JP5307190B2 - Thermally expandable joint for fireproof double-layer pipe joints - Google Patents

Description

The present invention relates to a thermal expansion property for an annular refractory double-layer pipe joint that is attached to a connecting end portion of a refractory double-layer pipe joint having a configuration in which a synthetic resin pipe joint is coated with an outer layer of mortar . Concerning joints .

A fire-resistant double-layer pipe with a synthetic resin pipe covered with a mortar pipe has been conventionally known. As a joint for connecting this fire-resistant double-layer pipe, a synthetic resin pipe joint is covered with an outer layer of mortar by injection molding. Refractory two-layer pipe joints having the following are also known. The reason why fire-resistant double-layer pipes and fire-resistant double-layer pipe joints are used is that the inner pipe is a synthetic resin pipe, so that drainage can flow smoothly, and the mortar coating covering the outer surface is the inner pipe due to the heat of the fire. This is because it has the advantage of preventing fire spread and high safety. As shown in Patent Document 1, the connection between the fireproof double-layer pipe and the fireproof double-layer pipe joint having such a structure is such that the volume expands to several to ten times when heat such as fire acts. The thermal expansion joint of the system is interposed, and the gap between the connecting portions is blocked to prevent the heat of the fire from affecting the internal synthetic resin pipe and pipe joint.

The pipe connection work is performed by inserting the pipe end of the fireproof double-layer pipe into the pipe connection end of the fireproof double-layer pipe joint and joining them together with an adhesive. , It is necessary to pay attention so that the annular thermal expansion joint set at the end of the refractory double-layer pipe does not fall off, and the work is relatively troublesome. However, this has the inconvenience that the work is messy and the work is troublesome.

In order to eliminate such inconvenience, as shown in Patent Document 2, an annular thermally expandable joint is attached to the end of the outer layer of the fireproof two-layer pipe joint with an adhesive, or as shown in Patent Document 3. In addition, it is considered that a recess is formed in the end face of the outer layer of the mortar of the fireproof two-layer pipe joint and an annular thermally expandable joint is fitted therein. Furthermore, the applicant has proposed that a thermally expansible joint is arranged in a mold for forming an outer layer of a fire-resistant two-layer pipe joint, and the joint is attached to the end face simultaneously with the formation of the outer layer (Patent Document 1). ). Note that the reason why the heat-expandable joint is not attached to the fire-resistant double-layer pipe even if it is attached to the fire-resistant double-layer pipe joint is that the fire-resistant double-layer pipe is often cut to adjust the length during piping construction. This is because it is not practical to attach a thermally expandable joint to the end portion of the fireproof double-layer pipe because it increases waste.

JP 2003-161392 A Japanese Patent Laid-Open No. 2002-228054 Japanese Patent Laid-Open No. 2002-3280

When attaching an annular thermally expandable joint to a fireproof two-layer pipe joint with an adhesive as in Patent Document 2, the inconvenience of forgetting to set the joint is eliminated, but adhesive application work and joint application work In general, since there are many types of pipe joints such as elbow type and branch type, it is difficult to attach by an automatic machine and it is a work that relies on manpower, which is not preferable because it takes time and increases costs. In addition, as in Patent Document 3, in the case where the thermally expansible joint is accommodated in the recess at the connection end of the fireproof two-layer pipe joint, the mortar around the recess is not cracked during mortar curing or transportation because the mortar around the joint is brittle. The thickness of the mortar must be increased to a certain extent, resulting in the inconvenience that the outer layer is increased in weight, making construction and transportation inconvenient, and the thermally expandable joints lurk in the recesses. There is a drawback that it is difficult to check visually from the outside. On the other hand, as in Patent Document 1, a thermally expandable joint having a width substantially equal to the thickness of the mortar outer layer is provided in the injection mold, and the joint is joined to the end face simultaneously with the formation of the mortar outer layer of the fireproof two-layer pipe joint. This eliminates the need to paste the joints, and the thickness of the joints appears to be striped from the outside, making it easier to check the joint setting, but the mold prevents mortar from adhering to the inner surface. The actual product is heated at 60 to 90 ° C., so that the joint is deformed as if the joint is twisted or waved by the heat of the mold, and the outer surface of the outer layer is deformed due to the deformation. As a result, the joints were loosened or protruded, and the joints dropped out during transportation and construction of the product. The time for which the joints are in contact with the mold is only about 5 seconds in a standard product, but the actual condition is that the joint is still deformed.

