CA1133877A - Ball valve and seat assembly - Google Patents
Ball valve and seat assemblyInfo
- Publication number
- CA1133877A CA1133877A CA362,710A CA362710A CA1133877A CA 1133877 A CA1133877 A CA 1133877A CA 362710 A CA362710 A CA 362710A CA 1133877 A CA1133877 A CA 1133877A
- Authority
- CA
- Canada
- Prior art keywords
- seat
- ball
- seat ring
- valve
- ball member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
- F16K5/06—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary with plugs having spherical surfaces; Packings therefor
- F16K5/0626—Easy mounting or dismounting means
- F16K5/0631—Easy mounting or dismounting means between two flanges
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
- F16K5/06—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary with plugs having spherical surfaces; Packings therefor
- F16K5/0663—Packings
- F16K5/0673—Composite packings
Abstract
BALL VALVE AND SEAT ASSEMBLY
(Abstract of the Disclosure) A ball valve having an improved relationship between the ball and associated seat rings and an improved seat ring design for such valves. The ball is mounted for selective rotation and limited axial movement in a valve body passageway. Seat rings disposed on diametrically opposite sides of the ball about valve inlet and outlet openings each include a first ball engaging surface. A frusto-conical disc spring mounted between each seat ring and an associated valve body shoulder urge the seat rings into engagement with the ball. A reinforcing ring disposed at the forward end of each seat ring acts as a rigid bearing surface. Component sizing is such that in the assembled valve, the seat rings are slightly rotatably flexed outwardly of each other in response to the first surfaces thereof engaging the ball. At the same time, the disc springs are partially compressed while continuously urging the seat ring first surfaces into ball engagement. When the valve is closed under fluid pressure conditions, the ball is shifted downstream causing the downstream seat ring to be further rotatably flexed in the direction of ball movement.
The upstream seat ring is simultaneously rotatably flexed in the same direction under the influence of its disc spring. At typical fluid operating pressures, the downstream disc spring is fully compressed to a generally flattened condition and the ball is shifted away from all contact by the upstream seat ring. In this condition, the upstream reinforcing ring prevents upstream seat ring displacement and also prevents seat ring distortion when the valve is reopened. A groove may be advantageously included in the seat ring rear faces to accommodate ease of rotational flexure.
(Abstract of the Disclosure) A ball valve having an improved relationship between the ball and associated seat rings and an improved seat ring design for such valves. The ball is mounted for selective rotation and limited axial movement in a valve body passageway. Seat rings disposed on diametrically opposite sides of the ball about valve inlet and outlet openings each include a first ball engaging surface. A frusto-conical disc spring mounted between each seat ring and an associated valve body shoulder urge the seat rings into engagement with the ball. A reinforcing ring disposed at the forward end of each seat ring acts as a rigid bearing surface. Component sizing is such that in the assembled valve, the seat rings are slightly rotatably flexed outwardly of each other in response to the first surfaces thereof engaging the ball. At the same time, the disc springs are partially compressed while continuously urging the seat ring first surfaces into ball engagement. When the valve is closed under fluid pressure conditions, the ball is shifted downstream causing the downstream seat ring to be further rotatably flexed in the direction of ball movement.
The upstream seat ring is simultaneously rotatably flexed in the same direction under the influence of its disc spring. At typical fluid operating pressures, the downstream disc spring is fully compressed to a generally flattened condition and the ball is shifted away from all contact by the upstream seat ring. In this condition, the upstream reinforcing ring prevents upstream seat ring displacement and also prevents seat ring distortion when the valve is reopened. A groove may be advantageously included in the seat ring rear faces to accommodate ease of rotational flexure.
Description
BACKGROUND OF THE INVENTION
This invention relates to the valve art and more paticularly to ball valves.
The invention is particularly applicable to a new and improved seat assembly and ball valve of the type having a so-called floating ball and will be described with reference thereto. However, it will become readily apparent to those skilled in the art that the invention is capable of broader applications and could be adapted for use in other types and styles of valves.
., ,,~, . . . .... .
4- Typical ball valve constructions in commercial use employ annular seats or seat rings formed of a resilient and deformable plastic. A pair of such seat rings are positioned in engagement with and on opposite sides of the ball member about the valve body inlet and outlet openings. Normally, the seats are designed to engage the ball with narrow band or line contact and to flex slightly under loads. The ball itself is mounted for a slight amount of free movement or shifting axially of the seat when the ball is in a valve closed position under fluid pressure conditions. Such shifting causes the ball to act aglainst and flex the downstream seat ring to enhance its ~5 sealing engagement with the ball. The amount of such flexin~
varies in accordance with the fluid pressure involved.
With increasing fluid pressure and resultant downstream shifting of the ball, thé ball is moving away from the upstream seat. The ball contact with the upstream seat may or may not be broken, depending upon the pressure and/or seat 113387~7 design. Some designs intentionally seal at the upstream seat while others deliberately prevent an upstream seal and do all the sealing on the downstream seat. Moreover, some ball valve designs utilize spring biasing means for continuously urging the opposed seat rings toward each other and into sealing engagement with the ball.
