KR20220006449A - Ventilation Pipe Structure for Construction of Precast Concrete Slab for Prevention of Dew Condensation and Freezing and Bursting at Cold Warehouses and Process thereof - Google Patents

Abstract

The present invention provides a ventilation pipe structure (50) for a precast concrete (PC) construction method, as a structure located between both side PC panels (30) installed on a beam (20), which includes: a ventilation pipe (51) with a diameter of 120-150 mm; and a plurality of lateral pipes (52) with a diameter of 75-100 mm attached to a lateral part of the ventilation pipe (51) at regular intervals to be coupled to perforated pipes (31), respectively, wherein the ventilation pipe (51) and the plurality of lateral pipes (52) are integrally formed. A system is built such that the perforated pipes (31) of all the PC panels (30) forming a slab of one layer can all perform ventilation, and in this case, in the ventilation pipe structure (50) located on both sides, the lateral pipes (52) are formed on only one side, not both sides. A blower may be installed on an air supply part (air intake part) side of the ventilation pipe (51) in order to increase an air flow speed (i.e., exhaust speed) in the perforated pipes (31) and the ventilation pipe structure (50), and a suction fan may be installed on an air exhaust part side. Heating coils (33) may be further installed on the perforated pipes (31) of the hollow core PC panels (30).

Description

Ventilation Pipe Structure for Construction of Precast Concrete Slab for Prevention of Dew Condensation and Freezing and Bursting at Cold Warehouses and Process thereof}

The present invention relates to a low-temperature logistics warehouse constructed with precast concrete (PC) panels. More specifically, the present invention relates to a construction method capable of preventing condensation and freezing occurring on the ground floor or inter-floor floor of a low-temperature logistics warehouse constructed with PC panels, an accessory member for use in the construction, and a ventilation system will be.

Low-temperature frozen warehouses are mainly constructed by the ready-mixed concrete reinforced concrete method (‘RC method’) or the precast concrete method (‘PC method’). Recently, in large warehouses, the PC method is preferred over the RC method to save construction period and cost. The PC method is widely applied not only to warehouses, but also to buildings such as factories, parking lots, and large discount stores.

The PC method is a method of constructing a warehouse in a prefabricated manner using prefabricated columns, girders, and panels.

The PC panel, as shown in FIG. 2, is made of a high-strength concrete panel having a width x length x thickness of 1200 x 11000 x 200 mm as an example. The PC panel is a panel in which 4 to 10 perforated tubes (hollow tubes) are formed in the longitudinal direction.

In Patent Registration No. 1980435, a PC hollow slab (panel) with shear reinforcement manufactured by extrusion molding to improve the abdominal shear strength at the end by fixing the CFRP sheet to the side end side of the panel body and the end inside the hollow part start

In the PC method, pre-fabricated columns are installed at regular intervals, a girder is installed on the column, and a PC panel is continuously assembled between the installed beams to construct a PC slab (floor).

1 shows a schematic front view of a warehouse constructed by the PC method. As shown in Figure 1, the pillars 10 are installed at regular intervals, and the beams 20 are installed in the transverse direction between the pillars and the pillars. A PC slab (floor) is constructed by continuously assembling the PC panel 30 between the beams installed in the transverse direction. Repeat the same method to construct a warehouse with the desired number of floors. The PC slab constitutes the floor surface, but when viewed from the floor directly below it constitutes the ceiling floor.

A process in which the PC panel 30 is constructed is shown in FIG. 3 . Concrete is filled in the space (G) between the PC panels 30 on both sides of the beam 20 to firmly bond the PC panels to each other. At this time, the perforated tube 31 is maintained in a closed state using a stopper (not shown). As shown in Figure 3b, by laying the overall concrete on the PC panel (30) top to form a topping concrete (topping concrete) (35) layer.

Patent Registration No. 1329443 discloses a precast concrete frame for a building using a precast concrete slab to have a continuous precast concrete slab using post tensioning and a construction method thereof.

Condensation and freezing are important problems to be solved in the case of constructing a low-temperature freezing warehouse by the PC method using PC panels. Since the low-temperature frozen warehouse should be maintained at about -25 degrees to -35 degrees below zero, condensation or freezing occurs due to a large temperature difference on the ground surface or the surface (slab) in contact with room temperature. In particular, the bottom floor in contact with the ground repeatedly freezes and thaws, causing serious damage such as cracking the floor or even collapsing the building.

