JP3397232B2 - Loose flange type pipe fittings for polyethylene pipes - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint for a plastic pipe used for transporting fluid such as waterworks, gas and sewers.

[0002]

2. Description of the Related Art In recent years, the use of plastic pipes has been recognized as water, sewage, gas, and other pipelines. Compared to conventional cast iron pipes and steel pipes, they have superior corrosion resistance and can be lightened in addition to corrosion-resistant coating applied to the inside and outside surfaces. Some have good workability and flexibility. . Although it is pointed out that the physical properties such as strength, pressure resistance, and elongation are still less than those of steel materials and other metal materials, it is pointed out that research and development has led to improvements in the plastic materials themselves, and relatively light load. In many cases, it is recognized that the advantages of the buried small-diameter pipe are superior.

Naturally, pipe joining is indispensable for the formation of pipes, and from the viewpoint of how efficiently construction can be performed and how to cope with ground fluctuations and impacts after being buried in the ground. Therefore, the structure of the pipe joint is comparatively evaluated.

In Japan, hard vinyl chloride pipes were mainly used as plastic pipes in the beginning, and they have been used for a long time for forming pipe lines. However, static, dynamic strength, corrosion resistance, weather resistance, and other quality over time. By comparing the rate of change, the superiority of polyethylene is recognized again, and especially as a pipe material for supplying drinking water, which has a close impact on human health, such as a water supply pipeline, it is harmless and does not change its corrosion resistance. The current situation is that it is highly evaluated. In addition, for example, a survey of a region directly hit by the Great Hanshin-Awaji Earthquake found that the damage to pipes made of polyethylene pipes was minimal, arousing strong social interest, and it is becoming increasingly important to form new pipes in the future. The position was reached.

Although the same plastic material is used, rigid vinyl chloride and polyethylene have completely different chemical components and molecular structures, so that there is a natural difference in joining pipes. Since the joining of pipes is indispensable for the formation of the pipeline, one of the requirements that cannot be overlooked is the difference in joining methods due to the difference in materials. Conventionally, rigid vinyl chloride joining methods are roughly divided into two types, one of which is TS
(Taper Size Solvent Weld
ing Method), which is a bonding method, in which an adhesive agent is applied to the joint surfaces and the tapered surfaces of the surface of the pipe material are chemically swollen (dissolved) at room temperature to press the pressed surfaces together. There is another method called the lavering method, but at present, the TS method is widely used as the main stream of rigid vinyl chloride joining.

On the other hand, in the case of polyethylene, a bonding method in which a chemical reaction is caused on the surface by a chemical such as hard vinyl chloride to partially melt (soften) is unsuitable. Therefore, in general, fusion bonding, that is, a bonding surface of materials is used. A method is adopted in which the materials are heated to partially heat-melt and are integrally surface-bonded. Of these fusion bonding methods, the most generalized method is the electrofusion method, in which nichrome wire is placed in advance in a mold corresponding to one of the two surfaces to be joined and then the molten polyethylene is melted. This is a method in which the injection molding is performed, and at the time of joining, electric current is applied to the embedded nichrome wire by superposing both surfaces of the joint, and the both surfaces are melted and integrally joined by the heat generation effect of the nichrome wire.

[0007] However, the fusion method such as electrofusion, which is the optimum joining method, is not suitable for the work of joining pipes to form a long pipe at the open-air site such as laying a water pipe. There is a big weakness that is unfamiliar. In other words, partially energizing the joint at the site of installation to partially melt the surface of the pipe material causes water droplets to adhere to it during rainfall and hinders reliable fusion, leading to fluctuations in the water sealing function of the joint. ing. In addition, when water flow was jetted out for some reason into the polyethylene pipe being used, a water leakage accident occurred and emergency repairs were required, even when the uninterrupted water method (live pipe repair) was applied, it was repaired. There is a quality problem that the water sealing action of the joint part cannot be guaranteed completely, and even in the piping work necessary for assembling and repairing equipment such as temporary piping that involves joining and dismantling removal, joining by fusion does not Refusing to reuse the material is unavoidable financial disadvantage.

