Fire-resistant seal structure for connecting portion

Abstract

To provide a fire resistant seal structure of a connecting part having an airtight seal member (20) for holding an outer periphery airtight state between an inner peripheral surface (21) of an outer cylinder (2) positioned on the outside and an outer peripheral surface (11) of an inner cylinder (1a) positioned on the inside in an insertion type connecting part for connecting one pipe body by inserting the other pipe body into the one pipe body, the connecting part having fire resistant airtightness only by providing a space for an airtight O-ring (20).SOLUTION: An outer peripheral surface (11) of an inner cylinder (1a) and an inner peripheral surface (21) of an outer cylinder (2) are respectively provided with engagement protrusions (12), (22) having facing surfaces facing each other in an insertion direction when connection is completed, and an expanded graphite-containing grease (30) mixed with expanded graphite using a base oil having a property of not affecting performances of an airtight seal member (20) is interposed between the facing surfaces.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fire-resistant seal structure for a connection part, and particularly to a fire-resistant seal structure for a plug-in type connection part in which one pipe body is inserted into the other pipe body and connected in an airtight state.

Background Art

[0002] For example, in the connection between the connection cylinder part of a gas cock and the joint member of a pipe, in a plug-in type connection part in which one of two pipe bodies through which fluid flows is inserted into the other and connected in an airtight state, in order to ensure airtightness, an O-ring as an airtight seal member (hereinafter referred to as an airtight O-ring) is interposed.

[0003] Specifically, an annular groove portion that opens toward the opposing circumferential surface is formed in the circumferential direction on either the inner circumferential surface of the outer cylinder located on the outside or the outer circumferential surface of the inner cylinder located on the inside, and the airtight O-ring is accommodated in the annular groove portion. When the inner cylinder is inserted into the outer cylinder and connected in this state, a part of the airtight O-ring that protrudes from the annular groove portion is pressed against the opposing circumferential surface and adheres in a deformed state. Thereby, the airtightness between the inner circumferential surface of the outer cylinder and the outer circumferential surface of the inner cylinder is maintained, and it is possible to prevent the inconvenience that the fluid flowing in the two pipe bodies leaks from the connection part.

[0004] In addition, in the case where a fire-resistant expansion packing as a fire-resistant seal member having a large coefficient of thermal expansion is provided together with the airtight O-ring, even when the connection part is heated to a high temperature during a fire or the like and the airtight O-ring disappears due to heat, the fire-resistant expansion packing expands due to heat, thereby ensuring the airtightness of the connection part and enabling prevention of leakage of gas or the like.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the fire-resistant seal structure of the type equipped with the fire-resistant expansion packing as described above, in addition to the annular groove for accommodating the airtight O-ring in the pipe body constituting the connection part, an annular groove for accommodating the fire-resistant expansion packing must be separately provided, and accordingly, the length of the pipe body must be set longer. Further, even if the airtight O-ring and the fire-resistant expansion packing are arranged side by side in one annular groove, the width of the annular groove must be formed wider by the space for accommodating the fire-resistant expansion packing. Thus, in the case of the fire-resistant seal structure provided with the fire-resistant seal member, compared with the seal structure provided only with the airtight seal member, the length of the pipe body must be set longer by the space for accommodating the fire-resistant expansion packing, and there is a problem that the connection part becomes larger.

[0007] The present invention has been made in view of the above problems, and is an insertion-type connection part in which the other pipe body is inserted into one pipe body and connected in an airtight state, and an object thereof is to provide a fire-resistant seal structure of a connection part having a fire-resistant airtight performance by providing only a space for an airtight seal member.

Means for Solving the Problems

[0008] The technical means for solving the above problems is an insertion-type connection part in which the other pipe body is inserted into one pipe body and connected, and in the fire-resistant seal structure of the connection part provided with an airtight seal member for maintaining an outer peripheral airtight state between the inner peripheral surface of the outer cylinder located on the outside and the outer peripheral surface of the inner cylinder located on the inside, engagement protrusion parts each having an opposing surface that opposes each other in the insertion direction at the time of completion of connection are provided on each of the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder, a grease containing expanded graphite mixed with a base oil having a property that does not affect the performance of the airtight seal member is interposed between the opposing surfaces of both engagement protrusion parts.