As a means for preventing such deformation, the applicant applies an annular thermally expandable joint having a width substantially equal to the thickness of the outer layer on the outer periphery of the end portion of the synthetic resin pipe joint on which the outer layer of the mortar is formed. After fitting, setting this in a heated injection mold, and forming the outer layer in contact with the thermally expandable joint around the synthetic resin pipe joint by the injected mortar, from the mold In the method of manufacturing a fire-resistant two-layer pipe joint in which a thermally expandable joint adheres to the end face of the outer layer by taking out and curing the mortar, at least a part of the portion where the injection mold comes into contact with the thermally expandable joint Was considered to be in an unheated state. Thus, the injected mortar flows between the inner wall of the heated injection mold and the outer surface of the synthetic resin pipe joint until it contacts the entire surface of the thermally expandable joint located at the end of the joint. Although a part of the mold that comes into contact with the joint is in an unheated state, the period from when the joint is set to the mold until the end of the injection and the product is removed from the mold In addition, the joint is not deformed by the heat of the mold, so that the end surface of the outer layer and the surface of the joint are in close contact with each other. Thereafter, when the mold is dismantled and the product is taken out and the mortar is cured and cured, the joints are joined and fixed to the extent that they do not easily fall off from the end face of the outer layer until the pipe construction. Further, since the outer layer has a uniform thickness and no thin portion, a durable and lightweight thermally expandable jointed fireproof two-layer pipe joint can be obtained.

The present invention facilitates the work of fitting an annular thermally expandable joint to the end of a synthetic resin pipe joint constituting a fireproof two-layer pipe joint, and is almost the same as the outer layer of mortar at the pipe connection end. An object of the present invention is to provide a thermally expandable joint for a fire-resistant double-layer pipe joint that can be fixed with a sufficient adhesive force that prevents the annular thermally expandable joint having a width from falling off, and can be applied to the above-described means for preventing deformation. To do.

In the present invention, in order to solve the above problems, in an annular thermally expandable joint for a refractory two-layer pipe joint attached to the end surface of the outer layer of a mortar formed around a synthetic resin pipe joint by injection molding, An annular hole in the thermally expandable joint is formed to be substantially equal to the outer diameter of the joint on the outer side near the end of the synthetic resin pipe joint, and the diameter is increased on the inner side near the middle part of the joint. The mortar approach space was provided between the peripheral surface of the synthetic resin pipe joint and the annular hole. By forming the annular hole in the tapered hole as described above, when the thermally expandable joint is fitted to the end portion of the synthetic resin pipe joint, it is easy to fit when fitted from the inner side whose diameter is increased. When the outer layer is formed, the mortar enters the mortar entry space formed between the annular hole and the taper hole, and the joint area between the mortar and the joint spreads out. Can be joined.

The above problem is, on the back surface in addition to a configuration in which the annular hole and tapered hole intumescent joints of the annular contact with the end surface of the outer layer of the mortar, a plurality of recessed holes formed at intervals, emitted It is also possible to appropriately solve the problem by fixing the joint to the end face of the outer layer by curing the mortar in a state where a part of the mortar enters the concave hole. In this case, since the mortar hardened in the concave hole fixes the joint, the bonding state with the outer layer is further strengthened.

Furthermore , in addition to the configuration of the tapered hole in the thermally expansible joint, a through hole penetrating the front and back is formed, and a part of the injected mortar is oozed out to the surface of the joint through the through hole. The above problem can also be solved by fixing the joint to the end face of the outer layer by curing in a wet state, and in this case, the columnar mortar hardened in the through-hole locks the joint, The joint fixing state of the joint is further improved.

