Pipe joint

Abstract

To provide a pipe joint capable of maintaining a non-leakage state of fluid under the circumstance of a more severe combustion test.SOLUTION: A pipe joint includes a joint body 1 provided with insertion ports in two places for pipe materials B to be inserted thereinto, the insertion ports communicating with each other; a ring-shaped follower 2 with opening parts through which the pipe materials B are inserted, and arranged so as to concentrically overlap with the joint body 1 from its insertion port sides; fasteners 3 for pushing the follower 2 in a direction of the joint body 1; gaskets 4 arranged in storage spaces encircled by the joint body 1 and the follower 2 while closely contacting the outer surfaces of the pipe materials B in a surrounding manner; and an inside ring part 21 formed on the follower 2 and extending along a pipe axial direction of the pipe material B. In the pipe joint, the gaskets 4 stored in the storage spaces are pushed by a front end 210 of the inside ring part 21. On outer surfaces 200, 220 of the follower 2 and on outer surfaces 100, 110 of the joint body 1, fire resistant sheets 50, 51, 52 and 60, 61, 62 are provided, respectively.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a pipe joint having improved fire resistance. [Background technology]

[0002] Pipe fittings used on ships and other vessels are required to have fire resistance that can withstand high temperatures. For example, ISO 19921 and 19922 require a combustion test to be performed for 30 minutes or more in a high-temperature environment of 800°C. After that, a specified water pressure test (2.4 MPa, 10 minutes) is performed, and the fittings must have the ability to maintain a leak-free state for the fluid. The pipe fitting disclosed in Patent Document 1 below is known as a pipe fitting that meets such requirements.

[0003] This pipe joint comprises a joint body having two insertion ports for inserting pipes and communicating between these insertion ports, a follower (retainer) formed in a ring shape with an opening for passing the pipe and arranged so as to overlap concentrically from each insertion port side of the joint body, a fastener for pressing the follower against the joint body, and a gasket that is in close contact with the outer surface of the pipe and is arranged in a storage space surrounded by the joint body and the follower. Furthermore, the follower is provided with a flame-retardant peripheral wall that fits around the end where the insertion port is provided in the joint body.

[0004] In addition, in the pipe joint of another patent document 2, a cylindrical fireproof cover is provided to cover the gasket and the end of the joint body (socket pipe).

[0005] In order to maintain a leak-tight state in a pipe joint, it is important that the performance of the gasket is maintained. The pipe joints in Patent Documents 1 and 2 are provided with a flame-retardant peripheral wall or a flame-retardant cover to prevent the gasket from being directly exposed to flames from outside the joint body and to insulate it from high-temperature environments as much as possible. This provides a pipe joint that can withstand use on ships. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Utility model registration No. 3154881 [Patent Document 2] Utility model registration No. 3175106 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above performance test, the pipe material was subjected to a high temperature environment of 800℃ for more than 30 minutes while a fluid (80℃ hot water) was flowing through it. Therefore, the heat dissipation effect of this fluid also affects the fire resistance.

[0008] However, in recent years, fire resistance performance under even harsher conditions than those mentioned above is required. Specifically, depending on the location where the pipe joint is used, it has become necessary to pass a fire resistance test without flowing a fluid. Even with the pipe joints disclosed in the above-mentioned Patent Documents 1 and 2, if a similar performance test is conducted in a dry state without using a fluid, the gasket is damaged by high heat, making it difficult to maintain a leak-tight state.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pipe joint that can maintain a fluid-tight state even under more severe combustion tests. [Means for solving the problem]

[0010] In order to solve the above problems, the pipe fitting [1] according to the present invention comprises: A joint body having at least two insertion ports for inserting pipes, the insertion ports being interconnected; Followers formed in a ring shape having an opening through which a pipe material passes and arranged so as to overlap concentrically from each insertion port side of the joint body; a fastener for pressing the follower toward the joint body; a gasket that is disposed in a storage space surrounded by the joint body and the follower and that is in intimate contact with the outer surface of the pipe material so as to surround the outer surface of the pipe material; An inner ring portion formed on the follower and extending along the axial direction of the pipe material, A pipe joint in which the gasket housed in the housing space is pressed by a tip end portion of the inner ring portion, The present invention is characterized in that an outer surface of the follower and an outer surface of the joint body are provided with a fire-resistant coating material.