In case of forming a space layer (pit layer) between the ground and the floor in order to solve the freezing problem occurring on the floor of the lowest floor, a ventilation pipe facility that allows air to flow by excreting a pipe, or a heating pipe facility there is also However, the construction of these facilities requires a separate construction cost, and even after installation, the problem of freezing has not been completely solved. Moreover, since the above-mentioned facilities cannot be installed on the floor surface forming the intermediate layer, not the floor surface of the lowest floor, the problem of condensation occurring on the floor surface (slab) of the intermediate floor has not been solved yet.

The dew condensation phenomenon of the PC panel is because air is present in the perforated tube 31 . If the inside of the perforated tube 31 is in a vacuum state, since there is no heat conduction, dew condensation does not occur. Considering the weight of the PC panel, it is impossible to manufacture the entire panel with concrete without forming a perforated pipe. In order to solve the condensation problem of the PC panel, a ripped plus panel was developed in which the inside of the perforated tube 31 was filled with Styrofoam, but this was also unsuccessful. The reason is that even if the inside of the perforated tube 31 is filled with Styrofoam, there is still air therein and thus a vacuum state cannot be achieved.

The present inventors have come to develop a new method of the present invention that can prevent dew condensation and freeze-up phenomenon by discharging the air in all the perforated tubes to the outside in the PC panel slab in which air exists in a state in which all perforated tubes are blocked in the conventional PC method. . This has been applied for as Patent Application No. 2020-83824.

This application is an application claiming domestic priority in Patent Application No. 2020-83824, in which a heating coil is installed in a hollow core PC panel perforated tube.

An object of the present invention is to provide a ventilation pipe structure for the precast concrete (PC) method that can prevent dew condensation by opening all the perforated pipes of the PC panel in the construction method using the PC panel and releasing the air in all the perforated pipes to the outside. it is for

Another object of the present invention is to provide a ventilation pipe structure for the PC method that can prevent the bottom surface from cracking and freezing while the bottom surface of the lowest floor in contact with the ground repeats freezing and thawing in a construction method using a PC panel. .

Another object of the present invention is to open all the perforated pipes of the PC panel in the construction method using the PC panel so that the air in all the perforated pipes is naturally discharged to the outside or discharged using a discharge means, thereby ) to provide a ventilation system that can prevent condensation and freezing.

Another object of the present invention is to use the ventilation pipe structure of the present invention in the construction method using the PC panel to open all the perforated pipes of the PC panel so that the air in all the perforated pipes is naturally discharged to the outside or discharged using a discharging means It is to provide a method of constructing a PC panel slab that can prevent condensation and freezing of the PC panel bottom surface (slab) by making it possible.

Another object of the present invention is to provide a method for constructing a PC panel slab capable of preventing condensation and frostbite on the floor by installing a heating coil in a halo core PC panel perforated pipe.

The above and other objects of the present invention can all be achieved by the present invention described in detail below.

The ventilation pipe structure 50 for the precast concrete (PC) construction method of the present invention is a structure located between the PC panels 30 on both sides installed on the beam 20, and the ventilation pipe 51 and the ventilation pipe 51 with a diameter of 120 to 150 mm ( 51) is attached to the side at regular intervals and is composed of a plurality of side pipes 52 with a diameter of 75 to 100 mm that are coupled to each perforated pipe 31, and the vent pipe 51 and the plurality of side pipes 52 are integrated characterized in that it is formed with

As the ventilation pipe 51, a metal pipe including stainless steel or a plastic pipe of various synthetic resins may be preferably used. The vent pipe 51 may be used in a straight or corrugated pipe type.

The side pipe 52 is attached to the side of the vent pipe 51 at regular intervals according to the interval of the perforated pipe 31 , and each side pipe is coupled to each of the adjacent perforated pipes 31 . The side tube 52 is preferably a flexible tube or a corrugated tube because it must be coupled with the perforated tube 31 or inserted into the perforated tube 31 .

The ventilation system using the ventilation pipe structure 50 for the PC method of the present invention places the ventilation pipe structure 50 between the PC panels 30 on both sides installed on the beam 20, and adjacent each side pipe 52. It is constructed by combining with each perforated pipe 31 , laying concrete on the ventilation pipe structure 50 , and then laying concrete thereon to form a layer of topping concrete 35 .

