JPH11336958A - Connection structure for plastic pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure for a plastic pipe capable of sufficiently ensuring strength of a connection part even in the case of passing a fluid of high pressure and high temperature in piping without delaying piping work. SOLUTION: This connection structure comprises coating a connection part of plastic pipes 1, 2 with a high strength fiber sheet 8 having high heat resistance, and coating the connection part of the plastic pipes 1, 2 connected by an electric fusing joint 11 with the high strength fiber sheet 8 having high heat resistance. The high strength fiber sheet 8 having high heat resistance is a woven fabric sheet by twisting many fiber filaments into a multi-filament and arranging a large number of these multi-filaments knitted in one or two directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining structure of a plastic pipe suitable for forming a pipe line made of a plastic pipe through which tap water, sewage water, hot spring water and the like flow.

[0002]

2. Description of the Related Art Conventionally, cast iron pipes have been used as transport pipes for distributing clean water, sewage water, hot spring water, etc. because of their high strength.
Metal pipes such as steel pipes were used. And, such a transport pipe has been used for 30 years, 40 years, unless otherwise damaged or ruptured.
Used for as long as a year. But cast iron tubes,
Metal pipes such as steel pipes are easily corroded by water, sewage, hot spring water and the like flowing through the pipes, and are easily corroded by rainwater, chemical substances, and the like, and have a problem in durability. In addition, since it has a large specific gravity and does not have flexibility, there is a problem that a great deal of time and labor is required for the installation work. Therefore, in recent years, plastic pipes made of vinyl chloride, phenol, polyethylene or the like have come to be used to solve such problems.

[0003] A pipe line for flowing clean water, sewage water, hot spring water and the like is formed by connecting a large number of such plastic conduits. In the case of a plastic conduit, a flange is formed and bolts and nuts are used. Since fastening and joining are not appropriate in terms of strength, the end faces of the plastic conduits are usually joined by heat welding. That is, as shown in FIGS. 7 and 8, the heater plate is brought into contact with the end faces of the plastic conduits 51 and 52 to be melted,
A butt fusion method in which the end surfaces of the plastic conduits 51 and 52 are brought into contact with each other and joined, as shown in FIG. 9, into a fitting hole 55 of an electric fusion joint 54 in which a heating wire 53 is disposed on the inner wall surface. An electric fusion method of inserting the ends of the plastic conduits 51 and 52, causing the heating wire 53 to generate heat, melting the ends of the plastic conduits 51 and 52, and joining the end faces of the plastic conduits 51 and 52, etc. This joins the end faces of the plastic conduit.

Here, the joint between the plastic conduits 51 and 52 may have a reduced pressure-resistant strength due to thermal fusion or may not be able to reliably prevent leakage or intrusion of fluid.
As shown in FIG. 9 to FIG. 9, a reinforcing tape 56 formed by knitting glass fibers or the like, a waterproof tape 57 such as a heat-shrinkable tube made of polyethylene, or the like is wound around the joint to prevent such a problem. Further, in the case where a high-pressure, high-temperature fluid is allowed to flow through a pipe line joined by the butt fusion method, the strength of the conventional reinforcing tape 56 cannot be sufficiently secured, and the joint may be deformed or the reinforcing tape may be deformed. 8 is melted, and fluid leaks and intrudes from the joint.
As shown in the figure, the reinforcing bands 58, 58 made of a thin stainless steel plate having a semicircular cross section are brought into contact with the joint,
It was tightened with bolts and nuts to ensure the strength of the joint.

[0005]

As described above, in a case where a high-pressure, high-temperature fluid is allowed to flow through a pipe line joined by the butt fusion method, the reinforcing bands 58, 58 are brought into contact with the joint portion. Work to tighten with bolts and nuts,
This was troublesome and time-consuming, and was a factor in delaying the work of forming the piping. It has been installed for 30 years, 40
After a lapse of years, the reinforcing bands 58, 58 are corroded by rainwater, chemical substances, and the like, and cannot function as a reinforcing material.