[0011] The action and effect of the pipe joint having such a configuration will be explained below. This pipe joint comprises a joint body, a follower, a gasket, and a fastener. The gasket is disposed in a storage space surrounded by the joint body and the follower, and is in close contact with the surface of the pipe. The fastener acts to press the follower against the joint body. This acts in a direction that compresses the gasket, ensuring close contact between the pipe surface and the gasket and maintaining a leak-tight state.

[0012] In addition, a fire-resistant coating is provided on the outer surface of the follower and the outer surface of the fitting body. This prevents heat from being transferred to the gasket in a severe high-temperature environment, and inhibits deterioration of the gasket. As a result, a pipe fitting can be provided that can maintain a leak-tight state even under severe combustion tests.

[0013] The pipe joint [2] according to the present invention is the pipe joint [1], wherein the follower has a vertical portion perpendicular to the pipe material, and an outer ring portion covering at least a portion of the outer surface of the joint body, Preferably, the outer surfaces of the vertical sections and the outer ring section are provided with a fire resistant coating.

[0014] The pipe fitting [3] according to the present invention is preferably the pipe fitting [1] or [2], further comprising a fire-resistant coating material provided on the tip of the outer ring portion.

[0015] The pipe fitting [4] according to the present invention is any of the pipe fittings [1] to [3], wherein a fire-resistant coating material is provided on the inner surface of the outer ring portion.

[0016] The pipe fitting [5] according to the present invention is any of the pipe fittings [1] to [4], wherein a fire-resistant coating material is provided on the inner surface of the vertical portion.

[0017] The pipe fitting [6] of the present invention is preferably configured such that, in any of the pipe fittings [1] to [5], the thickness of the fire-resistant sheet provided on the outer surface of the vertical portion and the outer surface of the outer ring portion is set to be thicker than the thickness of the fire-resistant covering material in other locations.

[0018] A pipe fitting [7] according to the present invention is any of the pipe fittings [1] to [6], wherein the fitting body comprises a central ring body along the pipe axis direction and end ring bodies provided on both ends of the central ring body, and it is preferable that a fire-resistant coating material is provided on the outer surface of the central ring body and the outer surface of the end ring bodies.

[0019] The pipe fitting [8] according to the present invention is preferably any one of the pipe fittings [1] to [7], in which the fire-resistant sheet is provided on each outer surface, and the fire-resistant sheets are overlapped at the boundary between the outer surfaces and subjected to a heat fusion treatment.

[0020] The pipe fitting [9] of the present invention is any of the pipe fittings [1] to [8], wherein the fastener is composed of a bolt and a nut, and a disc spring washer is interposed between the nut and the outer surface of the vertical portion. [Brief description of the drawings]