The system is built so that the perforated pipes 31 of all PC panels 30 forming a slab of one layer can all ventilate, and in this case, the ventilation pipe structures 50 located on both sides have side pipes 52 on both sides. formed only on one side. A blower is installed on the air supply (intake) side of the vent pipe 51 in order to increase the flow speed (ie, exhaust speed) of air in the perforated pipe 31 and the ventilation pipe structure 50 , and a suction fan is installed on the exhaust side. fan) can be installed.

In the present invention, the heating coil may be further installed in a zigzag manner on the perforated pipe 31 of the halo core PC panel 30 .

Hereinafter, the specific content of the present invention will be described in detail with reference to the accompanying drawings.

According to the present invention, all perforated pipes of the PC panel are opened in a construction method using a PC panel so that the air in all perforated pipes is discharged naturally or discharged using an exhaust means, thereby dew condensation and freezing of the PC panel bottom surface (slab) It has the effect of the invention to provide a ventilation pipe structure that can prevent

1 is a schematic front view of a warehouse constructed by the PC method.
2 is a schematic perspective view of a conventional PC panel 30 in which six perforated tubes 31 are formed.
3 is a view for illustrating a conventional construction method in which the PC panel 30 installed on the beam 20 is constructed, and FIG. 3a is a schematic perspective view before concrete is installed in the space G between the PC panels 30 3b is a cross-sectional view in which the concrete is laid and the topping concrete 35 layer is formed thereon again.
4 is a view for illustrating the construction method of the present invention in which the PC panel 30 installed on the beam 20 is constructed, and FIG. 4a is a ventilation pipe structure 50 installed in the space G between the PC panels 30 And, it is a schematic perspective view before the concrete is laid, Figure 4b is a cross-sectional view of the concrete is laid, the topping concrete 35 layer is formed thereon again.
5 is a schematic perspective view of a vent pipe structure 50 according to an embodiment of the present invention.
Figure 6 is a schematic front view of a warehouse consisting of a first basement floor and four above-ground floors.
7 is a schematic system configuration diagram showing the exhaust flow of air in which five ventilation pipe structures 50a to 50e are connected to all the perforated pipes of the PC panel 30 on one floor (slab) of a warehouse made of five beams.
8 is a view in which a heating coil 33 is installed in the perforated tube 31 of the halo core PC panel 30, (A) is a schematic perspective view of one embodiment, (B) is an internal arrangement of the heating coil 33 is a schematic perspective view showing

The present invention relates to a low-temperature logistics warehouse constructed with a PC panel, and to an accessory member, a system, and a construction method that can prevent dew condensation and freezing occurring on the ground floor or inter-floor floor of a low-temperature logistics warehouse constructed with a PC panel it's about

In the PC method, pre-fabricated columns are installed at regular intervals, a girder is installed on the column, and a PC panel is continuously assembled between the installed beams to construct a PC slab (floor).

1 shows a schematic front view of a warehouse constructed by the PC method. As shown in Figure 1, the pillars 10 are installed at regular intervals, and the beams 20 are installed in the transverse direction between the pillars and the pillars. A PC slab (floor) is constructed by continuously assembling the PC panel 30 between the beams installed in the transverse direction. Repeat the same method to construct a warehouse with the desired number of floors. The PC slab constitutes the floor surface, but when viewed from the floor directly below it constitutes the ceiling floor.

The PC panel 30, as shown in FIG. 2, is made of a high-strength concrete panel having a width x length x thickness of 1200 x 11000 x 200 mm as an example. In the PC panel, 4 to 6 perforated tubes (hollow tubes) 31 are formed in the longitudinal direction to reduce weight and save raw materials. The size of the panel and the number of perforated pipes can be changed as needed.

A process in which the PC panel 30 is constructed is shown in FIG. 3 . 3 is a view for illustrating a conventional construction method in which the PC panel 30 installed on the beam 20 is constructed, and FIG. 3a is a schematic perspective view before concrete is installed in the space G between the PC panels 30 3b is a cross-sectional view in which the concrete is laid, and the topping concrete 35 layer is formed thereon again. Concrete is filled in the space (G) between the PC panels 30 on both sides of the beam 20 to firmly bond the PC panels to each other. At this time, the perforated tube 31 is maintained in a closed state using a stopper (not shown). As shown in Figure 3b, by laying the overall concrete on the PC panel (30) top to form a topping concrete (topping concrete) (35) layer.