Therefore, for joining polyethylene pipes, it is a matter of course that a mechanical joining method, that is, a mechanical joint method is desired instead of the fusion-bonding method which is the main body of the prior art. . Similar to other pipe materials, the mechanical joint method is subdivided into various types, but the loose flange joint is the simplest method that requires less time, materials, and labor for on-site construction. In this method, as shown in FIG. 5, a polyethylene flange adapter 102 is welded to both ends of a polyethylene pipe 101 in a factory in advance by butt fusion, or using an electrofusion socket, and the pipe is laid on site. Bring in. The flange adapter is a flanged cylindrical body having a core portion 103 having the same inner and outer diameters as the polyethylene pipe and an annular protrusion 104 at the tip. For joining, the loose flanges 105 are fastened by bolt nuts 106 in contact with the outer surfaces of the annular protrusions 104 respectively, and a flat gasket 107 is pressed between the opposing inner surfaces of the annular protrusions to prevent water leakage from inside the pipe. It is configured to fulfill the water sealing function. This method has a simple on-site laying work and can be easily constructed by combining a small number of members, so it is used in a wide range of mechanical joint methods.

[0009]

With regard to the joining of polyethylene materials, which are mainly fusion-bonded, mechanical joints are evaluated to be more suitable for pipe joints where local construction is an essential condition. However, even in this case, a new problem remains due to the fact that the pipe material is polyethylene. FIG. 6 exemplifies one of the problems in the joint portion of the loose flange type mechanical joint shown in FIG. 5, and when both loose flanges 105, which are usually made of metal, are excessively tightened with bolts and nuts 106 during construction. Alternatively, even if the fastening is appropriately performed and the joining is completed, the flange adapter 102 may be rubbed into the ground due to the creep of the polyethylene itself with the passage of time.
It is undeniable that there is a possibility that the annular projection 104 at the distal end portion may be buckled and fall inward, resulting in a loss of the water sealing function of the gasket 107 that has been pressed between the annular projections, leading to a water leakage accident.

Further, FIG. 7 shows that the ground subsidence and the passage of the vehicle are repeatedly applied to the pipeline buried in the ground, an eccentric load is applied, or a sudden rocking due to an earthquake directly hits and the fastening force by the bolt nut 106 is applied. When it exceeds, since the joint has no swallowing margin, the loose flange 105 of the joint portion is displaced by an external force, the axis lines of the flange adapters 102 are displaced, and the surface contact of the end surface of the annular protrusion 104 is separated, and the water of the gasket 107 that is clinging is stuck. It is assumed that the sealing force will be lost and the cause of water leakage will be formed, and it is fully expected that such an accident will occur.

The conventional technique of replacing the step of joining pipes by a fusion bonding method with a mechanical structure that does not involve melting is a subject that is sometimes found when other materials are used. For example, in Japanese Unexamined Patent Publication No. 7-145885, as shown in FIG. 8, in order to perform renewal, extension, and branching of metal pipes for water supply and hot water supply, in particular, copper pipes, conventionally, a melting action due to heat, such as brazing, is used. Although I was using it, I presented a technology that changed to a mechanical joint so that it could be installed in a narrow space. In this configuration, the first and second flanges 203 and 204 are fastened to the joint portion of the two pipes 201 and 202,
Further, the second flange 204 is sandwiched by the taper ring 205.
And the third flange 206 are fastened together to fix the whole. However, although such a method enables non-melting joining and the advantage of improving the water sealing action can be evaluated, the number and types of members are large, and the mutual fastening work at the site is lost complicatedly. It cannot be said that the loose flange method of FIG. 5 can be substituted.

In addition to this, a special pipe type joining method, for example, a joint for a heat insulating pipe formed by extruding foamed plastic on a thin metal pipe (Japanese Patent Publication No. 58-40074), or a compressible lining for corrosion protection on a metal pipe Although there is no time to enumerate joints for pipes lined with a pipe (Japanese Patent Laid-Open No. 7-69030), all of them solve the above-mentioned problems while maintaining the features of the loose-flange system, which is convenient for local joining of polyethylene pipes. I have to say that there is a distant gap as a technical means.

In order to solve the above problems, the present invention is a new pipe joint that is most suitable for the on-site joining of polyethylene pipes by the loosest flange system, and that reliably prevents troubles due to the material during service. For the purpose of providing.