[0009] The above technical means act as follows. When the inner cylinder is inserted into the outer cylinder, the space between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder is kept in an airtight state by the airtight seal member, and the opposing surfaces of the respective engaging protrusions facing each other in the insertion direction face each other via the expanded graphite grease. This state is the connection completion state of the two pipe bodies, and further insertion is blocked. At this time, expanded graphite grease is interposed between the opposing surfaces. Even if this expanded graphite grease is pushed on both opposing surfaces and moves between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder and comes into contact with the airtight seal member, since the expanded graphite grease uses a base oil that does not affect the performance of the airtight seal member, the airtightness between the outer cylinder and the inner cylinder is maintained without affecting the sealing performance of the airtight seal member. When the connection part of the two pipe bodies is exposed to high temperature due to a fire or the like, the graphite in the grease has heat resistance and expands thermally. Thereby, even if the airtight seal member disappears due to heat, the expanded graphite can replace the airtight seal member to ensure the airtightness of the connection part, so that it is possible to prevent the inconvenience of fluid such as gas flowing in the pipe body from leaking to the outside.

[0010] In the fireproof seal structure of the above connection part, preferably, at the time of completion of the connection, the opposing surface of the engaging protrusion provided on the outer peripheral surface of the inner cylinder faces the opposing surface of the engaging protrusion provided on the inner peripheral surface of the outer cylinder on the deeper side in the insertion direction than the sealing portion between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder by the airtight seal member. By providing the engaging protrusion of the outer cylinder so as to be located deeper than the sealing portion by the airtight seal member between the outer cylinder and the inner cylinder, when the inner cylinder is inserted into the outer cylinder, the engaging protrusion provided on the outer peripheral surface of the inner cylinder can be smoothly inserted into the depth of the outer cylinder without accidentally catching on the front side of the outer cylinder than the sealing portion. At this time, if expanded graphite grease is applied in advance to the opposing surface of the engaging protrusion of the outer cylinder, the inner cylinder can be inserted into the outer cylinder without accidentally adhering the expanded graphite grease to the airtight seal member interposed between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder. Also, even if the graphite-injected grease flows to the front side of the outer cylinder after the connection is completed, it is blocked by the airtight seal member and does not flow out any further, so that the outflow of the graphite-injected grease to the outside can be prevented. Thereby, the airtightness during normal times is ensured at the sealing portion by the airtight seal member between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder, and at the same time, the airtightness during a fire can also be ensured by the graphite-injected grease on the deeper side.

[0011] In the fireproof seal structure of the connection part, preferably, an annular recess for holding the graphite-injected grease is provided on at least one of the opposing surfaces of both engaging protrusions so as to open toward the other opposing surface. The graphite-injected grease interposed between the opposing surfaces of both engaging protrusions is held in a manner of accumulating in the annular recess provided on at least one of the opposing surfaces, so that the inconvenience of the applied grease flowing away inadvertently can be prevented. In other words, until the connection is completed, the graphite-injected grease can be stably held on at least one of the opposing surfaces.

[0012] In the fireproof seal structure of the connection part, preferably, a joint member connected to the gas inlet part or the pipe of the gas equipment is used as the outer cylinder, the connection cylinder part of the gas plug is used as the inner cylinder, and the graphite-injected grease is applied to the opposing surface of the engaging protrusion protruding in the joint member. The joint member is used as an outer cylinder, and expanded graphite-containing grease is applied to the opposing surfaces of the engaging protrusions protruding from the inner peripheral surface thereof. As a result, by simply inserting the connection cylinder portion of the gas plug into the joint member, an expanded graphite-containing grease is interposed between the opposing surface of the engaging protrusion inside the joint member and the opposing surface of the engaging protrusion protruding from the outer peripheral surface of the connection cylinder portion of the gas plug, and the two can be connected. In this way, the connection operation of connecting the connection cylinder portion of the gas plug and the joint member in a state having a fire-resistant sealing structure can be easily performed. Moreover, during the connection operation, since the hand does not directly touch the expanded graphite-containing grease provided inside the joint member, the connection operation between the connection cylinder portion of the gas plug and the joint member can be performed without soiling the hand or the periphery of the device with grease. By interposing an airtight sealing member between the inner peripheral surface of the joint member and the outer peripheral surface of the connection cylinder portion of the gas plug, the joint member and the connection cylinder portion of the gas plug are connected in an airtight state on the outer periphery during normal times. When the periphery of the gas plug is heated to a high temperature during a fire and the airtight sealing member disappears due to heat, the expanded graphite in the grease thermally expands, so that the airtightness of the connection portion between the joint member and the connection cylinder portion of the gas plug can be ensured. In this way, the safety of the connection portion between the gas plug and the connection joint is ensured not only during normal times but also during a fire, and gas leakage can be prevented.