Small ball valves, that is, valves of l" and under, and low pressure ball valves are usually made with end loaded seats and a floating ball as described above. This is typical of small ball valve designs for two primary reasons. The shut-off pressure acts on the total seal dia~eter, either the outer diameter of contact between the ball and downstream seat or the outside diameter of the inlet seat. The total force tfluid pressure x area) must be carried by the ball. With a floating type ball, all the force is applied to the downstream seat and since the seat comprises an annulus of a smaller area, seat stress is always greater than the fluid pressure. At very high fluid pressures, the seal force crushes ordinary plastic type seats. Also, as the valve size increases, the ball force increases as a function of the square of the seal diameter whereas the annular seat does not increase in area at the same rate. Therefore, alternative valve constructions must be employed to overcome these problems. To that end, large ball valves, that is, valves over 2" and high pressure ball valves
This invention relates to the valve art and more paticularly to ball valves.
The invention is particularly applicable to a new and improved seat assembly and ball valve of the type having a so-called floating ball and will be described with reference thereto. However, it will become readily apparent to those skilled in the art that the invention is capable of broader applications and could be adapted for use in other types and styles of valves.
., ,,~, . . . .... .
4- Typical ball valve constructions in commercial use employ annular seats or seat rings formed of a resilient and deformable plastic. A pair of such seat rings are positioned in engagement with and on opposite sides of the ball member about the valve body inlet and outlet openings. Normally, the seats are designed to engage the ball with narrow band or line contact and to flex slightly under loads. The ball itself is mounted for a slight amount of free movement or shifting axially of the seat when the ball is in a valve closed position under fluid pressure conditions. Such shifting causes the ball to act aglainst and flex the downstream seat ring to enhance its ~5 sealing engagement with the ball. The amount of such flexin~
varies in accordance with the fluid pressure involved.
With increasing fluid pressure and resultant downstream shifting of the ball, thé ball is moving away from the upstream seat. The ball contact with the upstream seat may or may not be broken, depending upon the pressure and/or seat 113387~7 design. Some designs intentionally seal at the upstream seat while others deliberately prevent an upstream seal and do all the sealing on the downstream seat. Moreover, some ball valve designs utilize spring biasing means for continuously urging the opposed seat rings toward each other and into sealing engagement with the ball.
Small ball valves, that is, valves of l" and under, and low pressure ball valves are usually made with end loaded seats and a floating ball as described above. This is typical of small ball valve designs for two primary reasons. The shut-off pressure acts on the total seal dia~eter, either the outer diameter of contact between the ball and downstream seat or the outside diameter of the inlet seat. The total force tfluid pressure x area) must be carried by the ball. With a floating type ball, all the force is applied to the downstream seat and since the seat comprises an annulus of a smaller area, seat stress is always greater than the fluid pressure. At very high fluid pressures, the seal force crushes ordinary plastic type seats. Also, as the valve size increases, the ball force increases as a function of the square of the seal diameter whereas the annular seat does not increase in area at the same rate. Therefore, alternative valve constructions must be employed to overcome these problems. To that end, large ball valves, that is, valves over 2" and high pressure ball valves
2~ are usually constructed with a trunnion supported ball. The valve seats float and are pressure activated to seal against the ball. Large valves must have a trunnion mounted ball to avoid overstressing of the seat even at low pressures.
Existing valve designs have taken the approach of minimizing the seat area by sealing on the downstream seat `` 1133877 only. This reduces the effective area to considerably less than the full outside diameter of the inlet seat. However, if identical seats are used both upstream and downstream, this requires that the seat be designed to leak with upstream pressure, but seal with downstream pressure. Tnis has two disadvantages. First, to not seal as an inlet, there must be a way for pressure to bypass the inlet seat. This means the downstream seat must have two dynamic seals, i.e., one against the ball and another to seal the bypass. Usually, this involves an additional mechanism for sealing the seat against the downstream flange or fitting. Obviously, the use of two seal points provides a less reliable arrangement than a single seal. Second, if the inlet seat is bypassed, it cannot apply any force to the ball to hold it against the downstream seat at low pressure. The weight of the ball causes it to fall below the seat centerline and allows fluid leakage at low pressure.
This problem becomes more significant with larger valves because the weight of the ball increases with the cube of the size. Thus, a valve having a floating ball should have seats which are firmly held against the ball without system pressure so that a seal is formed regardless of how low the pressure may be. As noted above, this has been accomplished by placing a disc spring behind each seat. This feature not only provides a low pressure seal, but also assures an upstream seal at high seat loads.
An upstream seal, however, creates a second problem which also becomes more pronounced as valve size increases.
While the valve is being opened, this seat must span the hole or fluid opening through the ball. With a small ball and opening, the seat is quite rigid when loaded as a beam in bending and can easily bridge the gap. As the valve size and opening increase, the section modulus of the seat does not proportionately increase to retain the same stiffness. Thus, the seat may deflect further into the ball opening. Similarly, the outside diameter of the seat ring is normally supported only by a shoulder in the valve body. The area of the seat and, therefore, the force acting on it, increases as the square of the diameter. Since the supporting shoulder is usually quite narrow and its area is more closely related to the seat circumference, the supporting shoulder only increases in a linear fashion. Here also, the problem becomes more pronounced as the valve size increases.
