-diameter pipe, or the surrounding surface is covered with a layer of sand, etc., and the pipe is buried. However, it was not always satisfactory, as the construction was not only complicated but also uneconomical.

The inventors of the present invention have conducted intensive research to eliminate the above-mentioned drawbacks, and have found that the protective layer made of a thin synthetic resin pipe on the outer surface of the gas pipe body made of a thick synthetic resin pipe causes structural failure of one or more layers. We have completed a synthetic resin pipe for gas piping that prevents cracks from occurring due to damage during transportation or application for the purpose of interfacial excommunication.

Embodiments of the present invention shown in the drawings will be described in detail below. FIG. 1 is a sectional view showing an embodiment of a synthetic resin pipe for gas piping of the present invention, and 1 in the figure is made of medium density polyethylene as a material. The outer diameter is 207.0 mm and the thickness is 8.3 mm.
2 is a gas pipe main body made of a synthetic resin pipe with a thickness of 2 mm, and 2 is a gas pipe main body made of a synthetic resin pipe with a thickness of 2°51I1mO)'a made of high-density polyethylene layered on the outer surface of the gas pipe main body 1. 1 is a protective layer which is adhered to the gas pipe main body 1 so as to be peeled off by interfacial destruction without causing structural damage, and 2゛ is a protective layer on the outer surface of the first protective layer 2. Thickness 2. Made of layered high-density polyethylene.
The second protective layer is made of Onun's thin-walled synthetic resin pipe, and is adhered so that it can be peeled off due to interfacial failure without causing structural failure like the first protective layer.

In the present invention, the close contact means that the gas pipe main body and the protective layer that are layered, or that the protective layers have a thickness of 0.05 to 2.00 kg/cm.
, preferably has a peel strength of 0.20 to 1.30 kg/cm, which means lamination to the extent that interfacial failure occurs, and if the peel strength is 0.05 kg/cm or less, the peel strength is 0.05 kg/cm or less during handling. The layered part peels off due to impact etc.
On the other hand, in the case of those having a peel strength of 2.00 kg/cm or more, structural destruction occurs without interfacial destruction, and the damage caused in the second protective layer propagates to the gas pipe body 1, causing initial damage. It is not possible to prevent the target crack from propagating.

As shown in FIG. 2, the synthetic resin pipe for gas piping of the present invention is produced by cooling a comparatively thick synthetic resin pipe extruded into a tubular shape from the die 4 of the extruder 3 with a cooling soda 5 to form a gas pipe. The tube body 1 is molded, and in the next step G1, the force tube body 1 is passed through the cross of the extruder 6 and the throat diameter, a thin synthetic resin tube is layered on its outer surface, and it is cooled in the cold IJ tank 8. A protective layer 2 is formed, which is then taken up by a pulling machine 9G and cut into a regular length by a cutting machine 10, and a second protective layer is also formed in the same manner. In addition, when layering this cloth with Sododai 7, the peel strength of the layered surface is 0.05 to 2.00 kg/
cm, preferably 0.20 to 1.30 kg/ctn, while taking into account the compatibility of the layered material and the material to be layered, and the resin temperature, pressure, etc. of each layer.

In addition, as the synthetic resin used for the gas pipe main body l and the insulation layer 2 according to the present invention, it is preferable to use polyethylenes having different densities such as a combination of medium density polyethylene and low density polyethylene. Although the combination is not necessarily limited to such a combination, there is no problem in combining it with another synthetic tree as long as it satisfies the above requirements).

As is clear from the above, the synthetic resin pipe for power supply piping of the present invention has one or more protective layers made of thin-walled synthetic resin pipes on the outer surface of the gas pipe body made of thick-walled synthetic resin pipes, which causes structural failure. Because the structure is made of a structure that is tightly bonded so that it will peel off due to interfacial destruction without any damage, the surface may be scratched due to impact during transportation such as loading and unloading, or impact from debris or shovels during backfilling, and the scratches may be damaged after construction. Even if the crack propagates due to loads such as earth pressure or wheel pressure, the propagation of the crack is blocked at the interface between the gas pipe body and the protective layer, and the gas pipe body itself is not affected in any way. This eliminates gas leakage caused by the propagation of water, and eliminates the need to use protective pipes and bury sand to prevent cracks from developing due to loads such as earth pressure and wheel pressure after construction, unlike conventional products. Not only the workability is significantly improved, but also the economical efficiency is improved as well.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a synthetic resin pipe for gas piping according to the present invention, FIG. 2 is an explanatory view showing the manufacturing process, and FIG. 3 is a cross-sectional view showing another embodiment.

Claims (1)

[Claims] (11) A protective layer made of a thin-walled synthetic resin pipe is closely attached to the outer surface of the gas pipe body made of a thick-walled synthetic resin pipe so that one or more layers can be peeled off by interfacial destruction without causing structural damage. A synthetic resin pipe for gas piping, characterized in that it has a peel strength of 0.05 to 2.00 kg/
The synthetic resin pipe for gas piping according to claim 1, characterized in that it is am. (3) The synthetic resin pipe for gas piping according to claim 1, wherein the gas pipe main body and the protective layer are pipe bodies made of the same type of synthetic resin. (4) The synthetic resin pipe for gas piping according to claim 1, wherein the gas pipe main body and the retaining layer are made of polyethylene having different densities.