JP2012102802A - Seal structure of flange connection part, and sealing method of flange connection part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure which prevents fluid from leaking through a bolt hole without deteriorating air-tightness between flange mating surfaces with a simple constitution.SOLUTION: A seal structure 1 of flange connection part includes: an upper flange 7 and a lower flange 9 which are in contact with each other; an upper screw hole 721 which is disposed on the upper flange 7 and is opened to an upper contact surface 711; a lower screw hole 92 which is disposed on a lower flange 9 and is opened to a lower contact surface 91; a storage hole 722 which is opened to a clamping surface 712 while expanding the diameter from the upper screw hole 721; a fastener 6 which fastens the upper flange 7 and a lower flange 9 to integrate them; an O-ring 111 which is disposed so as to surround the bolt 61 in the storage hole 722; and a pressing member 112 which receives a fastening force of the fastener 6, pressing the O-ring 111 and swells the O-ring 111 in the radial direction of the bolt 61.

Description

  The present invention relates to a flange joint seal structure in which a pair of flanges in which screw holes are formed are integrated by a tightening means, and a flange joint seal method.

  Centrifugal compressors that compress fluid by utilizing centrifugal force are configured by housing a rotor, which is a rotating body, inside a casing. The casing is divided into two parts in the vertical direction and is integrated by bolt fixing. Is common. FIG. 13 is a schematic cross-sectional view showing a conventional fixing structure 100 for upper and lower casings. The upper casing 101 and the lower casing 102 are respectively provided with an upper flange 103 and a lower flange 104 so as to protrude sideways, and an upper screw hole 105 and a lower screw hole 106 are formed in the flanges 103 and 104, respectively. ing. The upper and lower casings 101 and 102 configured as described above are fixed to the screw holes 105 and 106 with the fixing bolts 107 in a state where the flanges 103 and 104 are in contact with each other, so that the washer 108 is attached. It is fixed by tightening the nut 109.

  By the way, in recent years when the size of centrifugal compressors has increased, in order to prevent an increase in the overall weight, the casing is designed to minimize the plate thickness, and there is a tendency to reduce the rigidity. Therefore, when the fluid pressure increases inside the casing, the upper and lower casings 101 and 102 are easily deformed as shown in FIG. When the casings 101 and 102 are deformed, a gap 110 is generated between the flange contact surfaces 103A and 104A of the flanges 103 and 104 that contact each other. Then, the fluid R inside the casing may leak from the gap 110 to the outside, or may leak to the outside from the upper screw hole 105 formed through the upper flange 103 through the gap. The generation of the gap 110 on the flange contact surfaces 103A and 104A and the fluid leakage cause the contact surfaces of the flanges 103 and 104 to extend to the inner peripheral surface side to a far position where the tightening force of the bolt 107 is difficult. It is particularly likely to occur at a location where the dimension L is long in FIG.

  As a seal structure of the flange joint for preventing such fluid leakage, a structure in which a gasket material is arranged on the mating surfaces of the upper and lower casing flanges has been conventionally used (see, for example, Patent Document 1). . In Patent Document 1, mounting grooves are formed so as to face the contact surfaces of the flanges, and a ring-shaped gasket material is mounted in a compressed state in the mounting grooves. According to such a configuration, even if a pressure is increased inside the casing and a gap is generated between the flanges, the fluid is prevented from leaking outside through the gap and the screw hole due to the presence of the gasket material.

Japanese Patent Laid-Open No. 2001-227643

  However, the conventional flange joint seal structure has a problem that the airtightness at the mating surfaces of the flanges is reduced by providing the gasket material between the upper and lower flanges. Further, in recent years when centrifugal compressors have become larger, in order to provide a ring-shaped gasket material over the entire circumference of the flange, a specially shaped gasket material having a diameter of several meters is required, and its production is difficult. There is also a problem.

  The present invention has been made in view of such circumstances, and the object thereof is to leak the fluid from the bolt hole with a simple configuration without reducing the airtightness of the flange contact surfaces 103A and 104A. Provide a means to prevent this.