It has, therefore, been desired to develop a ball valve and seat assembly which facilitate use of a floating ball in connection with higher system pressures than have heretofore been possible. Such a design would, in many cases, eliminate the necessity for utilizing trunnion mounted balls. Trunnion mountings are not considered practical unless the valve is quite large because their use substantially increases the size, complexity and cost of the valve.
The present invention contemplates a new and improved construction which overcomes all of the above referred to problems and others and provides a new and improved ball valve and seat assembly construction which produce increased pressure capabilities for a floating ball type of ball valve and wherein the seats may be formed from a wide variety of materials to suit a wide range of operating conditions or parameters.
BRIEF DESCRIPTION OF THE INVENTION
Generally, the present invention contemplates a new and improved ball valve and seat assembly wherein the seat ring assembly is flexible in one direction of travel and generally rigid in the opposite direction. A pair of such assemblies are disposed on opposite sides of a ball member and continuously urged toward the ball for maintaining it properly positioned in the valve body and providing valve sealing regardless of how low the fluid system pressure may be. When the valve is closed, the system pressure moves or shifts the ball downstream toward the downstream seat assembly so that it is further deflected against an associated disc spring. The upstream seat ring is simultaneously urged toward continued engagement with the ball by a disc spring operably associated therewith. In response to some system fluid pressure, the disc spring associated with the downstream seat assembly is fully deflected and the ball is moved away from engagement by the upstream seat assembly.
More specifically, the subject invention is particularly applicable to use in a valve of the type having a generally cylindrical passageway, a ball member disposed in the passageway and mounted for selective rotation therein between valve opened and closed positions. The ball member is shiftabi~ generally axially of the passageway at least when the valve is in the closed position under fluid pressure conditions. Annular seat rings are disposed in the passageway on opposite sides of the ball member between the ball member and an associated valve body shoulder with annular disc sprin~s _ disposed between each shoulder and the associated seat ring.
These disc springs continuously urge the seat rings toward sealing engagement with the ball member. Each seat r ing has a first continuous surface facing the ball member and a second surface facing an associated shoulder of the valve body with a disc spring interposed between each seat ring second surface and its associated shoulder. Each disc spring has a generally frusto-conical configuration in its unstressed condition with its smaller diameter end pointing toward the ball member. The components are dimensioned so that when the ball member, seat rings and disc springs are assembled between the valve body shoulders, the seat ring first surfaces engage the surface of the ball member with the seat rings being flexed slightly outward of each other. The frusto-conical disc springs, in turn, are partially stressed toward a flattened configuration for continuously urging the seat ring first surfaces toward engagement with the ball member. When the ball member is axially shifted in the passageway toward one of the valve body shoulders in response to fluid pressure acting thereon when the valve is closed, the seat ring associated with the one shoulder is further flexed toward the one shoulder with the first surface thereof remaining in engagement with the ball member and the disc spring associated with the one shoulder is further stressed toward a flattened configuration. The other seat ring is flexed toward the ball member in the direction of shifting thereof under the influence of its associated disc spring in order that the other seat ring first surface will be urged toward continued contact with the ball member.
In accordance with another aspect of the invention, the seat ring associated with the one shoulder may be flexed by shifting movement of the ball member in engagement with the seat ring first surface to a position where the associated disc spring is stressed to a substantially flattened configuration.
In that condition, the ball member has been moved away from contact by the first surface of the other seat ring. In the ~3387~7 preferred arrangement of the invention, the seat rings experience rotational type of flexure in response to engagement with and/or shifting of the ball.
According to another aspect of the present invention, a pair of reinforcing rings are also included in the passageway on opposite sides of the ball member axially inward of the seat rings. Each reinforcing ring includes means for locating it in a desired axial position in the passageway, a first surface facing an associated one of the valve body shoulders and a second surface generally facing the ball member in a spaced relationship therefrom. The first surface provides a rigid bearing surface for the associated seat ring to prevent seat ring distortion and displacement in the passageway. The provision of a rigid bearing surface is of significant value for the upstream seat ring-when the valve is closed and exposed to elevated system pressures and when the valve is moved from a closed to an open position under such elevated pressures.
According to a limited aspect of the present invention, the reinforcing rings are positively located in the valve body passageway by engagement with the end walls of passageway counterbores. In one case, the reinforcing rings may include radially outward extending flanges which engage the counterbore end walls. Alternately, the inner end walls of the reinforcing rings may engage the counterbore end walls.
2~ In accordance with another more limited aspect of the invention, each seat ring second surface further includes a relief groove extending therearound. Such grooves facilitate ease of flexure in the seat rings during valve operation under fluid pressu.e conditions.
11338~7 The principal object of the invention is the provision of a new and improved ball valve and seat assembly which allow higher pressure ratings to be obtained from a floating ball type of ball valve.
Another object of the present invention is the provision of such a ball valve and seat assembly which will effect valve sealing even at very low fluid system pressures.
Still another object of the invention is the provision of a new and improved ball valve and seat assembly which permits the seat rings to be formed or constructed from a wide variety of materials.
