JPH05293816A - Method for forming gap between inner and outer pipes of fire resistant double-layered pipe joint - Google Patents

Abstract

PURPOSE:To prevent an incombustible outer pipe from cracking by the expansion of a synthetic resin pipe due to the pressure of fluid flowing in the interior of the pipe joint by a method wherein the outer peripheral surface of the synthetic resin pipe joint, which is expanded by applying pressure to its interior, is covered with the incombustible material, of which the outer pipe consists, and, after that, the internal pressure is released so as to produce gap between the joint and the outer pipe. CONSTITUTION:Inorganic incombustible mortars 2a are fed with an extruder or the like through the gap between a connecting pipe 8 and a guide core 9 to a space formed between the outside part 1b of polyvinyl chloride pipe and the inner surface 7a of a mold. The interior 1a of the polyvinyl chloride pipe and the space formed between the outside part 1b and the mold 7a are sealed by sealing material 10 so as to fully expand the polyvinyl chloride pipe 1 by applying pressure through a hole 5a provided in advance on an adapter 5. The application of the pressure may well be performed either after the covering of the outer peripheral surface of the pipe 1 with the mortars 2a or before the curing of the mortars. Further, the timing of pressure release may also well be before the curing of the mortars 2a. By releasing the pressure, the polyvinyl chloride pipe 1 shrinks, resulting in producing gap between the pipe 1 and the mortars 2a.

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 pipe and an outer pipe of a refractory two-layer pipe joint comprising an inner pipe made of synthetic resin and an outer pipe made of a noncombustible material.

[0002]

2. Description of the Related Art Conventionally, pipes made of synthetic resin such as vinyl chloride are superior to metal pipes in chemical resistance, corrosion resistance, inner surface smoothness, workability, etc. tube,
Widely used for drainage pipes and ventilation pipes. However, the pipe made of synthetic resin such as vinyl chloride has weak fire resistance and is easily burned out in the event of a fire, and has the drawback that it spreads fire and produces toxic gas. In particular, in a high-rise condominium such as a condominium, there is a possibility that a fire may spread to other sections through the pipe made of vinyl chloride, which is a serious problem. Therefore, in order to cover such a defect, a fire-resistant double-layer pipe in which an outer peripheral surface of a synthetic resin pipe such as a vinyl chloride pipe is coated with a non-combustible material has been widely used. This refractory double-layer pipe is, for example, a vinyl chloride pipe or a plastic pipe 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 in the inner tube.
This has been a problem in that the inner and outer pipes are cracked.

Therefore, as a countermeasure against this, a protrusion is provided on the outside of the inner pipe to absorb these stresses to form a gap between the two, thereby preventing the inner and outer pipes from cracking. A technique for interposing a layered body such as expanded polyethylene between the inner and outer tubes has been proposed. In addition, with no intermediate material, the outer peripheral surface of the synthetic resin pipe joint is coated with an inorganic non-combustible material and then heat-treated, and the synthetic resin inner pipe is expanded to cover the outer peripheral surface of the non-combustible material. A technique has been proposed in which the material is expanded and then the inner tube made of synthetic resin is shrunk by curing, hardening and cooling to form a gap between the inner and outer tubes without any inclusions (Japanese Patent Publication No. 60-23010). issue).

However, most of the products obtained by the above method are used for drainage pipes or ventilation pipes where internal pressure is not applied, so that problems such as cracks in the inner and outer pipes occur. Did not reach. However, in the water supply pipe that expands due to the pressure from the fluid (for example, water) flowing inside the pipe, the gap obtained by the above measures is insufficient, and there is still a possibility that cracks may occur. Furthermore, the HI pipe (impact-resistant hard vinyl chloride pipe) made of synthetic resin, which is mainly used for water supply pipes, is tightly fitted to the straight pipe at the joint receiving portion to prevent water leakage at the joint. 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 outer diameter of the joint receiving part due to press fitting of the straight pipe is larger than the VU pipe (rigid vinyl chloride pipe) normally used for drainage pipes. Had a problem of cracking in the non-combustible outer tube.

Therefore, a first object of the present invention is to absorb the stress due to the 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 the pressure from the fluid flowing inside. Another object of the present invention is to provide a method for forming a fire-resistant double-layer pipe joint coated with a non-combustible material having a gap for preventing cracking of the non-combustible outer pipe due to expansion of the synthetic resin inner pipe. Further, a second object of the present invention is to have a gap sufficient to prevent cracking of the non-combustible outer pipe due to expansion of the outer diameter of the receiving portion of the two-layer pipe joint at the time of joining with a straight pipe during construction. 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.

