Housing type pipe joint and passage formation body

Abstract

To provide a housing type pipe joint which enables downsizing while securing sufficient fire resistance, and to provide a passage formation body.SOLUTION: A pipe joint 1 includes: a housing 2 which covers outer peripheral surfaces of ends of a pair of pipes T1, T2; a seal member 3 which is housed in the housing 2 and disposed spanning outer peripheral surfaces of both ends of the pipes T1, T2; and a fastening member 4 which fastens the housing 2 to the pipes T1, T2. The housing 2 has a pair of protruding parts 22, 22 protruding to the inner diameter side along a circumferential direction at both axial sides sandwiching the seal member 3. Fire resistant packings 5, 5 are provided on facing surfaces of the protruding parts 22, 22 facing the pipes T1, T2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a housing-type pipe joint and a flow passage forming body, and more particularly to a housing-type pipe joint and a flow passage forming body for connecting gas pipes. [Background technology]

[0002] Gas pipes are used in a variety of diameters depending on the structure of the building. For example, in commercial buildings and apartment buildings, where gas consumption is large, pipes with a relatively large diameter (generally 80A or more) are used. For gas pipes of 80A or more, steel pipes are generally used, and welding is the mainstream method of connection.

[0003] Welded connections have the advantage of being sturdy and strong, but performance such as weld strength depends on the skill of the welder. This concern is growing with the recent decline in the number of welders, and there are also concerns about the impact on construction time. In addition, when welding connections are made, the pipes must be extended in blocks as the work progresses. In addition, welding connections require preparation of the pipe end faces before welding. Preparation of the grooves requires preliminary work such as aligning the axes of the pipes to be connected and temporarily fixing them in place. As such, welding connections impose a heavy workload.

[0004] Coupling-type pipe joints have been known to reduce the workload of such pipe connections. Coupling-type pipe joints have a casing that is attached to the outer periphery of the ends of a pair of pipes, a seal member, and a fastening member. Here, pipe joints used for gas pipes need to have fire resistance to prevent gas from leaking from inside the pipe in the event of a fire and spreading the fire.

[0005] This fire resistance performance refers to the ability to prevent gas leakage to the outside when exposed to a high temperature environment for a specified period of time, or to keep leakage to a small amount even if leakage does occur. The standard for fire resistance required is generally to place the pipe fitting assembled to the pipe using normal construction methods in a fireproof furnace with a pressure equal to or greater than the actual operating pressure (air or nitrogen gas is used as the fluid), and to heat the pipe for 30 minutes according to standard heating curve A specified in JIS A 1304 "Fire resistance test method for building structures", and the leakage rate during heating should generally be equal to or less than 500cc / min.

[0006] Regarding fire resistance, for example, in the case of a welded connection, the pipes are completely melted and connected, so there is no need to consider the performance of the welded connection. On the other hand, in the case of a coupling type pipe joint, fire resistance must be ensured, but since the sealing material is burned under the above fire resistance test conditions, some kind of measure is required to prevent leakage.

[0007] As a countermeasure against this, a coupling-type pipe joint equipped with a fireproof packing is disclosed in Patent Document 1. When the fireproof packing is heated and reaches a certain temperature, its apparent volume expands several times to several tens of times.

[0008] FIG. 8 shows a cross-sectional view of a conventional coupling type pipe joint. FIG. 8 shows a state in which pipes are connected. As shown in FIG. 8, the coupling type pipe joint 6 has a casing 61, a retaining member (lock ring) 62, a seal member 63, a metal inner plate 64, and a fireproof packing 65. The seal member 63 is disposed across the outer peripheral surfaces of the ends of a pair of pipes T1 and T2, and the fireproof packing 65 is provided on its inner peripheral surface. The fireproof packing 65 is provided over almost the entire width of the area where the tip lip of the seal member 63 and the pipes T1 and T2 abut. The fireproof packing 65 is a cylindrical member having a thickness of, for example, about 2 mm, and is integrated with the inner plate 64.