[0021] [Figure 1A] FIG. 1 is a central cross-sectional view showing a configuration of a pipe joint according to a first embodiment; [Figure 1B] FIG. 1B is a front view of the pipe joint shown in FIG. 1A (as viewed from the pipe axis direction). [Figure 1C] Front view of the follower seen from the tube axis direction [Figure 1D]Rear view of the follower seen from the tube axis direction [Figure 1E] A central cross-sectional view showing a partially disassembled pipe joint [Diagram 2] FIG. 11 is a cross-sectional view showing a configuration of a pipe joint according to a second embodiment. [Diagram 3] FIG. 11 is a cross-sectional view showing a configuration of a pipe joint according to a third embodiment. [Figure 4] FIG. 13 is a cross-sectional view showing a configuration of a pipe joint according to a fourth embodiment. [Diagram 5] FIG. 13 is a cross-sectional view showing a configuration of a pipe joint according to a fifth embodiment. [Figure 6] FIG. 13 is a cross-sectional view showing a configuration of a pipe joint according to a sixth embodiment. [Figure 7] A diagram showing temperature measurement data for each part (without fireproof sheet) [Figure 8] A diagram showing temperature measurement data for each part (with fireproof sheet) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] A preferred embodiment of a pipe fitting according to the present invention will be described with reference to the drawings. Fig. 1 is a central cross-sectional view showing the configuration of a pipe fitting according to a first embodiment. Fig. 1B is a front view (viewed from the pipe axis direction) of the pipe fitting shown in Fig. 1A. Fig. 1C is a front view of the follower as viewed from the pipe axis direction. Fig. 1D is a rear view of the follower as viewed from the pipe axis direction. Fig. 1E is a central cross-sectional view showing a state in which a part of the pipe fitting is disassembled.

[0023] Fig. 1A shows a pipe joint A for connecting two pipes B. Fig. 1A is a cross-sectional view taken along a plane passing through the pipe axis. The pipe joint A includes a joint body 1, a follower 2, a fastener 3, and a gasket 4.

[0024] <Configuration of fitting body> The joint body 1 has two insertion ports for inserting the pipe material B, and as shown in Figure 1A, the pipe material B is inserted from the right and left insertion ports. A pair of followers 2 are arranged on either side of the joint body 1, but they have the same shape.

[0025] The joint body 1 is integrated with a central ring body 10 along the pipe axis direction and end ring bodies 11 provided on both ends of the central ring body 10. The left and right end ring bodies 11 have the same shape. The outer diameter of the central ring body 10 is set to be smaller than the outer diameter of the end ring bodies 11. The inner diameter of the central ring body 10 is set to be larger than the inner diameter of the end ring body 11 (the inner diameter of the portion adjacent to the central ring body 10 where the gasket 4 is not housed).

[0026] The end ring body 11 and the central ring body 10 are joined by welding, and the welded parts are shown by black triangles. The material of the joint body 1 is a general structural rolled steel material such as SS400, but other materials may also be used. The joint body 1 may be configured by integrally molding the central ring body 10 and the end ring body 11.

[0027] A predetermined gap is formed between the inner diameter of the central ring body 10 and the outer surface of the pipe material B. A small gap S1 is also formed between the aforementioned inner diameter of the end ring body 11 and the pipe material B. The size of the gap S1 is approximately 1.5 mm. This gap S1 allows the pipe material B to swing. The size of the gap S1 is not limited to the above numerical value and can be set appropriately. The pipe material B is shown inserted up to the position of the central ring body 10 of the joint body 1.

[0028] <Follower configuration> The follower 2 is integrally formed with a vertical section 20 perpendicular to the pipe material B, an inner ring section 21, and an outer ring section 22. The vertical section 20 is formed in a disk shape having a predetermined thickness. Fig. 1D is a rear view showing only the follower 2. As shown in Fig. 1D, it has an opening in the center for passing the pipe material B through, and six holes 202 are formed between the inner ring section 21 and the outer ring section 22 at equal intervals along the circumferential direction.

[0029] The followers 2 are arranged so as to overlap concentrically from each insertion port side of the joint body 1. The end ring body 11 of the joint body 1 is arranged so as to enter the space between the inner ring portion 21 and the outer ring portion 22. The outer ring portion 22 corresponds to the flameproof peripheral wall disclosed in the above-mentioned Patent Document 1.

[0030] The follower 2 has a vertical portion 20 that is perpendicular to the pipe material B, where "perpendicular" means that the pipe axis of the pipe material B and the central axis of the follower 2 are aligned, as shown in Figure 1A.

[0031] A gap S2 is formed between the outer surface of the inner ring portion 21 and the outer surface of the pipe material B. The gap S2 is approximately the same as the gap S1, that is, about 1.5 mm. The gap S2 is set in the same manner as the gap S1. The inner ring portion 21 extends along the pipe axis direction, and its tip portion 210 is capable of pressing the gasket 4.

