JP2002039395A - Expanded graphite ring packing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expanded graphite ring packing preventing the oxidation extinguishing of expanded graphite even in a temperature range exceeding a usage limit, keeping excellent sealing performance, and preventing squeezing out of the expanded graphite due to fastening. SOLUTION: In this expanded graphite ring packing A provided with a metallic grommet B, an surface portion b1 of the metallic grommet B, covering an end surface in an axial direction of the ring packing, is formed to be an arc-shape in a cross section having a radius R of curvature. The surface portion b1 is squashed by fastening force, and the width W of the grommet is widened. So that, the grommet tightly contacts with an inner peripheral surface of a vessel body 1 of a pressure vessel and an outer peripheral surface of a covering body 2, thereby giving good sealing performance between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved expanded graphite ring packing suitable for sealing a fluid such as gas or water for use in a valve or the like of a high-temperature and high-pressure apparatus.

[0002]

2. Description of the Related Art Conventionally, a metal seal ring has been known as a seal ring used for a valve of a high-temperature and high-pressure apparatus. In the case of this metal seal ring, if the seal portion is damaged during maintenance of the device, polishing and cutting must be performed to repair the damage, which increases maintenance costs. Would.

[0003] Therefore, as an alternative to a metal seal ring, a ring packing made of a soft and highly sealable expanded graphite is often used. There are various types of this expanded graphite ring packing, and the most common type is called a tape mold type, and a tape-shaped material obtained by slitting an expanded graphite sheet into a predetermined width is placed in a molding die. This is a ring-shaped packing obtained by spirally or concentrically winding and arranging, and then press-molding this in the tape width direction.

The expanded graphite ring packing has no risk of damaging the seal portion and is highly resilient, so that it can follow pressure fluctuations more sufficiently than a metal seal ring and has a sufficient tightening pressure even at a low tightening pressure. There is an advantage of exhibiting a sealing property. Further, a composite structure in which a metal foil, a wire mesh, or the like is buried as a reinforcing material inside the expanded graphite may be used.

[0005]

However, in the above-mentioned conventional expanded graphite ring packing, in a temperature range exceeding 400 ° C., the expanded graphite is oxidized and disappeared by oxygen in the atmosphere, and it is difficult to maintain a sealing property. There are disadvantages. Also, in the case of a fluid containing oxygen, the expanded graphite is similarly oxidized and disappeared in a temperature range exceeding 400 ° C., making it difficult to maintain the sealing property. Further, in the case of using only the expanded graphite, the expanded graphite may protrude from the gap when it is fastened and fixed. As a result, there is a problem that the sealing performance is reduced due to stress relaxation.

[0006] In view of the above problems, conventional ring packing made of expanded graphite uses a metal backup ring, grommet, or the like to prevent exudation of the expanded graphite. As an example, here is a utility model registration No. 2528365.
No. is shown. This publication discloses a structure in which a metal auxiliary seal member is provided on an axial end face of a gasket (ring packing) made of expanded graphite.

In the above structure, the lid is inserted into the shaft hole in the pressure vessel with the side of the metal auxiliary seal member fitted to the end face in the axial direction facing the atmosphere, and positioned by screws or split rings. When the lid is tightened from the axial direction by a tension bolt through the provided retainer ring, the expanded graphite molded body (ring packing) is compressed, and accordingly, the inner peripheral side bent edge portion of the auxiliary seal member and The outer peripheral side bent edge and the inner peripheral surface and the outer peripheral surface of the expanded graphite molded body are deformed radially inward and outward, and are brought into close contact with the inner peripheral surface of the pressure vessel and the outer peripheral surface of the lid. Sealed.

At this time, a tightening force acts on the ring-shaped expanded graphite molded body, but a part of the ring-shaped expanded graphite molded body is prevented from protruding in the axial direction by the end face regulating action by the auxiliary sealing member. The entry of air from the atmosphere side is also prevented by the presence of the auxiliary seal member.