[0014]

A loose-flange type pipe joint for polyethylene pipes according to the present invention has a polyethylene flange adapter 2 fused to the end faces of two polyethylene pipes 1, each having an inner and outer diameter of polyethylene pipe 1. A core portion 21 having the same diameter and an annular protrusion 22 projecting in a brim shape on a side surface opposite to the fusion-bonding portion 11, and a side surface on the opposite side with the gasket 3 sandwiched between the opposed side surfaces 23 of the annular projections 22. 24 is a pipe joint in which loose flanges 4 are attached and both loose flanges 4 are fastened with bolts and nuts 5, and in particular, a water-stop core pipe 6 existing between both flange adapters 2 is an inner circumference of the flange adapter 2. An annular core portion 61 attached to the surface
And the annular projections 22 are formed between the side surfaces 23 facing each other, and are formed of a metal cylinder body having a rigidity that can sufficiently resist the maximum external force expected from the material, and The gasket 3 that fits into the annular grooves 63 formed on both side surfaces of the water flange 62 is formed of a rubber ring having a D-shaped or O-shaped cross section, and a part of the gasket 3 is fitted into the annular groove 63. The above-mentioned problem was solved by providing a self-sealing action that deforms the water between both water stop flanges 62, and automatically increases the initial surface pressure when the water pressure increases to further strengthen the water sealing action.

As another embodiment, when one of the two parts to be joined is made of a polyethylene pipe 1 and the other is made of another material having higher rigidity such as ductile cast iron pipe, the core portion 6 of the water-stop core pipe 6A.
It is desirable that 1A be formed only on the side that fits inside the polyethylene pipe.

With this structure, the joint portion is reinforced by the water blocking core tube having rigidity sufficient to withstand the load of the external force expected, so that the flange adapter 2 receives the external force.
There is no concern that the annular projection 22 of the above will undergo creep deformation, and any water leakage accident from the gasket portion will be prevented.
In addition, even if an excessive eccentric load is directly hit by an earthquake or the like, the core part of the water-resistant core pipe with high rigidity maintains the relative positional relationship between the pipes against the shearing force that tends to shift the annular projection surface. Then, the above problem is solved by maintaining the water sealing action.

When one is a polyethylene pipe and the other is made of a different material such as ductile cast iron pipe, when a new pipeline is extended to an existing pipeline or when temporary piping is carried out in the facility due to construction work It is a mode that often occurs in such as. At this time, it is not necessary to reinforce the ductile cast iron pipe, which is originally highly rigid, so only one polyethylene pipe should be reinforced by fitting the core part of the water-stop core pipe inward, and the duct flange or push ring of the ductile cast iron pipe should be reinforced. It suffices to fasten the flange and the loose flange attached to the outer surface of the flange adapter fused to the polyethylene pipe. This has the advantage of reducing the weight of the waterproof core pipe and streamlining the construction.

With regard to the gasket, in the case of a flat rubber ring which has been generalized in the prior art, it is expected that if the center points of both annular projections of the flange adapter are not aligned at the time of joining, the result will be that the water will flow out. Although it is troublesome just to match the pipe axes, the work load was remarkably heavy in order to align and check the center of the rubber ring. However, in the case of the present invention, the annular groove 63 of the water stop flange 62 is previously joined before joining. If the gasket 3 is fitted, this complicated centering work is released. Further, when the gasket itself is interposed as a ring-shaped ring having a D-shaped or O-shaped cross section from the left and right, for example, when the polyethylene ring-shaped projection is about to be deformed under pressure by an external force, the initial surface pressure at the time of mounting is reduced. Since the so-called self-sealing action that increases proportionally works, the action that rapidly strengthens the water sealing function works to further promote the solution of the problem.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The object of the present invention relates to a pipe joint in which at least one pipe material is a polyethylene material, and FIG. 1 shows a mode in which two polyethylene pipes 1 are joined. The joint type belongs to the well-known loose flange system, and the end faces of the core portions 21 of the polyethylene flange adapters 2 are welded to the ends of both polyethylene pipes 1 by butt fusion or electrofusion sockets. Fix in part 11. The opposite end surface of the core portion 21 has an annular projection 22 protruding like a collar, and the water stop flange 62 of the water stop core tube 6 is sandwiched between the side surfaces 23 facing each other, and the side surface 24 on the opposite side of the annular projection 22 is provided. Along with this, the loose flange 4 is attached and the bolt nut 5 is used for fastening.