In addition to the configuration of the tapered hole described above at the periphery of the annular thermally expandable joint, a notch through hole is formed, and a part of the injected mortar oozes out to the surface of the joint through the notch through hole. Fixing the joint to the end face of the outer layer by curing in the cured state also improves the joint fixing state of the joint and the outer layer.

Further, in addition to the configuration of the tapered hole described above, the annular thermally expandable joint forms an annular concave groove on the back surface in contact with the end surface of the outer layer of the mortar, and a part of the injected mortar enters the concave groove. The joint state between the joint and the outer layer can also be improved by fixing the joint to the end face of the outer layer by curing the mortar in the state of entering.

The outer wall surface constituting the annular groove is formed on a slope inclined outward to the groove so as to widen the groove opening, and the inner wall surface constituting the groove is formed in the groove opening. By forming an overhanging slope inclined to the inside of the groove so as to narrow the groove, the injected mortar can easily enter the inside of the groove, and after the mortar hardens, it engages with the overhanging slope. The joints are less likely to fall off.

When injection molding is performed using the thermally expandable joints having the various configurations described above, the influence of heat can be achieved by making at least a part of the part where the injection mold comes into contact with the joint, if possible, all unheated. Thus, it is possible to prevent the deformation of the heat-expandable joint which is easily deformed and to manufacture a fire-resistant double-layer pipe joint with a heat-expandable joint having good adhesion to the injected mortar.

As the thermally expandable joint, one containing an epoxy resin is used, and a mortar containing ordinary Portland cement is used. Preferably, the composition of the thermally expandable joint is 35 ± 5% by mass, and the mortar When the composition of ordinary Portland cement is 45 ± 10% by mass, the joint between the joint and the outer layer becomes strong. In addition to the mortar entry space, a concave hole formed in the back surface of the thermally expandable joint, a through hole formed through the front and back of the joint, a notch through hole formed in the periphery of the joint, or the back surface The injected mortar enters and cures in the annular concave groove formed in (1).

According to the present invention, the annular hole of the thermally expandable joint is formed substantially equal to the outer diameter of the joint on the outer side near the end of the synthetic resin pipe joint, and the hole is formed on the inner side near the middle part of the joint. By forming the taper hole with an enlarged diameter, it becomes easy to fit the joint to the end of the synthetic resin pipe joint. A mortar entry space is formed between the annular hole, and when the mortar enters the space and hardens, the joint and the outer layer can be firmly bonded to each other. In addition, there is no need to attach a joint, and the effect of obtaining a lightweight and durable fireproof two-layer pipe joint can be obtained.

A plurality of recessed holes are formed at intervals on the back surface where the annular thermally expandable joint contacts the end surface of the outer layer of the mortar, and the mortar is cured with a part of the injected mortar entering the recessed hole. By doing so, the joint is more firmly joined to the outer layer by the mortar that has entered the concave hole.

Further, through holes are formed through the front and back surfaces of the annular thermally expansible joint, and a part of the injected mortar is cured in a state of leaching to the surface of the joint through the through holes. The joint is firmly fixed to the end face of the outer layer by the columnar mortar in the hole, and a work for attaching the joint is not required, so that a lightweight and durable fireproof two-layer pipe joint is obtained.

Further, a notch through hole is formed in the periphery of the annular thermally expandable joint, and a part of the mortar having a normal temperature to be injected is cured in a state of leaching to the surface of the joint through the notch through hole. As a result, the joint is firmly fixed to the end face of the outer layer by the mortar in the notch through hole, and the same effect as in the above case can be obtained.

An annular groove is formed on the back surface of the thermally expandable joint, and the injected mortar enters the groove and is hardened, because the joint is anchored by the annular mortar filling the groove. The joint can be firmly fixed to the outer layer, and the wall surface of the groove is composed of an inclined surface inclined to the outside of the recessed groove and an overhanged inclined surface inclined to the inside of the recessed groove. The mortar rotates evenly in the concave groove, and after the curing, the mortar and the joint are engaged by the overhang portion, so that the joint can be further firmly fixed.

