JPH1061867A - Pipe line installed using polyethylene pipe for steel pipe joint - Google Patents

Abstract

(57) [Abstract] [Problem] When laying a pipeline on site, it does not require any welding at the joint of the outer polyethylene-coated steel pipe, which is a constituent unit of the pipeline, and outer coating, and has excellent water stopping properties. In addition, the function of the pipeline is maintained by following the deformation of the pipeline due to ground displacement due to earthquake or land subsidence. SOLUTION: An outer surface polyethylene-coated steel pipe 2 provided integrally with a polyethylene pipe as a joint 3 at an end thereof is installed adjacent to form a conduit, and the polyethylene pipe at the end of the outer surface polyethylene-coated steel pipe 2 is provided. The end face 7 of the joint 3 is heat-fused to each other, and the length of the polyethylene pipe can be adapted to follow the deformation of the pipe due to the ground deformation generated during an earthquake or the like. A pipe installed using a polyethylene pipe as a steel pipe joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible and earthquake-resistant pipe provided by using a polyethylene pipe for a steel pipe joint. The pipeline of the present invention is used for applications such as water and gas, and other lifelines, and can follow the deformation of the pipeline due to ground deformation caused by an earthquake or land subsidence. .

[0002]

[Prior art]

(1) Conventionally, in the case where a steel pipe is welded to form a pipeline by welding, the pipeline is formed by ground deformation caused by an earthquake or land subsidence by integrating the pipeline by high toughness of the steel pipe and welding. The deformation is addressed. (2) Also, for large-scale ground deformation in a pipeline, a telescopic flexible tube is used, and the telescopic flexible tube is welded between steel pipes at a place where the ground deformation is predicted. Combine to deal with deformation. (3) For joining steel pipes to form pipes,
In some cases, a mechanical joint such as a flange joint is used.

[0003]

In the above-mentioned prior art, in the case of the welding joining of (1), the strength of the joining portion can be made equal to the strength of the pipe portion, and the water stopping performance is excellent. It is necessary to perform anticorrosion treatment on the part, and piping work is complicated and cost is increased. In the case of large-scale ground deformation, excessive stress may be generated and deformed, and the function as a pipeline may not be maintained due to the structure. In (2), in order to prevent the occurrence of excessive stress as described in (1), when a flexible tube is used, large-scale ground deformation can be dealt with. Due to the high cost, the cost is high. For this reason, the installation place of the flexible tube is limited to a place where a large-scale ground deformation is predicted in advance, and there is a local problem near the installation portion of the flexible tube. Can only follow the rank. In the case where the flexible tube is joined by welding, the same problem as in the case (1) remains. In the case of the mechanical joint by the flange joining or the like of (3), there are difficulties in water stoppage over time and water stoppage when excessive stress is applied.

[0004] The present invention has been made in view of the above-mentioned problems of the prior art, and when laying a pipeline on site, the joint of an outer polyethylene-coated steel pipe, which is a constituent unit of the pipeline, is used. It does not require any welding and painting of the inner and outer surfaces, has excellent water stopping properties, and maintains its function as a pipeline following the deformation of the pipeline due to ground deformation due to earthquake or land subsidence. An object of the present invention is to provide a pipeline provided by using a polyethylene pipe for a steel pipe joint for maintaining and securing a lifeline such as a pipe for transporting a fluid such as water and gas and an electric wiring pipe.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, a pipe provided by using a polyethylene pipe for a steel pipe joint according to the present invention has a polyethylene pipe integrated as a joint at an end. The present invention relates to a method in which the provided outer polyethylene-coated steel pipe is installed adjacently to form a pipe, and the end faces of the end of the outer polyethylene-coated steel pipe and the joints of the polyethylene pipe are heat-sealed to each other. The pipe provided by using a polyethylene pipe for the steel pipe joint of the present invention is provided with an outer polyethylene-coated steel pipe integrally provided with a polyethylene pipe as a joint at an end portion, which is installed adjacently to form a pipe. The end of the outer surface polyethylene-coated steel pipe and the end face of the joint of the polyethylene pipe are heat-sealed to each other, and the length of the polyethylene pipe is reduced by the deformation of the pipe due to ground deformation generated during an earthquake or the like. It relates to the ability to follow in response.

[0006] The outer surface polyethylene coated steel pipe according to the present invention is a method of extruding and coating molten polyethylene on the outer surface of the steel tube, a method of winding and coating the outer surface of the steel tube with the coating polyethylene, or a method of coating the outer surface of the steel tube with a cylindrical coating polyethylene. It is manufactured by a method of inserting, a method of bending a plate-like covering polyethylene along the circumferential direction of the outer surface of the steel pipe, and a method of joining a joint portion. Bonding between the steel pipe and the covering polyethylene or between the polyethylenes is performed by an adhesive or by heat fusion. The present invention relates to an outer polyethylene-coated steel pipe in which the ends of the steel pipe are not coated with the coating polyethylene as in the case of the conventional welding connection, and to an outer polyethylene-coated steel pipe in which the entire outer surface of the steel pipe is coated with the coating polyethylene. The same can be applied. In the present invention, a pipeline having an outer surface polyethylene-coated steel pipe as a constituent unit can be applied to various lifelines such as a water pipe having a diameter of 15 mm to 1000 mm, a gas pipe, an electric wiring, and the like.