Effects of the Invention

[0013] Since the present invention has the above configuration, it has the following specific effects. As a fire-resistant sealing member for the connection portion between two pipe bodies through which a fluid flows, instead of a fire-resistant expansion packing, expanded graphite-containing grease is adopted, and it is configured to be interposed between the opposing surfaces of the respective engaging protrusions facing each other inside the outer cylinder when the connection is completed. Therefore, for example, there is no need to provide a storage space for storing a fire-resistant expansion packing separately from the storage space for accommodating a rubber O-ring as an airtight sealing member. In other words, by simply providing a storage space for the airtight sealing member, both the airtightness during normal times and the airtightness during a fire of the plug-in type connection portion can be ensured. As a result, the manufacturing of parts becomes simple and space saving of the connection portion can be realized. Thus, for example, when adopted in the connection between a joint member to be connected to the gas inlet of a gas appliance or a pipe and the connection cylinder of a gas plug that is inserted into it in a non-loosening state for connection, the connection cylinder of the gas plug and the joint member can be miniaturized. In addition, since it is only necessary to apply the graphite-inflating grease to the opposing surface of the engaging protrusion inside the joint member, the amount of the graphite-inflating grease to be applied can be reduced, and the number of parts to be assembled is decreased, so that the connection work can be simplified. Furthermore, since the hand does not touch the grease during the connection work, there is no inconvenience that the hand or the periphery of the device is soiled by the adhesion of the grease, so the workability is good.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. What is shown in FIG. 1 is an explanatory diagram at the time of completion of the connection between the gas outflow cylinder part (1a) of the gas plug (1) provided with the fire-resistant seal structure of the connection part of the embodiment of the present invention and the joint member (2) screwed and connected to the gas inlet part (3) of the gas appliance (31). Note that a gas inlet cylinder portion (1b) is provided upstream of the plug accommodating portion (1c) of the gas plug (1). As shown by the two-dot chain line in the figure, a flexible tube (41) as a gas pipe is connected to the gas inlet cylinder portion (1b) via a pipe joint (40). Thereby, a gas flow path (4) is formed coaxially from the upstream end (the right end in the drawing) of the gas inlet cylinder portion (1b) to the downstream end of the gas outlet cylinder portion (1a).

[0016] The joint member (2) is a cylindrical body that can be externally fitted to the gas outlet cylinder portion (1a) in an airtight and retaining state, and a plug-in type connection portion that can be connected by inserting the gas outlet cylinder portion (1a) into the joint member (2) is configured. That is, the joint member (2) is set to function as one pipe body (outer cylinder) as a specific invention item, and the gas outlet cylinder portion (1a) of the gas plug (1) is set to function as the other pipe body (inner cylinder) as a specific invention item.

[0017] As shown in FIG. 2, on the outer peripheral surface (11) of the gas outlet cylinder portion (1a), one annular groove portion (10) having a size that can just accommodate a rubber airtight O-ring (20) as an airtight seal member is formed over the entire circumferential direction so as to open outward. The airtight O-ring (20) is made of an NBR material excellent in heat resistance and wear resistance, has an inner diameter that adheres to the annular bottom surface (10a) of the annular groove portion (10), and has a wire diameter that substantially matches the width of the annular groove portion (10) and is equal to or greater than the depth of the annular groove portion (10). Thereby, when the airtight O-ring (20) is accommodated in the annular groove portion (10), as shown in the figure, the outer peripheral end of the airtight O-ring (20) protrudes from the open end of the annular groove portion (10).

