Patent Application
20150377366
Not Applicable.
Not Applicable.
Not Applicable.
1. Field of the Invention
This invention relates generally to large industrial valves for controlling the flow of fluids therethrough. More particularly, this invention pertains to ball valves having valve seats that are selectively movable when the ball plugs of such valves are in the closed position.
2. General Background
Ball valves are used in various industries for controlling the flow of fluids. An advantage of using a ball valve over other types of valves is that, when open, fluid is able to pass through the valve unobstructed. Thus, very little pressure loss occurs as fluid passes through the ball plug. The ball plug is typically pivotally attached to the housing via a pair of trunnions in a manner such that it can pivot between opened and closed positions. In the closed position, a valve seat on the ball plug can be engaged with a valve seat on the housing to prevent the flow of fluid through the valve. Typically, the valve seats engage each other automatically when the ball plug is in the closed position. However, in some cases the engagement pressure between the valve seats is high enough to warrant some means of relieving at least some of the pressure between the valve seats prior to pivotally moving the ball plug away from or into the closed position. That has been accomplished by making the valve seat on the housing movable toward and away from the ball plug. For example, some valves are configured such that fluid pressure can be applied to an actuation chamber in a manner that moves and urges the valve seat of the housing against the valve seat of the ball plug. To disengage the valve seat of such valves from each other, the fluid pressure within the actuation chamber is decreased to at least a degree such that fluid pressure within the valve forces the valve seat of the housing away from the ball valve. Thus, to sealably close such a valve, the fluid pressure within the actuation chamber must be large enough to overcome the fluid pressure within the valve upstream of said valve seats. If a failure causes an appreciable drop in pressure within the actuation chamber, the valve can fail in a non-sealed mode.
The present invention is directed to ball valves. More specifically, the present invention is directed to ball valves that have at least one valve seat that is movable relative to another valve seat of the ball valve when the ball valve is in a closed position.
In one aspect of the invention, a ball valve comprises a housing and a ball plug. The housing comprises a primary fluid passageway and an annular valve seat. The primary fluid passageway extends through the housing. The ball plug is positioned within the primary fluid passageway of the housing and comprises a main body portion, a pair of trunnions, a primary fluid passageway, and a valve seat. The trunnions pivotally connect the ball plug to the housing in a manner such that the ball plug can pivot to and between an open position and a closed position relative to the housing. The primary fluid passageway of the ball plug extends through the main body of the ball plug. The ball valve is configured and adapted to allow fluid to flow through the annular valve seat of the housing and through the primary fluid passageway of the ball plug and the primary fluid passageway of the housing when the ball plug is in the open position. The valve seat of the ball plug is configured and adapted to engage the annular valve seat of the housing in a manner preventing fluid from passing through the annular valve seat of the housing when the ball plug is in the closed position. The valve seat of the ball plug is also selectively movable relative to the main body portion of the ball plug such that the valve seat of the ball plug can be selectively urged toward the trunnions.
Another aspect of the invention pertains to a method of operating a ball valve. The ball valve comprises a housing and a ball plug. The housing comprises a primary fluid passageway and an annular valve seat. The primary fluid passageway extends through the housing. The ball plug is positioned within the primary fluid passageway of the housing and comprises a main body portion, a pair of trunnions, a primary fluid passageway, and a moveable valve seat. The trunnions pivotally connect the ball plug to the housing in a manner such that the ball plug can pivot to and between an open position and a closed position relative to the housing. The primary fluid passageway of the ball plug extends through the main body of the ball plug. The method comprises disengaging the valve seat of the ball plug from the annular valve seat of the housing by moving the valve seat of the ball plug toward the trunnions.
In still another aspect of the invention, a ball valve comprises a housing and a ball plug. The housing comprises a primary fluid passageway, a movable annular valve seat, and at least one compression spring. The primary fluid passageway extends through the housing and through the annular valve seat of the housing. The ball plug is positioned within the primary fluid passageway of the housing and comprises a main body portion, a pair of trunnions, a primary fluid passageway, and a valve seat. The trunnions pivotally connect the ball plug to the housing in a manner such that the ball plug can pivot to and between an open position and a closed position relative to the housing. The primary fluid passageway of the ball plug extends through the main body of the ball plug. The ball valve is configured and adapted to allow fluid to flow through the annular valve seat of the housing and through the primary fluid passageway of the ball plug and the primary fluid passageway of the housing when the ball plug is in the open position, and such that the annular valve seat of the housing can be engaged with the valve seat of the ball plug when the ball plug is in the closed position. The ball valve is further configured and adapted such that the annular valve seat of the housing can be disengaged with the valve seat of the ball plug when the ball plug is in the closed position. The compression spring urges the annular valve seat of the housing away from the valve seat of the ball plug when the ball plug is in the closed position in a manner such that, absent other forces acting on the annular valve seat, the annular valve will be spaced from the valve seat of the ball plug.
In yet another aspect of the invention, a method of operating a ball valve comprises closing a ball valve. The ball valve comprises a housing and a ball plug. The housing comprises a primary fluid passageway, a movable annular valve seat, an actuation chamber, and at least one compression spring. The primary fluid passageway extends through the housing and through the annular valve seat of the housing. The actuation chamber is partially bound by the annular valve seat of the housing. The ball plug is positioned within the primary fluid passageway of the housing and comprises a main body portion, a pair of trunnions, a primary fluid passageway, and a valve seat. The trunnions pivotally connect the ball plug to the housing in a manner such that the ball plug can pivot to and between an open position and a closed position relative to the housing. The primary fluid passageway of the ball plug extends through the main body of the ball plug. The compression spring urges the annular valve seat of the housing away from the valve seat of the ball plug when the ball plug is in the closed position. The method further comprises pressurizing the actuation chamber of the housing when the ball plug is in the closed position in a manner overcoming the urging caused by the compression spring and such that the annular valve seat of the housing engages and seals against the valve seat of the ball plug. Still further, the method comprises disengaging the annular valve seat of the housing with the valve seat of the ball plug by depressurizing the actuation chamber of the housing and pressurizing the primary fluid passageway of the ball plug.
