JP2000249265A - Screw coupling type propelling pipe structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw coupling type propelling pipe structure capable of reducing damage due to friction with sediment or the like in propulsion and reducing the resin material cost and construction cost of a resin coating. SOLUTION: A screw coupling type propelling pipe 10 is formed by screw- joining an outer resin coated steel pipe 10a coated with resin 13 and an outer surface resin coated steep pipe 10b. The resin coating of a screw part 11 outer surface of a succeeding outer resin coated steel pipe 10a with respect to the propelling direction is a resin coating having the same hardness as that of the resin coating 13 of the outer surface resin coated steel pipe 10a, and on the other hand, a resin coating 14 having a hardness higher than that of the resin coating 13 of the screw part 11 outer surface of the outer surface resin coated steel pipe 10a is applied to the screw part 12 outer surface of the preceding outer surface resin coated steel pipe 10b. A resin coating having a higher hardness is applied only to a portion liable to be damaged in propulsion, so that the resin coating material cost and the resin coating construction cost including off-line can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a threaded joint type propulsion pipe structure in which the ends of adjacent outer resin-coated steel pipes are screwed.

[0002]

2. Description of the Related Art When water and sewage pipes, gas pipes, power / communication cable pipes, etc. are buried in the ground, if it is impossible to dig from the ground or if digging from the ground is undesirable, a predetermined 2. Description of the Related Art A propulsion method has been adopted in which pipes are sequentially connected to each other by a propulsion device provided in a shaft excavated at a position and propelled underground. For this propulsion method, a direct push propulsion method for directly propelling a main pipe, such as a gas pipe or a sewer pipe, into the soil is widely adopted for economic reasons. For connection between buried pipes laid underground by such a propulsion method, connection using a bayonet joint structure, butt welding, connection using a screw joint type propulsion pipe, or the like is employed.

[0003] Generally, the outer surfaces of these joints are uncovered, and when propelled, single pipes are dropped one by one from the ground into a shaft, joined to the rear end of the propelled pipe, and then joined to the outer surface of the joint. Anticorrosion treatment is performed on the whole. As anticorrosion method,
FRP lining by covering the entire outer surface of the joint with a heat-shrinkable polyethylene tube with an adhesive on the inner surface and shrinking by heating, or by impregnating a hardening resin such as epoxy resin or polyester resin with reinforcing fiber such as glass fiber on site And a method of covering the entire outer surface of the joint with a mold, injecting a curable resin, and molding.

[0004] However, when the pipes of the buried pipes are connected to each other with a bayonet joint, when a large displacement occurs in the ground due to an earthquake or the like, there is a possibility that the joint part, particularly the sealing material, is deformed and damaged. . If this joint breaks,
There is a problem that groundwater or the like flows into the pipe from the damaged joint. In addition, in the case where pipes are joined to each other by welding on-site, in order to perform multi-layer welding, skill is required for the welding work, and the work time is lengthened, and the efficiency of the entire propulsion method is reduced. .

A heat-shrinkable polyethylene tube having an adhesive on the inner surface is excellent as an anticorrosion material, but has a low Shore hardness (D) of about 45, which is low.
When the propulsion pipe is being propelled by the direct push propulsion method, the polyethylene tube is liable to be scratched due to friction with soil, gravel and the like. In addition, the FRP lining method requires a reaction hardening time for forming FRP. In addition, the method of covering the entire outer surface of the joint with a mold, injecting a curable resin and molding the mold requires time for mounting the mold, resin injection molding, and removing the mold.

Japanese Unexamined Patent Publication No. Hei 10-131666 discloses a threaded joint type propulsion tube and a method of preventing corrosion of the threaded joint type propulsion tube to solve the above problems.