Even when using heat-expandable joints with concave holes, through-holes, notched through-holes, or concave grooves, deformation of joints can be achieved by placing the part where the injection mold contacts the joints in a non-heated state. Therefore, the joint and the mortar can be in close contact with each other and the joint can be attached more firmly.

If the heat-expandable joint contains an epoxy resin and the mortar contains ordinary Portland cement, the familiarity between the outer layer and the joint will be improved, and the joint between the two will become stronger. When the composition of the epoxy resin of the expandable joint is 35 ± 5 mass% and the composition of the normal Portland cement of the mortar is 45 ± 10 mass%, a large joining state is obtained, and the work of pasting the joint is not required. A lightweight and durable fireproof double-layer pipe joint is obtained.

A cut-away side view showing an outline of the implementation of the present invention Front view of the thermally expandable joint shown in FIG. 2 is an enlarged cross-sectional view taken along line 3-3 in FIG. Perspective view of a synthetic resin pipe fitting set in an injection mold Cut-away side view of the use state of the joint for fireproof two-layer pipe joint of the present invention Front view of a modified example of thermally expandable joint Fig. 6 is an enlarged cross-sectional view taken along line 7-7. Front view of another modification of thermally expandable joint Enlarged sectional view taken along line 9-9 in FIG. Front view of still another modification of the thermally expandable joint Front view of an embodiment of the present invention FIG. 11 is an enlarged cross-sectional view taken along line 12-12 of FIG. FIG. 11 is a cut side view of the production state in which the thermally expandable joint shown in FIG. 11 is set in a mold. Back view of an embodiment in which a concave groove is formed on the back surface of the thermally expandable joint Sectional view taken along line 15-15 in FIG. Expanded cross-sectional view of the manufactured refractory double-layer pipe joint

The outline of the implementation of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to an elbow-type fireproof two-layer pipe joint. A layer pipe joint, 3 indicates a ring-shaped, thermally expandable joint having a uniform thickness provided at the end of the fireproof two-layer pipe joint 1. This fire-resistant double-layer pipe joint 1 is a synthetic resin pipe made of 90 ° -curved hard polyvinyl chloride having pipe connection ends 4 and 4 at both ends, which are enlarged so as to receive the ends of the fire-resistant double-layer pipe 2. It is comprised by the coupling 5 and the outer layer 6 which consists of mortar formed by the injection molding which coat | covers the outer periphery.

The fireproof two-layer pipe 2 is composed of a synthetic resin inner pipe 7 made of hard vinyl chloride and a mortar outer pipe 8 covering the outer periphery thereof. When injection molding mortar, if the mold temperature is not heated to 60 ° C or higher, preferably about 90 ° C with a heater or the like, the mortar will adhere to the inner surface of the mold and the mold will be disassembled. When the product is taken out, the outer layer 6 of the mortar is broken, and the outer layer 6 having a clean predetermined shape cannot be formed.

The thermal expansion joint 3 starts thermal expansion at about 200 ° C., expands about 4 to 10 times, and closes the gap between the connection portion of the fireproof double-layer pipe joint 1 and the fireproof double-layer pipe 2. At this time, it is possible to prevent the internal synthetic resin pipe joint 5 and the inner pipe 7 from spreading due to the heat spreading from the gap, and as a result, it is possible to prevent the fire from spreading to the upper room or the adjacent room.