[0032] The outer ring portion 22 extends along the pipe axis direction, and its length is longer than that of the inner ring portion 21. The end ring body 11 of the joint body 1 fits into a ring-shaped space (see FIG. 1D) formed between the inner ring portion 21 and the outer ring portion 22. A gap of a predetermined size is formed between the end ring body 11 and the outer ring portion 22 and between the end ring body 11 and the inner ring portion 21. This gap is at a level where the two are almost in contact with each other. In another embodiment described later, a fireproof sheet is attached to the outer surface of the end ring body 11 and the inner surface of the outer ring portion 22, and in this case, a gap of a similar level is also formed.

[0033] The follower 2 is preferably made of FCD450-10 (spheroidal graphite cast iron), but may be made of other materials.

[0034] <Fastening device configuration> The fastener 3 is composed of a stud bolt 30, a nut 31, and a disc spring washer 32. A hole 202 is formed in the vertical portion 20 of the follower 2, through which the stud bolt 30 can be inserted. The tip of the stud bolt 30 screws into a screw hole 114 formed in the end ring body 11. This allows the follower 2 to be pressed toward the joint body 1. Six screw holes 114 are also provided at equal intervals in the circumferential direction corresponding to the holes 202. By using the disc spring washer 32, it is possible to maintain the desired fastening force even if dimensional changes occur in each part due to environmental changes.

[0035] The number of stud bolts 30 does not have to be six, and may be, for example, eight, and is preferably three or more. Although the end ring body 11 has screw holes 114, the holes may be non-threaded, and the stud bolts 30 may be press-fitted or abutted to be fixed. The stud bolts 30 may be made of a material that is resistant to thermal expansion (chromium-based metal, stainless steel, titanium, etc.).

[0036] <Gasket composition> The gasket 4 is also formed in a ring shape, but its cross-sectional shape is trapezoidal as shown in Fig. 1A. The gasket 4 is stored in a storage space (see symbol C in Fig. 1E) formed between the joint body 1 and the follower 2. The gasket 4 is in close contact with and surrounds the outer surface of the pipe B. The storage space C has a cross-sectional trapezoidal shape that corresponds to the outer shape of the gasket 4.

[0037] The gasket 4 has a contact surface 40, a tapered surface 41, and a pressed surface 42. The contact surface 40 is in close contact with the surface of the pipe material. The pressed surface 42 is pressed by the tip 210 of the inner ring portion 21 of the follower 2. This causes the gasket 4 to be pressed in, increasing its adhesion to the surface of the pipe material. The tapered surface 41 causes a compressive force to act on the gasket 4 in the direction of the surface of the pipe material. The tip 210 is also a tapered surface, so that a pressing force acts in the direction of the surface of the pipe material.

[0038] As described above, because the gaps S1 and S2 are formed, the pipe material B is supported in a state in which it can swing around the position of the gasket 4. In addition, the pipe material B can move in the pipe axial direction while maintaining a tight contact state.

[0039] The gasket 4 is not limited to a specific material, but may be made of an appropriate material such as nitrile rubber with additives adjusted to provide a material with excellent flame retardancy and heat resistance.

[0040] <Attaching the fireproof sheet> Next, a fire-resistant sheet, which is an example of a fire-resistant covering material, will be described. As shown in Fig. 1A, a fire-resistant sheet is attached (provided) to the outer surface of the vertical part 20 of the pipe joint and the outer surface of the joint body 1. By attaching the fire-resistant sheet, it is possible to prevent the gasket 4 from becoming too hot in a high-temperature environment. An adhesive such as glue can be used for attachment.