A further object of the present invention is the provision of a new and improved ball valve and seat assembly wherein the seat rings are flexible in one direction of axial ball movement and generally rigid in the opposite direction.
Still other objects and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following specification.
BRIEF DESCRIPTION OF THE DRAWINGS
Tbe nvention may take physical form in certain parts and arrangements of parts, preferred and alternative embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and ~herein:
: FIGURE 1 is a cross-sectional view through a ball valve which incorporates the preferred embodiment of the invention thereinto;
FIGURE 2 is a cross-sectional view of the preferred seat assembly construction shown just prior to valve make-up ~13387'7 an~ with the ball member removed for ease of illustration;
FIGURE 3 is a slightly enlarged view of a portion of the valve of FIGURE 1 showing the ball in the valve opened position under a no-load condition;
FIGURE 4 is an enlarged cross-sectional view of a portion of a seat assembly when the valve is in the opened position of FIGURE 3;
FIGURE 5 is a view similar to FIGURE 3 with the ball member in the valve closed position under the influence of an elevated fluid pressure condition;
FIGURE 6 is an enlarged cross-sectional view showing a portion of the upstream seat assembly when the valve is in the closed position of FIGURE 5;
FIGURE 7 is an enlarged cross-sectional view of a portion of the downstream seat assembly when the valve is in the closed position of FIGURE 5; and, FIGURE 8 is a cross-sectional view similar to FIGURE 2 snowing a seat assembly which includes various alternative design features.
DESCRIPTION OF PREFERRED AND ALTERNATIVE EMBODIMENTS
Referring now to the drawings wherein the showings are for purposes of illustrating preferred and alternative embodiments of tne invention only and not for purposes of limiting the same, FIGU~E 1 shows a ball valve A having a pair of opposed seat assem~lies B disposed on opposite sides of a floating type spherical ball member C.
More particularly, and with reference to FIGURES 1 and
Existing valve designs have taken the approach of minimizing the seat area by sealing on the downstream seat `` 1133877 only. This reduces the effective area to considerably less than the full outside diameter of the inlet seat. However, if identical seats are used both upstream and downstream, this requires that the seat be designed to leak with upstream pressure, but seal with downstream pressure. Tnis has two disadvantages. First, to not seal as an inlet, there must be a way for pressure to bypass the inlet seat. This means the downstream seat must have two dynamic seals, i.e., one against the ball and another to seal the bypass. Usually, this involves an additional mechanism for sealing the seat against the downstream flange or fitting. Obviously, the use of two seal points provides a less reliable arrangement than a single seal. Second, if the inlet seat is bypassed, it cannot apply any force to the ball to hold it against the downstream seat at low pressure. The weight of the ball causes it to fall below the seat centerline and allows fluid leakage at low pressure.
This problem becomes more significant with larger valves because the weight of the ball increases with the cube of the size. Thus, a valve having a floating ball should have seats which are firmly held against the ball without system pressure so that a seal is formed regardless of how low the pressure may be. As noted above, this has been accomplished by placing a disc spring behind each seat. This feature not only provides a low pressure seal, but also assures an upstream seal at high seat loads.
An upstream seal, however, creates a second problem which also becomes more pronounced as valve size increases.
While the valve is being opened, this seat must span the hole or fluid opening through the ball. With a small ball and opening, the seat is quite rigid when loaded as a beam in bending and can easily bridge the gap. As the valve size and opening increase, the section modulus of the seat does not proportionately increase to retain the same stiffness. Thus, the seat may deflect further into the ball opening. Similarly, the outside diameter of the seat ring is normally supported only by a shoulder in the valve body. The area of the seat and, therefore, the force acting on it, increases as the square of the diameter. Since the supporting shoulder is usually quite narrow and its area is more closely related to the seat circumference, the supporting shoulder only increases in a linear fashion. Here also, the problem becomes more pronounced as the valve size increases.
It has, therefore, been desired to develop a ball valve and seat assembly which facilitate use of a floating ball in connection with higher system pressures than have heretofore been possible. Such a design would, in many cases, eliminate the necessity for utilizing trunnion mounted balls. Trunnion mountings are not considered practical unless the valve is quite large because their use substantially increases the size, complexity and cost of the valve.
The present invention contemplates a new and improved construction which overcomes all of the above referred to problems and others and provides a new and improved ball valve and seat assembly construction which produce increased pressure capabilities for a floating ball type of ball valve and wherein the seats may be formed from a wide variety of materials to suit a wide range of operating conditions or parameters.
BRIEF DESCRIPTION OF THE INVENTION
Generally, the present invention contemplates a new and improved ball valve and seat assembly wherein the seat ring assembly is flexible in one direction of travel and generally rigid in the opposite direction. A pair of such assemblies are disposed on opposite sides of a ball member and continuously urged toward the ball for maintaining it properly positioned in the valve body and providing valve sealing regardless of how low the fluid system pressure may be. When the valve is closed, the system pressure moves or shifts the ball downstream toward the downstream seat assembly so that it is further deflected against an associated disc spring. The upstream seat ring is simultaneously urged toward continued engagement with the ball by a disc spring operably associated therewith. In response to some system fluid pressure, the disc spring associated with the downstream seat assembly is fully deflected and the ball is moved away from engagement by the upstream seat assembly.