  In order to achieve the above object, the present invention employs the following means. That is, the seal structure of the flange joint portion according to the present invention includes a pair of flanges that are in contact with each other on the contact surface, a first screw hole that is provided on one flange and opens to the contact surface, and the other A second screw hole that is provided in the flange and is open to the contact surface, and is provided in the one flange, the diameter of the first screw hole is increased, and a tightening surface opposite to the contact surface is provided. A receiving hole that is open, a bolt that is screwed into the first screw hole and the second screw hole, and a fastening means that fastens and integrates the pair of flanges; A gasket member that surrounds the bolt, and a pressing member that is provided inside the housing portion and that bulges in the radial direction of the bolt by receiving the tightening force of the tightening means and pressing the gasket member And.

  According to such a configuration, when the pressure of the fluid increases inside the casing having a pair of flanges and a gap is generated between the contact surfaces, the fluid inside the casing passes through the gap, It will enter the gap between the bolt and the upper screw hole. However, the end opening on the side communicating with the accommodation hole of the upper screw hole is sealed by a gasket member that is pressed by the pressing member and bulges in the radial direction of the bolt. Therefore, even if the fluid that has entered the gap enters the screw hole, it is blocked by the gasket member and does not flow into the accommodation hole. Therefore, the fluid that has entered the gap does not leak to the tightening surface side through the accommodation hole.

  In the flange joint portion sealing structure according to the present invention, the one flange is provided with a main body portion in which an insertion hole is formed, the first screw hole and the accommodation hole, and is inserted into the insertion hole. And a jig.

  According to such a configuration, the accommodation hole for accommodating the gasket member and the pressing member is formed in the jig, and the jig is inserted into one flange, so the accommodation hole is directly formed in the one flange. Compared with the case of doing, the processing operation of the accommodation hole can be facilitated.

  Further, the flange joint seal structure according to the present invention is characterized in that the entire circumference of the jig is fixed to the main body by welding.

  According to such a configuration, the entire circumference of the jig is fixed to the main body portion of one flange by welding, and the gap between the jig and the main body portion is sealed by the welded portion. Yes. Therefore, the fluid inside the casing does not leak to the tightening surface side through the gap between the jig and the main body.

  Further, the flange joint seal structure according to the present invention is characterized in that the pressing member is elastically deformable in the axial direction of the bolt.

  According to such a configuration, the pressing member receiving the tightening force of the tightening means is elastically deformed in the axial direction of the bolt. Then, by utilizing the elastic force that the pressing member tries to restore to the original shape, the gasket member can be pressed and reliably bulged in the radial direction of the bolt.

  The flange joint sealing method according to the present invention includes a flange joint sealing method in a structure having a flange joint seal structure, a temporary fastening step of temporarily fastening the fastening means, and the structure. An evacuation process for evacuating the interior of the structure, a retightening process for retightening the tightening means, and an air introduction process for returning the interior of the structure to atmospheric pressure.

  According to such a method, the bolts are tightened to some extent so that the bolts do not rattle by the temporary tightening process. And the surface pressure in the contact surface of a pair of flange rises by an exhaust_gas | exhaustion process, and both will firmly_contact | adhere, and a fastening margin will arise in a fastening means. Further, the tightening means is tightened by the tightening margin generated in the exhaust process by the retightening process. Thereafter, the contact pressure of the contact surface is reduced by the air introduction process, and the pair of flanges are about to be separated from each other, whereby the tightening means is strongly tightened. Thereby, a pair of flanges are firmly joined to each other.

  Also, the flange joint sealing method according to the present invention is a flange joint sealing method in a structure that is integrated by bringing a pair of flanges into contact with each other and tightening with a tightening means. A temporary tightening step for temporarily tightening, an exhaust step for evacuating the inside of the structure, a retightening step for retightening the tightening means, and an air introduction step for returning the inside of the structure to atmospheric pressure It is characterized by including these.

  According to such a method, the bolts are tightened to some extent so that the bolts do not rattle by the temporary tightening process. And the surface pressure in the contact surface of a pair of flange rises by an exhaust_gas | exhaustion process, and both will firmly_contact | adhere, and a fastening margin will arise in a fastening means. Further, the tightening means is tightened by the tightening margin generated in the exhaust process by the retightening process. Thereafter, the contact pressure of the contact surface is reduced by the air introduction process, and the pair of flanges are about to be separated from each other, whereby the tightening means is strongly tightened. Thereby, a pair of flanges are firmly joined to each other.

  According to the seal structure of the flange joint portion according to the present invention, it is possible to prevent fluid from leaking from the bolt hole with a simple configuration without reducing the airtightness of the flange mating surface.