[0041] In the embodiment shown in FIG. 1A, a fire-resistant sheet 50 is attached to the outer surface 200 of the vertical portion 20, a fire-resistant sheet 51 is attached to the outer surface 220 of the outer ring portion 22, and a fire-resistant sheet 52 is attached to the tip portion 221 (corresponding to a part of the outer surface) of the outer ring portion 22.

[0042] In addition, a fire-resistant sheet 60 is attached to the outer surface 100 of the central ring body 10 of the joint body 1, and a fire-resistant sheet 61 is attached to the outer surface 110, which is the vertical surface, of the end ring body 11. In addition, a fire-resistant sheet 62 is attached to the welded parts of the central ring body 10 and the end ring body 11.

[0043] As the fire-resistant sheet, there can be used one which foams when the ambient temperature rises due to a fire or the like and reaches a predetermined temperature, forming a carbonized heat insulating layer.

[0044] The fire-resistant sheet is not limited to a specific material, but may be, for example, SK Taica sheet manufactured by SK Chemical Co., Ltd., or those described in JP-A-2021-41579 and JP-A-2005-60946. The thickness of the sheet is, for example, 1.5 mm, but is not limited thereto.

[0045] As described above, by attaching a fire-resistant sheet to the outer surface exposed to a high-temperature environment, it is possible to suppress the heat conduction to the gasket 4 and to suppress the deterioration of the gasket 4 at high temperatures. In the embodiment shown in Fig. 1A, the tip 221 of the outer ring portion 22 of the follower 2 has a length sufficient to cover the outer surface of the end ring body 11. This configuration also contributes to the fire resistance performance. In other words, the outer ring portion 22 has a length sufficient to completely cover the end ring body 11.

[0046] 1C is a diagram showing a state in which the fastener 3 has been removed, and the fire-resistant sheet 50 has a hole 500 for inserting the stud bolt 30. The diameter of the hole 500 is set to be smaller than the diameters of the nut 31 and the disc spring washer 32.

[0047] Basically, one fireproof sheet is attached to one surface. For example, the fireproof sheet 50 attached to the outer surface 200 of the vertical portion 20 and the fireproof sheet 51 attached to the outer surface 220 of the outer ring portion 22 are separate sheets. In this case, the fireproof sheets are overlapped and heat-sealed at the boundary between the outer surfaces. This prevents the outer surface from being exposed at the boundary (corner), so that fireproofness can be efficiently improved. This is the same for other boundary portions. The same treatment is also performed in the embodiment described below. The same is also applied to the boundary between the outer surface and the inner surface.

[0048] <Second embodiment> Next, a pipe joint according to a second embodiment will be described with reference to Fig. 2. The differences from the first embodiment will be mainly described. In the second embodiment, a fire-resistant sheet 63 is attached to the outer surface 113 of the end ring body 11 of the joint body 1. The length of the outer ring portion 22 is shorter than that of the first embodiment, but the outer ring portion 22 covers part of the outer surface of the end ring body 11. The fire-resistant sheet 63 penetrates into the inner peripheral surface of the outer ring portion 22, improving fire resistance.

[0049] <Third embodiment> Next, a pipe fitting according to a third embodiment will be described with reference to Fig. 3. The differences from the other embodiments will be mainly described. In the third embodiment, a fire-resistant sheet 52 is attached to the tip portion 221 of the outer ring portion 22, and a fire-resistant sheet 53 is attached to the inner surface 222 of the outer ring portion 22. The length of the outer ring portion 22 is the same as in the second embodiment, but the fire-resistant sheet 63 attached to the outer surface 113 of the end ring body 11 and the fire-resistant sheet 53 of the outer ring portion 22 are partially doubled to improve fire resistance.

[0050] <Fourth embodiment> Next, a pipe joint according to a fourth embodiment will be described with reference to FIG. 4. The difference from the third embodiment is that the fire-resistant sheets 50, 51, 52 attached to the outer surface of the follower 2 are two-ply, and are twice as thick as other parts. In addition, a fire-resistant sheet 54 is also attached to the inner surface 201 of the vertical part 20. This suppresses heat transfer to the inside through the follower 2. When changing the thickness, a thicker sheet may be attached instead of two-ply. For example, the fire-resistant sheets 50, 51, 52 may be 3 mm thick, and the other parts may be 1.5 mm thick.

