gasket

Abstract

To provide a gasket capable of preventing fluid flowing through a pair of pipes from leaking from opposing surfaces of a pair of flanges even when the opposing surfaces the pair of flanges are opened.SOLUTION: The present invention relates to a gasket 1 that is mounted to opposing surfaces 2aa, 2ba of a pair of flanges 2a, 2b provided at end parts of a pair of pipes 3a, 3b, the gasket comprising an annular member 11 having an annular hollow part 11a therein and capable of expanding / contracting in an axial direction of at least the pair of pipes 3a, 3b, and a fluid substance 12 that is filled in the hollow part 11a and can flow within the hollow part 11a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gasket. [Background technology]

[0002] Pipes are sometimes joined using a pair of flanges attached to each end of a pair of pipes. In this case, a gasket is often installed between the opposing surfaces of the flanges to prevent the fluid flowing through the pipes from leaking out from between the opposing surfaces of the flanges. For this reason, efforts are being made to improve the performance of gaskets in terms of their materials, structure, shape, etc.

[0003] For example, Patent Document 1 discloses a gasket to be attached to a joint of a structure exposed to a high-temperature environment. This gasket is composed of a plurality of gasket components, and the opposing surfaces formed at the joint are sorted according to the amount of gap change after thermal deformation, and a gasket component having a linear expansion coefficient that results in a thermal change amount equivalent to the amount of gap change in each region is disposed on the opposing surfaces of each region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-117653 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the flanges and piping used in a pair of flanges in a power plant or the like are heavy, the joint between the opposing surfaces of the pair of flanges can weaken and the opposing surfaces can separate (also referred to as "opposing surfaces opening") due to poor construction during plant construction, vibrations during plant operation, external forces acting on the piping, etc. When the opposing surfaces open, there is a risk that fluid flowing through the piping will leak from between the opposing surfaces of the pair of flanges.

[0006] An object of the present invention is to provide a gasket that can prevent fluid flowing in a pipe from leaking between the opposing surfaces of a pair of flanges even when the opposing surfaces of the pair of flanges are open. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a gasket that is mounted between opposing surfaces of a pair of flanges provided at the ends of a pair of pipes, the gasket comprising: an annular member having an annular hollow portion therein and capable of expanding and contracting at least in the axial direction of the pair of pipes; and a fluid material that is filled in the hollow portion and is capable of flowing within the hollow portion. The annular member has an annular disk between the hollow portion and a contact portion that contacts the opposing surfaces of the pair of flanges. do. [Effects of the Invention]

[0008] According to the present invention, even if the opposing surfaces of the pair of flanges are open, it is possible to prevent the fluid flowing through the pipe from leaking out from between the opposing surfaces of the pair of flanges. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view schematically showing a gasket according to a first embodiment of the present invention, a pair of flanges for mounting the gasket between opposing surfaces, and a pair of pipes each having one of the pair of flanges at its end. [Figure 2] 1 is a plan view schematically showing a gasket according to a first embodiment of the present invention. [Figure 3] 3 is a cross-sectional view of the gasket according to the first embodiment of the present invention taken along the line III-III in FIG. 2. FIG. [Figure 4] FIG. 1 is a side view showing a pair of pipes whose central axes are inclined relative to one another, a pair of flanges provided at the ends of each of the pair of pipes and having open opposing surfaces, and a gasket according to a first embodiment of the present invention installed between the pair of flanges. [Figure 5]1 is a plan view schematically showing a gasket according to a first embodiment of the present invention attached to the open opposing surfaces of a pair of flanges. [Figure 6] FIG. 6 is a cross-sectional view schematically showing a cross section taken along line VI-VI in FIG. 5. [Figure 7] FIG. 4 is a plan view schematically showing a gasket according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view schematically showing a cross section taken along line VIII-VIII in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0010] The configuration and operation of gaskets according to first and second embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments describe gaskets used when joining piping in a power plant with flange joints. However, the present invention is not limited to this, and the gasket according to the present invention can also be used for joining flange joints in other plants (for example, chemical plants) and piping in non-plants.