The present invention is to solve the problems of condensation and freezing in the case of building a low-temperature freezing warehouse by the PC method using a PC panel.

The ventilation pipe structure 50 for the precast concrete (PC) construction method of the present invention is a structure located between the PC panels 30 on both sides installed on the beam 20, and the ventilation pipe 51 and the ventilation pipe 51 with a diameter of 120 to 150 mm ( 51) is attached to the side at regular intervals and is composed of a plurality of side pipes 52 with a diameter of 75 to 100 mm that are coupled to each perforated pipe 31, and the vent pipe 51 and the plurality of side pipes 52 are integrated characterized in that it is formed with

4 is a view for illustrating the construction method of the present invention in which the PC panel 30 installed on the beam 20 is constructed, and FIG. 4a is a ventilation pipe structure 50 installed in the space G between the PC panels 30 And, it is a schematic perspective view before the concrete is laid, Figure 4b is a cross-sectional view of the concrete is laid, the topping concrete 35 layer is formed thereon again.

In the construction method using the ventilation pipe structure 50 for the PC method of the present invention, the ventilation pipe structure 50 is positioned between the PC panels 30 on both sides installed on the beam 20, and each side pipe 52 is placed adjacent to each other. It is constructed by combining with the perforated pipe 31, laying concrete as before on the installed ventilation pipe structure 50, and then laying concrete thereon again to form a topping concrete 35 layer.

5 is a schematic perspective view of a vent pipe structure 50 according to an embodiment of the present invention. As the ventilation pipe 51, a metal pipe including stainless steel or a plastic pipe of various synthetic resins may be preferably used. The vent pipe 51 may be used in a straight or corrugated pipe type.

The side pipe 52 is attached to the side of the vent pipe 51 at regular intervals according to the interval of the perforated pipe 31 , and each side pipe is coupled to each of the adjacent perforated pipes 31 . Since the side tube 52 must be coupled to the perforated tube 31 or inserted into the perforated tube 31, a flexible tube, that is, a typical corrugated tube is preferably used. When combining the side pipe 52 and the perforated pipe 31, a nipple (not shown) may be used. Means for coupling the side pipe 52 and the perforated pipe 31, including the nipple, can be easily implemented by those of ordinary skill in the art to which the present invention pertains. Attaching the side pipe 52 to the side of the vent pipe 51 is possible by conventional adhesive means, and this can also be easily performed by those skilled in the art to which the present invention pertains.

Figure 6 is a schematic front view of a warehouse consisting of a first basement floor and four above-ground floors. 6, the first basement floor (B1) is a low-temperature warehouse, the first floor (F1) above the ground is a room temperature warehouse, the second floor (F2) is a low-temperature warehouse, the third floor (F3) is a low-temperature warehouse, and the fourth floor (F4) is a room temperature warehouse. In the case of a warehouse, the slab (floor) S1, S2, S3, and S5 should be equipped with the ventilation system of the present invention. However, the slab S4 between the cold warehouses does not need to be equipped with a ventilation system. This is because, when the upper and lower layers are low temperature, there is no temperature difference, so there is no problem of condensation or freezing. As such, the ventilation system in the PC slab of the present invention does not need to be installed on all the floor surfaces of the warehouse, and may be installed on the floor surface where condensation or freezing may occur due to a temperature difference. This can be appropriately designed according to the structure of the warehouse in the design process of the warehouse.

The ventilation system according to the present invention is independently installed on a slab (floor surface) forming one layer. That is, there is no need to install a ventilation system in association with the slabs on the other floors. 7 shows a schematic configuration diagram of a system for discharging air by connecting the perforated pipes of all PC panels 30 on the bottom surface (slab) of one floor. 7 shows the exhaust flow of air by connecting the perforated pipes of all PC panels 30 by installing five ventilation pipe structures 50a to 50e on one floor (slab) of a warehouse made of five beams.

