JP2933251B2 - Method for forming gap between inner and outer pipes of refractory two-layer pipe joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a gap between an inner tube and an outer tube of a refractory two-layer pipe joint comprising an inner tube made of a synthetic resin and an outer tube made of a noncombustible material.

[0002]

2. Description of the Related Art Conventionally, pipes made of synthetic resin such as vinyl chloride have properties superior to chemical pipes, such as metal pipes, in terms of chemical resistance, corrosion resistance, inner surface smoothness, workability, etc., and therefore water supply. tube,
Widely used for drainage pipes and ventilation pipes. However, pipes made of synthetic resin such as vinyl chloride have poor fire resistance, are easily burned out in the event of a fire, and have the disadvantage of spreading fire and generating toxic gas. In particular, in high-rise apartment buildings such as condominiums, there is a risk that fire may spread to other compartments through this PVC pipe, which has become a serious problem. Therefore, in order to cover such a drawback, fire-resistant double-layer pipes in which the outer peripheral surface of a pipe made of a synthetic resin such as a pipe made of vinyl chloride is coated with a nonflammable material have come into wide use. This fire-resistant double-layer pipe is, for example, a pipe made of vinyl chloride or plastic coated with fiber-reinforced mortar. In such a fire-resistant double-layer pipe,
Conventionally, stress is generated between the inner and outer tubes due to shrinkage due to drying of the outer tube or thermal expansion due to passage of hot water or the like in the inner tube,
This has caused one problem that cracks occur in the inner and outer tubes.

Therefore, as a countermeasure, a protrusion is provided on the outer side of the inner tube to absorb these stresses, and a gap is formed between the two to prevent a crack from being generated in the inner and outer tubes. There has been proposed a technique of interposing a layered body such as foamed polyethylene between the inner and outer tubes. In addition, assuming that no intermediate material is interposed, the outer peripheral surface of the pipe joint made of synthetic resin is coated with an inorganic noncombustible material and then heat treated, and the outer pipe is expanded by expanding the inner pipe made of synthetic resin. A technique has been proposed in which the material is expanded, and then the inner tube made of synthetic resin is contracted by curing, hardening, and cooling to form a gap between the inner and outer tubes without any inclusion (Japanese Patent Publication No. 60-23010). issue).

However, most of the products obtained by the above-mentioned method are used for drainage pipes or ventilation pipes which are not subjected to internal pressure. Did not reach. However, in a water supply pipe that expands due to pressure from a fluid (for example, water) flowing through the inside of the pipe, the gap obtained by the above measures is insufficient, and there is still a possibility that cracks may occur. Furthermore, synthetic resin HI pipes (impact-resistant hard vinyl chloride pipes) mainly used for water supply pipes are tightly fitted with straight pipes at joint receiving ports to prevent water leakage at joints. There is a need to. Therefore, when a straight pipe and a pipe joint are joined at the time of construction, the expansion of the joint receiving portion outer diameter due to press-fitting of the straight pipe is larger than the VU pipe (hard PVC pipe) normally used for drainage pipes. Had a problem that cracks occurred in the non-combustible outer tube.

Therefore, a first object of the present invention is to absorb the stress caused by expansion and contraction of the inner and outer pipes without providing an intervening member between the inner and outer pipes of the two-layer pipe joint, and particularly to reduce the pressure from the fluid flowing inside. It is an object of the present invention to provide a method for forming a fire-resistant double-layer pipe joint coated with a non-combustible material having a gap for preventing the generation of cracks in a non-combustible outer pipe due to expansion of an inner pipe made of a synthetic resin. Further, a second object of the present invention is to provide a gap that is sufficient to prevent the occurrence of cracks in the noncombustible outer pipe due to an increase in the outer diameter of the receiving portion of the double-layer pipe joint at the time of joining with a straight pipe during construction. An object of the present invention is to provide a method for forming a fire-resistant double-layer pipe joint coated with a noncombustible material.

[0005]

According to the present invention, the pipe joint made of synthetic resin is expanded by applying pressure to the inside thereof.
An outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material constituting an outer tube, and after coating the non-combustible material, the pressure inside the synthetic resin pipe joint is released to release the synthetic resin pipe joint. Is contracted to form a gap between the synthetic resin pipe joint and the outer pipe made of a noncombustible material, thereby achieving the first and second objects.

According to the second aspect of the present invention, a member having a diameter equal to or slightly larger than the outer diameter of the straight pipe to be joined at the time of construction is press-fitted into the socket of the synthetic resin pipe joint to enlarge the socket. The synthetic resin pipe joint is contracted by covering the outer peripheral surface of the enlarged synthetic resin pipe joint with the non-combustible material constituting the outer tube, and removing the member after coating the non-combustible material. The first and second objects are achieved by forming a gap between a synthetic resin pipe joint and an outer pipe made of a noncombustible material. According to the third aspect of the present invention, pressure is applied to the inside of the synthetic resin pipe joint to expand the pipe joint, and the outer diameter of the straight pipe joined to the socket of the synthetic resin pipe joint at the time of construction is slightly larger than that of the straight pipe. A member having a diameter is press-fitted to enlarge the receiving portion, and the outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material constituting an outer pipe. By releasing the pressure inside, and by removing the member, the synthetic resin pipe joint is contracted to form a gap between the synthetic resin pipe joint and the outer pipe made of a noncombustible material. The first and second objects are achieved.