Further features and advantages of the present invention, as well as the operation of the invention, are described in detail below with reference to the accompanying drawings.
Reference numerals in the written specification and in the drawing figures indicate corresponding items.
A ball valve in accordance with the invention is shown in the figures, as indicated by reference numeral 20. The ball valve 20 comprises a housing 22 and a ball plug 24. The ball plug 24 is pivotally mounted within and relative to the housing 22 about an axis such that the ball plug can pivot between a fully opened position and a fully closed position. When the ball plug 24 is in the opened position, fluid is permitted to flow unobstructed through the ball valve 20 and ball plug. When the ball plug 24 is in the closed position, the ball plug can prevent fluid from flowing through the ball valve 20.
The housing 22 comprises a generally cylindrical and tubular valve body 26. The valve body 26 comprises a fluid passageway 28 that extends through the valve body from an upstream end 30 to a downstream end 32 of the valve body. The housing 22 also comprises a movable upstream annular valve seat 34 and a stationary downstream annular valve seat 36 that are secured to the valve body 26. As shown in
The ball plug 24 is pivotally secured within the fluid passageway of the valve body 26 and to the valve body via trunnions 50. Like the valve body 26, the ball plug 24 comprises a fluid passway 52 that extends through the ball plug perpendicular to the axis of the trunnions 50. The ball plug 24 also comprises a movable downstream annular valve seat 54 and a stationary upstream annular valve seat 56. The upstream annular valve seat 56 of the ball plug is bolted to the main body 58 of the ball plug. The downstream annular valve seat is secured to the main body 58 of the ball plug 24 by a removable retaining ring 60. A plurality of compression springs 62 are circumferentially spaced from each other and urge the movable downstream valve seat 54 of the ball plug 24 away from the trunnions 50 (i.e., downstream when the ball plug is in its closed position). An actuation chamber 64 is formed collectively by the retaining ring 60 and the downstream valve seat 54 and is fluidly sealed from the fluid passageway 28 of the valve body 26 by O-rings 66. A pressure supply passageway 68 extends through one of the trunnions 50, the main body 58 of the ball plug 24, and the retaining ring of the ball plug 24, and is operatively connected to the actuation chamber 64 of the ball plug.
In operation, the upstream annular valve seats 34, 56 or the downstream annular valve seats 36, 54 can be used to prevent fluid from passing through the valve 20 when the ball plug 24 is in its closed position. The downstream annular valve seats 36, 54 are preferably the primary valve seats and the upstream annular valve seats 34, 56 preferably serve as “safety” valve seats. However, in some applications, it could be beneficial to use the upstream annular valve seats 34, 56 as primary valve seats. Moreover, it should be appreciated that the upstream annular valve seats 34, 56 operate independently of the downstream annular valve seats 36, 54 and a valve in accordance with the invention need not comprise both upstream and downstream sets of valve seats.
Since the downstream annular valve seats 36, 54 are preferably the primary valve seats, the use of the downstream annular valve seats 36, 54 will be described first. With the ball plug 24 in its closed position, the downstream annular valve seats 36, 54 can be engaged with each other to thereby prevent fluid from passing through the downstream annular valve seat 36 of the housing 22, as is shown in
In view of the foregoing it should be appreciated that any leak or loss of pressure in the actuation chamber 64 or pressure supply passageway 68 of the ball plug 24 will not cause the downstream annular valve seats 36, 54 of the valve 20 to unseat when the valve is closed. Moreover, it should be appreciated that the actuation chamber 64 and pressure supply passageway 68 of the ball plug 24 need only be pressurized when opening or closing the valve 20.
Turning now to the upstream annular valve seats 34, 56, reference is made to
Although a ball valve 20 may incorporate either only the upstream annular valve seats 34, 56 or the downstream annular valve seats 36, 54, providing a ball valve with both has additional advantages. For example, if the downstream annular valve seats 36, 54 serve as the primary valve seats and the stationary downstream annular valve seat 36 of the housing 22 is in need of servicing, the upstream annular valve seats 34, 56 can be used to close the valve while the downstream annular valve seat 36 is being serviced. Following such servicing, the downstream annular valve seats 36, 54 could be seated and a bypass line could thereafter be used to pressurize the fluid passageway between the upstream annular valve seats and the downstream annular valve seats until the upstream annular valve seat unseat. Thereafter, normal operation of the downstream annular valve seats 36, 54 could resume.
In view of the foregoing, it should be appreciated that the invention has several advantages over the prior art.
As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.
It should also be understood that when introducing elements of the present invention in the claims or in the above description of exemplary embodiments of the invention, the terms “comprising,” “including,” and “having” are intended to be open-ended and mean that there may be additional elements other than the listed elements. Additionally, the term “portion” should be construed as meaning some or all of the item or element that it qualifies. Moreover, use of identifiers such as first, second, and third should not be construed in a manner imposing any relative position or time sequence between limitations. Still further, the order in which the steps of any method claim that follows are presented should not be construed in a manner limiting the order in which such steps must be performed, unless such an order is inherent.