FIG. 4 is a half sectional view showing a screw joining step of the screw joint type propulsion pipe. FIG. 4 (a) is a view showing a state before screw joining, and FIG. It is a figure showing a state after. The screw joint type propulsion tube 1 is composed of a screw joint type propulsion tube 1a joined to the propelled screw joint type propulsion tube 1b. The screw joint type propulsion tube 1 has an outer polyethylene coated steel pipe 2 (hereinafter referred to as a coated steel pipe) and a coated steel pipe. Male screw part 3 and female screw part 4 welded and joined to both ends of
And the anticorrosion protection layers 5 and 6 formed on the outer surface of the joint between the male screw 3 and the female screw 4. Anticorrosion protection layer 5,
Reference numeral 6 denotes a step formed of a synthetic resin having a hardness higher than the hardness of the polyethylene coating layer of the coated steel pipe in a cylindrical shape, and having a predetermined length and depth at the boundary between the flange surface and the outer peripheral surface at the tip end.
b, and the end of the coated steel pipe covering the polyethylene coating layer has a tapered surface.

[0008] As shown in Fig. 1 (a), packing 8 is attached to the male screw portion 3 of the propelled screw joint type propulsion tube 1a and the flange surface of the anticorrosion protection layer 5, and as shown in Fig. 2 (b). The female thread portion 4 of the threaded joint type propulsion tube 1b to be connected is screwed into the male screw of the threaded joint type propulsion tube 1a, and the female thread portion 4 and the flange surface of the anticorrosion protection layer 6 are firmly pressed against the packing 8. As a result, a U-shaped groove 9 having a depth and a length corresponding to the steps 7a and 7b of the anticorrosion protection layers 5 and 6 is formed at the joint portion, and a rubber-based adhesive is applied in the U-shaped groove 9 for heat shrinkage. An anticorrosion sheet made of a conductive polyethylene sheet is wound, and is heated and shrunk by a heating device such as a burner to be fixed.

According to the above screw joint type propulsion tube, the joint between the coated steel pipe and the screw portion of the screw joint type propulsion tube can be reliably protected from corrosion, and the corrosion protection layer is formed of a synthetic resin having high hardness. It is described that when the screw joint type propulsion pipe is propelled, it is possible to prevent the corrosion protection layer from being damaged by friction with earth and sand.

[0010]

However, the technique disclosed in Japanese Patent Application Laid-Open No. 10-131666 has the following problems.

When laying a coated steel pipe in the ground by the propulsion method, it is necessary to reduce the time required for the propulsion method, and to include the resin material cost and the offline required for coating the resin on the outer surface of the joint. It is required to reduce the cost of resin coating. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reduces damage due to friction with earth and sand at the time of propulsion, as well as a resin material cost required for resin coating of an outer surface of a screw portion and a resin coating construction cost. It is an object of the present invention to provide a threaded joint type propulsion pipe structure capable of reducing the like.

[0012]

A first aspect of the present invention is a screw joint type propulsion pipe structure in which the ends of adjacent outer resin-coated steel pipes are screw-connected, and wherein the outer resin-coated steel pipes are screwed to each other. Resin coating is applied to the outer surface of the outer portion, and the resin coating on the outer surface of the threaded portion of the preceding outer surface resin coated steel pipe is harder than the resin coating on the outer surface of the threaded portion of the subsequent outer surface resin coated steel tube with respect to the propulsion direction. And a screw joint type propulsion pipe structure characterized by being a resin coating having a high hardness.

A second invention is characterized in that, in the first invention, the screw portion of the following outer resin-coated steel pipe is a male screw portion, and the screw portion of the preceding outer resin-coated steel pipe is a female screw portion. The screw joint type propulsion pipe structure according to claim 1. According to the present invention, with the above configuration, at least the surface layer of the resin coating on the outer surface of the thread portion of the outer resin-coated steel pipe preceding the propulsion direction is harder than the resin coating on the outer surface of the screw portion of the subsequent outer resin-coated steel pipe. High abrasion resistance due to high resin coating, reduces damage due to friction with earth and sand during propulsion, and reduces resin material cost required for resin coating on the outer surface of screw part, resin coating construction cost, etc. it can.