In the case where a high-pressure, high-temperature fluid is allowed to flow through a pipe line joined by the electric fusion method, stress concentration occurs at both end positions of the electric fusion joint 54 of the plastic conduits 51, 52. And cracks, damage, and the like are likely to occur.

The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to supply a high-pressure, high-temperature fluid through a pipe line.
An object of the present invention is to provide a joint structure for a plastic pipe, which can secure the strength of the joint sufficiently, does not delay the operation of forming the piping path, and can secure the strength of the joint for a long period of time.

[0008]

In order to achieve the above object, a joint structure for a plastic conduit according to the present invention comprises a joint portion of a plastic conduit coated with a high-strength fiber sheet having high heat resistance. It is.

Further, the joint structure of a plastic conduit according to the present invention is obtained by coating a joint portion of a plastic conduit joined by an electric fusion joint with a high-strength fiber sheet having high heat resistance.

Here, if a bonding agent is attached to both outer sides of the electrofusion joint and a high-strength fiber sheet having high heat resistance is coated thereon, the strength of the bonding portion can be further improved, which is preferable. .

When a high-strength fiber sheet having high heat resistance is spirally wound around a joint portion of a plastic conduit and impregnated with a curing agent from above, and fixed, a high-strength fiber sheet having high heat resistance can be formed. It can be completely integrated at the junction of the production conduit.

Further, if the high-strength fiber sheet having high heat resistance is spirally wound around the joining portion of the plastic conduit so as to overlap, and a plurality of fiber sheet layers are formed, the pressure resistance and the durability can be further improved. Can be improved.

The high-strength fiber sheet having high heat resistance is formed into a knitted and woven fabric sheet by knitting a number of fiber filaments into a multifilament and arranging and knitting the multifilaments in a large number in one or two directions. The filament is preferably a fiber having flexibility, high elastic modulus, and high tensile strength, such as aramid fiber.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, since the plastic conduit is joined by heat fusion, the plastic conduit which is an object of the present invention is a conduit made of a thermoplastic resin such as vinyl chloride or polyethylene.

First, the joining structure of the plastic conduit of the present invention when the butt fusion method is adopted will be described.
The work procedure will be described. In the butt fusion method, as shown in FIG. 1, a heater plate 3, a conduit moving pressing device 4, and the like are used.

The end of the plastic conduit 1 is fixed to the fixed support 5 of the conduit moving and pressing device 4 and the end of the plastic conduit 2 is fixed to the moving support 6 of the conduit moving and pressing device 4 in advance.
While supporting, the plate support leg 7 is fixed to the conduit moving pressing device 4. First, the heater plate 3 is lowered, and the heater surfaces 3a and 3b are connected to the plastic conduits 1 and 2.
, And the ends of the plastic conduits 1 and 2 are melted. Next, after raising the heater plate 3, the moving support portion 6 is slid to move the plastic conduit 1.
The end face of the plastic pipe 2 is brought into contact with the end face of the plastic pipe 2 and pressed with a predetermined pressure for a predetermined time to completely join the plastic pipes 1 and 2.

Then, as shown in FIG. 2, a high-strength fiber sheet 8 having high heat resistance is coated on the joints of the fused plastic conduits 1 and 2, and a polyethylene heat-shrinkable tube is further placed thereon. And the like.

As shown in FIG. 7, the high-strength fiber sheet 8 is formed by twisting hundreds to thousands of fiber filaments to form a multifilament 10.
Are knitted and woven fabric sheets formed by knitting a large number in one direction or two directions. As the fiber filament, a fiber having flexibility, high elastic modulus, high heat resistance and high tensile strength, such as aramid fiber, can be used. The aramid fiber has a specific gravity of 1.38 and a tensile strength of about 141 kg / mm ² , is lightweight and has high strength, and is particularly preferable.

The aramid fiber is an aromatic polyamide having a benzene ring in the main chain, and has various properties such as high strength, high elastic modulus, high heat resistance and high chemical resistance. Such aramid fibers are manufactured and sold under the trade names "Kevlar" (registered trademark) by DuPont of the United States, "Twaron" (registered trademark) by Akzo Nobel of the Netherlands, and "Technola" (registered trademark) by Teijin Limited. ing.

