BALL VALVE WITH CRYOGENIC SEAT

Abstract

The invention relates to a ball valve with a cryogenic seat, which has a valve body with inlet and outlet ducts, a ball with a through hole arranged in an inner recess of the valve body between the inlet and outlet ducts, a closing seat for each duct having a sealing gasket that has a first portion which is inserted into a housing defined in the wall of the inner recess wherein the ball is arranged and a second portion which protrudes from the housing and is in contact with the ball, and a pressure element which pushes the sealing gasket against the ball, wherein the pressure element is arranged in the housing of the wall of the inner recess wherein the ball is arranged, in contact with the first portion of the sealing gasket.

Claims

1. A ball valve with a cryogenic seat, which comprises: a valve body with inlet and outlet ducts, a ball with a through hole which is arranged in an inner recess of the valve body between the inlet and outlet ducts, the ball being able to rotate between a position connecting the through hole to the inlet and outlet ducts and a position wherein it interrupts the passage between said inlet and outlet ducts, and a closing seat for each inlet and outlet duct comprising: a sealing gasket having a first portion which is inserted into a housing defined in the wall of the inner recess wherein the ball is arranged and a second portion which protrudes from the housing and is in contact with the ball, and a pressure element which pushes the sealing gasket against the ball, wherein the pressure element is arranged in the housing of the wall of the inner recess wherein the ball is arranged in contact with the first portion of the sealing gasket.

2. The ball valve with a cryogenic seat, according to claim 1, wherein the first portion of the sealing gasket has an annular lip which is retained in the housing by the pressure exerted by the pressure element.

3. The ball valve with a cryogenic seat, according to claim 1 wherein the pressure element is a hollow toroidal spring.

4. The ball valve with a cryogenic seat, according to claim 1, further comprising a channel which connects the inner recess of the valve to the housing.

Description

DESCRIPTION OF THE FIGURES

[0022] FIG. 1 shows a partial cross-sectional view of the closing seat of a ball valve according to the state of the art.

[0023] FIG. 2 shows a perspective view of a partial cross section of the ball valve of the invention.

[0024] FIG. 3 is a complete longitudinal cross-sectional view of the valve of the previous figure.

[0025] FIG. 4 is an enlarged detailed view of the closing seat of the ball valve invention, according to a first embodiment.

[0026] FIG. 4A shows a perspective view of the sealing gasket of the closing seat of the previous figure.

[0027] FIG. 5 is an enlarged detailed view of the closing seat of the ball valve invention, according to a second embodiment.

[0028] FIG. 5A shows a perspective view of the sealing gasket of the closing seat of the previous figure.

[0029] FIG. 6 is an enlarged detailed view of the closing seat of the ball valve invention, according to a third embodiment.

[0030] FIG. 6A shows a perspective view of the sealing gasket of the closing seat of the previous figure.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The invention relates to a ball valve of the kind arranged in conduits carrying fluids, particularly for applications in cryogenic temperature conditions, in the order of temperatures between 29 C. and 196 C.

[0032] FIGS. 2 and 3 show a ball valve according to the invention comprising a valve body (1) having an inner recess with a spherical configuration with which they connect corresponding opposite ducts (2), one being an inlet and the other an outlet of the passage through the valve, a ball (3) having a through hole (4) and which is joined to a control rod (5) being housed in the inner recess. By means of the rod (5), the ball (3) can rotate between a position wherein the through hole (4) establishes a connection between the inlet and outlet ducts (2) of the valve body (1), leaving the passage open to through the valve, and another position wherein the ball (3) interrupts the connection between said inlet and outlet ducts (2) of the valve body (1), leaving the passage through the valve closed.

[0033] The valve comprises a cryogenic seat having a closing seat for each inlet and outlet duct (2) of the valve in order to achieve an airtight seal between the ball (3) and the wall (6) of the inner recess wherein the ball (3) is arranged. The closing seat is arranged around the inner mouth of each of the inlet and outlet ducts (2) of the valve, and comprises a sealing gasket (7) made of elastic material having a first portion (7.1) which is inserted into a housing (8) of the wall (6) of the inner recess wherein the ball (3) and a second portion (7.2) protruding from the housing (8) are arranged and is in contact with the ball (3), and a pressure element (9) which pushes the sealing gasket (7) against the ball (3).