[0005]

According to a first aspect of the present invention, a synthetic resin pipe joint is expanded by applying pressure to the inside.
The outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material forming the outer pipe, and after coating the non-combustible material, the pressure inside the synthetic resin pipe joint is released to release the synthetic resin pipe joint. By shrinking to form a gap between the synthetic resin pipe joint and the outer pipe made of an incombustible material, thereby achieving the first and second objects.

According to the second aspect of the present invention, a member having a diameter that is the same as or slightly larger than the outer diameter of the straight pipe joined at the time of construction is press-fitted into the receiving port of the synthetic resin pipe joint to enlarge the receiving port portion. The synthetic resin pipe joint is contracted by covering the outer peripheral surface of the synthetic resin pipe joint with the enlarged receiving portion with a non-combustible material forming the outer pipe, and by removing the member after coating the non-combustible material. The first and second objects are achieved by forming a gap between the synthetic resin pipe joint and the outer pipe made of a noncombustible material. In the invention according to claim 3, pressure is applied to the inside of the synthetic resin pipe joint to expand it, and the outer diameter of the straight pipe joined to the receiving port of the synthetic resin pipe joint at the time of construction is the same or slightly larger. A member having a diameter is press-fitted to enlarge the receiving portion, the outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material forming an outer pipe, and the synthetic resin pipe joint is coated with the non-combustible material. By releasing the pressure inside and shrinking 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. 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 of the invention, pressure is applied from the inside of the synthetic resin inner pipe to expand the non-combustible material before the non-combustible material is cured, and the non-combustible material is coated After that, the synthetic resin pipe joint shrinks due to the release of pressure, curing, hardening, and cooling, 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 claim 2, the member is press-fitted into the straight pipe insertion port of the synthetic resin pipe joint before the noncombustible material is hardened to expand the outer diameter of the receiving port After that, since the synthetic resin pipe joint is contracted by removing the member, curing, hardening, and cooling, a necessary gap is automatically formed between the inner and outer pipes without any inclusions.

In the gap forming method for 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-combustible material before the non-combustible material is cured. Before hardening, the member is press-fitted into the straight pipe insertion port of the synthetic resin pipe joint to expand the outer diameter of the receiving part, and then the synthetic resin pipe joint shrinks by releasing the pressure, removing the member, curing, curing and cooling. As such, a larger gap is automatically formed between the inner and outer tubes without any inclusions.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first and second embodiments of the method for forming the gap between the inner and outer pipes of the fire-resistant double-layer pipe joint according to the present invention will be described below with reference to FIG.
It will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view showing a method for manufacturing a pipe joint for a refractory double-layer pipe by using a method for forming a gap between an inner pipe and an outer pipe according to an embodiment of the present invention. The inorganic non-combustible mortars 2a are
Passing between the connecting pipe 8 and the guiding core 9, the outer side portion 1b of the PVC pipe
And the inner surface 7a of the mold. Inside the PVC pipe 1
Since the space portion formed by a, the exterior 1b of the PVC pipe and the mold 7a is completely sealed by the sealing material 10, the PVC pipe 1 has a hole 5a provided in the adapter 5 in advance.
It is inflated sufficiently by the pressure applied from the hose 4 leading to.

Water, oil, air or the like can be used to pressurize the inside of the vinyl chloride pipe 1, but it is preferable to use water considering that the product is used as tap water. In this case, the adapter 6 is provided with an air vent hole (not shown) that can be opened and closed. In this example, the water pressure inside the PVC pipe 1 was 15 kg / cm ² , but 0.5 kg / cm ² to 4 kg.
0 kg / cm ² is possible, preferably 5 kg / c
m ^{2 to} 25 kg / cm ² . The pressure inside the PVC pipe 1 may be applied after the outer peripheral surface is coated with the mortar 2 which is a non-combustible material and before the curing and curing of the non-combustible material. Within 2 hours before heating and curing after coating, the coating portion has sufficient plasticity, so that the coating portion can be expanded by the expansion of the PVC pipe 1. In addition, the outer tube made of non-combustible material can be compressed and densified.

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

Further, in this embodiment, the PVC pipe 1 may be preheated before pressurization. In this case, the PVC pipe 1
Further expands, so that it has the effect of further increasing the gap 3 with the mortar 2, which is the outer tube after release of pressure, curing and cooling. The heating temperature for the PVC pipe 1 in this case is 55 ° C.
However, the temperature can be 40 ° C to 70 ° C, and preferably 50 ° C to 65 ° C. FIG. 2 is a cross-sectional view of a refractory two-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
The higher the pressure applied to the inside of, the larger the gap 3 formed can be. Therefore, the gap 3 having a desired size can be obtained by adjusting the applied pressure. The gap 3 formed in this way absorbs the expansion of the PVC pipe 1 due to the internal pressure when used for water supply and the stress due to the thermal expansion of the PVC pipe 1 when passing through hot water when used as a drainage pipe, and thus the mortar It is possible to prevent cracks from occurring in the noncombustible outer tube made of class 2.