[0011] (First embodiment) FIG. 1 is a side view schematically showing a gasket 1 according to a first embodiment of the present invention, a pair of flanges 2a, 2b for mounting the gasket 1 between opposing surfaces, and a pair of pipes 3a, 3b each having the pair of flanges 2a, 2b at its end.

[0012] As shown in FIG. 1, a gasket 1 is mounted between opposing surfaces 2aa and 2ba of a pair of flanges 2a and 2b provided at the ends of a pair of pipes 3a and 3b.

[0013] The pair of pipes 3a, 3b are, for example, large-diameter (e.g., φ700 mm) circular pipes used as main steam system pipes that send steam generated in a power plant to a turbine, and flanges 2a, 2b are attached to the ends of the pair of pipes 3a, 3b, for example, by welding. Note that the method of attaching the flanges 2a, 2b to the ends of the pipes 3a, 3b is not limited to welding, and they may be attached, for example, by screwing male threads provided on the ends of the pipes 3a, 3b with female threads provided on the flanges 2a, 2b.

[0014] The flanges 2a and 2b are, for example, annular metal disks attached to the ends of the pipes 3a and 3b so as to protrude radially outward.

[0015] Each of the flanges 2a, 2b has a plurality of bolt holes (not shown). Each of the plurality of bolt holes in one of the pair of flanges 2a, 2b is arranged to overlap with one of the plurality of bolt holes in the other of the pair of flanges 2a, 2b. When joining the flanges, the pair of flanges 2a, 2b are positioned so that the bolt holes in the pair of flanges 2a, 2b form a plurality of bolt hole pairs through which a bolt (not shown) passes. Then, a bolt (not shown) is inserted into each of the plurality of bolt hole pairs, and a nut (not shown) is tightened onto the bolt protruding from each of the plurality of bolt hole pairs, thereby joining the pair of flanges 2a, 2b.

[0016] 1, when the central axes of a pair of pipes 3a, 3b are aligned, the pressure applied from the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b to the gasket 1 is approximately uniform. Therefore, the axial thickness W1 of the gasket 1 sandwiched between the opposing surfaces 2aa, 2ba is approximately uniform, and the gap G1 between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b can be approximately uniform.

[0017] Fig. 2 is a plan view schematically showing the gasket 1 according to this embodiment. Fig. 3 is a cross-sectional view schematically showing the gasket 1 according to this embodiment taken along the line III-III in Fig. 2.

[0018] The gasket 1 is a sealing member formed in an annular shape to fit the shape of the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b, and has, for example, a flattened doughnut shape as shown in FIG.

[0019] The thickness W0 of the gasket 1 before being sandwiched between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b is, for example, 10 mm, which is larger than the axial thickness W1 of the gasket 1 sandwiched between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b. Also, the radial width B0 of the gasket 1 before being sandwiched between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b is, for example, 25 mm, which is smaller than the radial width B1 of the gasket 1 sandwiched between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b.

[0020] As shown in Figures 2 and 3, the gasket 1 comprises an annular member 11 having an annular hollow portion 11a therein and capable of expanding and contracting at least in the axial direction of a pair of pipes 3a and 3b, and a fluid material 12 filled in the hollow portion 11a.

[0021] The annular member 11 may be expandable not only in the axial direction but also in the radial direction, and is preferably formed of, for example, a rubber material. Since the gasket 1 according to this embodiment is used in a power plant, there is a risk that thermal stress will be generated in the rubber material forming the annular member 11 when, for example, a heat transfer medium flows through the pipes 3a and 3b. Therefore, it is more preferable that the annular member 11 be formed of a heat-resistant rubber material, for example, silicone rubber. Furthermore, when the gasket 1 is used in a chemical plant, it is preferable that the annular member 11 be formed of a rubber material that is not only heat-resistant but also chemical-resistant, for example, fluororubber.