FIG. 2 is a sectional front view (A) and a partial side view (B) of only the waterproof core pipe 6 which is commonly fitted in the core portion of the flange adapter 2. The water-stop core tube is composed of a core portion 61 and a water-stop flange 62, the outer diameter of the core portion 61 is made to the minimum inner diameter tolerance of the core portion 21 of the flange adapter, and the water-stop flange projecting to the outer peripheral side in the center. 62 is manufactured integrally, but it is also possible to divide both and manufacture two cylindrical bodies and one donut-shaped annular plate separately and combine them. The important requirements are the maximum external force expected during service, even when subjected to severe horizontal and vertical swings during an earthquake,
By maintaining the rigidity to reinforce from the back side so that the tube axes of the core parts on both sides are not displaced or the annular projection itself is buckled and deformed so that the surface contact of the annular projection 21 is not released and the water seal state is broken. Yes, because it is a metal material with this mechanical strength, and it is required to be a material that does not rust or pollute the water quality even if it constantly contacts water flow,
It is desirable to select from non-ferrous metals such as 18-8 stainless steel, corrosion resistant alloy steel of equal or higher grade, and copper alloy.

An annular groove 63 is formed on both sides of the water-stop flange 62 of the water-stop core tube 6, and a part (curved surface) of the gasket 3 made of a rubber ring having a D-shaped cross section is fitted into the groove. But
The cross section may be O-shaped. These gaskets are not only flatly sandwiched between opposed flange surfaces like a flat gasket (eg, gasket 107 in FIG. 6) often used in the prior art, but are also preliminarily formed in the annular groove of the waterproof core pipe in advance. There is no need for core alignment because it is used for joining work after fitting a part of it, workability is improved, and there is no concern that the water sealing action will be reduced due to misalignment of the core. In addition, the gasket of this form has a characteristic that a so-called self-sealing effect appears, and the initial surface pressure is given by the fastening of the bolts and nuts, but thereafter, when the water pressure is newly increased, the surface pressure automatically increases. As a result, the function of further strengthening the water-sealing action is exerted, so that it is possible to guarantee a high water-sealing function which is not found in the flat gaskets of the prior art.

3 (A), (B) and (C) are vertical sectional front views showing the procedure for joining the pipe joint according to the present invention. FIG. (A) One of the water-stop core pipes 6 in which loose flanges 4 are attached to the side surfaces 24 of the annular protrusions 22 of the flange adapter 2 fused to the polyethylene pipe 1, and the curved surface portions of the D-shaped gaskets 3 are fitted respectively. The core portion 61 is fitted into the core portion 21 of the one flange adapter, and is inserted until the one gasket 3 comes into contact with the side surface 23 of the opposed annular projection 22. (B) Insert the other polyethylene pipe 1 until the other gasket 3 fitted to the water stop flange 62 comes into contact with the side surface 23 of the other annular projection 22. Figure (C) Insert the bolt and nut 5 and tighten to the specified torque to finish the joining work.

FIG. 4 is a vertical sectional front view (A) and side view (B) of a waterproof core pipe 6A showing another embodiment of the present invention. One joint pipe is a polyethylene pipe while the other is a ductile cast iron pipe. It shows the case of other tube types. As described above, the object of the present invention includes pipe joining of dissimilar materials having higher rigidity than general plastic materials such as ductile cast iron pipe or steel pipe, or concrete pipe if at least one is a polyethylene pipe, According to the above, other forms are similarly applied. In this case, since reinforcement of polyethylene is not necessary for the high-strength ductile cast iron pipe, the dedicated water-stop core pipe 6A is sufficient with the core portion 61A on one side and the water-stop flange 62A protruding from the end face. The water stop flange 62A may be bolted directly to the socket flange of the ductile cast iron pipe, or may be fastened to the push ring flange, or a known joint structure may be applied, and in this case as well, both surfaces of the water stop flange 62A may be used. Section D with enhanced water sealing
There is no change in that the O-shaped gasket 3A is partially fitted into the annular groove 63A.