In the above, the resin coating on the outer surface of the screw portion of the subsequent outer resin-coated steel pipe can be coated with the same or similar hardness as the resin coating of the outer resin-coated steel pipe.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view showing an embodiment of the present invention, and FIG. 2 is a side sectional view of FIG.

The screw joint type propulsion tube 10 has an externally threaded portion 11 at the end, an outer surface resin-coated steel tube 10a having an outer surface coated with a resin 13, and an inner threaded portion 12 at the end, and an outer surface coated with a resin. It has a structure in which the outer resin-coated steel pipe 10b formed as above is screwed. Here, the male screw portion 11 and the female screw portion 12 have the same inner diameter as the outer resin-coated steel pipes 10a and 10b, and are screwed together by increasing the outer diameter. As a result, fluids such as gas and water in the outer resin-coated steel pipes 10a and 10b are smoothly transported.

An anticorrosion sheet 16 made of a heat-shrinkable polyethylene sheet coated with a rubber-based adhesive is wound around an exposed portion by screw bonding, and is shrunk by heating with a heating device such as a burner and fixed. In order to prevent the fixing portion from being turned up during propulsion, the female screw portion 1 of the outer resin-coated steel pipe 10b is used.
A step 15 is provided at the tip of the second member.

The screw joint type propulsion tube 10 is propelled in a propulsion direction shown by an arrow. The male screw part 11 is an outer resin-coated steel pipe 10
The female screw 12 is welded to the end of the outer resin-coated steel pipe 10b to be integrated with the end of the outer resin-coated steel pipe 10b. A resin coating is applied to the outer surfaces of the screw portions of the screwed outer resin-coated steel pipes 10a and 10b.
A polyethylene resin-coated steel pipe or the like is used for the outer resin-coated steel pipes 10a and 10b.

The resin coating on the outer surface of the screw portion 11 of the outer resin-coated steel pipe 10a following the propulsion direction is the same resin coating as the resin coating 13 of the outer resin-coated steel pipe 10a. When a polyethylene resin-coated steel pipe is used as the outer resin-coated steel pipe 10a, the resin coating 13 on the outer surface of the screw portion 11 is also coated with polyethylene.

However, the present invention is not limited to the resin coating having the same hardness as the resin coating 13 of the outer resin-coated steel pipe 10a.
The hardness can be set to about ± 10, and a resin coating corresponding to the range can be applied. This is because a difference in wear resistance is hard to appear in this range. Outer surface resin coated steel pipe 10a
When a polyethylene steel pipe is used, the polyethylene resin-coated steel pipe has a Shore hardness (D) of 44 to 50. Therefore, a Shore hardness (D) of 35 to 44 and a hardness of about 50 to 60 are treated as similar hardness. For example, a fluororesin (tetrafluoroethylene-hexafluoropropylene copolymer:
The Shore hardness (D) of PFEP is 50-6 among 55).
0 can be treated as a resin coating of similar hardness.

After the outer resin-coated steel pipe 10a is buried in the soil by the propulsion method, it is required to have a function such as corrosion protection by resin coating. Since the same function as that of the resin coating of the steel pipe 10a is required, a resin coating having the same function and a similar hardness can be used.

On the other hand, the outer surface of the screw portion 12 of the preceding outer resin-coated steel pipe 10b has a resin coating 1 having a higher hardness than the resin coating 13 of the outer resin-coated steel pipe 10a (the outer resin-coated steel pipe 10b).
4 is required.

The thread portion 1 of the preceding external resin-coated steel pipe 10b
(2) The resin coating 14 on the outer surface is replaced by the subsequent outer resin-coated steel pipe 10a
The resin coating 14 having a higher hardness than the outer surface of the screw portion 11 is used for the following reason.

