JP4290153B2 - Leakage prevention device for cryogenic flange joints - Google Patents

Description

  The present invention relates to a preventive device provided in the event of micro-leakage of liquid or gas from a flange portion such as a pipe or valve lid used for a live line for high-pressure and cryogenic fluid.

Conventionally, lines that handle high-pressure and cryogenic fluids are welded pipes, but the connection between the valve lid and piping and the machine is connected by flange connection. It is fastened with bolts and nuts with a gasket interposed.
This gasket is known to relieve stress when used for a long period of time, resulting in a decrease in sealing performance.

For example, as shown in FIG. 8, a conventional leakage prevention device 50 that seals a gap portion of a flange wraps a seal packing 51 made of an adhesive resin-impregnated cloth member around an outer peripheral surface 46 of the flange 45, and the seal packing 51 A seal packing 53 made of liquid silicone rubber is injected and filled in the gap between the opened injection hole 52 and the flange 45, and seal caps 56, 56 are put on the bolts and nuts 49 connecting the flange 45, and the screw holes 48 are inserted. Prevention of leakage is performed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-269090

Further, the leakage preventing device 60 shown in FIG. 9 is provided between the fastening bracket 61 divided in a strip shape extending along the outer peripheral surface 46 of the flange 45 and the outer peripheral surface 46 of the flange 45. A seal packing 62 made of sponge rubber, and spacers 63 are attached to both ends of the seal packing, and both ends of the fastening fitting 61 are tightened with bolts and nuts 65, whereby both sides of the seal packing 62 are held by the spacers 63. Has entered a gap between the flanges 45 for sealing, and a device for preventing leakage from the screw holes 48 by covering the bolts and nuts 49 connecting the flanges 45 with a seal cap 69 is known (for example, Patent Documents). 2).
JP-A-9-264476

  When the seal packing 51 shown in Patent Document 1 is applied to a flange 45 for a live line in a cryogenic region, the temperature of the fluid leaking from the gap between the flanges 45 is extremely low, so that the flange 45 in contact with air is used. Since the surface of is frosted, it is difficult to adhere the seal packing 51 made of a synthetic resin material. Further, the seal packing 53 made of a curable rubber material has many problems such as difficulty in joining to the surface of the flange cooled by the leaked fluid.

  Also in the seal packing 62 shown in Patent Document 2, since the sponge rubber itself is cured in the extremely low temperature region, the elastic repulsive force necessary for the seal packing 62 is lost and it is difficult to seal the leaked portion. The pressing force that simply covers the bolt and nut 49 with the seal cap 69 cannot withstand the fluid pressure leaking from the screw hole 48, and has many problems such as high possibility of leaking immediately. .

  Therefore, the present invention is simple and safe without stopping the operation of the plant and the pipeline in preparation for the slight leakage from the flange part of the piping and valve used in the plant handling the high pressure / cryogenic fluid. The purpose is to reliably repair and prevent leakage.