More specifically, the subject invention is particularly applicable to use in a valve of the type having a generally cylindrical passageway, a ball member disposed in the passageway and mounted for selective rotation therein between valve opened and closed positions. The ball member is shiftabi~ generally axially of the passageway at least when the valve is in the closed position under fluid pressure conditions. Annular seat rings are disposed in the passageway on opposite sides of the ball member between the ball member and an associated valve body shoulder with annular disc sprin~s _ disposed between each shoulder and the associated seat ring.
These disc springs continuously urge the seat rings toward sealing engagement with the ball member. Each seat r ing has a first continuous surface facing the ball member and a second surface facing an associated shoulder of the valve body with a disc spring interposed between each seat ring second surface and its associated shoulder. Each disc spring has a generally frusto-conical configuration in its unstressed condition with its smaller diameter end pointing toward the ball member. The components are dimensioned so that when the ball member, seat rings and disc springs are assembled between the valve body shoulders, the seat ring first surfaces engage the surface of the ball member with the seat rings being flexed slightly outward of each other. The frusto-conical disc springs, in turn, are partially stressed toward a flattened configuration for continuously urging the seat ring first surfaces toward engagement with the ball member. When the ball member is axially shifted in the passageway toward one of the valve body shoulders in response to fluid pressure acting thereon when the valve is closed, the seat ring associated with the one shoulder is further flexed toward the one shoulder with the first surface thereof remaining in engagement with the ball member and the disc spring associated with the one shoulder is further stressed toward a flattened configuration. The other seat ring is flexed toward the ball member in the direction of shifting thereof under the influence of its associated disc spring in order that the other seat ring first surface will be urged toward continued contact with the ball member.
In accordance with another aspect of the invention, the seat ring associated with the one shoulder may be flexed by shifting movement of the ball member in engagement with the seat ring first surface to a position where the associated disc spring is stressed to a substantially flattened configuration.
In that condition, the ball member has been moved away from contact by the first surface of the other seat ring. In the ~3387~7 preferred arrangement of the invention, the seat rings experience rotational type of flexure in response to engagement with and/or shifting of the ball.
According to another aspect of the present invention, a pair of reinforcing rings are also included in the passageway on opposite sides of the ball member axially inward of the seat rings. Each reinforcing ring includes means for locating it in a desired axial position in the passageway, a first surface facing an associated one of the valve body shoulders and a second surface generally facing the ball member in a spaced relationship therefrom. The first surface provides a rigid bearing surface for the associated seat ring to prevent seat ring distortion and displacement in the passageway. The provision of a rigid bearing surface is of significant value for the upstream seat ring-when the valve is closed and exposed to elevated system pressures and when the valve is moved from a closed to an open position under such elevated pressures.
According to a limited aspect of the present invention, the reinforcing rings are positively located in the valve body passageway by engagement with the end walls of passageway counterbores. In one case, the reinforcing rings may include radially outward extending flanges which engage the counterbore end walls. Alternately, the inner end walls of the reinforcing rings may engage the counterbore end walls.
2~ In accordance with another more limited aspect of the invention, each seat ring second surface further includes a relief groove extending therearound. Such grooves facilitate ease of flexure in the seat rings during valve operation under fluid pressu.e conditions.
11338~7 The principal object of the invention is the provision of a new and improved ball valve and seat assembly which allow higher pressure ratings to be obtained from a floating ball type of ball valve.
Another object of the present invention is the provision of such a ball valve and seat assembly which will effect valve sealing even at very low fluid system pressures.
Still another object of the invention is the provision of a new and improved ball valve and seat assembly which permits the seat rings to be formed or constructed from a wide variety of materials.
A further object of the present invention is the provision of a new and improved ball valve and seat assembly wherein the seat rings are flexible in one direction of axial ball movement and generally rigid in the opposite direction.
Still other objects and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following specification.
BRIEF DESCRIPTION OF THE DRAWINGS
Tbe nvention may take physical form in certain parts and arrangements of parts, preferred and alternative embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and ~herein:
: FIGURE 1 is a cross-sectional view through a ball valve which incorporates the preferred embodiment of the invention thereinto;
FIGURE 2 is a cross-sectional view of the preferred seat assembly construction shown just prior to valve make-up ~13387'7 an~ with the ball member removed for ease of illustration;
FIGURE 3 is a slightly enlarged view of a portion of the valve of FIGURE 1 showing the ball in the valve opened position under a no-load condition;
FIGURE 4 is an enlarged cross-sectional view of a portion of a seat assembly when the valve is in the opened position of FIGURE 3;
FIGURE 5 is a view similar to FIGURE 3 with the ball member in the valve closed position under the influence of an elevated fluid pressure condition;
FIGURE 6 is an enlarged cross-sectional view showing a portion of the upstream seat assembly when the valve is in the closed position of FIGURE 5;
FIGURE 7 is an enlarged cross-sectional view of a portion of the downstream seat assembly when the valve is in the closed position of FIGURE 5; and, FIGURE 8 is a cross-sectional view similar to FIGURE 2 snowing a seat assembly which includes various alternative design features.