The screw joint type propulsion pipe to which the present invention is directed is:
It is laid in the soil by a direct push propulsion method of propelling directly into the soil, and the outer surfaces of the threaded portions 11 and 12 of the outer resin-coated steel pipes 10a and 10b are screwed by expanding the outer diameter as described above. are doing. For this purpose, when the screw joint type propulsion pipe is propelled, the tapered resin coatings 13a and 14a coated on the outer diameter-enlarged portions of the screw portions 11 and 12 connected to the external resin-coated steel pipes 10a and 10b are separated from each other. It was thought to be severely damaged compared to the part.

However, from actual experience, etc., the tapered resin coating 13a covering the enlarged diameter portion on the outer surface of the screw portion 11 of the subsequent external resin-coated steel pipe 10a is hardly damaged, and the preceding external resin-coated steel pipe 10a is hardly damaged. In the present invention, the tapered resin coating 14a coated on the enlarged diameter portion of the outer surface of the threaded portion 10b is severely damaged in a biased manner.
The resin coating on the outer surface of the screw portion 12 of 0b is limited to applying the resin coating 14 having at least a surface layer having a higher hardness than the resin coating 13 on the outer surface of the screw portion 11 of the subsequent external resin-coated steel pipe 10a. This can increase wear resistance and reduce damage to the same or lesser extent than other parts.

The reason why the hardness is selected based on the wear resistance standard is as follows. Wear is a phenomenon in which the surface of a solid gradually decreases due to friction with other objects, but is a very complex phenomenon. The vertical load on the contact surface, the relative speed at the contact surface, the state of the friction surface ( Surface roughness, hardness, uneven shape, etc.).

In the present invention, based on the above, the hardness of the frictional surface is selected based on the hardness, and the outer surface resin-coated steel pipe 10a,
In the resin coating on the outer surfaces of the threaded portions 11 and 12 of 10b, at least the surface layer portion of the resin coating on the outer surface of the threaded portion 12 of the outer surface resin-coated steel tube 10b in the propulsion direction includes the screw of the preceding outer surface resin-coated steel tube 10a. Resin coating 13 on outer surface of part 11
The resin coating 14 having higher hardness is applied.

In the resin coating 14 on the outer surface of the screw portion 12,
At least the surface layer, by applying a higher hardness resin coating on the surface layer affected during propulsion,
By reducing damage to the same or lesser extent than other parts. When only the surface layer is coated with a resin having high hardness, the lower layer is coated with a resin having the same or similar hardness as the outer surface resin-coated steel pipe 10a, and the screw portion 12 after propulsion is formed.
The outer surface can be protected similarly to the outer surface resin-coated steel pipe 10a.

Further, the entire resin coating on the outer surface of the screw portion 12 is
By applying a resin coating having higher hardness, the outer surface of the screw portion 12 after propulsion can be protected by itself in the same manner as the outer resin-coated steel pipe 10a.

Outer surface resin-coated steel pipes 10a, 10b
In the case where a polyethylene-coated steel pipe is used, the resin coating on the outer surface of the screw portion 12 of the subsequent outer resin-coated steel pipe 10b will be described.

As described above, the polyethylene coating hardness of the polyethylene-coated steel pipe is 44 in Shore hardness (D).
Therefore, the resin coating 14 mainly composed of a hard vinyl chloride resin was applied as the resin coating 14 to the outer surface of the screw portion 12 of the preceding external resin-coated steel pipe 10b. Hard vinyl chloride resin has a Shore hardness (D) of 65 to 80, and hard vinyl chloride resin is also used as a material for a propulsion pipe because of its light weight, corrosion resistance, and wear resistance.

The tricyclic dicyclopentadiene is coated with a resin (commercially available) substituted with an alkyl such as methyl or ethyl, an alkenyl such as vinyl, an acrylidene such as ethylidene, or an aryl such as phenyl. be able to. It is known that the resin coating has a Shore hardness (D) of about 80.