[0009] In the coupling-type pipe joint 6 of Fig. 8, in the event of a fire, the fireproof packing 65 expands and fills the gaps between the retaining member 62 and the side wall portion 61a of the housing 61 and the outer circumferential surfaces of the pipes T1, T2, thereby preventing the fluid inside the pipes from leaking to the outside. Here, the inner plate 64 has the function of preventing the expanded fireproof packing 65 from flowing into the pipes T1, T2 when the fireproof packing 65 expands, in order to prevent a decrease in the density of the fireproof packing 65 filling the inside of the housing 61. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2019-65909 A Summary of the Invention [Problem to be solved by the invention]

[0011] In the conventional coupling type pipe joint as described above, the gap between the seal member 63 and the outer circumferential surface of the pipes T1 and T2 is relatively large. Therefore, the fireproof packing itself needs to be of a certain size. Also, an inner plate 64 is required to prevent the fireproof packing 65 from flowing into the inside of the pipes T1 and T2 during expansion, which tends to increase the dimensions of the coupling type pipe joint and may also lead to increased costs. Also, if the volume to be filled by the fireproof packing 65 is large, the filling density when expanded tends to vary, and as a result, the fireproof performance tends to vary.

[0012] The present invention has been made in consideration of the above circumstances, and has an object to provide a housing-type pipe joint and a flow passage forming body that can be made compact while ensuring sufficient fire resistance. [Means for solving the problem]

[0013] The housing-type pipe joint of the present invention is a housing-type pipe joint comprising a housing covering the outer peripheral surfaces of the ends of a pair of pipes, a sealing member accommodated inside the housing and positioned across the outer peripheral surfaces of both end parts of the pipes, and a fastening member for fastening the housing to the pipes, characterized in that the housing has a pair of protrusions protruding circumferentially toward the inner diameter side on both axial sides sandwiching the sealing member, and a fire-resistant gasket is provided on the surface of the protrusions facing the pipes.

[0014] In a state in which a pipe is connected to the housing-type pipe joint, the fireproof packing may be sandwiched between the opposing surface of the protrusion and the outer circumferential surface of the pipe.

[0015] The housing may be made up of a pair of semi-annular housings, each of which has a pair of flanges at both circumferential ends, and the housings may be fastened together by joining the pair of flanges of each semi-annular housing to each other.

[0016] In each semi-annular housing, a fireproof gasket is provided on the joint surface of one of the pair of flange portions and the opposing surface of the pair of convex portions, and each semi-annular housing may be fastened so that the fireproof gaskets provided on the joint surfaces do not overlap each other.

[0017] The protrusion may be engaged in a circumferential groove provided in the end of the tube.

[0018] The flow path forming body of the present invention is a flow path forming body comprising a pair of pipes forming a part of a flow path of a fluid, and a housing-type pipe joint connecting the ends of the pipes, wherein the housing-type pipe joint has a housing covering the outer surfaces of the ends of the pair of pipes, a sealing member contained inside the housing and arranged across the outer surfaces of both end portions of the pipes, and a fastening member fastening the housing to the pipes, and is characterized in that the housing has a pair of protrusions protruding circumferentially toward the inner diameter side on both axial sides sandwiching the sealing member, and a fire-resistant gasket is sandwiched and interposed between the opposing surfaces of the protrusions and the outer surface of the pipes. Effect of the Invention

[0019] According to the housing type pipe joint and the flow passage forming body of the present invention, by adopting the above-mentioned configuration, it is possible to reduce the size while ensuring sufficient fire resistance. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is an exploded perspective view of the housing-type pipe joint of the present invention. [Diagram 2] 1 is a cross-sectional view of a housing-type pipe joint of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view of a housing-type pipe joint of the present invention. [Figure 4] FIG. 13 is a schematic diagram of a pair of semi-annular housings assembled together; [Diagram 5] 1 is a graph showing the results of fire resistance tests of Examples 1 and 2 and Comparative Example 1. [Figure 6] 1 is a photograph of the embodiment of Example 3 and a graph showing the results of a fire resistance test. [Figure 7] 1 is a graph showing the results of a fire resistance test for Examples 4 and 5. [Figure 8] FIG. 1 is a cross-sectional view of a conventional coupling-type pipe joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A housing type pipe joint (hereinafter simply referred to as a pipe joint) of the present invention will be described below with reference to the drawings.