7 is a warehouse in which five beams are installed, and the PC panel 30 is positioned on each beam. Ventilation pipe structures 50b, 50c, 50d are installed in the space between the PC panels 30, and each side pipe is coupled to each perforated pipe. Ventilation pipe structures 50a and 50e are installed on the left and right sides, and in these vent pipe structures 50a and 50e, the side pipe 52 is formed only on one side, not on both sides. Concrete is laid on the installed ventilation pipe structures 50a to 50e, and concrete is laid thereon to form a topping concrete layer.

7, when both ends of the vent pipe 51 of the vent pipe structures 50a to 50e are opened, air flows along the vent pipe. Since the perforated tubes of all PC panels 30 are connected by the side tubes 52 , the air in the perforated tubes is discharged to the outside. A blower is installed on the air supply (intake) side of the vent pipe 51 in order to increase the flow speed (ie, exhaust speed) of air in the perforated pipe 31 and the ventilation pipe structure 50 , and a suction fan is installed on the exhaust side. fan) can be installed.

If a blower and a suction fan are to be installed in the system of FIG. 7 , a blower (not shown) is installed at one end ( b1 , d1 ) of the ventilation pipe structures 50b and 50d to inject air. At this time, the other ends (b2, d2) of the ventilation pipe structures (50b, 50d) block the air from being discharged. Meanwhile, a suction fan (not shown) is installed at one end a2, c2, and e2 of the ventilation pipe structures 50a, 50c, and 50e to discharge air. At this time, the other ends (a1, c1, e1) of the ventilation pipe structures (50a, 50c, 50e) block the air is not discharged. The air injected by the blower at one end (b1, d1) of the ventilation pipe structures 50b and 50d passes through the ventilation pipe and all perforated pipes, and then at the ends a2, c2, e2 of the ventilation pipe structures 50a, 50c, 50e. discharged to the outside by In this way, the slab constructed with the PC panel is ventilated through the perforated pipe, and as a result, condensation or freezing phenomenon can be completely prevented.

On the other hand, instead of installing a suction fan (not shown) at one end a2, c2, e2 of the ventilation pipe structures 50a, 50c, 50e, the ventilation pipes are vertically installed at each end a2, c2, e2. extend up to The vertically extended vent pipe acts as a chimney, and the air inside the vent pipe can be exhausted to the outside by a stack effect without power such as a suction fan. In this case, it is not necessary to install a blower at the ends b1 and d1 of the ventilation pipe structures 50b and 50d through which air flows. This is because air is naturally introduced by the stack phenomenon, and the introduced air is discharged to the outside through a vertical vent pipe.

In this case, one end b1, d1 of the vent structure 50b, 50d is open, the other end b2, d2 is blocked, and one end a2, c2 of the vent structure 50a, 50c, 50e is closed. , e2) extends vertically to the roof, and the other ends a1, c1, e1 are blocked.

7 shows a ventilation system when five ventilation pipe structures 50a to 50e are installed on one floor surface (slab) of a warehouse made of five beams, but the number of ventilation pipe structures installed on one floor surface (slab) is changed However, the system for it can be easily implemented by those skilled in the art to which the present invention pertains.

In another embodiment of the present invention, a heating coil 33 may be further installed in the perforated tube 31 of the halo core PC panel 30 . 8 is a view in which the heating coil 33 is installed in the perforated tube 31 of the halo core PC panel 30, (A) is a schematic perspective view of one embodiment, (B) is the internal arrangement of the heating coil 33 is a schematic perspective view showing As shown in FIG. 8 , the heating coil 33 is installed along the perforated pipe 31 in a zigzag manner. Even if the heating coil 33 is installed in the perforated pipe 31, there is no problem in inserting the side pipe 52. This is because the heating coil 33 occupies a relatively small volume compared to the side pipe 52 .

The heating coil 33 can be heated to a predetermined temperature when necessary by passing a power source (not shown) through the current. The heating method of the heating coil 33 through a controller (not shown) can be easily implemented by those skilled in the art to which the present invention pertains.

The present invention can prevent condensation and freezing of the PC panel bottom surface (slab) by allowing all perforated pipes of the PC panel to be opened so that the air in all perforated pipes is discharged naturally or by using an exhaust means, and additionally, the PC panel (30) By further installing the heating coil in the perforated pipe 31 in a zigzag manner, it is possible to prevent condensation and freezing of the PC panel bottom surface (slab).