[0007]

In the method for forming a gap between the inner and outer pipes of the fire-resistant double-layer pipe joint according to the first aspect, before the non-combustible material is cured, pressure is applied from inside the synthetic resin inner pipe to expand the inner pipe, thereby covering the non-combustible material. Later, since the synthetic resin pipe joint contracts due to release of pressure, curing, hardening, and cooling, a necessary gap is automatically formed between the inner and outer pipes without any inclusions. In the method for forming a gap between the inner and outer pipes of the fire-resistant double-layered pipe joint according to the second aspect, the member is pressed into the straight pipe insertion port of the pipe joint made of synthetic resin before the incombustible material is cured, and the outer diameter of the receiving port is enlarged. After that, the synthetic resin pipe joint shrinks due to the removal, curing, hardening, and cooling of the member, so that a necessary gap is automatically formed between the inner and outer pipes without any inclusions.

In the method for forming a gap between the inner and outer pipes of the fire-resistant double-layer pipe joint according to the third aspect, pressure is applied from the inside of the synthetic resin inner pipe to expand the non-flammable material before the non-combustible material is cured, and Before curing, the member is press-fitted into the straight pipe insertion port of the synthetic resin pipe joint to increase the outer diameter of the socket, and then the synthetic resin pipe joint contracts due to release of pressure, removal of the member, curing, curing, and cooling As a result, a larger gap is automatically formed between the inner and outer tubes without any inclusions.

[0009]

FIG. 1 shows a first embodiment and a second embodiment of a method for forming a gap between inner and outer pipes of a fire-resistant double-layered pipe joint according to the present invention.
This will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view illustrating a method of manufacturing a pipe joint of a fire-resistant double-layer pipe using a method of forming a gap between inner and outer pipes according to an embodiment of the present invention. The inorganic non-combustible mortar 2a is extruded by an extruder or the like.
PVC pipe outer part 1b passing between connecting pipe 8 and guide core 9
And the inner surface of the mold 7a. PVC pipe inside 1
a, and the space formed by the PVC pipe outer part 1b and the mold 7a is completely sealed by the sealing material 10, so that the PVC pipe 1 has a hole 5a provided in the adapter 5 in advance.
Is sufficiently inflated by the pressure from the hose 4 passing through the hose.

Water, oil, air or the like can be used for pressurizing the inside of the PVC pipe 1, but it is preferable to use water in consideration of the fact that the product is used for tap water. In this case, the adapter 6 is provided with an openable / closable air vent hole (not shown). In this embodiment, the water pressure inside the PVC pipe 1 was 15 kg / cm ² , but was 0.5 kg / cm ² to 4 kg / cm ^2.
0 kg / cm ² is possible, preferably 5 kg / c
m ² -25 kg / cm ² . The pressurization of the inside of the PVC pipe 1 may be performed after the outer peripheral surface is coated with the mortar 2 as a non-combustible material, but before the curing of the non-combustible material. Within 2 hours before coating and heat curing after coating, the coating portion has sufficient plasticity, so that the coating portion can be expanded by expansion of the PVC pipe 1. Further, the outer tube made of a noncombustible material can be compressed and densified.

The timing of releasing the pressure applied to the inside may be before or after curing of the mortar 2 as a non-combustible material. Even before curing and curing, the expanded covering portion (mortars 2) has a sufficient shape-retaining force, so that the covering portion does not immediately contract upon contraction of the PVC pipe 1 due to pressure release, If the pressure is released before curing, a gap 3 is formed at this point.

Furthermore, in this embodiment, the PVC pipe 1 may be pre-heated before pressurizing.
Has an effect of further increasing the gap 3 with the mortar 2 which is the outer tube after releasing the pressure, curing, and cooling. In this case, the heating temperature of the PVC pipe 1 is 55 ° C.
However, a temperature of 40 ° C. to 70 ° C. is possible, and preferably 50 ° C. to 65 ° C. FIG. 2 is a sectional view of the fire-resistant double-layer pipe joint in which the gap 3 is formed in this embodiment. The gap 3 formed between the PVC pipe 1 and the mortar 2 of this product was 0.5 mm. In this embodiment, the PVC pipe 1
When the pressure applied to the inside of the space is made higher, the gap 3 formed can be made larger. Therefore, the gap 3 having a desired size can be obtained by adjusting the applied pressure. The gap 3 formed in this manner absorbs the stress caused by the expansion of the PVC pipe 1 due to the internal pressure when it is used for water supply and the thermal expansion of the PVC pipe 1 when it is used for drainage, and The generation of cracks in the noncombustible outer tube of Class 2 can be prevented.