Then, the high-strength fiber sheet 8 is spirally wound around the joint of the plastic conduits 1 and 2 and then impregnated with a hardening agent to fix the high-strength fiber sheet 8 thereon. It can be completely integrated into the joint of the conduits 1 and 2, and the joint structure of the plastic conduit of the present invention is constituted.

As the curing agent, methacrylate resin (MMA), methyl ethyl ketone peroxide (ME
KPO), benzoyl peroxide (BPO) and the like can be used. Also, 1/2, 2/3, and 3/4 of the width
It is preferable to spirally wind around the joint of the plastic conduits 1 and 2 so that the fiber sheet 8 and the high-strength fiber sheet 8 overlap each other, and form a plurality of fiber sheet layers of two, three and four layers.

By fixing the high-strength fiber sheet 8 to the joint between the plastic conduits 1 and 2, the high-strength fiber sheet 8 bears the load, pressure and the like received by the joint, and when a large load is applied, Even when high pressure is transported, the joint has sufficient pressure resistance and durability. When a plurality of fiber sheet layers are formed, the pressure resistance and the durability can be further improved.

Since the high-strength fiber sheet 8 has high heat resistance, the high-strength fiber sheet 8 is melted even when a high-pressure, high-temperature fluid is allowed to flow through the piping, and the fluid leaks from the joint. In addition, since the high-strength fiber sheet 8 is simply wound around the joining portion in a helical manner, and is then impregnated with a curing agent and fixed thereon, the joining operation is simple and time-consuming. There is no delay in the work of forming the piping. In addition, since the high-strength fiber sheet 8 is made of an organic material and has high chemical resistance, it does not lose its function as a reinforcing material by being corroded by rainwater, a chemical substance, or the like. Ensure strength.

Next, the joining structure of the plastic pipe according to the present invention in the case where the electrofusion method is adopted will be described step by step. In the electric fusion method, as shown in FIGS. 3 and 4, an electric fusion joint 11 in which a heating wire 13 is disposed on an inner wall surface 12 a of a fitting hole 12 is used. As shown in FIG. 4, the electric fusion joint 11 is formed by winding the heating wire 13 densely a plurality of times at both ends of the inner wall surface 12a to form winding portions 13a and 13b, and connecting both ends 13c and 13d to electrodes. Terminals 15a, 15 disposed on mounting portions 14a, 14b
b.

First, the ends of the plastic conduits 1 and 2 are inserted into the insertion holes 12 of the electrofusion joint 11 until the end surfaces thereof substantially contact each other, and the electrodes 1 are inserted into the electrode mounting portions 14a and 14b.
6a and 16b are mounted. Next, the electrodes 16a, 16b
When a voltage is applied to the heating wire 13 to cause a current to flow to generate heat, the ends of the plastic conduits 1 and 2 are heated and melted. To be joined.

Then, the electrodes 16a and 16b are removed from the electrode mounting portions 14a and 14b, and are joined to the joints of the plastic conduits 1 and 2 integrated with the electric fusion joint 11 as shown in FIG. A high-strength fiber sheet 8 having high heat resistance is coated, and a waterproof tape 9 such as a polyethylene heat-shrinkable tube is further coated thereon.

As described above, the high-strength fiber sheet 8 is a knitted and woven sheet formed by knitting a multifilament 10 formed by twisting fiber filaments in one or two directions as shown in FIG. It is.

This high-strength fiber sheet 8 is
The high-strength fiber sheet 8 is integrated with the electrofusion joint 11 by spirally winding around the joint portion of the plastic conduits 1 and 2 integrated with 1 and by impregnating the hardening agent appropriately thereon and fixing it. It can be completely integrated with the joining portion of the plastic conduits 1 and 2 which has become the above, and the joining structure of the plastic conduit of the present invention is constituted.

Here, the same curing agent as described above can be used. It is also preferable to form a plurality of fiber sheet layers.