The present invention is a leakage prevention structure of a flange portion connecting pipes and valve lids used for a cryogenic fluid live line, and is detachably attached to the leakage portion of the outer peripheral surface 46 of the flange 45, Excellent mechanical strength and sealing performance that seals the leaked portion of the outer peripheral surface 46 of the flange covered with the fastening base frame 2 and the fastening base frame 2 composed of a pair of frame pieces 3 formed by division. One or more cryogenic seal packings 13 formed in a ring shape by covering and braiding the outer peripheral surface of a core material made of carbon fiber having elasticity in a low temperature region with PTFE (tetrafluoroethylene resin) fibers; the packing 13, 16 made of the packing 16. for low temperature space having rigidity and formed in a ring shape by PTFE sheet, is interposed between the clamping Chakumotowaku 2 and the outer circumferential surface 46 the packings A packing retainer 20 comprising a pair of pressure-bonding pieces 21 formed by dividing by providing a pressing portion 23 for pressure-bonding 13 and 16, a plurality of pressure-resistant bag nuts 29 having gaskets 31 attached to the lower surface, A screw portion 28 to be screwed is provided at both ends, and a plurality of shaft bolts 27 are inserted through bolt holes 48 provided in the flange 45. Further, the constituting fastening Chakumotowaku 2, a pair of frame pieces 3 formed in a semicircular shape formed by dividing a short tube shape, the gap portions α and between the flanges 45, 45 on the inner surface portion 4, respectively Packing boxes 5 for accommodating the packings 13 and 16 for sealing the space provided between the outer peripheral surface (46) of the flange and the inner surface (4) of the fastening base frame (2), A plurality of screw holes 6 that are detachably attached with fastening bolts 25 so as to match a plurality of holes 24 provided in the crimping piece 21 of the packing retainer 20, and a bolt hole 8 that is detachably connected with end faces that contact each other with bolts 10. It is characterized in that a connecting collar portion 7 having the above is provided. Further, packing pressers (20) each formed in a ring shape by facing a pair of crimping pieces (21) formed in a semicircular shape , respectively , are provided on the outer peripheral surface 46 of the flange. A pressing portion 23 for crimping the packings 13, 16 to one end of the portion 22, and holes 24 are provided on the upper surface of the crimping piece 21 at positions matching the screw holes 6 provided in the frame piece 3 of the fastening base frame. It is characterized by that. Furthermore, it is a leakage prevention structure of a flange portion that connects piping used for a cryogenic fluid live line, a valve lid, etc., and leakage of the outer peripheral surface 46 of the flange covered with the fastening base frame (2). A fastening base frame 35 provided with a plurality of screw holes 37 on both upper and lower surfaces of a pair of frame pieces 36 formed by dividing a convex portion 38 that is in contact with the portion at an inner surface intermediate portion , and a convexity of the fastening base frame PTFE (tetrafluoroethylene resin) fibers are used for the outer peripheral surface of the core material made of carbon fiber that is housed in packing boxes 39 provided above and below the portion 38 and has excellent mechanical strength and sealing properties and elasticity in the cryogenic region. And at least one cryogenic seal packing 13 formed in a ring shape by covering and braiding, and holes 24 at positions corresponding to the screw holes 37 of the frame piece 36, respectively, Crimp packing 13 A packing retainer 20 in which a pair of pressure-bonding pieces 21 formed by dividing by providing a pressing portion 23 is attached by fastening bolts 25, a plurality of pressure-resistant bag nuts 29 having gaskets 31 attached to the lower surface, and screw-engaged with the pressure-resistant bag nuts And a plurality of shaft bolts 27 attached to bolt holes 48 provided in the flange 45.

  Accordingly, the packing 13 of the fastening base frame 2 mounted on the outer peripheral surface 46 of the flange 45 is accommodated in the packing box 5 with the seal packing 13 and the space packing 16 interposed therebetween, and the packing presser 20 presses the packing tightly. The hexagon bolts and nuts connecting the flanges 45 are replaced with the cap nuts 29 having the shaft bolts 27 and the gaskets 31 and tightened without stopping the operation of the plant. Only the valve of the leak point or the flange part of the pipe can be safely and easily repaired to seal the leak.

  Further, the convex portion 38 of the fastening base frame 35 is brought into contact with a gap portion α provided between the high-pressure and cryogenic fluid flanges 45 as a spacer, and the packing box 39 provided above and below the convex portion 38 is attached to the packing box 39. The accommodated seal packing 13 is attached to the upper and lower surfaces of the frame piece 36 and crimped by the packing presser 20, and is fastened and connected to the bolt hole of the flange by a cap nut 29 having a shaft bolt 27 and a gasket 31. Without shutting down the plant, it is possible to safely and easily repair only the valve or pipe flange portion of the leak location to seal the leak.

FIG. 1 is an exploded perspective view of a leakage preventing apparatus according to the present invention. FIG. 2 is a partially broken plan view showing a state in which a fastening base frame is attached to a flange. 3 is a cross-sectional view taken along line AA of FIG. 2, FIG. 4 is an enlarged cross-sectional view of a main part showing a packing portion of the fastening base frame, and FIG. 5 is an enlarged cross-sectional view of the packing partially omitted. The leakage prevention apparatus 1 according to the present application includes a fastening base frame 2 formed in a short cylindrical shape that is detachably attached to an outer peripheral surface 46 of a flange 45, and a gap between the fastening base frame 2 and the outer peripheral surface 46 of the flange 45. Packing 13 that seals the leaking portion of the part β , a packing 16 for space, and a packing for pressing the packings 13 and 16 accommodated in the packing box 5 formed between the fastening base frame 2 and the flange 45 And a presser 20.