It is desirable that the thermally expandable joint 3 is attached with a good appearance and a sufficient adhesive force at the same time when the outer layer 6 of mortar is injection molded on the outer periphery of the synthetic resin pipe joint 5. In this case, the thermally expandable joint 3 having the annular hole 9 corresponding to the outer diameter of the end 4 of the synthetic resin pipe joint 5 as shown in FIGS. 2 and 3 is made of synthetic resin as seen in FIG. The pipe fitting 5 is fitted into the end portions 4 and 4 and is first set in an injection mold 13 heated to, for example, 90 ° C. (FIG. 5). Then, a mortar 17 having a room temperature is injected from the mortar inlet 15 into the space corresponding to the thickness of the outer layer 6 existing between the synthetic resin pipe joint 5 and the mold 13, and the mortar is filled to every corner of the space. Since the expandable joint 3 is easily deformed by heat and causes the above-described disadvantages, the mold lid 13 prevents the deformation of the closed lid portion 13a in contact with the thermally expandable joint 3 by making it unheated. When the mold 13 is disassembled when the mortar 17 is filled, the outer layer 6 of the mortar is formed on the outer periphery of the synthetic resin pipe joint 5, and the thermally expandable joint 3 is attached to the end surface of the outer layer 6. When the outer layer 6 is cured and cured, the joint 3 is fixed to the end face thereof, and the fire-resistant two-layer pipe joint 1 with the thermally expandable joint is obtained without the above-mentioned difficulties and troubles. As a means for obtaining this non-heated state, in the embodiment, the portion 13a of the closing lid constituting the mold 13 is left at room temperature before filling with mortar to leave it unheated. You may make it cool to normal temperature grade. By making the mold in such a non-heated state, deformation of the thermally expandable joint 3 is prevented, and as a result, the joint 3 is bonded to the entire end surface of the outer layer 6 and the joint 3 is formed when the mortar is cured. It comes to join strongly with the end face. You may make it make all the parts of the metal mold | die 13 which contact this joint 3 into a non-heating state.

Note that the illustrated mold 13 is a two-part mold having a horizontal surface and a paper surface, and when disassembling or assembling, one of the molds moves in a direction perpendicular to the paper surface and is closed. The lid portion 13a was moved in the horizontal direction with respect to the paper surface. The mortar injection time is about 2 to 3 seconds for a standard product, and the time for the thermally expandable joint 3 to contact the mold 13 is about 5 seconds even if the assembly and disassembly time for the mold before and after that is included. .

The thermally expandable joint 3 includes joints (joint A) composed of 6 ± 3% by mass of thermally expandable graphite (graphite type) and 59 ± 5% by mass of an inorganic filler, and 13 ± of thermally expandable graphite (graphite type). A joint (joint B) comprising 5% by mass, aluminum hydroxide 33 ± 5% by mass, ethylene propylene rubber 33 ± 5% by mass, process oil 21 ± 5% by mass is used. The color of these joints is dark gray because graphite is mixed therein. As the mortar 17, a general mortar composed of ordinary Portland cement 45 ± 10 mass%, inorganic fine aggregate / inorganic admixture 50 ± 10 mass%, and organic fiber 5 ± 1 mass% is used. The injection pressure of the mortar was 90 kg / cm ² .

In order to examine the adhesion and fixing state of the outer layer 6 and the joint A, the joint A is fitted to both end portions 4 of the elbow type synthetic resin pipe joint 5 having an outer diameter of 83 mm, and this is not heated. The mortar at normal temperature is injected from the mortar inlet 15 by setting the portion 13a and the inside of the injection mold 13 heated to 90 ° C., and the outer layer 6 made of mortar having the above composition of 10 mm thickness is made of the synthetic resin pipe joint 5 Formed on the outer periphery. The joint A has a thickness of 4 mm, an outer diameter of 103 mm, and the annular hole 9 has a diameter of 82.8 mm. The mold 13 is disassembled, and the refractory two-layer pipe joint 5 of the semi-finished product in which the mortar is uncured and the joint A is attached to the end face of the outer layer 6 is taken out and cured for 24 hours to cure the mortar. A joint 1 was obtained. The joint A was not twisted or wave-distorted and joined to the end face of the outer layer. And when the peeling test of this joint A was done, it did not peel to the load of 4 kg / cm < ² >. This peeling load is a load that is not applied to the joint in a normal state until the fire-resistant double-layer pipe joint 5 is manufactured and used for piping construction, and the joint may fall off before the piping construction. Judged not.