It is a schematic perspective view which shows the compressor provided with the seal structure of the flange junction part which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows the seal structure of the flange junction part which concerns on 1st Embodiment. It is a schematic perspective view which shows the seal structure of the flange junction part which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the modification of 1st Embodiment. It is a schematic perspective view which shows the external appearance of a pressing member. It is a schematic sectional drawing which shows the state which has arrange | positioned the press member on the O-ring. It is explanatory drawing which shows the effect of the seal structure of the flange junction part which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the seal structure of the flange junction part which concerns on 2nd Embodiment. It is a schematic sectional drawing which shows the seal structure of the flange junction part which concerns on 3rd Embodiment. The schematic diagram which shows the whole structure of the compressor plant to which the sealing method of the flange junction part which concerns on embodiment is applied. It is a schematic sectional drawing of the flange junction part in a compressor. It is a schematic perspective view which shows the lower flange of a lower casing. It is a schematic sectional drawing which shows the conventional fixing structure of an upper and lower casing.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. First, a description will be given of a seal structure for a flange joint according to the first embodiment of the present invention. FIG. 1 is a schematic perspective view showing a compressor 2 including a flange joint seal structure 1 according to the first embodiment. The compressor 2 includes a substantially cylindrical casing 3, a rotor (not shown) that is a rotating body accommodated in the casing 3, and a plurality of pipes 4 appropriately connected to the casing 3. is there.

  As shown in FIG. 1, the casing 3 includes a casing body 5 that is divided into two vertically and a plurality of fastening means 6 that fasten and fix the two divided casing bodies 5. .

  As shown in FIG. 1, the casing body 5 has a substantially semicircular cross section and an upper casing 8 provided with an upper flange 7 projecting sideways. Similarly, the casing body 5 has a substantially semicircular cross section and a lower flange. 9 has a lower casing 10 provided so as to protrude sideways. The upper flange 7 of the upper casing 8 and the lower flange 9 of the lower casing 10 are joined to each other by the fastening means 6, and a fluid (not shown) accommodated in the casing 3 is externally connected to the flange joint. A seal structure for preventing leakage is provided.

  Here, FIGS. 2 and 3 are views showing the seal structure 1 of the flange joint portion according to the first embodiment, FIG. 2 is a schematic sectional view, and FIG. 3 is an exploded perspective view. The flange joint seal structure 1 is formed by tightening the upper flange 7 of the upper casing 8, the lower flange 9 of the lower casing 10, the sealing means 11 provided on the upper flange 7, and the upper flange 7 and the lower flange 9. Tightening means 6 to be provided.

As shown in FIGS. 2 and 3, the upper flange 7 includes a main body 71 having an insertion hole 713 formed through the upper contact surface 711 that contacts the lower flange 9 so as to reach the fastening surface 712 on the opposite side. And a jig 72 inserted into the insertion hole 713 of the main body 71.
On the other hand, the lower flange 9 has a lower screw hole 92 (second screw hole) formed in the lower contact surface 91 that contacts the upper flange 7. The lower screw hole 92 may be formed so as to penetrate the lower flange 9.

  The jig 72 is for accommodating the sealing means 11. As shown in FIGS. 2 and 3, the jig 72 is a substantially cylindrical member, and the height dimension thereof is formed substantially equal to the thickness of the upper flange 7. An upper screw hole 721 (first screw hole) having a diameter substantially the same as that of the lower screw hole 92 of the lower flange 9 is formed on the bottom surface of the jig 72. The upper screw hole 721 has a female screw cut on the inner peripheral surface thereof, and extends to the middle portion of the upper flange 7 in the thickness direction. On the other hand, an accommodation hole 722 having a diameter larger than that of the upper screw hole 721 is formed on the upper surface of the jig 72. The accommodation hole 722 extends to an intermediate portion in the thickness direction of the upper flange 7, and a lower end thereof communicates with an upper end of the upper screw hole 721. Accordingly, a stepped surface 723 is formed at the connecting portion between the accommodation hole 722 and the upper screw hole 721 due to a difference in diameter between the accommodation hole 722 and the upper screw hole 721.