  As shown in FIG. 1, the fastening base frame 2 is formed of a material that does not cause low-temperature embrittlement, for example, an aluminum material or an aluminum alloy material, and is formed into a short cylindrical shape and divided into a semicircular shape. An inner surface portion 4 made of the frame piece 3 is provided on the inner side of the frame piece to be joined to the outer peripheral surface 46 of the flange 45, and the gap portion α generated between the mutually facing surfaces of the flange 45 is sealed on the inner surface portion. A plurality of screw holes 6 for removably attaching the packing retainer 20 are provided at regular intervals on the packing 13, the packing box 5 having a stepped portion 5 a for accommodating the space packing 16, and the upper surface of the frame piece 3. It is. A connecting collar portion 7 is formed on each end surface of the frame piece 3 that abuts each other, and a plurality of bolt holes 8 are provided in the connecting collar portion in the horizontal direction, and fastening bolts 10 are screwed into the bolt holes. The fastening base frame 2 is fastened to the flange 45 so as to be removable. The fastening base frame 2 is fastened with the fastening bolts 10, and by providing a joint portion β where the inner surface portion 4 of the frame piece 3 and the outer peripheral surface 46 of the flange 45 abut, the connecting flange portion 7 is joined to each other. Airtightness is maintained by γ.

  The packing is composed of a seal packing 13 and a space packing 16, and one packing 13 is made of a material having excellent mechanical strength and sealing property and having elasticity even in a cryogenic region, for example, spun carbon fiber. The outer peripheral surface of the middle core material is formed into a ring shape by covering and braiding with PTFE (tetrafluoroethylene resin material) fibers. The space packing 16 is formed in a ring shape from a metal or resin material having rigidity capable of withstanding extremely low temperatures, for example, the PTFE plate described above.

  As shown in FIG. 5, the seal packing 13 and the space packing 16 are provided with slits 14 and 17 whose ends are cut obliquely, respectively, so that the diameter can be increased. Is easily attached to the outer peripheral surface 46. Further, the packings 13 and 16 are not limited to the above-described materials, but are other materials that are excellent in mechanical strength and sealing properties even in a cryogenic region, or have elasticity, or have rigidity and can withstand cryogenic temperatures. Of course, it may be made of a metal material or a resin material. The width of the packing 16 is usually 9 mm or less, but in the case of 9 mm or more, a material other than a resin such as so-called SUS304 or A1 material may be used.

  The packing presser 20 is formed in a ring shape by facing a pair of crimping pieces 21 formed in a semicircular shape, and the crimping piece has an inner surface in contact with the outer peripheral surface 46 of the flange. The fastening bolts 25 are respectively inserted into the portions 22, the pressing portions 23 that project the lower end or upper end of the inner surface portion, and the upper surfaces of the crimping pieces 21 at positions that match the screw holes 6 provided in the frame piece 3. A plurality of holes 24 are provided. The pressing portion 23 can press-fit the packings 13 and 16 that are fitted in the packing box 5 of the fastening base frame 2 and accommodated therein.

  The shaft bolt 27 and the pressure-resistant bag nut 29 are used in place of normal bolts and nuts connecting the flange 45 and the flange 45, and are respectively attached to both ends of the shaft bolt 27 inserted through the bolt holes 48 of the flange 45. Are provided with threaded portions 28 and 28 that are screwed into the pressure-resistant bag nut 29, provided with a ring-shaped recess 30 in the circumferential direction of the lower surface of the pressure-resistant bag nut 29, 29, and a seat portion of the pressure-resistant bag nut in the recess. A gasket 31 for maintaining airtightness with the flange 45 is accommodated.

  As another embodiment of the fastening base frame 2, as shown in FIG. 6, a fastening base frame 35 is formed in a short cylinder shape by an aluminum material or an aluminum alloy material, and the fastening base frame is divided into semicircles. A shaped frame piece 36 is provided. A space convex portion 38 of a gap portion α between the facing surfaces of the flange 45 is formed in a substantially intermediate portion of the inner peripheral surface of the frame piece 36, and the packing 13 is formed on the upper and lower step portions of the convex portion 38. And a screw hole 37 for detachably attaching the packing presser 20 is provided on each of the upper and lower surfaces of the frame piece 36.

  The fastening base frame 35 is of course used as a fastening base frame attached to a high pressure / low temperature flange, but can also be used as a flange seal for high pressure / normal temperature fluid pipes or valves.