In order to more firmly fix the thermally expandable joint 3 to the outer layer 6, the inner diameter of the annular hole 9 of the joint 3 corresponds to the end 4 of the synthetic resin pipe joint 5 as shown in FIGS. 11 and 12. The outer side 9a is formed to be substantially equal to the outer diameter D of the end portion 4, and the inner side 9b corresponding to the inner side of the joint 5 is enlarged to D + α to form a tapered hole. When the annular hole 9 is fitted in the end 4 of the synthetic resin pipe joint 5 and set in the split mold 13 of the injection molding machine as shown in FIG. 13, the peripheral surface of the synthetic resin pipe joint 5 A wedge-shaped mortar entrance space 16 is formed between the annular hole 9 and the annular hole 9. Then, when the mortar 17 is press-fitted from the mortar inlet 15 of the mold 13, a part of the mortar also enters the mortar entry space 16. Since the joint 3 hardens in a state of being in close contact with not only the mortar on the end surface of the outer layer 6 but also the mortar that has entered the mortar entry space 16, the joint 3 is more firmly fixed. When the joint B is used in this example and mortar is injected under the same conditions as in FIG. 5, the joint 3 is not deformed, and the peel load from the outer layer 6 of the joint 3 is 6.5 kg / cm. ² Met.

As shown in FIGS. 6 and 7, a plurality of concave holes 18 may be formed in the thermally expandable joint 3 at an appropriate interval on the back surface 10 in contact with the end surface of the outer layer 6. In the case of a joint, when it is fitted into the end of the synthetic resin pipe joint 5 and set in the mold 13 and the mortar 17 is injected to form the outer layer 6, a part of the mortar enters the inside of the concave hole 18. The fireproof two-layer pipe joint 1 in the entered state is obtained. Even if this is taken out from the mold 13, the joint 3 is not deformed, and the mortar hardened in the concave hole 18 improves the joining and fixing properties between the end face and the joint 3.

When the concave hole 18 having a depth of 2.5 mm is formed in the joint B having a thickness of 4 mm and the fireproof two-layer pipe joint 1 is manufactured by injection molding in the same manner as the joint A, the peel load is measured. 4kg / cm ² It did not peel until. The dimensions of the joint B were the same as the joint A, and the dimensions of the synthetic resin pipe joint 5 were also the same as the joint A. This peeling load is a load that is not applied to the joint in a normal state until the fireproof double-layer pipe joint 5 is manufactured and used for piping as described above. It can be determined that it will not fall out.

Further, as shown in FIGS. 8 and 9, the annular thermally expandable joint 3 made of the joint B is changed to one having through holes 12 penetrating the front and back of the joint, and the joint 3 is made of a synthetic resin. The outer layer 6 of mortar was injection-molded after being set in the injection mold 13 while being fitted to the end 4 of the pipe joint 5. The dimensions of the synthetic resin pipe joint 5 and the joint 3, the composition of the mortar, and the injection conditions are the same as those in the example of FIG. 5. The injected mortar exudes from the back surface 10 of the joint to the front surface 11 through the through-holes 12, and is cured in the through-holes 12 when the mortar is cured by taking out from the mold 13 without deformation of the joint 3. The mortar column was firmly fixed to the end surface of the outer layer 6. The peel load of the joint 3 was 6 kg / cm 2, and the strength was sufficient to prevent the joint from falling off the outer layer 6.

Further, the annular thermally expansible joint 3 made of the joint B is changed to a notch formed in the periphery of the joint as shown in FIG. 10, and the joint 3 is the same as the above case. The outer layer 6 of mortar was injection-molded by setting it in the injection mold 13 while being fitted to the end 4 of the synthetic resin pipe joint. The dimensions of the synthetic resin pipe joint 5 and the joint 3, the composition of the mortar, and the injection conditions are the same as those in the example of FIG. 5. The injected mortar oozes from the back surface 10 of the joint through the notched through hole 19 to the front surface 11, and the joint 3 is not deformed. When this is taken out from the mold 13 and the mortar is cured, the notched through hole It was firmly fixed to the end face of the outer layer 6 by a mortar column cured in 19. The peel load of this joint is 6 kg / cm ² Met.