  As shown in FIG. 2, the jig 72 configured in this manner is inserted into the insertion hole 713 of the upper flange 7, and the entire circumference of the bottom thereof is welded to the main body 71 of the upper flange 7. It is fixed. Thereby, the gap 73 between the main body 71 of the upper flange 7 and the jig 72 is sealed by the welded portion 74, and the fluid inside the casing 3 is prevented from leaking to the outside through the gap 73. ing.

  The means for fixing the main body 71 of the upper flange 7 and the jig 72 is not limited to welding, and any conventionally known method can be used. Further, in the present embodiment, an accommodation hole 722 for accommodating the sealing means 11 is formed in the jig 72, and this jig 72 is attached to the upper flange 7. Instead, as shown in FIG. The upper screw hole 721 and the accommodation hole 722 may be directly formed in the upper flange 7. However, the method of forming the accommodation hole 722 in the jig 72 as in this embodiment has an advantage that the processing operation of the accommodation hole 722 can be facilitated as compared with the case where the accommodation hole 722 is formed in the upper flange 7. is there.

  As shown in FIGS. 2 and 3, the tightening means 6 includes a bolt 61 having a male screw cut on the outer peripheral surface, a nut 62 having a female screw cut on the inner peripheral surface and capable of being screwed to the bolt 61, And a washer 63 interposed between the nut 62 and the upper flange 7. As shown in FIG. 2, the tightening means 6 configured as described above has bolts 61 screwed into the upper screw hole 721 and the lower screw hole 92, and a washer 63 placed on the upper flange 7. After that, the nut 62 is screwed onto the bolt 61 and tightened. The configuration of the tightening means 6 is not limited to the present embodiment, and can be appropriately changed. For example, the configuration without the washer 63 or the configuration using the bolt 61 with a head instead of the nut 62 is possible. May be.

  As shown in FIGS. 2 and 3, the sealing unit 11 includes an O-ring 111 (gasket member) having a substantially O-shaped cross section, and a plurality of pressing members 112 that are plate-like members. .

  The O-ring 111 is a ring-shaped member made of an elastic member such as rubber. As shown in FIGS. 2 and 3, the inner diameter of the O-ring 111 is slightly larger than the outer diameter of the bolt 61, and the outer diameter is It is formed slightly smaller than the hole diameter of the accommodation hole 722. The O-ring 111 configured in this way is provided on the step surface 723 inside the accommodation hole 722. The gasket member according to the present invention is not limited to the O-ring 111 as in the present embodiment, and the material, cross-sectional shape, and the like can be appropriately changed in design.

  The pressing member 112 is for pressing and elastically deforming the O-ring 111. Here, FIG. 5 is a schematic perspective view showing the appearance of the pressing member 112. The pressing member 112 is a plate-like member made of an elastically deformable member, and includes a substantially rectangular base piece 112a and a washer abutting piece 112b extending at an obtuse angle from one longitudinal end of the base piece 112a. And an O-ring contact piece 112c extending at an obtuse angle from the other longitudinal end of the base piece 112a. When the washer abutting piece 112b and the O-ring abutting piece 112c are subjected to the action of an external force, as shown by the dotted lines in FIG. Deformable.

  The pressing member 112 configured in this manner is disposed above the O-ring 111 inside the accommodation hole 722 as shown in FIG. More specifically, in the state where the O-ring 111 is placed on the stepped surface 723 as shown in FIG. 6, the O-ring contact piece 112 c faces down and the base piece 112 a is attached to the shaft portion of the bolt 61. The pressing member 112 is disposed on the O-ring 111 so as to be along. At this time, the pressing member 112 is in a state in which a part of the O-ring contact piece 112 c comes into contact with the O-ring 111 and the washer contact piece 112 b protrudes from the opening of the accommodation hole 722. In this way, the plurality of pressing members 112 are arranged at predetermined intervals along the circumferential direction of the O-ring 111.

  Then, in a state where the pressing member 112 is disposed on the O-ring 111 as shown in FIG. 6, after the washer 63 is placed thereon, the nut 62 is screwed onto the bolt 61 and tightened. Then, the pressing member 112 pressed by the washer 63 has a substantially U-shape in which the washer abutting piece 112b and the O-ring abutting piece 112c are substantially orthogonal to the base piece 112a, as shown by a one-dot chain line in FIG. It is elastically deformed. Then, the elastically deformed pressing member 112 tries to restore the original shape indicated by the solid line in FIG. 5 so that the washer contact piece 112b presses the washer 63 upward, while the O-ring contact piece 112c is O-shaped. The ring 111 is pressed downward. The O-ring 111 pressed against the O-ring contact piece 112c is elastically deformed so as to be crushed, and the space between the accommodation hole 722 and the shaft portion of the bolt 61 is filled with the O-ring 111. As a result, the upper screw hole 721 is in a state where the end opening on the side communicating with the accommodation hole 722 is sealed by the O-ring 111.