[0051] <Fifth embodiment> Next, a pipe joint according to a fifth embodiment will be described with reference to FIG. 5. In the fifth embodiment, the shape of the joint body 1 differs from that of the other embodiments. The joint body 1 has a central ring body 15 and an end ring body 17. The central ring body 15 and the end ring body 17 have the same outer diameter. A storage space C is formed inside the end ring body 17 to store a gasket 4. The joint body 1 has two upright ring bodies 16, which are joined to the central ring body 15 by welding. The welded points are indicated by black triangles. The upright ring bodies 16 may be manufactured integrally with the central ring body 15 and the end ring bodies 17.

[0052] The fastener 3 includes a bolt 30, a nut 31, and a disc spring washer 32. A hole 160 is formed in the upright ring body 16 for inserting the bolt 30. As in the other embodiments, a gap S1 is formed between the joint body 1 and the pipe material B, and a gap S2 is formed between the follower 2 and the pipe material B. The fastener 3 acts to press the follower 2 against the joint body 1.

[0053] The outer ring portion 22 of the follower 2 has a length sufficient to cover the standing ring body 16. Two layers of fire-resistant sheets 50 are attached to the outer surface 200 of the vertical portion 20 of the follower 2, two layers of fire-resistant sheets 51 are attached to the outer surface 220 of the outer ring portion 22, and two layers of fire-resistant sheets 52 are attached to the tip portion 221 of the outer ring portion 22.

[0054] In the joint body 1, a fire-resistant sheet is attached to the outer surface between the two standing ring bodies 16. Specifically, a fire-resistant sheet 60 is attached to the outer surface 152 of the central ring body 15, and a fire-resistant sheet 61 is attached to the outer surface 161 of the standing ring body 16. In addition, a fire-resistant sheet 62 is also attached to the surface of the welded portion.

[0055] Sixth Embodiment Next, a pipe joint according to a sixth embodiment will be described with reference to Fig. 6. In the sixth embodiment, the joint body 1 is generally the same as in the fifth embodiment. The fastener 3 is provided so as to fasten the left and right followers 2 with one stud bolt 30. Therefore, a hole for inserting the stud bolt 30 is formed in the followers 2. The stud bolt 30 is fastened with a nut 31 via two disc spring washers 32 and one flat washer 33.

[0056] Fire-resistant sheets 50, 51, 52 are attached to the outer surfaces 200, 220, 221 of the follower 2. A fire-resistant sheet 60 is attached to the outer surface of the joint body 1.

[0057] <Experimental Results> Fig. 7 is a graph showing the temperature change at each part of the pipe joint when no fire-resistant sheet is attached. Fig. 8 is a graph showing the temperature change at each part of the pipe joint when a fire-resistant sheet is attached. The pipe joint and the attachment location of the fire-resistant sheet are those of the embodiment shown in Fig. 3. The pipe joint is shown diagrammatically. The vertical axis of the graph shows temperature (°C) and the horizontal axis shows the passage of time (min).

[0058] The temperatures at locations (1) to (6) were measured using thermocouples. (1) indicates the center of the inner surface of the fitting body 1. (2) indicates the position of the tapered surface of the gasket 4. (3) indicates the location of the gasket 4 that is in close contact with the pipe material B. (4) indicates the surface temperature of the follower 2. (5) indicates the surface temperature of the pipe material B that is on the outside of the fitting body 1. (6) indicates a position a specified distance away from the outer surface of the center of the fitting body 1. (6) indicates the value of the heating temperature.

[0059] As can be seen from Figure 7, when no fire-resistant sheet is used, the temperature around the gasket (2) and (3) rises to nearly 500°C. In contrast, as shown in Figure 8, when a fire-resistant sheet is used, the temperature around the gasket (2) and (3) is kept below 200°C. This makes it possible to prevent the gasket from deteriorating even in harsh environments.