[0034] FIG. 1 shows a closing seat made according to the prior state of the art. The first portion (7.1) of the sealing gasket (7) is inserted into the housing (8) of the wall (6) of the inner recess wherein the ball (3) is arranged, while the second portion (7.2) of the sealing gasket (7) protrudes from the housing (8) in contact with the ball (3), in that arrangement the pressure element (9) is located between the wall (6) of the inner recess wherein the ball (3) and the second portion (7.2) of the sealing gasket (7) are arranged, such that the pressure element (9) pushes the second portion (7.2) of the sealing gasket (7) against the surface of the ball (3). In this manner, an airtight seal is ensured due to the fact that the second portion (7.2) of the sealing gasket (7) is pressed on the surface of the ball (3) by the action of the pressure element (9); however, at low cryogenic temperatures the fluid tends to leak from the inner recess through the housing (8) wherein the first portion (7.1) of the sealing gasket (7) is inserted.

[0035] The invention proposes solving this problem by arranging the pressure element (9) in the housing (8) of the wall (6) of the inner recess wherein the ball (3) is arranged, the pressure element (9) being in contact with the first portion (7.1) of the sealing gasket (7). With this arrangement, the housing (8) is not completely covered by the first portion (7.1) of the sealing gasket (7), but rather part of the housing (8) is occupied by the pressure element (9), such that the fluid leaking from inside the valve tends to occupy the space of the housing (8) wherein the pressure element (9) is located, the fluid being retained in said space. The fluid due to the very pressure thereof compresses the sealing gasket (7) in the housing (8) pushing it against the ball (3), which helps prevent fluid from escaping the housing (8) and the sealing gasket (7) from pressing against the ball (3). At the same time, the pressure of the fluid helps the pressure element (9) exert force on the sealing gasket (7) and thus put more pressure on the ball (3).

[0036] According to a preferred embodiment of the invention, the first portion (7.1) of the sealing gasket (7) has an annular lip (7.11) which is retained in the housing (8) by the pressure exerted by the pressure element (9). The annular lip (7.11) is arranged on the outside of the sealing gasket (7) such that it is retained between the pressure element (9) and the upper wall of the housing (8), while the fluid leaking from the inside of the valve tends to enter the housing (8) from the lower portion thereof. In this manner, the pressure of the fluid helps the pressure element (9) to tighten the annular lip (7.11) of the sealing gasket (7), thereby improving the seal preventing the fluid from escaping the housing (8), even at cryogenic temperatures wherein the sealing gasket (7) loses elasticity.

[0037] Preferably, the pressure element (9) is a hollow toroidal spring, meaning an annular helical spring, such that by being a hollow element it enables the fluid to flood the housing (8) and exert a suitable pressure which helps press the sealing gasket (7) against the ball (3), as well as press the annular lip (7.11) against the upper wall of the housing (9).

[0038] As seen in the exemplary embodiments of FIGS. 5 and 6, it is foreseen that the valve additionally comprises a channel (10) which connects the inner recess wherein the ball (3) is arranged to the housing (8). In this manner a connection is established which ensures that the fluid enters the housing (8), ensuring that the pressure of the very fluid is used to improve the sealing properties of the valve even at cryogenic temperatures.

[0039] In small valves and being applicable to conduits carrying fluids at low pressure, the securing of the assembly of the sealing gasket (7) can be established by a simple grip on one of the edges thereof, as in the example of FIGS. 5 and 5A, thereby facilitating the valve assembly. However, in large valves and being applicable to conduits carrying fluids at high pressure, the securing of the assembly of the sealing gasket (7) comprises two annular portions, as seen in the example of FIGS. 6 and 6A, with which a greater resistance to the pressure of the fluids is achieved in effective conditions for an airtight sealing of the valve.