  Note that the shape of the pressing member 112 is not limited to the present embodiment, and the design can be changed as appropriate. For example, although not shown in detail in the drawing, the pressing member 112 may be formed in a ring shape in plan view, and this one pressing member 112 may be disposed so as to surround the shaft portion of the bolt 61.

  Next, the function and effect of the flange joint seal structure 1 according to the first embodiment will be described. When the pressure of the fluid rises inside the casing 3 and the force acting on the casing 3 increases, as shown in FIG. 7, there is a slight gap between the upper flange 7 of the upper casing 8 and the lower flange 9 of the lower casing 10. The gap 12 may occur. In this case, the fluid R inside the casing 3 enters the gap 13 between the upper screw hole 721 and the bolt 61 through the gap 12. However, since the end opening on the side communicating with the accommodation hole 722 of the upper screw hole 721 is sealed by the O-ring 111 as described above, the fluid R that has entered the gap 13 is blocked by the O-ring 111, It does not flow into the receiving hole 722. Therefore, the fluid R that has entered the gap 13 does not leak to the outside.

(Second Embodiment)
Next, a flange joint sealing structure according to a second embodiment of the present invention will be described. FIG. 8 is a schematic cross-sectional view showing a flange joint seal structure 20 according to the second embodiment. The seal structure 20 of the flange joint part according to the second embodiment is different from the first embodiment only in the configuration of the pressing member 21 constituting the seal means 11. Since the other configuration is the same as that of the first embodiment, the same reference numerals as those in FIG. 2 are given in FIG. 8, and description thereof is omitted here.

  As shown in FIG. 8, the pressing member 21 is a so-called coil spring, and is housed in a compressed state inside the housing hole 722 of the jig 72. One end of the pressing member 21 abuts on the O-ring 111 and the other end is a washer. 63 abuts. According to such a configuration, the other end portion of the pressing member 21 presses the O-ring 111 downward when the pressing member 21 in the compressed state attempts to restore the natural length state. As a result, the O-ring 111 pressed by the pressing member 21 is elastically deformed and the end opening of the upper screw hole 721 is sealed by the O-ring 111, so that the same operational effects as those of the first embodiment are exhibited. Furthermore, since the pressing member 21 is composed of a single member, the installation work of the pressing member 21 is easier and more reliable than the first embodiment in which a plurality of pressing members 112 are arranged on the O-ring 111. There is an advantage that can be done.

(Third embodiment)
Next, a description will be given of a seal structure for a flange joint according to a third embodiment of the present invention. FIG. 9 is a schematic cross-sectional view showing the flange joint sealing structure 30 according to the third embodiment. The flange joint seal structure 30 according to the third embodiment is also different from the first embodiment only in the configuration of the pressing member 31 constituting the sealing means 11. Since the other configuration is the same as that of the first embodiment, the same reference numerals as those in FIG. 2 are given in FIG. 9, and the description thereof is omitted here.

  The pressing member 31 is made of a member that cannot be elastically deformed, and has a substantially U-shaped cross section as shown in FIG. As with the pressing member 112 of the first embodiment, the pressing member 31 includes a base piece 31a, a washer abutting piece 31b extending substantially orthogonally from one longitudinal end of the base piece 31a, and the longitudinal length of the base piece 31a. And an O-ring contact piece 31c extending substantially orthogonally from the other end in the direction.

  As shown in FIG. 9, the pressing member 31 configured in this way has the O-ring contact piece 31 c down and the base piece 31 a in a state where the O-ring 111 is placed on the stepped surface 723. The pressing member 31 is disposed on the O-ring 111 such that the pressing member 31 extends along the shaft portion of the bolt 61. At this time, the entire pressing member 31 of the pressing member 31 is in contact with the O-ring 111, and the washer contacting piece 31 b protrudes from the opening of the accommodation hole 722.