[0022] FIG. 1 shows an exploded perspective view of a pipe joint. The pipe joint 1 is used to connect the ends of a pair of pipes T1 and T2. The pipes T1 and T2 are pipes that form a gas flow path, and metal pipes such as carbon steel pipes and stainless steel pipes are used. The nominal diameter of the pipes T1 and T2 is not particularly limited and is, for example, 20A to 200A, and the pipe joint 1 is suitable for use with relatively large diameter pipes of 80A or more, which are mainly constructed by welding.

[0023] As shown in Fig. 1, the pipe fitting 1 is a pipe fitting mainly used to connect gas pipes, and includes a housing 2, a seal member 3, and a fastening member 4, as well as a fireproof packing 5 for ensuring fire resistance. The assembled pipe fitting 1 has a cylindrical shape as a whole.

[0024] In Fig. 1, the housing 2 is made of metal and is composed of a pair of semi-annular housings 2A, 2B. The semi-annular housings 2A, 2B are split into two halves on a plane including the central axis O (see Fig. 2) of the pipe fitting 1, and are fastened together by a fastening member 4 to form a cylindrical housing. The semi-annular housings 2A, 2B have the same shape. The semi-annular housing 2A has a pair of flanges 23, 23 at both circumferential ends, and these flanges 23, 23 are joined to a pair of flanges of the semi-annular housing 2B and fastened together.

[0025] The housing 2 is attached so as to cover the outer peripheral surfaces of the ends of the tubes T1 and T2. The tube T1 is inserted into one opening of the housing 2, and the tube T2 is inserted into the other opening. A groove 21 is provided along the circumferential direction on the inner peripheral surface of the housing 2, and the seal member 3 is accommodated in the groove 21. The housing 2 also has a pair of protrusions 22, 22 protruding toward the inner diameter side along the circumferential direction on both axial sides. The groove 21 and the seal member 3 are disposed between the protrusions 22, 22. The protrusions 22, 22 are portions that are pressed toward the tubes T1 and T2 when the tubes are connected. In FIG. 1, the protrusion 22 on one axial side engages with a circumferential groove T1a provided at the end of the tube T1, and the protrusion 22 on the other axial side engages with a circumferential groove T2a provided at the end of the tube T2.

[0026] The seal member 3 is a cylindrical member and is housed inside the housing 2. As shown in Fig. 2, the seal member 3 is disposed so as to straddle the outer circumferential surfaces of both ends of the tubes T1, T2, and seals between the housing 2 and the outer circumferential surfaces of the tubes T1, T2. The seal member 3 is pressed by fastening the fastening member 4 and comes into close contact with the outer circumferential surfaces of the tubes T1, T2. The seal member 3 is made of rubber, such as nitrile butadiene rubber (NBR) or ethylene propylene diene rubber (EPDM).

[0027] In Fig. 1, the fastening member 4 is composed of two sets of bolts 41 and nuts 42. The shaft of the bolt 41 is inserted into the through hole 24 provided in the flange portion 23 of the semi-annular housings 2A, 2B, and the nut 42 is screwed onto the shaft. When the pipe joint 1 is fastened with the bolt 41 and the nut 42, the seal member 3 on the inside of the housing 2 is brought into close contact with the pipes T1, T2, and the protrusions 22, 22 are pressed against the circumferential grooves T1a, T2a of the pipes T1, T2. As a result, the seal member 3 provides sealing properties, and the protrusions 22, 22 provide pull-out prevention properties.