The annular heat-expandable joint 3 made of the joint B was changed to one having an annular concave groove 20 formed on the back surface 10 of the joint as shown in FIGS. The concave groove 20 has an outer wall surface formed on an inclined surface 21 inclined to the outer side of the concave groove so as to widen the concave groove opening, and the inner wall surface of the concave groove narrows the concave groove opening. It formed in the overhanging slope 22 inclined to the inner side of the ditch | groove. The annular hole 9 is a tapered hole similar to the case of FIG. This joint 3 is set in injection molding metal mold 3 while fitted to an end portion 4 of the case as well as synthetic resin pipe joint 5 of the, injection molded an outer layer 6 of the mortar. The dimensions of the synthetic resin pipe joint 5 and the joint 3, the composition of the mortar, and the injection conditions are the same as those in the example of FIG. 5. In the obtained joint 1, the mortar sufficiently enters the inside of the concave groove 20 as shown in FIG. 16 even in a short injection time, and the peel load is 7 kg / cm 2. I never missed it.

In addition, when manufacturing the fireproof two-layer pipe joint 1 using what the said heat expansible joint 3 formed the concave hole 18, the through-hole 12, the notch through-hole 19, and the concave groove 20, the thickness of a joint is produced. If is large, it is possible to perform injection molding without bringing the mold part in contact with the joint into a non-heated state, but the jointability between the joint 3 and the outer layer 6 is inferior to that in the non-heated state.

DESCRIPTION OF SYMBOLS 1 Fireproof two-layer pipe joint, 2 Fireproof two-layer pipe, 3 Thermal expansion joint, 4 End part, 5 Synthetic resin pipe joint, 6 Outer layer, 9 Annular hole, 9a Outside, 9b Inside, 10 Back, 11 Surface, 12 Through hole, 13 injection mold, 13a part, 16 mortar entry space, 17 mortar, 18 concave hole, 19 notch through hole, 20 concave groove, 21 slope, 22 overhang slope,

Claims (6)

In an annular thermally expandable joint for a refractory double-layered pipe joint that is attached to an end face of an outer layer of a mortar formed around a synthetic resin pipe joint by injection molding, the annular hole of the thermally expandable joint is On the outer side near the end of the resin pipe joint, it is formed with a taper hole with an enlarged diameter on the inner side near the middle part of the joint, and the peripheral surface of the synthetic resin pipe joint. A thermally expandable joint for a refractory double-layer pipe joint, wherein a mortar entry space is provided between the annular hole and the annular hole. The injected mortar enters and hardens the back surface of the mortar of the thermally expandable joint that contacts the end surface of the outer layer so that a concave hole for fixing the thermally expandable joint to the end surface of the outer layer is spaced. The heat-expandable joint for fireproof double-layer pipe joints according to claim 1, wherein a plurality of the joints are formed. A through-hole is formed through the front and back of the annular thermally expandable joint, and a part of the injected mortar is cured in a state of oozing to the surface of the joint through the through-hole. The thermally expandable joint for fireproof two-layer pipe joint according to claim 1, wherein the joint is fixed to an end face of the outer layer. A notched through hole is formed in the peripheral edge of the annular thermally expandable joint, and the joint is cured by curing a part of the injected mortar to the surface of the joint through the notched through hole. The thermally expandable joint for a fireproof two-layer pipe joint according to claim 1, wherein the thermally expandable joint is fixed to an end face of the outer layer. An annular recess for fixing the joint to the end surface of the outer layer by curing the mortar with a part of the injected mortar entering the back surface of the thermally expandable joint in contact with the end surface of the outer layer of the mortar. The thermally expandable joint for a fireproof two-layer pipe joint according to claim 1, wherein a groove is formed. The outer wall surface of the annular groove is formed on an inclined surface that is inclined to the outside of the groove so as to widen the opening of the groove, and the inner wall surface of the groove is recessed so as to narrow the opening of the groove. The thermally expandable joint for a refractory double-layer pipe joint according to claim 1, wherein the joint is formed on an overhanging slope inclined to the inside.