FIG. 3 is a cross-sectional view showing formation of the gap 3 in the second embodiment of the present invention. The straight pipe insertion port 1c of the PVC pipe 1 has the press-fitting member 11 preliminarily press-fitted therein so that the outer diameter of the receiving port portion is enlarged. The outer diameter of the press-fitting member 11 is selected to be the same as or slightly larger than the outer diameter of the straight pipe joined at the time of construction, and specifically, it is 0 to 2 mm larger 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 side portion 1b having an enlarged outer diameter of the receiving portion is covered with the inorganic non-combustible mortar 2, but the press-fitting of the press-fitting member 11 is performed before the outer peripheral surface is coated with the mortar 2, Even after the coating, the non-combustible material may be cured, and the PVC pipe 1 may be heated and thermally expanded before press fitting. The press-fitting depth of the press-fitting member 11 is determined by the insertion depth of the straight pipe, but it is desirable that the press-fitting member 11 be press-fitted as deep as possible. Further, the press-fitting member 11
In order to facilitate press-fitting, a lubricant such as oil or paraffin may be applied to the inner peripheral surface of the straight pipe insertion port of the PVC pipe 1 for lubrication.

The press-fitting member 11 may be removed before or after the non-combustible material is cured, but it is preferable to remove it after curing and curing. This press-fitting member 11 is
Pull out 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 the PVC pipe 1 and the mortar 2 in the second embodiment. According to this embodiment, in the refractory two-layer pipe joint, a larger gap 3 is formed near the receiving portion where cracks are most likely to occur.
Can be formed. The gap 3 formed in this way can absorb the stress due to the expansion of the PVC pipe 1 due to the internal pressure when used for water supply, and prevent the noncombustible outer pipe made of the mortar 2 from cracking. In addition, when used as a drainage pipe, it is possible to absorb the stress due to the thermal expansion of the PVC pipe 1 when hot water is passed through, and prevent the noncombustible outer pipe made of mortar 2 from cracking.

[0015]

When a gap is formed by the gap forming method for the inner and outer pipes of the pipe joint of the fire-resistant double-layer pipe according to the first aspect, a desired gap is formed, and for example, it is used for a water supply pipe to which internal pressure is applied. It is possible to prevent the noncombustible outer pipe from cracking due to the expansion of the synthetic resin pipe joint. A desired gap is formed when the 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, and a desired gap is formed. It is possible to prevent the noncombustible outer tube from cracking due to the expansion of the diameter. Claim 3
When the gap is formed by the method for forming the gap between the inner and outer pipes of the pipe joint of the fire-resistant double-layer pipe described above, the gap is formed by both the internal pressure and the press-fitted member, so that a larger size gap can be obtained.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing 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 the fire-resistant double-layer pipe according to the second embodiment of the present invention.

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

[Explanation of symbols]

 1 ... PVC pipe 2 ... Mortars 3 ... Gap 4 ... Hose 5 ... Adapter 6 ... Adapter 7 ... Mold 8 ... Connection pipe 9 ... Guide core 10 ... Sealing member 11 ... Press-fitting member

Claims (3)

[Claims] 1. A synthetic resin pipe joint is expanded by applying pressure to the inside thereof, and an outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material forming an outer pipe, and after the non-combustible material is coated. The internal pressure of the synthetic resin pipe joint is released to contract the synthetic resin pipe joint, and a gap is formed between the synthetic resin pipe joint and the outer pipe made of a noncombustible material. Method for forming a gap between inner and outer pipes of a fire-resistant double-layer pipe joint. 2. A member having a diameter that is the same as or slightly larger than the outer diameter of a straight pipe joined at the time of construction is press-fitted into the receiving port of the synthetic resin pipe joint to expand the receiving port, and the receiving port is enlarged. The outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material forming the outer pipe, and the synthetic resin pipe joint is contracted by removing the member after coating the non-combustible material, and the synthetic resin pipe joint is contracted. A method for forming a gap between an inner pipe and an outer pipe of a fire-resistant double-layer pipe joint, characterized in that a gap is formed between the inner pipe and the outer pipe made of a noncombustible material. 3. A synthetic resin pipe joint is expanded by applying pressure to the inside thereof, and has a diameter equal to or slightly larger than the outer diameter of a straight pipe joined at the time of construction at the receiving port of this synthetic resin pipe joint. The member is press-fitted to enlarge the receiving port, the outer peripheral surface of the synthetic resin pipe joint is coated with a non-combustible material forming the outer pipe, and after coating the non-combustible material, the inside of the synthetic resin pipe joint is covered. Releasing the pressure and shrinking 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 noncombustible material. Method for forming gap between inner and outer pipes of flexible double-layer pipe joint.