[0028] Here, in the pipe joint 1, fireproof packings 5, 5 are provided on the surfaces of the protruding parts 22, 22 of the housing 2 facing the pipes T1, T2. In Fig. 1, the fireproof packings 5 ​​are provided on both axial sides of the semi-annular housings 2A, 2B along the circumferential direction, covering half the circumference. In other words, the housing 2 as a whole is provided with the fireproof packings 5 ​​on both axial sides (two rows) over the entire circumferential direction.

[0029] Next, the arrangement of the fireproof packing 5 will be further explained with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the flange of the pipe joint 1, and Figure 3 is a cross-sectional view cut at a different location from the flange. In each figure, the upper half above the central axis O of the pipe joint 1 shows a cross-sectional view of the state in which the pipes T1 and T2 are connected, and the lower half shows a cross-sectional view of the pipe joint 1. In order to make it easier to see where the fireproof packing 5 is installed, the areas other than the cut surface of the fireproof packing 5 are painted black.

[0030] 2 and 3, in the pipe joint 1, the fireproof packing 5 is provided on the surfaces 22a, 22a of the protrusions 22, 22 facing the pipes T1, T2. In this embodiment, the band-shaped fireproof packing 5 is attached along the circumferential direction. The fireproof packing 5 is arranged so as to fill the gap connecting the internal space of the housing 2 (such as the space in which the seal member 3 is housed) and the external space of the housing 2. In other words, the fireproof packing 5 is provided so as to be sandwiched and interposed between the opposing surfaces 22a, 22a of the housing 2 and the outer circumferential surfaces of the pipes T1, T2 when the pipes are connected.

[0031] The fireproof packing 5 may be sandwiched and interposed between the opposing surfaces 22a, 22a of the protrusions 22, 22 and the outer circumferential surfaces of the pipes T1, T2 when the pipes are connected, and the manner in which the fireproof packing 5 is provided is not particularly limited. For example, as shown in Figs. 1 to 3, the fireproof packing 5 may be provided integrally with the housing 2 by being attached to the protrusions 22, 22 in advance, or may be separately attached between the protrusions 22, 22 and the pipes T1, T2 and sandwiched and interposed therebetween. When attaching the fireproof packing 5, a double-sided tape or an adhesive may be used.

[0032] In the conventional pipe joint, as shown in FIG. 8, the fireproof packing 65 is arranged so as to expand in the event of a fire or the like to fill the space inside the housing 61, thereby minimizing leakage. In contrast, in the pipe joint 1 of the present invention, the fireproof packing 5 is arranged to fill the gap in advance, and the fireproof packing 5 is pressed against the pipes T1 and T2 when the pipes are connected, so that the fireproof packing itself has sealing properties. In other words, in the event of a fire or the like, the fireproof packing 5 mainly exerts an effect of preventing leakage due to its sealing properties, and the prevention of leakage due to expansion is a secondary effect. In addition, in the pipe joint 1, when the fireproof packing 5 expands, the fireproof packing 5 flows out to the outside of the housing 2 in no small amount, so in the pipe joint 1, it is possible to visually confirm from the outside that the fireproof packing 5 has performed its function.

[0033] In the pipe joint 1, the fireproof packing 5 is provided on the protrusions 22, 22 of the housing 2 so that it is sandwiched between the outer circumferential surfaces of the pipes T1, T2 when the pipes are connected, and this allows the size (volume) of the fireproof packing 5 to be smaller than that of conventional pipe joints. In other words, the width and thickness of the fireproof packing 5 can be reduced, which also leads to cost reduction. In addition, the dimensions of the pipe joint itself can be reduced.

[0034] For example, the width of the fireproof packing 5 is a length that does not exceed the width (axial length) of the opposing surface 22a of the protrusion 22, and is, for example, 1.0 mm to 20 mm, and an appropriate length may be selected depending on the performance. The thickness of the fireproof packing 5 is 0.5 mm to 3.0 mm, and an appropriate length may be selected depending on the performance.

