JPS6242193B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a large-diameter ball valve used in pipelines, etc., and more specifically to a fire-safe valve, that is, a ball valve that maintains its sealing function even in the event of a fire. Regarding.

BACKGROUND ART FIG. 1 shows a sectional view of main parts of a conventional large-diameter ball valve, in which a stem (not shown) is installed in a housing 1.
A ball 2 serving as a valve body is housed so as to be able to rotate around a fluid passage 3 in the housing.
Open and close. Generally, in such a large-diameter valve, an annular seat retainer 4 is fitted into the housing so as to surround the fluid passage in order to prevent fluid from leaking from the fluid passage into the housing cavity. An annular valve seat 6 is attached between the outer ring 5 and the outer ring 5 fixed to the valve body, facing the valve body. The seat retainer is biased from the back side toward the valve body by compression springs 7 at regular intervals in the circumferential direction, so that the annular valve seat is brought into contact with the surface of the valve body, and the seat retainer and the valve body are pressed together. There is a seal in between. Further, a seal ring 8 is installed in a groove on the outer peripheral surface where the seat retainer slides on the inner wall surface of the housing.
A seal is formed between the housing and the seat retainer. In particular, when fluid pressure is applied to the fluid passage, the area of the annular portion whose width is the difference between the seal point diameter of the valve seat and the outer diameter of the seat retainer, and the product of the differential pressure between the fluid pressure and the pressure inside the cavity 9. Since a so-called self-tightening force proportional to 2 is applied from the back side of the seat retainer, the valve body is more reliably sealed by the valve seat.

However, the above-mentioned valve seats and seal rings are generally made of an elastic material such as rubber or synthetic resin in order to improve the sealing performance by making the balls adhere well to the sliding surface of the housing. Furthermore, since these are flammable, they will be deformed or burned down in the event of a fire, and the sealing function will be lost.

That is, as is easily understood, if the valve seat or seal ring is deformed or burnt out, the fluid in the fluid passage will flow not only between the valve body and the seat retainer as shown by arrow a, but also between the valve body and the seat retainer as shown by arrow b. As shown, it leaks into the cavity through the spaces between the inner wall surface of the housing and the outer circumferential surface of the seat retainer, and between the inner wall surface of the housing and the outer circumferential surface of the outer ring.

Therefore, various ball valves have been proposed that have a so-called fire-safe function that maintains a sealing function even in the event of a fire or the like.

For example, in JP-A-56-109956, an annular valve seat member is provided with a heat-collapsible seal ring that faces the ball and is pressed against the ball by a compression spring. A non-combustible graphite seal ring is placed between the heat-collapsible spacer rings at the rear end of the seat member, and this non-combustible seal ring is also biased by the above-mentioned compression spring to provide a fire-safe function. A ball valve with

According to this ball valve, the seal ring made of non-combustible graphite, which performs a sealing function in the event of a fire, etc., is configured to be unavoidably combined with the heat-collapsible spacer ring. After the heat-collapsible spacer ring collapses, the graphite seal ring, which is biased by the compression spring as described above, is compressed to seal the space between the valve seat member and the adapter, and to prevent fires, etc. This graphite seal ring shuts off the

Therefore, according to the conventional ball valve described above, the seal ring made of non-combustible graphite as the fire-safe seal ring does not have any biasing force or elastic force by itself, and during the fire-safe operation, As mentioned above, compression by a compression spring is necessary. Moreover, when manufacturing a ball valve equipped with such a compression spring, it is difficult to design and manufacture the spring so as not to exceed the allowable stress.

Problems to be Solved by the Invention Therefore, the technical problem of the present invention is that even if a combustible valve seat or seal ring is deformed or burned down due to a fire or the like and loses its sealing function, the compression Fire-safe, which does not require additional members such as springs, and can create a metal contact seal between the fluid passage and the housing cavity using the elastic force of the non-flammable seat ring itself. Our goal is to provide ball valves.

Means for Solving the Problems The technical configuration for solving the above problems will be explained based on FIGS. 2 to 4. In these drawings, the same members as in FIG. 1 are given the same reference numerals.

The ball valve according to the invention has a housing 1
a movable ball 2 that opens and closes a fluid passage within the housing; an annular seat retainer 4 fitted into the housing so as to face the ball and surround the fluid passage; A ball valve comprising an annular flammable valve seat 6 mounted facing the ball, and a flammable seal ring 8 provided on the outer circumferential surface of the seat retainer in sliding contact with the inner wall surface of the housing, wherein the valve seat and An annular steel 10 is provided on the outer circumferential surface of the seat retainer in sliding contact with the inner wall surface of the housing of the seat retainer between the seal ring and the annular steel is cut out so as to have a step surface 11 or a slope 12 extending in the longitudinal direction at both free ends. A ball valve is constructed by fitting a non-combustible seal ring 13, which is a manufactured ring and has an elastic force that tends to spread toward the outer circumference, into the annular groove, and urging the seat retainer from its back side. ing.

Function Therefore, according to the ball valve of the present invention, while the valve seat and seal ring have a normal sealing function, as described above, the valve seat does not contact the ball, and the seal ring does not contact the housing sliding surface. They abut each other to seal between the fluid passageway and the housing cavity. If the valve seat and seal ring are deformed or burnt out and lose their sealing function, the seat retainer is biased toward the ball from the back, so the front of the seat retainer will come into direct contact with the ball, causing the metal In addition to sealing by contact, the nonflammable seal ring is made of an annular steel ring as described above, and is in metal contact with the inner wall surface of the housing due to its own elastic force that tries to spread to the outer periphery. The stepped or sloped surfaces are also brought into contact by the fluid pressure from the back of the seal ring, creating a surface pressure, and fluid leakage is also prevented at this end, thus ensuring that there is no metal contact between the housing cavity and the fluid passage. A seal is formed.