FIG. 3 is a sectional view showing the formation of the gap 3 in the second embodiment of the present invention. The press-fitting member 11 is press-fitted into the straight pipe insertion port 1c of the PVC pipe 1 in advance, and the outer diameter of the receiving port portion is enlarged. The outer diameter of the press-fitting member 11 is selected to be equal to or slightly larger than the outer diameter of the straight pipe to be joined at the time of construction, and specifically, is larger by 0 to 2 mm than the reference outer diameter. This reference outer diameter is determined by the outer diameter of the straight pipe to be joined. Next, the PVC pipe outer portion 1b having the enlarged outer diameter of the receiving portion is coated with the inorganic non-combustible mortar 2, and the press-fitting member 11 is pressed before the outer peripheral surface is coated with the mortar 2, The coating may be performed before the curing of the nonflammable material even after the coating, and the PVC pipe 1 may be heated and thermally expanded in advance at the time of press-fitting. Although the press-fitting depth of the press-fitting member 11 is determined by the insertion depth of the straight pipe, it is desirable to press-fit as deep as possible. Further, the press-fit member 11
In order to facilitate the press-fitting, a lubricating material such as oil or paraffin may be applied to the inner peripheral surface of the straight pipe insertion opening of the PVC pipe 1 for lubrication.

The press-fitting member 11 may be removed before or after the incombustible material is cured, but it is preferable to remove it after curing and curing. This press-fit member 11
Pull the handle (not shown) to remove it. FIG. 4 is a sectional view of a refractory two-layer pipe joint in which a gap 3 is formed between a PVC pipe 1 and a mortar 2 in the second embodiment. According to this embodiment, a larger gap 3 is formed in the vicinity of the socket where cracks are most likely to occur in the fire-resistant double-layer pipe joint.
Can be formed. The gap 3 thus formed absorbs the stress caused by the expansion of the PVC pipe 1 due to the internal pressure when it is used for water supply, and can prevent the non-combustible outer pipe made of the mortar 2 from being cracked. In addition, when used for a drain pipe, it also absorbs the stress caused by the thermal expansion of the PVC pipe 1 when hot water is passed through, and can prevent the non-combustible outer pipe made of the mortar 2 from being cracked.

[0015]

According to the first aspect of the present invention, when a gap is formed by the method for forming a gap between the inner and outer pipes of the pipe joint of the refractory double-layer pipe, a desired gap is formed. Cracks can be prevented from occurring in the nonflammable outer pipe due to expansion of the synthetic resin pipe joint. When a gap is formed by the method for forming a gap between the inner and outer pipes of the pipe joint for a fire-resistant double-layer pipe according to claim 2, a desired gap is formed. A crack can be prevented from occurring in the nonflammable outer tube due to the increase in the diameter. Claim 3
When a gap is formed by the above-described method for forming a gap between the inner and outer pipes of the pipe joint of the refractory double-layer pipe, a gap having a larger size can be obtained because the gap is formed by both the internal pressure and the press-fitted members.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a method of forming a gap between inner and outer pipes of a refractory double-layer pipe according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a gap formed according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing a method for forming a gap between the inner and outer pipes of a refractory double-layer pipe according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a gap formed according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... PVC pipe 2 ... Mortars 3 ... Gap 4 ... Hose 5 ... Adapter 6 ... Adapter 7 ... Die 8 ... Connection pipe 9 ... Guide core 10 ... Seal member 11 ... Press-fit member

Claims (3)

(57) [Claims] 1. A synthetic resin pipe joint is expanded by applying pressure to the inside thereof, the outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material constituting an outer tube, and after the non-combustible material is coated. By releasing the internal pressure of the synthetic resin pipe joint and contracting the synthetic resin pipe joint, a gap is formed between the synthetic resin pipe joint and an outer pipe made of a noncombustible material. For forming a gap between inner and outer pipes of a refractory two-layer pipe joint. 2. A member having a diameter equal to or slightly larger than the outer diameter of a straight pipe to be joined at the time of construction is press-fitted into a socket of a synthetic resin pipe joint to enlarge the socket, and the socket is enlarged. The outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material constituting an outer tube, and after coating the non-combustible material, the member is removed to shrink the synthetic resin pipe joint, thereby making a synthetic resin pipe joint. Forming a gap between the inner pipe and the outer pipe made of a non-combustible material. 3. The synthetic resin pipe joint is expanded by applying pressure to the inside thereof, and has a diameter equal to or slightly larger than an outer diameter of a straight pipe to be joined at the time of construction at a receiving port of the synthetic resin pipe joint. The member is press-fitted to enlarge the receiving portion, and the outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material constituting an outer pipe. After the non-combustible material is coated, the inside of the synthetic resin pipe joint is formed. Releasing the pressure, and contracting the synthetic resin pipe joint by removing the member to form a gap between the synthetic resin pipe joint and the outer pipe made of a noncombustible material. For forming a gap between inner and outer pipes of a flexible double-layer pipe joint.