[0035] In addition, unlike conventional pipe joints, the fireproof packing 5 in the pipe joint 1 is not arranged to cover the gap between the pair of pipes T1, T2, and does not have an inner plate 64 (see FIG. 8). In the pipe joint 1, the fireproof packing 5 is sandwiched and interposed between the outer circumferential surfaces of the pipes T1, T2 when the pipes are connected, so that the fireproof packing 5 provides sealing properties. In addition, when the sealing member 3 is burned down due to a fire or the like, the fireproof packing 5 mainly expands within the narrow space sandwiched between the opposing surface 22a and the circumferential grooves T1a, T2a, so there is no need to provide an inner plate 64 to prevent the fireproof packing 5 from flowing into the inside of the pipes T1, T2.

[0036] In addition, the inner plate in a conventional pipe joint is required to have a certain thickness to withstand the pressure caused by the expansion of the fireproof packing, and therefore tends to be large. Therefore, by not requiring an inner plate, the pipe joint can be further miniaturized and cost reduced. Furthermore, in a conventional pipe joint, it was necessary to manage (position) the insertion amount of the pipe into the pipe joint so that the inner plate is reliably positioned in the gap between the pipes. Specifically, it was necessary to mark a position that would be a benchmark line when inserting the pipe at a position a predetermined axial length from the pipe end on the outer peripheral surface of the pipe, and insert the pipe into the pipe joint so that the position of the benchmark line coincides with the end of the pipe joint when inserting the pipe, but this work burden can also be reduced.

[0037] Incidentally, when connecting gas pipes using a pipe joint, the pipe is also required to have a pull-out prevention force. In the pipe joint 1 of Fig. 2 and Fig. 3, the protrusions 22, 22 are engaged with and caught in the circumferential grooves T1a, T2a of the pipes T1, T2, respectively, thereby obtaining a high pull-out prevention force. The pull-out prevention force of the pipe joint 1 is superior to that of a conventional pipe joint using a lock ring, and is about the same as that of a threaded joint.

[0038] In the pipe fitting 1 shown in FIG. 2, in addition to the opposing surfaces 22a, 22a of the semi-annular housing 2A, a fireproof packing 5 is also provided on the joint surfaces 23a, 23a of a pair of flanges 23, 23. The joint surfaces 23a, 23a are surfaces that join with the joint surfaces of the other semi-annular housing. The fireproof packing 5 provided on the joint surfaces 23a, 23a is provided in a substantially U-shape so as to connect the convex portion 22 on one axial side to the convex portion 22 on the other axial side. By providing the fireproof packing 5 on the joint surfaces where the semi-annular housings are joined, gas leakage from the joint surfaces can be effectively suppressed.

[0039] The fireproof packing 5 is manufactured, for example, by kneading raw rubber, a graphite intercalation compound that expands thermally in an unfoamed state, and, if necessary, a filler, a softener, a vulcanizing agent, etc. to obtain a rubber composition, filling the rubber composition in a mold, forming the rubber composition, and then press-vulcanizing the rubber composition. For example, the fireproof packing 5 is made of graphite-containing nitrile butadiene rubber.

[0040] In the fireproof packing 5, the expansion start temperature, expansion speed, expansion ratio, shape retention after expansion, etc. can be appropriately set by adjusting the rubber composition. Note that the expansion start temperature of the fireproof packing 5 is preferably lower than the ignition temperature of the seal member 3.

[0041] 2, a protrusion 25 protruding perpendicularly to the joint surface 23a is provided on the joint surface 23a of one flange 23 of the semi-annular housing 2A, and a recess 26 recessed perpendicularly to the joint surface 23a is formed on the joint surface 23a of the other flange 23. Similarly, a corresponding protrusion and recess are formed on the semi-annular housing 2B. When joining the semi-annular housings together, the protrusion of one semi-annular housing fits into the recess of the other semi-annular housing, thereby enabling a stronger joining.