[0018] A predetermined range continuing from the open end edge of the annular groove portion (10) to the downstream side of the gas outlet cylinder portion (1a) is defined as an engaging protrusion portion (12). The downstream side of the gas outlet cylinder portion (1a) from the engaging protrusion portion (12) is a small-diameter cylinder portion (15) having a smaller diameter than the upstream side of the engaging protrusion portion (12). A concave groove (13) for fitting a C-shaped stop ring (23) for retaining, which will be described later, is formed on the outer peripheral surface near the downstream end thereof.

[0019] The joint member (2) has a structure in which the gas outflow cylinder part (1a) is inserted from one open end part (2a) thereof, and is screwed and connected to the gas inlet part (3) of the gas appliance (31) by a connecting female screw part (33) formed on the other open end part (2b) side.

[0020] At a predetermined position on the inner peripheral surface (21) closer to the one open end part (2a) than the connecting female screw part (33) of the joint member (2), an engaging protrusion part (22) protrudes inward.

[0021] The inner diameter of the engaging protrusion part (22) is set larger than the outer diameter of the small-diameter cylinder part (15) of the gas outflow cylinder part (1a). When the gas outflow cylinder part (1a) is inserted into the joint member (2) from one open end part (2a) of the joint member (2), the small-diameter cylinder part (15) on the downstream end side passes through the engaging protrusion part (22) of the joint member (2), and the opposing surface (12a) of the engaging protrusion part (12) located at the base end part of the small-diameter cylinder part (15) faces the opposing surface (22a) of the engaging protrusion part (22) in the insertion direction. In this way, the state where the opposing surface (22a) of the engaging protrusion part (22) and the opposing surface (12a) of the engaging protrusion part (12) face each other in contact with each other is the state when the connection between the gas outflow cylinder part (1a) and the joint member (2) is completed, and further insertion is blocked.

[0022] In this embodiment, grease containing expanded graphite (30) is applied in advance to the opposing surface (22a) of the engaging protrusion part (22) from one open end part (2a) side of the joint member (2). The base oil of the grease containing expanded graphite (30) is a mineral oil, synthetic oil, silicone oil, or a mixture thereof that does not adversely affect the performance of the airtight O-ring (20) made of NBR, and expanded graphite is mixed therein. Note that the ratio of the expanded graphite mixed into the base oil is desirably 5 wt% or more, and the particle size of the expanded graphite is +80 mesh, and 86% is desirable.

[0023] Accordingly, when the gas outflow cylinder part (1a) of the gas plug (1) is inserted into the joint member (2) from the side of the one open end part (2a), the small-diameter cylinder part (15) on the downstream end side of the gas outflow cylinder part (1a) passes through the engaging projection part (22) of the joint member (2), and the opposing surface (12a) of the engaging projection part (12) in the gas outflow cylinder part (1a) opposes the opposing surface (22a) of the engaging projection part (22) via the expanded graphite-containing grease (30). At this time, the outer peripheral end of the airtight O-ring (20) accommodated in the annular groove part (10) of the gas outflow cylinder part (1a) is in a state of being pressed and deformed and adheres to a predetermined position on the inner peripheral surface (21) of the joint member (2) closer to the one open end part (2a) than the engaging projection part (22). The location where the airtight O-ring (20) adheres to the inner peripheral surface (21) of the joint member (2) becomes a sealing location, and the inner peripheral surface (21) of the joint member (2) and the outer peripheral surface (11) of the gas outflow cylinder part (1a) are held in an outer peripheral airtight state.

[0024] In this inserted state, the stop ring (23) is inserted into the joint member (2) from the other open end part (2b), passes through the engaging projection part (22), and is fitted into the concave groove (13) provided in the small-diameter cylinder part (15) of the gas outflow cylinder part (1a) protruding toward the other open end part (2b). As a result, when trying to pull out the gas outflow cylinder part (1a) from the joint member (2), the stop ring (23) comes into contact with the engaging projection part (22) of the joint member (2), and the gas outflow cylinder part (1a) and the joint member (2) are connected in a state where they are prevented from coming off.