[0060] <Another embodiment> In this embodiment, various embodiments have been described, but the configuration of one embodiment may be appropriately adopted for other embodiments. For example, in the second embodiment, a fireproof sheet may be attached to the tip of the outer ring portion 22 as in the first embodiment.

[0061] The surface of the fire-resistant sheet may be appropriately painted.

[0062] Instead of the fireproof sheet, a fireproof coating material can be provided by painting with a fireproof paint. As the fireproof paint, a paint that foams and forms a carbonized insulation layer when the surrounding temperature rises due to a fire or the like and the paint reaches a predetermined temperature can be used. The fireproof paint is not limited to a specific material, but for example, SK Taica Coat manufactured by SK Chemical Co., Ltd., and those described in JP 2021-41579 A, ​​JP 2005-60946 A, etc. can be used. The thickness of the paint film made of the fireproof paint can be, for example, 1.5 mm, but is not limited thereto.

[0063] The joint body 1 needs to have at least two insertion ports for the pipe material B, and the number of insertion ports may be increased to configure a three-way or four-way joint. [Explanation of symbols]

[0064] A Pipe Fitting B Tube material C. Storage space S1, S2 gap 1 Fitting body 100,110 outer surface 10,15 Center ring body 11,17 End ring body 2 Followers 20 Vertical section 200 outer surface 21 Inner ring part 210 Tip 22 Outer ring part 220 External surface 221 Tip 222 Inner surface 3 Fasteners 30 Stud bolt 31 Nut 32 Disc spring washer 4 Gasket 50,51,52,53,54 Fireproof sheet 60,61,62,63 Fireproof sheet

Claims

1. A joint body having at least two insertion ports for inserting pipes, the insertion ports being connected to each other; Followers formed in a ring shape having an opening through which a pipe material passes and arranged so as to overlap concentrically from each insertion port side of the joint body; a fastener for pressing the follower toward the joint body; a gasket that is disposed in a storage space surrounded by the joint body and the follower and that is in intimate contact with the outer surface of the pipe material so as to surround the outer surface of the pipe material; An inner ring portion formed on the follower and extending along the axial direction of the pipe material, A pipe joint in which the gasket housed in the housing space is pressed by a tip end portion of the inner ring portion, A pipe joint, characterized in that an outer surface of the follower and an outer surface of the joint body are provided with a fire-resistant coating material.

2. The follower has a vertical portion perpendicular to the pipe material; and an outer ring portion covering at least a portion of the outer surface of the joint body, 2. The pipe fitting according to claim 1, wherein an outer surface of said vertical portion and an outer surface of said outer ring portion are provided with a fire-resistant coating.

3. 3. The pipe joint according to claim 2, wherein a fire-resistant coating is provided on a tip of the outer ring portion.

4. 4. A pipe joint according to claim 2 or 3, characterized in that an inner surface of the outer ring portion is provided with a fire-resistant coating material.

5. 5. A pipe fitting according to claim 4, characterized in that the inner surface of said vertical section is provided with a fire-resistant coating.

6. 4. A pipe fitting according to claim 2 or 3, characterized in that the thickness of the fire-resistant coating material provided on the outer surface of the vertical portion and the outer surface of the outer ring portion is set to be thicker than the thickness of the fire-resistant coating material in other locations.

7. The pipe joint according to any one of claims 1 to 3, characterized in that the joint body comprises a central ring body along the pipe axial direction, and end ring bodies provided on both ends of the central ring body, and the fire-resistant coating material is provided on outer surfaces of the central ring body and the end ring bodies.

8. A pipe joint according to any one of claims 1 to 3, characterized in that a fire-resistant sheet is provided as the fire-resistant covering material on each outer surface, and the fire-resistant sheets are overlapped and heat-sealed at the boundary between the outer surfaces.

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