[0042] The pipe joint 1 shown in Figs. 1 to 3 is installed, for example, in the following procedure. (1) Near the ends of a pair of tubes T1 and T2, concave circumferential grooves T1a and T2a (grooves) are formed by plastic working. (2) After the seal member 3 is placed between the circumferential groove T1a and the circumferential groove T2a, it is attached. (3) A fireproof gasket 5 is attached in advance to the convex portions 22, 22 and the flange portions 23, 23 of each semi-annular housing 2A, 2B, and the pipes T1, T2 are placed over the fireproof gaskets 5 so that the convex portions 22, 22 with the fireproof gaskets 5 fit into the circumferential grooves T1a, T2a, and the pipes are tightened using bolts 41 and nuts 42.

[0043] In Fig. 2, the semi-annular housing 2A (similar to the semi-annular housing 2B in this case) is provided with fireproof gaskets 5 on both joint surfaces 23a, 23a of the pair of flanges 23, 23, so that the fireproof gaskets 5 go around the inner edge of the semi-annular housing 2A, but for example, the fireproof gasket 5 may be provided only on the joint surface of one of the pair of flanges. Such a configuration is shown in Fig. 4.

[0044] Fig. 4 is a schematic diagram showing how a pair of semi-annular housings 2A', 2B' are fastened together. As shown in Fig. 4, in the semi-annular housings 2A', 2B', the fireproof packing 5 is provided on the joint surface 23a of one of the pair of flanges 23, 23' and on the opposing surfaces of the protrusions 22, 22. For example, the semi-annular housings 2A', 2B' can be obtained with the fireproof packing 5 integrated therewith by continuously attaching a strip-shaped fireproof packing 5 to both the left and right protrusions 22, 22 of the semi-annular housings 2A', 2B' and continuously attaching the strip-shaped fireproof packing 5 to the joint surface 23a of one of the flanges 23.

[0045] The semi-annular housings 2A', 2B' are fastened facing each other so that the fireproof packings 5 ​​provided on the joint surfaces 23a do not overlap each other. That is, the joint surface 23a of the semi-annular housing 2A' is joined to face the joint surface 23a' of the semi-annular housing 2B', and the joint surface 23a' of the semi-annular housing 2A' is joined to face the joint surface 23a of the semi-annular housing 2B'. In this way, the fireproof packings 5 ​​can be provided continuously between the pair of pipes without overlapping.

[0046] The pipe joint of the present invention is not limited to the configuration described above with reference to FIGS.

[0047] In the above, a pair of semi-annular housings is shown as the housing, but the present invention is not limited to this, and a cylindrical housing, a C-shaped housing having a joint in a part of the circumferential direction, etc. can also be used. Even in this embodiment, a fireproof packing is provided at least on the opposing surfaces of the protrusions on both axial sides of the housing.

[0048] In the above description, the fireproof packing 5 is provided so as to extend continuously on each surface, but the fireproof packing 5 may be provided in a discontinuous divided manner. For example, the fireproof packing 5 may be provided over substantially the entire circumference in the circumferential direction while leaving gaps. In this case, it is preferable to set the gaps between the divided fireproof packings within a range that ensures fire resistance.

[0049] The flow path forming body of the present invention includes a pair of pipes that form a part of a flow path of a fluid, and a pipe joint that connects the ends of the pipes together. The pipe joint in this flow path forming body can be the pipe joint of the present invention described above. EXAMPLES

[0050] [Example 1 and Comparative Example 1] A pipe joint of Example 1 was prepared. In the pipe joint of Example 1, a thin band-shaped fireproof packing was continuously attached to a pair of protrusions on both axial sides of each semi-annular housing and to one of the flanges (see FIG. 4). The semi-annular housings with the fireproof packing attached were faced to each other so that the fireproof packings on the flanges did not overlap each other, and fastened so that the seal member was housed inside. The width dimension (W), thickness (t), and total volume (A) of the fireproof packing provided on the protrusions and the fireproof packing provided on the flange in the pipe joint of Example 1 are shown in Table 1 below.