[0022] The planar shape of the annular member 11 of this embodiment is a circular ring shape with a substantially uniform radial width B0, as shown in Fig. 2. The annular member 11 also includes an inner diameter portion 11b that forms the radially inner side surface of the annular member 11, and an outer diameter portion 11c that forms the radially outer side surface of the annular member 11.

[0023] 3, the cross-sectional shape of the inner diameter portion 11b taken along a plane (III-III cross section) passing through the central axis of the annular member 11 is preferably an arc shape that protrudes toward the center of the annular member 11 (i.e., a curve that is convex toward the center of the annular member 11). Also, the cross-sectional shape of the outer diameter portion 11c taken along a plane (III-III cross section) passing through the central axis of the annular member 11 is preferably an arc shape that protrudes toward the radially outward direction of the annular member 11 (i.e., a curve that is convex toward the radially outward direction of the annular member 11).

[0024] The hollow portion 11a is a hollow space provided inside the annular member 11. The hollow portion 11a is annular, and is filled with a fluid material 12. It is preferable that the thickness t (see FIG. 3) of the annular member 11 covering the hollow portion 11a is uniform. This makes the internal pressure applied to the annular member 11 by the fluid material 12 filled in the hollow portion 11a approximately uniform.

[0025] The flowable material 12 is a material that can flow within the hollow portion 11a. For the flowable material 12, it is preferable to use a material that is not likely to corrode the rubber material that forms the annular member 11, that exhibits little change in viscosity even in high-temperature environments, and that is not likely to oxidize when in contact with air, such as machine oil. It is also more preferable to use a high-viscosity index hydraulic oil that has been added with an anti-wear agent, an antioxidant, and a pour-point depressant to provide good flowability at low temperatures, particularly a high-viscosity index hydraulic oil with a viscosity index of 130 or higher that can be used over the entire operating temperature range.

[0026] In addition, in order to suppress oxidation of the machine oil in the hollow portion 11a, in the process of filling the hollow portion 11a with the machine oil, it is preferable to seal the hollow portion 11a after confirming that the hydraulic oil has overflowed from the hollow portion 11a and that no air remains in the hollow portion 11a.

[0027] Furthermore, the fluid material 12 may be, for example, powdered expanded graphite, which is expanded graphite that is excellent in flexibility, chemical resistance, adhesiveness, and high temperature resistance, and is made into a powder form.

[0028] Because the fluid material 12 is capable of flowing within the hollow portion 11a, the fluid material 12 can flow within the hollow portion 11a in accordance with an external force applied to the annular member 11 from the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b. When an external force is applied, contact portions 11d, 11e of the annular member 11 that come into contact with the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b deform into a shape that conforms to the opposing surfaces 2aa, 2ba, and the fluid material 12 within the hollow portion 11a of the annular member 11 flows in accordance with the deformation of the annular member 11. Therefore, the gasket 1 can maintain close contact between the annular member 11 and the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b and seal the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b.

[0029] [effect] Fig. 4 is a side view schematically showing a pair of pipes 3a, 3b whose central axes are inclined relative to each other, a pair of flanges 2a, 2b whose opposing surfaces are open, and a gasket 1 according to a first embodiment of the present invention attached to the open opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b. Fig. 5 is a plan view schematically showing the gasket 1 according to the first embodiment of the present invention attached to the open opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b. Fig. 6 is a cross-sectional view schematically showing the VI-VI cross section of Fig. 5.

[0030] As described above, the pair of pipes 3a, 3b used in a power plant have large diameters and heavy weights. Due to poor construction during plant construction, vibrations during plant operation, external forces acting on the pipes 3a, 3b, and other factors, the central axes of the pair of pipes 3a, 3b may be tilted by, for example, θ degrees relative to one another, causing the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b to be open, as shown in Fig. 4. In this case, the opposing surfaces of the pair of flanges 2a, 2b are open θ degrees, and compared to the distance G1 between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b when the central axes of the pair of pipes 3a, 3b are aligned, the width G2 of the outer diameter portion 11ca on the side where the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b close becomes narrower, and the width G3 of the outer diameter portion 11cb on the side where the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b open becomes wider.