  As for the connection of the frame pieces 36, as in the fastening base frame 2, the connection flange portions 41 are respectively formed on the end surfaces that face each other, and a plurality of screw holes 42 are provided in the horizontal direction of the connection flange portions, A fastening bolt 43 is screwed into the screw hole and attached to the outer peripheral surface 46 of the flange 45 so as to be fastened.

  Hereinafter, the operation of the embodiment of the present invention will be described. In the case where the fluid leaked from the gap portion α between the flanges 45 and 45, which are connecting portions such as pipes and valves for high pressure and cryogenic temperature, is sealed by the leakage prevention device 1. The pair of frame pieces 3 constituting the fastening base frame 2 are respectively positioned on the outer peripheral surface 46 of the flange 45 so that the connecting flange portions 7 are joined to each other, and the fastening bolts 10 are attached to the bolt holes 8 of the connecting flange portions. A packing box 5 for accommodating the seal space packings 13 and 16 is formed in a space provided between the fastening base frame 2 and the outer peripheral surface 46 of the flange 45 by screwing and fixing. It is.

  As shown in FIG. 4, the packings 13 and 16 accommodated in the packing box 5 have a plurality of elastic sealing packings 13 positioned below the packing box 5, and the portions corresponding to the gap α of the flange The space packing 16 having high rigidity is positioned, and a plurality of seal packings 13 having elasticity are similarly stacked on the upper side of the packing 16.

If a packing with low rigidity and is easily deformed is used as a packing for the space of the gap portion α of the flange, it is deformed by the pressure of the packing presser when the packing is pressed with the packing presser 20, and the gap between the flange end surface and the gasket There is a possibility that the space packing 16 may enter and the effective volume of the sealing packing 13 may be reduced. If the effective volume of the seal packing 13 is reduced, the tightening surface pressure may be reduced and leakage may not be prevented. Therefore, the space gap 16 of the flange is prevented from being deformed by using a highly rigid space packing 16 that is not deformed even by the pressing force of the packing presser 20, and the mechanical strength and sealing performance are excellent on both the upper and lower sides of the packing 16. In addition, by accommodating a plurality of sealing packings 13 having elasticity even in the extremely low temperature region, the gap portion α of the flange and the joint portion β between the flange 45 and the fastening base frame 2 are sealed, and leakage is reliably prevented. .

  Next, the pressing portion 23 of the packing retainer 20 positioned on the upper surface of the fastening base frame 2 is positioned above the packing box 5, and the fastening bolts 25 are inserted into the holes 24 of the respective crimping pieces 21 so that the frame piece 3. The screw holes 6 are respectively fastened and connected.

  When the packing presser 20 is fastened to the fastening base frame 2 with the fastening bolts 25, the packing 13 in the packing box 5 is slightly deformed by being pressed by the pressing part 23 of the packing presser, and the outer peripheral surface of the flange. The gap between 46 and the inner surface portion 5 of the fastening base frame 2 can be sealed for reliable sealing.

  Further, when the packing presser 20 is fastened to the fastening base frame 2 with the fastening bolts 25, a fixed gap is provided between the fastening base frame 2 and the packing presser 20. By providing a gap between the fastening base frame 2 and the packing presser 20, the fastening pressure of the plurality of elastic packings 13 can be adjusted by the fastening force of the fastening bolt 25, and the fastening bolt 25 It is possible to adjust the tightening by means of.

The number of sealing packings 13 accommodated in the packing box 5 is increased or decreased depending on the pressure of the fluid. In the case of a high pressure / cryogenic fluid, three sheets are interposed vertically with a space packing 16 in between. . Further, since the side pressure for sealing the outer peripheral surface 46 of the flange of the packing 13 is normally about 60% of the tightening surface pressure, if a tightening surface pressure of 40 N / mm ² is given, The seal surface pressure is 24 N / mm ² , and can cope with the high pressure field.

  The joint part β in which the outer peripheral surface 46 of the flange and the inner surface part 4 of the fastening base frame 2 directly contact each other and the contact part γ formed by joining the connecting collar part 7 together constitute the fastening base frame 2. Since a high surface pressure is generated by an appropriate value of fastening force by the fastening bolt 10 that connects the frame pieces 3 to be sealed and airtightness is maintained, even if permeation leakage occurs across the packing 13, it is directly from the contact portion γ. Does not leak to the outside.