  Then, in the state where the pressing member 31 is disposed on the O-ring 111 as shown in FIG. 9, after the washer 63 is placed thereon, the nut 62 is screwed onto the bolt 61 and tightened. Then, the pressing member 31 pressed by the washer 63 sinks downward as it is without being elastically deformed, and the whole is housed in the housing hole 722. Thereby, the O-ring contact piece 31c presses the O-ring 111 downward as much as the pressing member 31 sinks downward. Thereby, since the O-ring 111 pressed by the pressing member 31 is elastically deformed and the end opening of the upper screw hole 721 is sealed by the O-ring 111, the same operational effects as the first embodiment are exhibited. Furthermore, since the pressing member 31 is made of a member that cannot be elastically deformed, the O-ring contact piece 31c and the washer contact piece 31b are replaced with the O-ring 111 and the washer 63 as compared with the first embodiment in which the pressing member 112 is elastically deformed. On the other hand, there is an advantage that it can be more reliably brought into close contact.

  Next, a method for sealing a flange joint according to an embodiment of the present invention will be described. FIG. 10 to FIG. 12 are diagrams for explaining the flange joint sealing method according to the present embodiment, and FIG. 10 shows the overall configuration of the compressor plant 40 to which the sealing method according to the present embodiment is applied. FIG. 11 is a schematic cross-sectional view of a flange joint, and FIG. 12 is a schematic perspective view showing a lower flange 52 of the lower casing 51.

  As shown in FIG. 10, the compressor plant 40 includes a compressor 41 in which a rotor (not shown) is accommodated in the casing 3, an exhaust pipe 42 connected to the compressor 41, and the exhaust pipe 42. A rotary pump 43 and a vacuum pump 44 connected to each other, a first exhaust valve 45 and a second exhaust valve 46 for opening or closing the exhaust pipe 42, an intake pipe 47 connected to the compressor 41, and the intake pipe 47 And a leak valve 48 that opens or closes the valve.

  Further, as shown in FIGS. 11 and 12, an upper screw hole 501 is formed through the upper flange 50 of the upper casing 49 constituting the compressor 41. On the other hand, a plurality of lower screw holes 521 are formed on the surface of the lower flange 52 of the lower casing 51 constituting the compressor 41, and a ring receiving groove 522 is formed so as to surround the lower screw holes 521. ing.

  When joining the upper flange 50 of the upper casing 49 and the lower flange 52 of the lower casing 51, the worker first performs a temporary fastening process of the fastening means 6. That is, the operator houses the O-ring 53 in the ring housing groove 522 of the lower flange 52. At this time, although not shown in detail in the drawing, the top of the O-ring 53 protrudes from the ring housing groove 522. Then, the operator brings the upper flange 50 into contact with the lower flange 52. As a result, the O-ring 53 protruding from the upper surface of the lower flange 52 is crushed by the upper flange 50 and filled into the ring receiving groove 522.

  In this state, the operator screws the bolts 54 into the upper screw holes 501 and the lower screw holes 521, and then screwes the nuts 56 with the washers 55 sandwiched between the bolts 54, and then uses a torque wrench or the like. As a result, the nut 56 is temporarily tightened until the bolt 54 does not rattle.

  Next, the operator performs an exhaust process for evacuating the inside of the compressor 41. That is, the operator opens the first exhaust valve 45 with the leak valve 48 and the second exhaust valve 46 shown in FIG. 10 closed, and performs so-called roughing of the inside of the compressor 41 using the rotary pump 43. . Thereafter, when the inside of the compressor 41 reaches a predetermined degree of vacuum, the operator closes the first exhaust valve 45 and opens the second exhaust valve 46, and uses the vacuum pump 44 to check the inside of the compressor 41. The so-called book withdrawal is performed. Thereby, the inside of the compressor 41 is in a high vacuum state.

  Next, the operator performs a retightening process of the tightening means 6. That is, when the inside of the compressor 41 is in a high vacuum state by the exhaust process, the surface pressure between the upper flange 50 and the lower flange 52 is increased and the two are more closely attached to each other, so that the nut 56 is tightened. Therefore, the operator tightens the nut 56 by the amount of the tightening allowance by grasping and turning the nut 56 by hand.