[0007] When the polyethylene pipe joint is formed separately from the coating polyethylene portion of the outer polyethylene-coated steel pipe, the polyethylene molded as a joint is inserted into the end of the steel pipe, and the coating polyethylene is formed by heat fusion or the like. Integrate with In this case, if there is a steel pipe exposed portion at the steel pipe end of the outer polyethylene coated steel pipe, the inner surface of the joint of the polyethylene pipe is also joined to the exposed steel pipe. Also, as described above, the polyethylene pipe joint is not made separately from the coating polyethylene part of the outer polyethylene-coated steel pipe, but the polyethylene pipe joint is formed integrally with the coating polyethylene part of the outer polyethylene-coated steel pipe. Can be created in a typical way. In this case, for example, a polyethylene part as a joint and a part of the end of the coating polyethylene part of the steel pipe are integrally formed, and the integrally formed tubular body is inserted into the end of the steel pipe, or The integrally formed plate is wound and joined to the end of the steel pipe by heat fusion (see FIG. 4). Alternatively, as described above, in the case of forming the outer surface polyethylene-coated steel pipe by bending the plate-shaped coating polyethylene along the circumferential direction of the outer surface of the steel pipe and joining the joints, The joints may be continuously formed at both ends of the polyethylene for heat-sealing with an adhesive or the like, bent together with the polyethylene for coating, and the joints of the joints may be joined by heat-sealing. The process up to the step of integrating the joint of the polyethylene pipe with the outer surface polyethylene coated steel pipe is preferably performed in a factory. The polyethylene coated on the main body of the steel pipe may be continuously projected from the end of the steel pipe to a required length. . The thickness of the polyethylene pipe portion of the protrusion is increased.

The joint made of a polyethylene pipe may be formed by providing a stiffening rib in order to increase the sectional rigidity in the radial direction. The stiffening rib forms a plurality of ring-shaped protrusions on the outside of the polyethylene tube. Further, a stiffening steel ring may be provided inside a joint made of a polyethylene pipe.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an arrangement of a pipeline 1 provided by using a polyethylene pipe to a joint 3 of an outer surface polyethylene-coated steel pipe 2 according to the present invention, and includes a pipe shaft of a portion A near the joint in FIG. 1 in FIG. 2 shows an enlarged view of a cross section. In FIG. 2, an outer surface polyethylene-coated steel pipe 2 has a steel pipe 4 coated with a coating polyethylene 5 on the outer surface. In this example, the steel pipe 4
Is an outer polyethylene-coated steel pipe 2 having a portion that is not coated with the coating polyethylene 5 on the outer surface of the end 4a. Therefore, as shown in FIG. 2, the joint 3 made of a polyethylene pipe is inserted and mounted so as to be in contact with the end 4a of the steel pipe 4 and to overlap and contact the end of the coating polyethylene 5. . Joint 3 made of polyethylene pipe
Is integrated with the coating polyethylene 5 by heat fusion and an adhesive, and is joined to the end 4 a of the steel pipe 4. The inner surface of the outer polyethylene-coated steel pipe 2 is coated with an inner surface 6.
The outer surface polyethylene-coated steel pipes 2 provided with the polyethylene pipe joints 3 are installed adjacent to each other to form a pipe at the site, and the end faces 7 of the polyethylene pipe joints 3 facing and facing each other are heat-fused to each other. The pipe line 1 which joined and the outer surface polyethylene-coated steel pipe 2 was joined is provided. For the on-site heat fusion bonding, a known method such as an electrofusion joint (EF), a butt fusion joint, or a burner heating method may be used.

FIG. 3 shows an outer polyethylene-coated steel pipe 2 in which the entire outer surface of a steel pipe 4 is coated with polyethylene 5 for coating.
Shows a case where a joint 3 made of a polyethylene pipe is joined by heat fusion. FIG. 4 shows a case in which a part 5a of the outer end polyethylene-coated steel pipe 2 on the pipe end side of the coating polyethylene 5 is formed integrally with the joint 3 of the polyethylene pipe. A joint 3 of a polyethylene pipe formed into a tube together with a part 5a on the tube end side of the coating polyethylene 5 is inserted into the steel tube 4 or a tube end of the polyethylene tube 3 and the coating polyethylene 5 to be formed into a tube. Is wound around a steel pipe 4 from a plate-like state to form a joint 3 of a polyethylene pipe, and the joint 3 of the polyethylene pipe is integrated with the polyethylene 5 for coating. 5b is a seam between the polyethylene 5 for coating of the outer surface polyethylene-coated steel pipe 2 and a part 5a of the polyethylene 5 for coating formed integrally with the joint 3 of the polyethylene pipe.