  Furthermore, since the outer peripheral surface 46 of the flange for high pressure and cryogenic temperature is cooled to around −100 ° C. by the heat conduction of the fluid, the fastening base frame 2 made of aluminum is used for heat transfer of the outer peripheral surface 46 of the flange. As the heat shrinkage occurs, the packings 13 and 16 in the packing box 5 are also forcedly shrunk, so that the surface pressure inevitably increases and the airtightness can be improved.

  The flange connection bolt hole 48 located in the gap between the outer side of the gasket 47 and the outer peripheral surface 46 of the flange 45 interposed between the facing flanges 45 is sealed after the outer peripheral surface of the flange is sealed. A plurality of hexagon bolts 49 connecting 45 are pulled out one by one, a shaft bolt 27 is inserted into the extracted bolt hole 48, and a gasket 31 is attached to the bottom of both ends of the threaded portion 28 of the shaft bolt. The nuts 29 are respectively fastened to seal the gaps between the bolt holes 48.

  The replacement work of the hexagon bolt 49, the shaft bolt 27, and the pressure-resistant cap nut 29 is performed safely and reliably with a specified torque for each one, so that the tightening force can be reduced to the extent that one bolt is pulled out for a short time. The pressure inside the pipe of the high-pressure fluid does not affect the fastening force connecting the flanges, and the replacement operation can be performed safely and reliably.

  In the unlikely event that a high pressure / cryogenic fluid leaks, the number and width of the seal packing 13 and space packing 16, adjustment of the tightening surface pressure, etc. It is possible to cope with almost by adjusting the. In order to prevent leakage of the high-pressure fluid or to enhance safety and durability, the high-pressure fastening base frame 35 shown in FIG. 6 is used for sealing.

  In order to increase safety and durability against a higher pressure and a cryogenic fluid, the convex portion 38 provided on the inner surface of the fastening base frame 35 has sufficient rigidity for high tightening of the seal packing 13. The surface pressure of the packing is correctly transmitted to the outer peripheral surfaces 46 of both flanges and the packing box 39 to improve the sealing performance. Further, the high-pressure fastening base frame 35 formed of aluminum material is forced to shrink due to the heat shrinkage caused by the heat transfer of the flange 45, so the surface pressure of the packing inevitably increases and the airtightness can be improved. Has an effect.

  Furthermore, the packing box 39 provided above and below the convex portion 38 formed in the intermediate portion of the inner surface of the fastening base frame 35 is a material having excellent mechanical strength and sealing properties and having elasticity even in a cryogenic region, such as spun carbon. A plurality of the packings 13 formed in a ring shape by covering and braiding the outer peripheral surface of the center material made of fibers with PTFE (tetrafluoroethylene resin material) fibers were accommodated, and the packings were attached to the upper and lower surfaces of the frame piece 36. By pressing the packing presser 20 with the fastening bolts 25 from above and below, a high fastening surface pressure is maintained, so that leakage can be completely prevented.

  Since the effect of the packing retainer 20 and the seal of the bolt hole 48 of the hexagon bolt 49 connecting the flange are the same as those in the above embodiment, the description thereof is omitted.

It is a disassembled perspective view of the leak prevention apparatus concerning this invention. It is the partially broken top view which shows the state which attached the fastening base frame to the flange. It is the sectional view on the AA line of FIG. It is a principal part expanded sectional view which shows the packing part of the fastening base frame. It is an expanded sectional view of the packing which a part was omitted. It is explanatory drawing which abbreviate | omitted partially which shows other embodiment of the fastening base frame. It is a principal part expanded sectional view which shows the state which sealed the outer peripheral surface of the flange using the fastening base frame of FIG. It is a principal part expanded sectional view of the conventional leakage prevention apparatus. It is a principal part expanded sectional view which shows the other conventional leakage prevention apparatus.