DESCRIPTION OF PREFERRED AND ALTERNATIVE EMBODIMENTS
Referring now to the drawings wherein the showings are for purposes of illustrating preferred and alternative embodiments of tne invention only and not for purposes of limiting the same, FIGU~E 1 shows a ball valve A having a pair of opposed seat assem~lies B disposed on opposite sides of a floating type spherical ball member C.
More particularly, and with reference to FIGURES 1 and
3, ball valve A includes a body or housing generally designated 10 having a main or central body section 12 and opposed end ~3387~7 flttings 14,16. Seat assemblies B and ball C are centrally mounted within main body section 12 with the ball member being arranged for selective rotation by a stem and actuating handle assembly generally designated 18.
The details of all portions of the valve illustrated in FIGURES 1 and 3, except for the ball and seat ring assemblies, may be modified as desired and~or necessary to accommodate different types or styles of ball valve constructions. In general, however, and for purposes of describing the subject invention, the valve body includes a generally cylindrical central passageway or axially extending fluid flow opening 20 which is only slightly larger in diameter than ball C. Each of end fittings 14,16 is releasably connected to central body section 12 by a plurality of longitudinally extending tie bolts generally designated 22 (FIGURE 1). The end fittings are also provided with internal threaas 24,26 or any other convenient means to accommodate connecting the valve to an associated fluid system or piping.
The stem and actuating handle assembly 1~ as illustrated includes a stem member 30 having a lower end 32 shaped as shown for sliding receipt in a slot or groove 34 included in the upper end of ball C. This arrangement allows the ball to be rotated between valve opened and closed positions while at the same time permitting the ball to have some freedom of ~ovement for shifting axially in valve body passageway 20 when the valve is in a closed position.
Stem member 30 extends outwardly through an opening 36 in central body section 12. Suitable packing rings 33,40 and 42 are positioned in opening 36 and sealingly engage the opening and stem member 30. As shown, lower packing ring 42 rests upon an inwardly extending flange 44 formed within opening 36. A split thrust washer 46 is positioned below fiange 44 and is clamped thereto by an outwardly extending shoulder or flange 48 formed at the base of stem member 30.
The stem is held in position by a packing gland 50 and a packing nut 52. As shown in FIGURE 1, tightening of packing nut 52 applies pressure to packing rings 38,40,42 to assure a fluid tight seal about the stem.
Although it is possible to actuate the valve stem by 1~ many different types of actuators, including both manual or automatic, a handle member 54 has been shown. This handle is releasably secured to stem member 30 by a nut 56 which clamps the handle to the top of packing nut 52. Cooperating flats 58,60 are advantageously formed in the handle opening and on the exterior of the stem outer end for properly positioning the handle on the stem. Moreover, the position of the handle and, in turn, the position of ball member C are limited by depending stop members 60,62 carried by handle 54. These stop members engage suitable surfaces on central body section 12 to provide fixed stops for the valve in the full opened and full closed positions.
With continued reference to both FIGURES 1 and 3, the ball seat arrangement utilized in the subject invention includes a pair of seat ring assemblies B disposed on opposite sides of bali member C. As shown, the seat ring assemblies are clampingly maintained in position on opposite sides of the ball adjacent opposite ends of the central body section passageway or opening 20. In the preferred embodiment here under discussion, the seat ring assemblies are located substantially equidistantly on diametrically opposite sides of the axis of il3387~7 rotation of the ball member. While the seat ring assemblies could be maintained in position by many different or alternative arrangements, they are shown in the preferred embodiment as being located by shoulders 70,72 defined by end S faces 74,76 of end fittings 14~16, respectively. The inward limit of movement of the seat ring assemblies is defined by a pair of shoulders 78,80 which are formed by the inner end walls of counterbores extending inwardly of valve body passageway or opening 20. Still further, a seal is provided between central body section 12 and end fittings 14,16 by means of O-rings 82,84 which are received in second counterbores 86,88, respectively. Each O-ring is disposed about the outer circumference or outer peripheral surface of a portion of the associated seat ring assembly B.
The structural details of ball valve A described hereinabove are with reference to the preferred valve construction. It will be readily apparent to those skilled in the art, however, that modifications may readily be made thereto to accommodate particular operational needs and/or requirements. Such changes are not deemed to affect the overall intent or scope of the present invention as will be describtd in detail hereinafter.
With reference to FIGURE 2, description will be made of the s~ecific details of seat assemblies B. FIGU~E 2 shows a cross-sectional view of the seat assembly disposed at end fitting 14, it being appreciated that the other assembly is identical thereto unless otherwise specifically noted. Also, ball member C has been deleted for ease of understandin~ and appreciating the seat assembly construction.