[0024]

INDUSTRIAL APPLICABILITY As described above, the present invention is highly adaptable to disasters, lightweight, excellent in workability, and superior in corrosion resistance to polyethylene. Remaining issues and work on joining pipes,
We have succeeded in improving the mechanical joint, which replaces the joining method that depends on fusion bonding. Specifically, the following effects are realized by putting the present invention into practical use. Compared with metal, the rigidity that does not reach is strengthened, so deformation due to creep is eliminated and high water sealing property is maintained. Similarly, even when a sudden eccentric load such as an earthquake hits directly,
There is no risk of impairing the water sealing property because the relative positional relationship between the two pipes is retained without the pipe axis shifting. Compared with the mechanical joint of the prior art, the self-sealing effect is remarkably exhibited by specifying the cross-sectional shape of the gasket, and the risk of surface pressure drop and water leakage due to the creep of polyethylene itself is eliminated. After fitting a part of the gasket into the water-stop core pipe in advance at the time of joining, the flange adapter pipe end is inserted and the pipes are fastened with bolts and nuts, so both pipe axes do not shift and the gasket is It does not deviate from the pipe axis, and construction is easy and accurate, eliminating the concern about water leakage due to this cause. If a pipe joint is formed by a fusion method, which is the mainstream for joining polyethylene, for example, an electrofusion method, disassembling after joining is impossible except for cutting the pipe. However, according to the pipe joint of the present invention, The joints can be easily removed and detached, and various pipes such as temporary pipes, local repairs, renewals, and branches can be easily joined and dismantled, and pipes can be reused repeatedly, reducing material costs. The effect of reducing is extremely large.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view showing an embodiment of the present invention (A).
FIG. 3B is an enlarged view (B) of the main part (range divided into rectangles).

FIG. 2 is a vertical sectional front view (A) and a partial side view (B) showing only a waterproof core tube in the same embodiment.

FIG. 3 is a vertical sectional front view showing a joining procedure according to the present invention by (A), (B) and (C).

FIG. 4 is a vertical sectional front view (A) and a side view (B) showing a water blocking core pipe applied to another embodiment of the present invention.

FIG. 5 is a partially longitudinal front view showing an example of a conventional technique.

FIG. 6 is a partially longitudinal front view showing one of the problems of the conventional technique.

FIG. 7 is a vertical sectional front view showing another aspect of the same conventional technique.

FIG. 8 is a partial vertical sectional front view showing another conventional technique.

[Explanation of symbols]

1 polyethylene pipe 2 Flange adapter 3 gasket 4 loose flange 5 bolt nut 6 Water-stop core tube 11 Fusion part 21 Core part 22 annular protrusion 23 Side surface (opposite side of annular projections) 23 Side (opposite side) 61 Core part 62 Water stop flange 63 annular groove

Continuation of the front page (56) Reference JP-A-9-14545 (JP, A) JP-A-7-40458 (JP, A) Actually open Sho 48-47018 (JP, U) Actually open Sho 57-132855 (JP , U) Actual development Sho 57-190191 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16L 21/06 F16L 23/036

Claims (2)

(57) [Claims] 1. A polyethylene flange adapter 2 fused to the end faces of two polyethylene pipes 1 has a core part 21 having the same inner and outer diameters as the inner and outer diameters of the polyethylene pipe 1, and a side face opposite to the fused part 11. Annular protrusion 22 protruding in a brim shape
The gasket 3 is sandwiched between the side surfaces 23 where the annular projections 22 face each other, and the loose flange 4 is attached along the opposite side surface 24.
In the loose-flange type pipe joint for polyethylene pipes to be fastened together with each other, the water-stop core pipe 6 existing between the flange adapters 2 has an annular core portion 61 attached to the inner peripheral surface of the flange adapter 2 and annular protrusions 22 facing each other. The water blocking flanges 62 interposed between the side surfaces 23 are formed of a metal cylinder having a rigidity sufficient to withstand the maximum expected external force in terms of material. The gasket 3 that fits into the engraved annular groove 63 is formed of a rubber ring having a D-shaped or O-shaped cross section, and a part of the gasket 3 is fitted into the annular groove 63, and the remaining portion is between the water-stop flanges 62. A loose-flange type pipe joint for polyethylene pipes, characterized by a self-sealing action that automatically increases the initial surface pressure when the water pressure increases due to strain deformation. 2. The side according to claim 1, wherein one side to be joined is made of a polyethylene pipe 1 and the other side is made of another material having higher rigidity such as ductile cast iron pipe, and the core portion 61A of the water-stop core pipe 6A is fitted inside the polyethylene pipe. A loose flange type pipe joint for polyethylene pipes, characterized in that it is formed only on the.