Explanation of symbols

2 Fastening base frame 3 Frame piece 4 Inner surface portion 5 Packing box 6 Screw hole 7 Connection flange 8 Bolt hole 10 Bolt 13 Packing 14 Slit 16 Packing 20 Packing retainer 21 Crimping piece 22 Inner surface portion 23 Pressing portion 24 Hole 25 Fastening bolt 27 Shaft bolt 28 Threaded portion 29 Pressure-resistant bag nut 31 Gasket 35 Fastening base frame 36 Frame piece 37 Screw hole 38 Convex portion 39 Packing box 41 Connecting flange 42 Bolt hole 43 Bolt 45 Flange 46 Outer peripheral surface 48 Bolt hole α Flange and flange Β Joint part between the outer peripheral surface of the flange and the inner peripheral surface of the fastening base frame γ Adhering part of the connecting flange part that joins together

Claims (4)

It is a leak prevention structure for the flange part that connects piping and valve lids used for cryogenic fluid live lines,
A fastening base frame (2) comprising a pair of frame pieces (3) which are detachably attached to a leakage portion of the outer peripheral surface (46) of the flange (45) and formed separately;
The outer periphery of the core material made of carbon fiber that seals the leaked portion of the outer peripheral surface (46) of the flange covered with the fastening base frame (2) and is excellent in mechanical strength and sealing property and has elasticity in a cryogenic region. At least one or more cryogenic seal packings (13) formed in a ring shape by coating and braiding the surface with PTFE (tetrafluoroethylene resin) fibers, and a rigid electrode formed in a ring shape by the PTFE plate material A packing (13, 16) comprising a packing (16) for a low-temperature space ;
The tightening Chakumotowaku (2) and said outer peripheral surface (46) and a pair of crimping pieces formed by dividing the pressing portion (23) provided for crimping the packing (13, 16) to be interposed between the (21 Packing presser foot (20) consisting of
Bolt holes (48) provided in the flange (45) by providing a plurality of pressure-resistant bag nuts (29) with gaskets (31) attached to the lower surface and screw portions (28) screwed to the pressure-resistant bag nuts at both ends. A leakage preventing device for a cryogenic flange joint, comprising: a plurality of shaft bolts (27) inserted into the flange joint. A pair of frame pieces (3) that are formed in a short cylinder shape and are divided into a semicircular shape, constituting the fastening base frame (2), are respectively connected to the flanges (45, 45) on the inner surface portion (4). clearance between (alpha) and housing the gasket (13, 16) for sealing the space provided between the inner surface portion (4) of the outer peripheral surface of the flange (46) and said clamping Chakumotowaku (2) A packing box (5) and a plurality of screws which are detachably attached with fastening bolts (25) in alignment with a plurality of holes (24) provided in the crimping pieces (21) of the packing presser (20) on the upper surface thereof. The pole according to claim 1, characterized in that a hole (6) and a connecting collar part (7) having a bolt hole (8) removably connected to each other by a bolt (10) are provided on the end faces abutting each other. Leakage prevention device for flange joints for low temperatures. The packing presser (20), which is formed in a ring shape by facing a pair of crimping pieces (21) formed in a semicircular shape, is provided on the outer peripheral surface (46) of the flange. pressing portion for crimping the packing (13, 16) at one end of the inner surface portion (22) and (23), a screw hole provided on the upper surface on the fastening base frame of the frame pieces of the piezoelectric wear piece (21) (3) (6) and the security apparatus of the cryogenic flange joint according to claim 1, characterized in that each provided a hole (24) in matching positions. Leakage prevention structure of the flange part connecting pipes and valve lids used for live lines of high pressure and cryogenic fluid,
Upper and lower surfaces of a pair of frame pieces (36) formed by providing a convex portion (38) that abuts against a leaked portion of the outer peripheral surface (46) of the flange covered with the fastening base frame (2) in the middle portion of the inner surface. A fastening base frame (35) provided with a plurality of screw holes (37) in
The outer periphery of a core material made of carbon fiber having excellent mechanical strength and sealing property and having elasticity in a cryogenic region, accommodated in packing boxes (39) provided above and below the convex portion (38) of the fastening base frame At least one or more cryogenic seal packings (13) formed in a ring shape by coating and braiding the surface with PTFE (tetrafluoroethylene resin) fibers ;
A pressing portion (23) having holes (24) at positions corresponding to the screw holes (37) of the frame piece (36) and pressing the packing (13) in the packing box (39) is provided. A packing presser (20) for attaching a pair of divided crimping pieces (21) formed by fastening bolts (25);
Bolt holes (48) provided in the flange (45) by providing a plurality of pressure-resistant bag nuts (29) with gaskets (31) attached to the lower surface and screw portions (28) screwed to the pressure-resistant bag nuts at both ends. And a plurality of shaft bolts (27) to be attached to.

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