  Finally, the operator performs an air introduction process for returning the interior of the compressor 41 to atmospheric pressure. That is, the operator opens the leak valve 48 with the first exhaust valve 45 and the second exhaust valve 46 shown in FIG. 10 closed. Thereby, air flows into the compressor 41 from the outside through the intake pipe 47 due to the pressure difference between the inside and the outside of the compressor 41. Then, the pressure inside the compressor 41 returns to the atmospheric pressure, the surface pressure between the upper flange 50 and the lower flange 52 decreases, and the nuts 56 are strongly tightened by trying to separate them. Thereby, the upper flange 50 and the lower flange 52 are firmly joined to each other.

  In the present embodiment, the case where the present sealing method is applied to the flange joint shown in FIG. 11 at the time of joining the upper flange 50 and the lower flange 52 has been described as an example. However, the present sealing method is not limited to this, and it is also possible to apply the present sealing method during the joining operation of the upper flange 7 and the lower flange 9 with respect to the seal structures 1, 20, 30 of the flange joints according to the first to third embodiments. It is.

  The various shapes, combinations, operation procedures, and the like of the constituent members shown in the above-described embodiments are merely examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Seal structure of flange junction 2 Compressor 3 Casing 4 Piping 5 Casing body 6 Tightening means 7 Upper flange 8 Upper casing 9 Lower flange 10 Lower casing 11 Sealing means 12 Gap 13 Gap 20 Seal structure 21 of flange joint 21 Pressing member 30 Sealing structure 31 of flange joint portion Press member 40 Compressor plant 41 Compressor 42 Exhaust piping 43 Rotary pump 44 Vacuum pump 45 First exhaust valve 46 Second exhaust valve 47 Intake piping 48 Leak valve 49 Upper casing 50 Upper flange 51 Lower Casing 52 Lower flange 53 O-ring 54 Bolt 55 Washer 56 Nut 61 Bolt 62 Nut 63 Washer 71 Main body 72 Jig 73 Clearance 74 Welding portion 91 Lower abutting surface 92 Lower screw hole 100 Fixing structure 101 Upper casing 102 Lower casing 103 Upper F 103A flange contact surface 104 lower flange 104A flange contact surface 105 upper screw hole 106 lower screw hole 107 bolt 108 washer 109 nut 110 clearance 111 O-ring 112 pressing member 501 upper screw hole 521 lower screw hole 522 ring receiving groove 711 upper contact Contact surface 712 Clamping surface 713 Insertion hole 721 Upper screw hole 722 Receiving hole 723 Stepped surface 112a Base piece 112b Washer contact piece 112c O-ring contact piece 31a Base piece 31b Washer contact piece 31c O-ring contact piece R Fluid

Claims (6)

A pair of flanges that abut each other on the abutment surface;
A first screw hole provided in one of the flanges and opening in the contact surface;
A second screw hole provided in the other flange and opening in the contact surface;
A receiving hole provided in the one flange and having an enlarged diameter from the first screw hole and opening in a fastening surface opposite to the contact surface;
A fastening means having a bolt screwed into the first screw hole and the second screw hole, and fastening and integrating the pair of flanges;
A gasket member provided to surround the bolt inside the accommodation hole;
A pressing member that is provided inside the accommodating portion and that bulges in the radial direction of the bolt by receiving the tightening force of the tightening means and pressing the gasket member;
A flange joint seal structure comprising:   The one flange includes a main body portion in which an insertion hole is formed, and a jig that is provided with the first screw hole and the accommodation hole and is inserted into the insertion hole. 2. The seal structure of the flange joint part according to 1.   3. The flange joint seal structure according to claim 1, wherein the jig is fixed to the main body by welding all around.   4. The flange joint seal structure according to claim 1, wherein the pressing member is elastically deformable in an axial direction of the bolt. 5. In the flange joint part sealing method in the structure having the seal structure of the flange joint part according to any one of claims 1 to 4,
A temporary fastening step of temporarily fastening the fastening means;
An exhaust process for evacuating the inside of the structure;
A retightening step of retightening the tightening means;
An air introduction step for returning the inside of the structure to atmospheric pressure;
A method for sealing a flange joint, comprising: A method of sealing a flange joint in a structure that is integrated by bringing a pair of flanges into contact with each other and tightening with a tightening means,
A temporary fastening step of temporarily fastening the fastening means;
An exhaust process for evacuating the inside of the structure;
A retightening step of retightening the tightening means;
An air introduction step for returning the inside of the structure to atmospheric pressure;
A method for sealing a flange joint, comprising:

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