However, in the expanded graphite gasket having the auxiliary seal member, even if the tightening force of the retainer ring is applied to the auxiliary seal member, the expansion due to the deformation of the auxiliary seal member in the radial direction is small, and the pressure vessel has It is difficult to adhere to the inner peripheral surface and the outer peripheral surface of the lid, and the effect of preventing the oxidation of expanded graphite is not actually exhibited,
Also, the effect of preventing the exfoliated graphite from exuding is small.

The present invention has been made in order to solve the problem of the expanded graphite gasket described in the above-mentioned publication, and there is no loss of oxidation of the expanded graphite even in a temperature range exceeding a use limit temperature, and excellent sealing performance is obtained. It is a primary object of the present invention to provide an expanded graphite ring packing that can be maintained and that does not protrude when expanded.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a ring packing made of expanded graphite, which has an axial end surface, a surface portion covering the end surface, and an inner peripheral surface and an outer peripheral surface side of the ring packing. A metal grommet comprising a bent edge portion extending slightly toward the metal grommet is provided. The gist of the invention is that the surface of the metal grommet is machined into an arc-shaped cross section.

The expanded graphite ring packing includes:
What is obtained by winding and molding an expanded graphite tape in a ring shape is used. A ring packing having a square cross section or a wedge cross section is used. The metal used for the grommet has a melting point exceeding 400 ° C., is softer than the body of a valve or the like on which a ring packing is mounted, and preferably has a thickness of 1.0 mm or less. For example, aluminum, nickel, copper, iron, etc. Can be used.

[0013]

Preferred embodiment of the embodiment of the present invention, as shown in FIG. 1, the end surface in the axial direction of the expanded graphite ring packing A cross-section wedge-shaped, with a surface portion b ₁ covering the end face A metal grommet B is provided which comprises bent edges b ₂ and b ₃ slightly extending from the surface of the ring packing toward the inner peripheral surface and the outer peripheral surface.

[0014]

7 (a), 7 (b) and 7 (c) show the deformation of a metal grommet when the expanded graphite ring packing A provided with the metal grommet B is used as a shaft seal of a pressure vessel. It shows the state. That is, the surface portion b ₁ having the radius of curvature R of the metal grommet B is crushed by the tightening force, the width W of the grommet increases, and the inner circumference of the body 1 of the pressure vessel and the outer circumference of the lid 2 are in close contact. Thus, a good sealing function is provided between the two.

[0015]

1 to 4 show sectional views of expanded graphite ring packings according to various embodiments of the present invention. In the figure, A is a ring packing made of expanded graphite, and B is a metal grommet made of a metal plate having a thickness of 0.3 mm. A surface portion b ₁ This metal grommet B is covering the end face in the axial direction of the expanded graphite ring packing A,
Folded edges b ₂ , slightly extending from the surface b ₁ toward the inner peripheral surface and the outer peripheral surface of the ring packing, respectively.
b _3, and the surface portion b ₁ is formed in an arc-shaped cross section having a radius of curvature R.

FIGS. 1 and 2 show an example in which a metal grommet B is provided on an expanded graphite ring packing A having a wedge-shaped cross section, and FIGS. The example which provided grommet B is shown. The ring packing A made of expanded graphite having a wedge-shaped cross section in FIG. 2 is provided with a metal grommet B ′ having a U-shaped cross section that covers the wedge-shaped tip portion.

The radius of curvature R of the arc-shaped surface portion b ₁ is preferably a radius of about the same as the width of the ring packing. R
Is larger than the width of the ring packing, the deformation at the time of pressurization described later is small, so that the metal grommet B does not easily adhere to the container body and the lid. If the radius of R is smaller than the width of the ring packing, the metal grommet B hardly adheres to the container body and the lid or remains deformed unless the deformation under pressure is increased. Become.