[0025] In this connected state, the space between the opposing surface (12a) of the engaging projection (12) and the opposing surface (22a) of the engaging projection (22) is filled with graphite-impregnated grease (30). Even if the graphite-impregnated grease (30) applied to the opposing surface (22a) of the engaging projection (22) is pushed by the opposing surface (12a) of the engaging projection (12) within the gas outflow cylinder portion (1a) and moves so as to flow between the outer peripheral surface (11) of the gas outflow cylinder portion (1a) and the inner peripheral surface (21) of the joint member (2), since the base oil used for the graphite-impregnated grease (30) does not adversely affect the performance of the airtight O-ring (20) made of NBR, it does not adversely affect the sealing performance of the airtight O-ring (20) at the sealing location.

[0026] When the graphite-impregnated grease (30) moves to the inner peripheral surface (21) of the joint member (2), the frictional force between the outer peripheral surface (11) of the gas outflow cylinder portion (1a) and the inner peripheral surface (21) of the joint member (2) is reduced, and the gas outflow cylinder portion (1a) can be easily and smoothly inserted into the joint member (2). Also, since the opposing surface (12a) of the engaging projection (12) and the opposing surface (22a) of the engaging projection (22) are set to face each other via the graphite-impregnated grease (30) deeper inside the joint member (2) than the sealing location between the gas outflow cylinder portion (1a) and the joint member (2), when inserting the gas outflow cylinder portion (1a) into the joint member (2), there is no inconvenience that the graphite-impregnated grease (30) inadvertently adheres to the airtight O-ring (20) provided on the gas outflow cylinder portion (1a). Also, after assembly, since the airtight O-ring (20) is provided on the side of one open end portion (2a) of the joint member (2) rather than the application area of the graphite-impregnated grease (30), the graphite-impregnated grease (30) is blocked by the airtight O-ring (20) and does not flow out to the outside.

[0027] In the above connection state, under normal conditions, the airtight O-ring (20) ensures airtightness between the inner peripheral surface (21) of the joint member (2) and the outer peripheral surface (11) of the gas outflow cylinder portion (1a) of the gas plug (1). When the connection part is exposed to high temperature due to a fire or the like and the airtight O-ring (20) disappears due to heat, the heat-resistant expanded graphite in the expanded graphite grease (30) thermally expands, thereby ensuring the airtightness of the connection part.

[0028] In addition, when the connection part was heated at 800 degrees without the airtight O-ring (20), fluid leakage occurred immediately from the connection part when the expanded graphite grease (30) was not applied. However, in the connection part where the expanded graphite grease (30) was applied, almost no leakage was observed even after 30 minutes. Therefore, it can be said that it is clear that the fire-resistant airtightness of the connection part is ensured by the expanded graphite grease (30).

[0029] In the connection operation between the gas outflow cylinder portion (1a) of the gas plug (1) and the joint member (2) described above, after the airtight O-ring (20) is accommodated in the annular groove portion (10) of the gas outflow cylinder portion (1a) and the expanded graphite grease (30) is applied to the opposing surface (22a) of the engaging projection portion (22) in the joint member (2), the gas outflow cylinder portion (1a) is inserted into the joint member (2), and only a normal assembly operation of making it in a non-removable state with the stop ring (23) is performed. Since the airtight O-ring (20) and the expanded graphite grease (30) can be provided at the connection part between the gas outflow cylinder portion (1a) of the gas plug (1) and the joint member (2), the connection operation of the connection part having fire-resistant airtight performance is easy.

[0030] Also, since there is no need to separately provide an annular groove or the like for accommodating the expanded graphite grease (30), the lengths of the gas outflow cylinder portion (1a) of the gas plug (1) and the joint member (2) can be set shorter accordingly, and the gas outflow cylinder portion (1a) of the gas plug (1) and the joint member (2) can be miniaturized. Thereby, space saving of the connection part can be realized. In addition, since there is no need to separately provide a fireproof sealing member such as a fireproof expansion packing or to separately form a groove for accommodating the same, the manufacturing of parts becomes easier, the number of parts can be reduced, and the assembly work can be simplified.

[0031] FIG. 3 shows an enlarged cross-sectional view of the main part of another embodiment showing the connection between the joint member (2) and the gas outflow cylinder part (1a) of the gas plug (1). An annular recess (24) is formed in the opposing surface (22a) of the engaging projection part (22) so as to open toward the one open end part (2a) side. In this case, when the graphite grease with expansion graphite (30) is applied to the engaging projection part (22), the graphite grease with expansion graphite (30) enters and accumulates in the annular recess (24), so that the graphite grease with expansion graphite (30) can be stably held inside the joint member (2).