[0031] In this case, conventional gaskets cannot deform to follow the opposing surfaces 2aa, 2ba of the flanges 2a, 2b, so gaps form between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b and the gasket, causing the problem that the fluid flowing through the pipes 3a, 3b leaks out through these gaps.

[0032] However, the gasket 1 of this embodiment includes an annular member 11 having an annular hollow portion 11a therein and capable of expanding and contracting in the axial direction of at least a pair of pipes 3a, 3b, and a fluid material 12 that is filled in the hollow portion 11a and is capable of flowing within the hollow portion 11a. Therefore, as shown in Fig. 4, when the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b are opened, the gasket 1 of this embodiment operates as follows.

[0033] 6, the axial thickness W2 of the gasket 1 of the outer diameter portion 11ca on the side where the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b close is smaller than the axial thickness W1 of the gasket 1 when the central axes of the pair of pipes 3a, 3b are aligned. In other words, the outer diameter portion 11ca on the closing side shrinks in the axial direction of the gasket 1.

[0034] 6, the axial thickness W3 of the gasket 1 at the outer diameter portion 11cb on the opening side of the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b is greater than the axial thickness W1 of the gasket 1 when the central axes of the pair of pipes 3a, 3b are aligned. In other words, the opening side outer diameter portion 11ca extends in the axial direction of the gasket 1.

[0035] In addition, the volume of the hollow portion 11aa located on the closing side of the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b decreases, while the volume of the hollow portion 11ab located on the opening side of the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b increases, so that the fluid material 12 flows from the upper hollow portion 11aa toward the lower hollow portion 11ab.

[0036] As a result, the contact portions 11d and 11e of the gasket 1 that come into contact with the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b can be held in close contact with the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b. Therefore, even if the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b are separated, the use of the gasket 1 according to this embodiment can maintain a seal between the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b, and can prevent the fluid flowing through the pipes 3a and 3b from leaking out from between the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b.

[0037] Furthermore, due to the above-described effect, the gasket 1 can seal between the pair of flanges 2a, 2b without highly accurate alignment of the pipes 3a, 3b. This simplifies the process of aligning the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b and the process of installing the pipes 3a, 3b while maintaining the alignment of the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b, and improves work efficiency during construction.

[0038] In addition, if the annular member 11 is made of a rubber material that expands and contracts in the axial and radial directions of the gasket 1, the outer diameter portion 11ca of the annular member 11 is thought to move in the radial direction of the gasket 1 as follows.

[0039] 5 and 6 is greater than the radial width B1 of the gasket 1 when the central axes of the pair of pipes 3a and 3b are aligned.

[0040] 5 and 6 is smaller than the radial width B1 of the gasket 1 when the central axes of the pair of pipes 3a and 3b are aligned.

[0041] That is, in the gasket 1 according to the first embodiment, the annular member 11 expands and contracts in the axial direction of the gasket 1, thereby expanding and contracting in the radial direction of the gasket 1.

[0042] In this case, the same effect as above can be obtained.

[0043] Furthermore, in the gasket 1 of this embodiment, the cross-sectional shape of the inner diameter portion 11b taken along a plane passing through the central axis of the annular member 11 is an arc shape that protrudes toward the center of the annular member 11, and the cross-sectional shape of the outer diameter portion 11c taken along a plane passing through the central axis of the annular member 11 is an arc shape that protrudes toward the radially outward direction of the annular member 11. This makes it possible to prevent stress concentration from occurring in the inner diameter portion 11b and the outer diameter portion 11c.

[0044] (Second embodiment) Fig. 7 is a plan view schematically showing a gasket 21 according to a second embodiment of the present invention, and Fig. 8 is a schematic cross-sectional view taken along line VIII-VIII in Fig. 7.