Screw part 1 of the preceding external resin-coated steel pipe 10b
(2) The resin coating on the outer surface can be easily applied off-line using a mold or the like.

In the embodiment shown in FIGS. 1 and 2, the outer resin-coated steel pipe 10a and the outer resin-coated steel pipe 10b are screwed together by screwing the externally resin-coated steel pipe 10a with a male screw in the propulsion direction. Although the case where the screw portion 12 of the preceding outer resin-coated steel pipe 10b is preferably a female screw portion has been described, the screw portion 12 of the preceding outer resin-coated steel tube 10b may be a male screw portion. .

As shown in the above embodiment, in the present invention, when the screwed outer resin-coated steel pipe is propelled, the gap between the tapered portion of the expanded threaded portion of the preceding outer resin-coated steel pipe and the earth and sand is reduced. Even if friction occurs, the outer surface layer of the screw part is coated with a resin that is harder than other parts, so it has high abrasion resistance and damages to the same extent or less as other parts. Can be reduced.

According to the present invention, a resin coating having a higher hardness is applied only to portions where damage is likely to occur during propulsion, and other portions are applied with a resin coating having the same or similar hardness as the resin coating of the outer resin-coated steel pipe. It is possible to reduce the cost of the coating material and the cost of the resin coating including the off-line.

FIG. 3 is a sectional side view of a main part showing another embodiment of the present invention. 1 and 2 are denoted by the same reference numerals, and a part of the description is omitted. The screw joint type propulsion pipe 17 is formed by screwing an external resin-coated steel pipe 10a having a male threaded portion 11 at an end and coated with a resin 13 and an external resin-coated steel pipe 10b having a female threaded portion 12 at an end and coated with a resin 14. It has a joined structure. A polyethylene-coated steel pipe was used as the outer resin-coated steel pipe. The resin coating 14 has a multilayer structure, and is formed of a surface layer portion 18 and a lower layer 19. The resin coating of the surface layer portion 18 is a dicyclopentadiene resin coating,
The lower layer 19 was provided with a polyethylene coating.

According to the above screw joint type propulsion pipe structure, damage due to friction with sand or the like during propulsion is reduced, and characteristics such as corrosion resistance after propulsion are equal to or higher than the resin coating 13 of the outer resin-coated steel pipe. Can be held.

[0039]

According to the present invention, it is possible to reduce damage due to friction with earth and sand during traveling, and also to reduce resin material costs required for resin coating of the outer surface of the screw portion, resin coating construction costs, and the like.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a sectional side view of a main part showing another embodiment of the present invention.

FIG. 4 is a half sectional view showing a screw joining step of a conventional screw joint type propulsion pipe.

[Explanation of symbols]

 10, 17 Screw joint type propulsion pipe 10a, 10b Outer resin-coated steel pipe 11 Male screw part 12 Female screw part 13 Resin coating 14, 20 Resin coating 13a, 14a Tapered resin coating 15 Step 16 Corrosion prevention sheet 18 Surface layer 19 Lower layer 19

Continuation of the front page (72) Eiji Matsuyama Inventor 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 3H013 JB03 JB05

Claims (2)

[Claims] 1. A screw joint type propulsion pipe structure in which ends of adjacent outer resin-coated steel pipes are screw-joined, wherein an outer surface of a screw-joined screw portion of the outer resin-coated steel pipe is resin-coated, and propulsion is performed. With respect to the direction, the resin coating of the threaded outer surface of the preceding outer resin-coated steel pipe is characterized in that at least the surface layer is a resin coating having a higher hardness than the resin coating of the screwed outer surface of the subsequent outer resin-coated steel pipe. Screw joint type propulsion pipe structure. 2. The screw joint type according to claim 1, wherein the screw portion of the following outer resin-coated steel pipe is a male screw portion, and the screw portion of the preceding outer resin-coated steel pipe is a female screw portion. Propulsion pipe structure.