113387'7 Each seat assembly is preferably comprised of three components, i.e., a reinforcing ring 100, a seat ring 102 and a frusto-conical disc spring 104. Reinforcing ring 100 has an annular configuration and is desirably constructed from a rigid material such as steel or other suitable metal. In FIGURE 2, reinforcing ring 100 is shown as including a first continuous surface or end face 110 which faces the associated shoulder 70 of end fitting 14. A second continuous surface 112 faces generally toward the ball member (not shown) but is dimensioned to be spaced therefrom in order to prevent any contact or interference therewith. A radially outward extending flange 114 is configured and dimensioned to engage shoulder 78 in cent~al body section passageway 20 to establish a positive forwardmost or home position for the reinforcing ring. The outer circumference or peripheral surface 116 of ring 100 is closely disposed to the side wall of passageway 20.
Referring still to FIGURE 2, it will be seen that seat ring 102 also comprises an annular or ring-like member having a central opening therethrough. A first continuous ball engaging surface 120 initially has a generally frusto-conical conformation concentric with the seat ring itself. A seat ring second surface 122 generally faces the associated shoulder 70 of end fitting 14. A third surface 124 faces reinforcing ring first continuous surface 110 and is conveniently stepped as at area 12~ radially inward from outer peripheral surface 12B.
This stepped area is dimensioned and configured to be received over a portion of the reinforcing ring and engage first continuous surface 110 thereof. As will become more readi~y apparent, surface 110 acts as a bearing surface to provide rigid support for the upstream seat ring during exposure to fluid pressure.
~13387'7 A flange or lip 130 extends axially outward of surface 122 generally at outer peripheral surface 128. This lip or flange is preferably continuous about the seat ring and so located that its radial inner surface generally corresponds to the outside diameter of conical disc spring 104. Flange or lip 130 is beveled at the radial outermost area thereof and is rolied over the radial outer edge of the disc spring in the manner shown. While not necessary, this arrangement advantageously maintains the seat ring and disc spring together as a sub-assembly.
In the preferred arrangement of the invention, seat rings 102 are constructed from a resilient plastic material such as polytetrafluoroethylene or the like. It should be readily appreciated, however, that other types of materials such as acetal resins and the like could also be advantageously utilized. The particular material chosen will, to some extent.
be dependent upon the operating conditions to which the valve is to be subjected. Moreover, various design modifications may be incorporated into the seat assembly components as will be described hereinafter with reference to FIGURE 8.
Frusto-conical disc spring 104 includes an outer end 140 and an inner end 142. The diameter at the outer end is such that a disc spring may be received within the cylindrical cavity defined by the inner wall of seat ring axial flange 130 and second surface 122. The inner diameter of the spring at end 142 is substantially equal to the diameter of the opening through the seat ring.
The spring is selected so that its force is sufficient under partial deflection to continuously urge the seat ring tcward ~he ball and toward bearing engagement with surface 110 11338~q of reinforcing ring 100. The spring must aiso allow stressing or compression thereof toward a flattened condition to accommodate ball shifting in engagement with seat ring first surface 12~. In the preferred embodiment here under discusslon, seat ring second surface 122 is configured so as to partially stress disc spring 104 when the seat ring and disc spring are joined as a sub-assembly. Such stressing is approximately equal to one half of the distance from the free state toward the fully stressed or substantially flattened configuration. However, it should be appreciated that this stressing is not necessary to satisfactory operation of seat assemblies B and the presence or absence thereof is a function of the relative dimensional characteristics between seat ring second surface 122 and disc spring 104.
Disc spring 104 advantageously accommodates generally rotational flexure of the seat ring at least until the spring has been moved to a substantially flattened condition. Such operation provides for improved valve sealing results in a manner to be described. Dependin~ upon the type, size and ~0 style of ball valve involved, conical disc springs 104 may be advantageously constructed from a number of different metals which have spring properties falling within an acceptable range.
Referring to FIGURES 3-7, description will hereinafter be made with reference to operation of the new ball valve and seat assembly. FIGURE 3 shows the valve in a fully assembled valve opened position (no load fluid pressure condition). In this position, the two seat assemblies B have been shifted from the unstressed condition shown in FIGURE 2 to a partially stressed condition. Sizing of ball member C, seat assemblies B
and shoulders 70,72 are such as to provide this relationship at ball valve assembly or make-up.
~33877 More particularly, and with continued reference to FIGURE 3 as well as with reference to FIGURE 4, the seat assemblies are moved such that opposed seat rings 102 are slightly rotatably flexed away from each other generally about their outer peripheries and against disc springs 104 in response to engagement between seat ring first surfaces 120 and ball member C. This action slightly compresses the associated disc springs toward a flattened condition. In the position of FIGURE 3, the disc springs are preferably deflected through approximately half of their remaining travel~ In addition to positioning the ball member, this spring deflection assures a seal force between the two seat rings and ball at first surfaces 120 regardless of how low the system pressure may be.
It also assures that the seat ring disposed adjacent the valve inlet will form a seal with the overall seat load being dependent upon the area of the seat ring outside diameter.