[0051] A conventional product as shown in Fig. 8 was prepared as the pipe joint of Comparative Example 1. In the pipe joint of Comparative Example 1, a cylindrical flat fireproof packing is placed inside the seal member, and a metal inner plate is placed further inside that. The width (W), thickness (t) and total volume (B) of the fireproof packing in the pipe joint of Comparative Example 1 are shown in Table 1 below.

[0052] [Table 1]

[0053] As shown in Table 1, the total volume of the fireproof packing in Example 1 was 17.5% (nominal diameter 100A) and 6% (nominal diameter 200A) of the total volume of Comparative Example 1, and the amount of fireproof packing used could be significantly reduced. This reduction in the volume of the fireproof packing also allows for a significant reduction in costs. In addition, the pipe joint in Example 1 does not require an inner plate, which leads to further cost reduction.

[0054] A fire resistance test was carried out using the pipe fittings of Example 1 and Comparative Example 1. These pipe fittings were assembled to pipes using normal construction methods, and placed in a fireproof furnace with a pressure equal to or greater than the actual operating pressure (air or nitrogen gas was used as the fluid), and heated for 30 minutes according to standard heating curve A specified in JIS A 1304 "Fire resistance test method for building structures." The pass / fail line was set as a leakage amount of 500cc / min or less during heating as the judgment criterion. The results are shown in Figures 5(a) to (c).

[0055] As shown in Figures 5(a) and (b), in the case of Example 1, even after the test time exceeded 30 minutes for both 100A and 200A, the leakage amount was only a few cc / min, and almost no leakage occurred. These leakage amounts were very small, about 2% of the pass / fail criterion. On the other hand, in the case of Comparative Example 1 (100A), normal leakage occurred after 20 minutes and then gradually increased. At the end of the test, the leakage had increased to 470cc / min, but remained within the standard (see Figure 5(c)).

[0056] [Example 2] Next, based on the arrangement of the fireproof packing in Example 1, several fireproof tests were carried out, taking into consideration the tolerance variation of the fireproof packing and the change in the crimping force due to the tightening torque of the bolts and nuts, and the results were as good as those in Example 1.

[0057] For example, a similar fire resistance test was carried out using a fireproof packing of W1.5mm×t1.0mm (1 / 4 the volume of that of Example 1), which exceeds the lower limit of the dimensional variation tolerance of the fireproof packing at 200A, as Example 2. As a result, as shown in Fig. 5(d), although the leakage amount increased to 30cc / min compared to Example 1 (200A), it was confirmed that the leakage amount was less than 10% of the pass / fail criterion and had a sufficient safety factor.

[0058] [Example 3] In Example 3, unlike Examples 1 and 2, the fireproof packing was provided so as to be discontinuous on each surface. Specifically, as shown in the photograph of Figure 6(a), 5 mm gaps (white portions) were provided at three locations at 45° positions on the protruding portion of the housing and at two locations at the bends of the flange. The nominal diameter was 200A, which was 80 mm (= 16 locations x 5 mm each) shorter than the fireproof packing of Example 1. This shortening amount was about 5% of the total length. The results of the fireproof test are shown in Figure 6(b).

[0059] As shown in Fig. 6(b), there was almost no leakage, and the results were similar to those of Example 1, in which the fireproof packing was provided continuously. For example, if the fireproof packing is made into a single piece that is continuous with the protrusion and the flange, the mold size may become large, which may lead to increased costs. In contrast, by attaching multiple fireproof packings formed to a certain size to the required locations, as shown in Fig. 6(a), it is expected that the effect of cost reduction can be achieved by standardizing parts.

[0060] From the results of Example 3, it was found that even if the fireproof gaskets are attached so that gaps are formed between them, the fireproof gaskets can fully exhibit their fireproof performance if they expand a necessary amount before the sealing material is burned and the sealing ability of the sealing material is lost.