Next, FIG. 5 shows a case where a stiffening rib 8 made of polyethylene is provided in a joint 3 made of a polyethylene pipe, and FIG. 6 shows a case where a stiffening steel ring 9 is provided. The stiffening steel ring 9 is incorporated in the joint 3 as in this example.

[0012] The pipe provided by using a polyethylene pipe for the joint of the steel pipe of the present invention can be adapted to follow the deformation of the pipe due to the ground displacement generated during an earthquake or the like. The present invention, for example, 15mm ~ 1000m diameter
It was made by paying attention to adopting a joint made of polyethylene which is a completely different material from steel for joining between outer surface polyethylene coated steel pipes such as for m-class water pipes, etc. the thickness of the well Naru tube t, the length s _p of the polyethylene pipe portion of the joint, it is necessary to provide the necessary fixing length s of the polyethylene coating. Here, the thickness t, the length _sp , and the length s are respectively shown in FIG. 2, and the equations for calculating them are shown below.

[0013]

T = (pDF _S ) / (2σ) where, t: thickness of the polyethylene pipe at the joint, p: internal pressure, D: inside diameter, σ: tensile strength of polyethylene, F _S ;
Safety factor.

[0014]

[Number 2] _{s p = (L S F S} ) / ε where, s _p; joint polyethylene pipe portion of the length of,
L _s : displacement amount per one tube (ground strain), ε: elongation at break of polyethylene, F _s : safety factor.

[0015]

Equation 3] _{s = P / (φ S τ} S) , where, s; requires fixing the length of the polyethylene coating, P; axial force acting on the tube, phi _S; circumferential length of the steel pipe, tau _S; steel pipe and polyethylene Shear adhesion of the coating.

[0016]

As described above, according to the present invention, the following effects can be obtained. (1) The present invention does not require any welding at the joint of the outer polyethylene-coated steel pipe, which is a constituent unit of the pipe, and no inner / outer coating at the time of laying the pipe at the site. Welding and inner / outer surface painting can be omitted, so that the process can be shortened and the construction cost can be reduced. The present invention, for example, 15mm diameter ~
This effect was realized by paying attention to adopting a joint made of polyethylene, which is a material completely different from steel, for joining between large-diameter outer-surface polyethylene-coated steel pipes such as for a 1000 mm-class water pipe. (2) At the site, the watertightness of the joint can be ensured by heat fusion bonding of the polyethylene to the joint of the outer surface polyethylene coated steel pipe without welding. (3) With respect to land subsidence and ground deformation during an earthquake, compared to the case where a telescopic flexible tube is used as a conventional steel pipe, it is able to follow ground distortion (including the meaning of absorption) and seismic resistance equal to or more than that of a conventional steel pipe. It can maintain and secure the function of the pipeline as a lifeline for fluid transportation, electrical wiring, etc. at the time of disaster or the like.

[Brief description of the drawings]

FIG. 1 is a view for explaining an arrangement of a pipeline provided by using a polyethylene pipe for a steel pipe joint of the present invention.

FIG. 2 is an enlarged view of a cross section including a tube axis in a portion A in FIG. 1;

FIG. 3 is an enlarged view of a cross section of another example of the portion A in FIG. 1;

FIG. 4 is an enlarged view of a cross section of another example of the portion A in FIG. 1;

FIG. 5 is a diagram showing an example in which a joint of a polyethylene pipe has a stiffening rib.

FIG. 6 is a view showing an example in which a stiffening steel ring is incorporated in a polyethylene pipe joint and the joint is stiffened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipeline 2 Outer polyethylene coated steel pipe 3 Joint 4 Steel pipe 5 Coating polyethylene 6 Inner coating 7 End face 8 Stiffening rib 9 Stiffened steel ring 10 Telescopic flexible pipe

Claims (5)

[Claims] An outer polyethylene-coated steel pipe integrally provided with a polyethylene pipe as a joint at an end thereof is installed adjacently to form a pipe, and a joint of the polyethylene pipe at an end of the outer polyethylene-coated steel pipe is provided. A pipe line provided by using a polyethylene pipe to a joint of a steel pipe, wherein end faces of the pipes are heat-welded to each other. 2. An outer polyethylene-coated steel pipe integrally provided with a polyethylene pipe as a joint at an end thereof is installed adjacently to form a pipe, and a joint of the polyethylene pipe at an end of the outer polyethylene-coated steel pipe is provided. The steel pipe joint is characterized in that the length of the polyethylene pipe can be adapted to the deformation of the pipe due to the ground deformation that occurs during an earthquake, etc. Pipeline installed using polyethylene pipes. 3. The steel pipe joint according to claim 1, wherein the end of the outer surface polyethylene coated steel pipe and the joint made of the polyethylene pipe are integrated by heat fusion bonding. Pipeline. 4. A pipe arranged using a polyethylene pipe as the steel pipe joint according to claim 1, wherein the polyethylene pipe joint is formed by providing a stiffening rib made of polyethylene. Road. 5. A steel pipe joint according to claim 1, wherein a stiffening steel ring is provided on the polyethylene pipe joint. Pipe.