[0032] Furthermore, if a similar annular concave groove (14) is also formed in the opposing surface (12a) of the engaging projection part (12) of the gas outflow cylinder part (1a), when the opposing surface (22a) of the engaging projection part (22) of the joint member (2) and the opposing surface (12a) of the engaging projection part (12) of the gas outflow cylinder part (1a) are opposed to each other, the graphite grease with expansion graphite (30) applied to the opposing surface (22a) of the engaging projection part (22) will be firmly held by the two annular recesses (24)(14), and the inconvenience of the graphite grease with expansion graphite (30) flowing out inadvertently in the normal state can be prevented. Therefore, the graphite grease with expansion graphite (30) can be held more stably between the opposing surfaces (12a)(22a) of the two engaging projection parts (12)(22).

[0033] Note that, at the completed state of the connection between the gas outflow cylinder part (1a) and the joint member (2), since the gap between the opposing surface (12a) of the engaging projection part (12) and the opposing surface (22a) of the engaging projection part (22) that face each other is narrow, the application amount of the graphite grease with expansion graphite (30) can be small. In addition, the graphite-inflated grease (30) is provided inside the joint member (2), and the two can be connected simply by performing the normal assembly operation of inserting the gas outflow cylinder portion (1a) of the gas plug (1) into the joint member (2). Therefore, during the connection operation, it is possible to prevent the inconvenience that the graphite-inflated grease (30) adheres to the outer surface of the hand or other equipment and gets soiled, and also to prevent the graphite-inflated grease (30) from flowing out externally even after the connection is completed.

[0034] The above-described embodiment is applied to the connection portion between the gas outflow cylinder portion (1a) of the gas plug (1) and the joint member (2) which is a flexible joint, but it may also be applied to the fixing seal portion, and the mounting space for the fireproof seal member can be omitted.

Explanation of Reference Numerals

[0035] (1a) ····· Gas outflow cylinder portion (inner cylinder) (11) ····· Outer peripheral surface (12) ····· Engagement protrusion (12a) ····· Opposing surface (2) ······ Joint member (outer cylinder) (21) ····· Inner peripheral surface (22) ····· Engagement protrusion (22a) ····· Opposing surface (20) ····· Airtight O-ring (airtight seal member) (30) ····· Graphite-inflated grease

Claims

1. An insertion-type connection part for inserting and connecting one pipe body into another pipe body, in a fireproof seal structure of a connection part provided with an airtight seal member for maintaining an outer peripheral airtight state between the inner peripheral surface of an outer cylinder located on the outside and the outer peripheral surface of an inner cylinder located on the inside, on each of the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder, engaging protrusion parts having opposing surfaces that face each other in the insertion direction when the connection is completed are provided, a fireproof seal structure of a connection part, characterized in that an expanded graphite grease mixed with expanded graphite using a base oil having a property that does not affect the performance of the airtight seal member is interposed between the opposing surfaces of both engaging protrusion parts.

2. In the fireproof seal structure of the connection part according to Claim 1, when the connection is completed, the opposing surface of the engaging protrusion part provided on the outer peripheral surface of the inner cylinder faces the opposing surface of the engaging protrusion part provided on the inner peripheral surface of the outer cylinder on the back side in the insertion direction from the seal part between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder by the airtight seal member. A fireproof seal structure of a connection part is characterized by this.

3. In the fireproof seal structure of the connection part according to Claim 1 or 2, a fireproof seal structure of a connection part, characterized in that at least one of each opposing surface of both engaging protrusion parts is provided with an annular recess for holding the expanded graphite grease so as to open toward the other opposing surface.

4. In the fireproof seal structure of the connection part according to Claim 3, a fireproof seal structure of a connection part, wherein a joint member to be connected to a gas inlet part or a pipe of a gas appliance is used as the outer cylinder, the connection cylinder part of a gas plug is used as the inner cylinder, and the expanded graphite grease is applied to the opposing surface of the engaging protrusion part protruding inside the joint member.

Images