By fixing the high-strength fiber sheet 8 to the joint of the plastic conduits 1 and 2 integrated with the electrofusion joint 11, the high-strength fiber sheet 8 bears the load, pressure and the like received by the joint. Since stress concentration at both ends of the plastic fusion joints 11 of the plastic conduits 1 and 2 is reduced and cracks, damages, and the like are less likely to occur, the strength of the joint can be ensured for a long period of time. When a plurality of fiber sheet layers are formed, the pressure resistance and the durability can be further improved.

As shown in FIG. 6, a bonding agent 17 is applied to the outside of both ends of the electric fusion joint 11 to further reduce the stress concentration at both ends of the electric fusion joint 11 of the plastic conduits 1 and 2. The high-strength fiber sheet 8 having high heat resistance may be coated thereon in a slant manner.

As the bonding agent, methacrylate resin (MMA), methyl ethyl ketone peroxide (MEKPO), benzoyl peroxide (BPO) and the like can be used in the same manner as the above-mentioned curing agent.

According to this configuration, the steps at the outer ends of both ends of the electrofusion joint 11 can be eliminated, and the load, pressure and the like received by the joint can be reduced by the high-strength fiber sheet 8 and the joining agent 1.
7 and the high-strength fiber sheet 8 is more completely fixed, so that stress concentration at both end positions of the electric fusion joint 11 of the plastic conduits 1 and 2 can be further reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a case where a plastic conduit is joined by a butt fusion method.

FIG. 2 is a longitudinal sectional view showing a joining structure of a plastic conduit of the present invention when a butt fusion method is adopted.

FIG. 3 is an explanatory view of a case where a plastic conduit is joined by an electrofusion method.

FIG. 4 is a longitudinal sectional view of the electric fusion joint.

FIG. 5 is a longitudinal sectional view showing a joining structure of a plastic conduit of the present invention when an electrofusion method is adopted.

FIG. 6 is a longitudinal sectional view showing a case where a bonding agent is adhered to both outer ends of the electrofusion joint in FIG. 5;

FIG. 7 is a plan view of a high-strength fiber sheet.

FIG. 8 is a longitudinal sectional view showing a conventional joining structure of plastic conduits when a butt fusion method is adopted.

9A and 9B show a case in which a reinforcing band made of a thin stainless steel plate having a semicircular cross section is mounted in FIG. 8, FIG. 9A is a side view, and FIG.

FIG. 10 is a longitudinal sectional view showing a conventional joint structure of a plastic conduit when an electrofusion method is adopted.

[Explanation of symbols]

 1, 2 plastic conduit 8 high-strength fiber sheet 10 multifilament 11 electric fusion joint 17 bonding agent

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kaoru Goto 843-18 Kasugaura, Oji, Oita

Claims (7)

[Claims] 1. A joining structure for a plastic conduit in which a joining portion of the plastic conduit is coated with a high-strength fiber sheet having high heat resistance. 2. A joint structure for a plastic conduit in which a joint portion of a plastic conduit joined by an electric fusion joint is coated with a high-strength fiber sheet having high heat resistance. 3. The plastic conduit according to claim 2, wherein a bonding agent is attached to both outer ends of the electrofusion joint, and the high heat resistant high strength fiber sheet is coated thereon. Joint structure. 4. The high-strength fiber sheet having high heat resistance is spirally wound around a joining portion of a plastic conduit, and is impregnated with a curing agent from above and fixed. The joint structure for a plastic conduit according to item 1. 5. A high-strength fiber sheet having high heat resistance is spirally wound around a joint of a plastic conduit so as to overlap, and a plurality of fiber sheet layers are formed. The joint structure for a plastic conduit according to item 1. 6. The high-strength fiber sheet having high heat resistance is a knitted and woven fabric sheet in which a number of fiber filaments are twisted into a multifilament, and the multifilaments are arranged in a large number in one or two directions and knitted. The joint structure for a plastic conduit according to any one of claims 1 to 5, wherein: 7. The plastic conduit joining structure according to claim 6, wherein the fiber filament is a fiber having flexibility, high elastic modulus, and high tensile strength, such as aramid fiber.