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

10: column 20: girder
30: precast concrete (PC) panel
31: perforated tube (hollow tube) 33: heating coil
35: topping concrete (topping concrete)
50: ventilation pipe structure 51: ventilation pipe
52: side pipe S (S1 to S5): slab (slab)

Claims (12)

A PC panel in which the columns 10 are installed at regular intervals, the beams 20 are installed between the columns in the transverse direction, and the perforated pipes 31 are formed between the beams 20 and 20 installed in the transverse direction. In the PC slab (floor) constructed by continuously assembling (30),
As a structure located between the PC panels 30 on both sides installed on the beam 20, a plurality of vent pipes 51 and a plurality of vent pipes attached to the sides of the vent pipes 51 at regular intervals to be coupled to the respective perforated pipes 31 Consists of a side pipe (52), the ventilation pipe (51) and the plurality of side pipes (52) are formed integrally, the ventilation pipe structure (50) for precast concrete (PC) construction method.
According to claim 1, wherein the vent pipe 51 is a metal pipe including stainless steel or a plastic material of various synthetic resins in the form of a straight or corrugated pipe, and the side pipe 52 is a flexible pipe or a corrugated pipe. A ventilation pipe structure (50) for the PC method.
According to claim 1 or 2, wherein the vent pipe 51 has a diameter of 120 to 150 mm, the side pipe 52 has a diameter of 75 to 100 mm for the PC method, characterized in that the vent pipe structure (50) .
[4] The ventilation pipe structure (50) for PC method according to claim 3, wherein each of the side pipes (52) is coupled to each of the perforated pipes (31) by a coupling means such as a nipple.
A PC panel in which the columns 10 are installed at regular intervals, the beams 20 are installed between the columns in the transverse direction, and the perforated pipes 31 are formed between the beams 20 and 20 installed in the transverse direction. In the PC panel slab (floor) constructed by continuously assembling (30),
The ventilation pipe structure 50 according to any one of claims 1 to 4 is positioned between the PC panels 30 on both sides installed on the beam 20, and each side pipe 52 is adjacent to each perforated pipe ( 31), both ends of the vent pipe structure 50 are opened so that the air in the perforated pipe 31 of the PC panel 30 is discharged to the outside through the vent pipe 51. ventilation system.
The ventilation system of claim 5, wherein the side pipe (52) is formed on only one side of the ventilation pipe structure (50) located on both sides of the PC panel slab.
7. The ventilation system of a PC slab according to claim 5 or 6, characterized in that at each end (a2, c2, e2) of the ventilation pipe structure (50a, 50c, 50e) the ventilation pipe extends vertically to the roof.
According to claim 7, wherein one end (b1, d1) of the vent structure (50b, 50d) is open, the other end (b2, d2) is closed, one end of the vent structure (50a, 50c, 50e) ( a2, c2, e2) extend vertically to the roof, and the other ends (a1, c1, e1) are blocked.
7. The method according to claim 5 or 6, wherein a blower is installed at one end (b1, d1) of the vent pipe structure (50b, 50d) and the other end (b2, d2) is blocked, and the other vent pipe structure (50a, 50c, A ventilation system for a PC slab, characterized in that a suction fan is installed at one end (a2, c2, e2) of 50e) and the other end (a1, c1, e1) is blocked.
The ventilation system of claim 5 or 6, wherein a heating coil (33) is further installed in the perforated pipe (31) of the PC panel (30) in a zigzag manner along the perforated pipe (33).
A PC panel in which the columns 10 are installed at regular intervals, the beams 20 are installed between the columns in the transverse direction, and the perforated pipes 31 are formed between the beams 20 and 20 installed in the transverse direction. In the method of constructing a PC panel slab (floor) by continuously assembling (30),
Positioning the vent pipe structure (50) according to any one of claims 1 to 4 between the PC panels (30) on both sides installed on the beam (20);
engaging each side tube (52) with each adjacent perforated tube (31);
laying concrete on the vent pipe structure 50; and
Placing concrete again on the laid concrete and the PC panel 30 to form a topping concrete (35) layer;
A method of constructing a PC panel slab comprising the steps of:
[Claim 12] The PC panel slab construction according to claim 11, further comprising the step of vertically extending the ventilation pipe from each end (a2, c2, e2) of the ventilation pipe structure (50a, 50c, 50e) to the roof. Way.

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