[0045] The gasket 21 of this embodiment differs from the gasket 1 of the first embodiment in that the gasket 21 of this embodiment has annular discs (annular discs 212a, 212b) between the hollow portion 11a and the contact portions 11d, 11e that contact the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b.

[0046] The annular discs 212a and 212b are, for example, metal plates 1 mm thick, with an outer diameter smaller than that of the annular member 211 and an inner diameter larger than that of the annular member 211, and are embedded between the contact portions 11d and 11e and the hollow portion 11a.

[0047] [effect] In this embodiment, annular disks 212a, 212b are provided between the hollow portion 11a and contact portions 211d, 211e that come into contact with the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b. This makes it possible to suppress fluctuations in the pressure of the contact portions 211d, 211e on the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b at each location due to the flow of the fluid material 12, and to maintain a substantially uniform sealing surface pressure, thereby improving the sealing performance of the gasket 21.

[0048] Furthermore, since the annular disks 212a and 212b are made of metal, the annular disks 212a and 212b do not deform even at high temperatures, and the surface pressure on the opposing surfaces 2aa and 2ba of the pair of flanges 2a and 2b can be maintained.

[0049] Furthermore, the gasket 21 according to this embodiment includes annular disks 212a, 212b between the contact portions 211d, 211e and the hollow portion 11a. Therefore, the annular member 211 is prevented from shrinking in the radial direction of the gasket 21 compared to the annular member 11 of the first embodiment. Therefore, the gasket 21 according to this embodiment has the advantage that it is possible to prevent a reduction in the contact area between the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b and the outer diameter portion 11c on the side where the opposing surfaces 2aa, 2ba of the pair of flanges 2a, 2b open, and thus it is easy to maintain sealing performance.

[0050] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0051] The present invention may also be embodied in the following manner: For example, the pair of pipes may be square pipes, the pair of flanges may be rectangular plates having a rectangular hole in the center, and the gasket may be formed in a rectangular ring shape along the opposing surfaces of the pair of flanges.

[0052] Furthermore, the contact portions 11d and 11e of the gasket 1 with the pair of flanges 2a and 2b may be bonded to the flanges 2a and 2b with an adhesive or the like. The bonding may be applied to only a portion of the contact portions 11d and 11e. By bonding the two together in this manner, even if the flanges 2a and 2b widen, the gasket 1 can more easily follow the deformation of the flanges 2a and 2b, making it easier to maintain close contact between the flanges 2a and 2b and the gasket 1. [Explanation of symbols]

[0053] 1,21...gasket, 2a,2b...flange, 2aa,2ba...opposite surface, 3a,3b...piping, 11,211...annular member, 11a...hollow part, 11b...inner diameter part, 11c...outer diameter part, 11d,11e,211d,211e...contact part, 12...flowable substance, 212a,212b...annular disc

Claims

1. A gasket to be fitted between opposing surfaces of a pair of flanges provided at the ends of a pair of pipes, an annular member having an annular hollow portion therein and capable of expanding and contracting in at least the axial direction of the pair of pipes; a fluid material filled in the hollow portion and capable of flowing within the hollow portion, The annular member is a gasket having an annular disk between the hollow portion and a contact portion that contacts the opposing surfaces of the pair of flanges.

2. 2. The gasket of claim 1, A gasket characterized in that the annular member is made of a rubber material.

3. 2. The gasket of claim 1, a cross-sectional shape of the inner diameter portion of the annular member taken along a plane passing through a central axis of the annular member is an arc shape protruding toward the center of the annular member, A gasket characterized in that the cross-sectional shape of the outer diameter portion of the annular member taken along a plane passing through the central axis of the annular member is an arc shape that protrudes radially outward from the annular member.

4. 2. The gasket of claim 1, A gasket characterized in that the annular disk is made of metal.

5. 3. The gasket of claim 2, A gasket characterized in that the rubber material is silicone rubber or fluororubber.

6. 2. The gasket of claim 1, A gasket characterized in that the flowable material is machine oil or powdered expanded graphite.

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