Embodiments Below, embodiments of the valve according to the present invention will be described based on the drawings.

FIG. 2 is a cross-sectional view of a main part showing an embodiment of the valve according to the present invention, in which an annular seat retainer 4 is fitted into a housing 1 surrounding a fluid passage 3, and an outer ring 5 fixed to the annular seat retainer 4. An annular combustible valve seat 6 is mounted between the ball 2 and the ball 2 so as to face the ball 2. The above seat retainer is
Compression springs 7 installed in blind holes provided at regular intervals in the circumferential direction on the inner wall of the housing are biased toward the ball from the back side, and the annular valve seat is brought into contact with the ball surface and the seat It seals between the retainer and the ball. Further, a combustible seal ring 8 is installed in a groove on the outer circumferential surface of the seat retainer in sliding contact with the inner wall surface of the housing to seal between the housing and the seat retainer.

An annular groove 10 for mounting a nonflammable seal ring 13 is provided on the outer peripheral surface of the seat retainer between the flammable valve seat and the seal ring. The non-combustible seal ring has a free end, an example of which is shown in FIG. 3, and has a stepped surface 11 cut out together at the free end and extending in the longitudinal direction of the seal ring. Further, the seat ring can also be manufactured by coating the outer periphery of an elastic core metal with asbestos and molding the same. FIG. 4 shows another example of a non-combustible seal ring, which is formed by notching the end portion to have a slope 12. The above-mentioned non-combustible seal ring can be easily manufactured by, for example, forming a rectangular steel bar made of ordinary steel or impermeable steel into an annular shape, and tends to expand toward the outer periphery due to its own elastic force. have power.

Therefore, during normal operation, as mentioned above,
The valve seat contacts the ball and the combustible seal ring contacts the housing sliding surface to seal between the fluid passage and the housing cavity.
When the flammable valve seat and seal ring are deformed or burnt out and lose their sealing function, the compression spring 7 urges the seat retainer toward the front ball, so the front surface of the seat retainer This comes into direct contact with the ball, thereby preventing the fluid from leaking into the cavity from the fluid passage indicated by the arrow a.

Furthermore, when the sealing function of the combustible seal ring is lost, the nonflammable seal ring shown in FIGS. 3 and 4 is in metal contact with the inner wall surface of the housing, as shown in FIG. Fluid pressure is applied from the back side of the non-combustible seal ring, and the stepped surfaces or slopes come into contact with each other under surface pressure, so that leakage of fluid into the cavity is also prevented at this end. In this way, leakage of fluid from the fluid path indicated by the arrow b into the cavity is prevented.

Further, according to the ball valve of the present invention, since the nonflammable seal ring is provided on the seat retainer so as to be in contact with the inner wall surface of the housing, the sealing between the flammable valve seat and the seal ring is properly performed. During this time, the above-mentioned self-tightening force is not affected in any way, and when fluid pressure is present in the fluid passage, reliable sealing is performed by these combustible valve seats and seal rings.

Effects of the Invention As described above, according to the ball valve of the present invention, in the event of a fire, etc., when the flammable seal ring collapses, the ring-shaped steel ball valve has an elastic force that tends to spread toward the outer circumference. The non-combustible seal ring made of a ring comes into metal contact with the inner wall surface of the housing due to its own elastic force, and its stepped or sloped surface contacts with the fluid pressure from the back of the seal ring, causing surface pressure. and is also sealed at this end, thus creating a metal contact seal between the housing cavity and the fluid passageway upstream of the valve.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing a conventional ball valve, FIG. The perspective view and FIG. 5 are main part sectional views showing an annular groove and a nonflammable seal ring fitted into the annular groove. DESCRIPTION OF SYMBOLS 1...Housing, 2...Ball, 3...Fluid passage, 4...Seat retainer, 6...Flammable valve seat, 8...Flammable seal ring, 10...
Annular groove, 11... step surface, 12... slope, 13...
Nonflammable seal ring, 14...Front surface, 15...Top surface, 16...Compression spring.

Claims (1)

[Scope of Claims] 1. A housing, a movable ball that opens and closes a fluid passage within the housing, and an annular seat retainer fitted into the housing so as to face the ball and surround the fluid passage. , a ball valve comprising: an annular flammable valve seat attached to the seat retainer facing the ball; and a flammable seal ring provided on the outer peripheral surface of the seat retainer in sliding contact with the inner wall surface of the housing, An annular groove made of steel is provided between the valve seat and the seal ring on the outer circumferential surface that makes sliding contact with the inner wall surface of the housing of the seat retainer, and the free ends thereof are cut out so as to have stepped surfaces extending in the longitudinal direction. A ball valve characterized in that a nonflammable seal ring having a resilient force that tends to expand toward the outer circumference is fitted into the annular groove, and the seat retainer is biased from the back side thereof. 2 a housing, a movable ball that opens and closes a fluid passage within the housing, an annular seat retainer fitted into the housing so as to face the ball and surround the fluid passage; A ball valve comprising an annular flammable valve seat mounted opposite to a ball, and a flammable seal ring provided on an outer peripheral surface of the seat retainer in sliding contact with an inner wall surface of the housing, wherein the valve seat and the seal ring are provided. an annular steel ring provided with an annular groove on the outer circumferential surface slidingly in contact with the inner wall surface of the housing of the seat retainer, and having an annular groove cut out at both free ends so as to have slopes extending in the longitudinal direction, the outer circumferential side A ball valve characterized in that a non-combustible seal ring having an elastic force that tends to expand is fitted into the annular groove, and the seat retainer is biased from the back side thereof.