FIGS. 5 and 6 show an example in which the ring packing A made of expanded graphite with a metal grommet configured as described above is mounted as a shaft seal of a pressure vessel. 5 to 6, reference numeral 1 denotes a body of a pressure vessel, 2 denotes a lid, 3 denotes a tension bolt, 4 denotes a retainer ring, and ring packing A made of expanded graphite uses a metal grommet B as an atmosphere side and the body 1 is formed. Lid 2
And fixed by the retainer ring 4 and tightened by the operation of the tension bolt 3.

FIGS. 7A, 7B and 7C show the deformed state of the metal grommet B when tightening with the tension bolt. That is, the surface portion b ₁ of the metal grommet B having the radius of curvature R is crushed by the tightening force of the tension bolt, the width W of the grommet is increased, and the inner peripheral surface of the body 1 of the pressure vessel and the outer periphery of the lid 2 are formed. A good sealing function is provided between the two.

Since the metal grommet B has a function of suppressing the protrusion of the expanded graphite ring packing A, it is effective to protrude into the gap between the inner peripheral surface of the pressure vessel and the outer peripheral surface of the retainer ring 4. And the sealing function is favorably maintained for a long time.

Further, even if air on the atmospheric pressure side attempts to enter the ring packing through the gap, the intrusion of air is prevented by the metal grommet, and the possibility that the expanded graphite of the ring packing is oxidized and eliminated is eliminated. High sealing properties are exhibited over a long period of time even under usage conditions exceeding.

A sample of the expanded graphite ring packing with the metal grommet according to the present invention was mounted on the shaft sealing portion of the pressure vessel, and the change in weight was confirmed. Table 1 below shows a comparison with Table 1. Here, as the acceleration test, the gap between the pressure vessel and the lid was set to a standard gap of about JIS B 0401, which is generally used as a loose fit, and 0.1 mm larger than the standard gap.
The example is shown on an enlarged scale when the test temperature is 650 ° C.

As is clear from the results shown in Table 1, it was confirmed that the product of the present invention hardly lost heat even if the air-side gap was standard or enlarged, and the oxidation of expanded graphite was effectively prevented. . Further, as a result of performing a water pressure resistance test of 100 MPa on the product of the present invention, it was confirmed that there was no leakage.

[0024]

[Table 1]

[0025]

As described in detail above, according to the present invention,
An expanded graphite ring packing is obtained in which the expanded graphite is not oxidized and disappears even in a temperature range exceeding the service limit temperature, excellent sealability can be maintained, and the expanded graphite does not protrude due to tightening.

[Brief description of the drawings]

FIG. 1 is a sectional view of an expanded graphite ring packing showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view of an expanded graphite ring packing showing another embodiment.

FIG. 3 is a sectional view of an expanded graphite ring packing showing another embodiment.

FIG. 4 is a sectional view of an expanded graphite ring packing showing another embodiment.

FIG. 5 is a cross-sectional view of a pressure vessel loaded with an expanded graphite ring packing having a wedge-shaped cross section.

FIG. 6 is a sectional view of a pressure vessel loaded with a ring packing made of expanded graphite having a square cross section.

FIG. 7 is an explanatory view showing a deformed state of a metal grommet when the expanded graphite ring packing is tightened.

[Explanation of symbols]

A Ring packing made of expanded graphite B, B 'Metal grommet b ₁ Surface of metal grommet on packing end surface side b ₂ Bent edge on packing inner peripheral surface b ₃ Bending edge on packing outer peripheral surface side 1 Pressure Container body 2 Lid 3 Tension bolt 4 Retainer ring

Claims (2)

[Claims] 1. A surface portion covering an end surface in an axial direction of an expanded graphite ring packing, and slightly extending from the surface portion toward an inner peripheral surface side and an outer peripheral surface side of the ring packing. A ring packing made of expanded graphite, wherein a metal grommet including a bent edge portion is provided, and a surface portion of the metal grommet is processed into an arc-shaped cross section. 2. The expanded graphite ring packing according to claim 1, wherein the expanded graphite ring packing is a ring packing having a square cross section or a wedge cross section.