[0061] [Example 4] For the purpose of further improving workability and reducing costs, a fire resistance test was carried out using a pipe joint in which the flange was omitted (no fire resistance packing was provided on the flange) from the arrangement of the fire resistance packing in Example 1 (100A). As a result, as shown in Figure 7(a), the leakage amount was within the standard, but it was relatively large compared to Example 1.

[0062] [Example 5] In the above-mentioned Examples 1 to 4, the fireproof packing was attached to the housing in advance (pre-integrated), but in Example 5, the fireproof packing was attached during construction. A cylindrical fireproof packing was attached to the protruding part of the housing by fitting it to the circumferential groove of the pipe and fastening it. Also, a sheet-like fireproof packing was sandwiched between the opposing joint surfaces of the flange part of the housing during the process from the installation of the housing to the threading of the bolt. As a result of the fireproof test, as shown in FIG. 7(b), it was found that even if the fireproof packing was not pre-integrated, the fireproof performance was sufficiently exhibited by sandwiching and interposing the fireproof packing between the opposing surface of the protruding part and the outer peripheral surface of the pipe.

[0063] In this way, the pipe joints of the respective embodiments can be made compact while still maintaining sufficient fire resistance. It is believed that these effects are achieved by the fireproof packing being sandwiched between the opposing surface of the protrusion and the outer circumferential surface of the pipe, functioning like a gasket. [Explanation of symbols]

[0064] 1: Pipe fittings (housing type pipe fittings) 2: Housing 2A, 2B, 2A', 2B': Semi-annular housing 21: Groove 22: Convex 22a: Opposing surface 23: Brim 23a: Joint surface 24:Through hole 25: Convex 26: Recess 3: Sealing material 4: Fastening member 41: Bolt 42: Nut 5: Fireproof packing T1, T2: tube T1a, T2a: Circumferential groove

Claims

1. A housing-type pipe joint comprising: a housing that covers outer peripheral surfaces of the ends of a pair of pipes; a seal member that is accommodated inside the housing and is disposed across the outer peripheral surfaces of both ends of the pipes; and a fastening member that fastens the housing to the pipes, A housing-type pipe fitting characterized in that the housing has a pair of protrusions protruding circumferentially toward the inner diameter side on both axial sides of the sealing member, and a fire-resistant gasket is provided on the surfaces of the protrusions facing the pipe.

2. 2. A housing-type pipe joint as claimed in claim 1, characterized in that, when the pipe is connected to the housing-type pipe joint, the fire-resistant gasket is sandwiched between the opposing surface of the convex portion and the outer peripheral surface of the pipe.

3. The housing is made up of a pair of semi-annular housings, each of which has a pair of flanges at both circumferential ends, 3. A housing type pipe joint according to claim 1, wherein the housings are fastened by joining the pair of flange portions of each of the semi-annular housings together.

4. 4. The housing-type pipe joint according to claim 3, characterized in that in each of the semi-annular housings, the fireproof gasket is provided on a joint surface of one of the pair of flange portions and an opposing surface of the pair of convex portions, and each of the semi-annular housings is fastened so that the fireproof gaskets provided on the joint surfaces do not overlap each other.

5. 3. A housing type pipe joint according to claim 1, wherein the protrusion is engaged with a circumferential groove provided on the end of the pipe.

6. A flow path forming body including a pair of pipes forming a part of a flow path of a fluid and a housing-type pipe joint connecting ends of the pipes, The housing-type pipe joint has a housing covering the outer peripheral surfaces of the ends of the pair of pipes, a sealing member accommodated inside the housing and positioned across the outer peripheral surfaces of both end portions of the pipes, and a fastening member fastening the housing to the pipes, and the housing has a pair of protrusions protruding circumferentially toward the inner diameter side on both axial sides of the sealing member, and a fire-resistant gasket is sandwiched and interposed between the opposing surfaces of the protrusions and the outer peripheral surfaces of the pipes.

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