FIGURE 4 shows an enlarged partial view of the downstream seat assembly B which is disposed at end fitting 14 when the valve is in the opened position of FIGURE 3. In this valve position, the upstream seat assembly associated with end fitting 1~ assumes a substantially identical relationship. As there shown, frusto-conical seat ring first or ball engaging surface 120 is in sealing engagement with the surface of the ball member C. The ball slightly deforms a portion of surface 120 so that at least that portion has a concave spherical conformation. Simultaneously, seat ring 102 is rotatably flexed against disc spring 104 so as to slightly compress the disc spring. Because of the rotational flexing in seat ring 102, the surface of seat ring stepped area 126 is moved away from a contacting relationship with reinforcing ring first surface 11~.
~133877 FIGURE 5 shows the valve in a closed position under elevated fluid pressure conditions with the direction of fluid flow being designated by arrow P adjacent the valve inlet.
Depending upon the system pressure, the ball is forced to shift axially of passageway 20 in the direction of fluid flow toward the outlet or downstream seat assembly. As a result of this shifting, the seat ring of the upstream seat assembly will be moved back toward its original unstressed conformation as shown in FIGURE 6 under the influence of the associated disc spring 104. Thus, the upstream seat ring is rotatably flexed or shifted toward the ball as the Dall moves downstream. At the same time, the outlet seat ring is further shifted or rotatably flexed downstream as shown in FIGURE 7 to further compress its associated disc spring. Up to this point, both seat rings are approximately equally flexible with deflection occurring across the full annulus of the seat from the outside diameter to the inside diameter.
Once the inlet seat deflects back to its original unstressed condition, it changes from a flexible to a much more rigid member. In this condition, the surface of seat ring stepped area 126 bears against first surface 110 of the associat:ed reinforcing ring (FIGU~E 6). The aforementioned bearing engagement virtually stops the inlet seat from any further movement toward the ball as the system pressure continues to increase. Conversely, the downstream seat ring assembly remains flexible and continues to rotatably flex until the associated disc spring is moved to its su~stantially fully flattened configuration (FIGURE 7).
As the downstream seat ring is rotatably flexed, and with the seat ring constructed from polytetrafluoroethylene or the like, ball member C further deforms first or ball engaging surface 120 thereof so that an increasing surface portion assumes a concave spherical conformation. In the preferred structural arrangement here described, substantially all of first surface 120 will matingly engage the ball member when the downstream disc spring is fully stressed. This relationship is shown in FIGURE 7. A lesser amount of deformation in first surface 120 would be present in those cases where the seat ring is constructed from harder materials such as acetal resins and the like. When ball member C has shifted an amount to substantially fully deflect the downstream disc spring, the ball memDer is moved away from all contact by ball engaging surface 120 of the upstream seat ring. A gap x (FIGURES 5 and 6) is formed therebetween and no sealing whatsoever occurs on the upstream side of the ball.
This result minimizes downstream seat loading and wear as well as reducing the turning torque required to rotate ball member C back to the valve opened position. Within the predetermined operational li~,its of the valve, ball engaging surface 120 of the downstream seat ring will not generally be substantially further deformed due to system pressures from the conformation generally shown in FIGURE 7. Substantial further deformation could undesirably cause the downstream seat ring to break down and/or be completely destroyed.
Reinforcing ring 100 associated with the upstream seat assembly prevents failure of the associated seat ring 102 by providing a large bearing surface so that the bearing stress will only be approximately 1 1~2 to 2 times the fluid system pressure. This bearing stress is well within the capabilities of most plastic materials utilized in constructing ball valve 1~3387~7 seat rings. ~oreover, and as the valve approaches the opening point, i.e., when the ball C is rotated from the position shown in FIGURE 5 back to the position shown in FIGURE 3, only seat ring ball engaging surface 120 must span the ball opening.
This greatly reduces the unsupported area and length of the span. First surface 110 of the reinforcing ring also provides support substantially across the entire span of upstream seat ring third surface 124. The combined effect of support across the ball opening and a wide bearing shoulder at seat ring stepped area 126 prevents the upstream or inlet seat ring from distorting. It is essential to prevent such distortion in order to preclude subsequent damage to the downstream seat ring. When an unsupported upstream seat ring deforms into the ball opening, it forms a bulge in a sector of the seat ring.
This bulge, in turn, pushes the ball member off center and forces it to cut or distort the downstream seat. Such downstream seat ring distortion causes it to leak at both high and low pressures.
The ball valve A with seat assemblies B described in detail hereinabove is deemed to provide a substantial improvement over those arrangements previously known in the art. The subject design permits the seat assemblies to be flexible and deflect when acting as a downstream seat but to be rigid when acting as an upstream seat. The assemblies are spring loaded at initial assembly to facilitate sealing at low pressures. The seat ring and ball movements are proportioned to release the upstream seat ring from sealing against the ball at high pressures. The upstream seat is supported by a reinforcing ring during valve opening to prevent distortion.
Also, this reinforcing ring provides a large bearing support 1~3387'7 area to prevent the upstream seat ring from shearing at the valve body shoulder or being otherwise displaced from its proper location within the valve.
FIGURE 8 shows a number of design modifications or features which may be advantageously incorporated into seat assemblies B. Such modifications accommodate component machining and valve use as will become apparent. Moreover, the modifications may be individually adopted to use and are not dependent on each other for successful seat assembly operation. For ease of illustrating these alternative design features, like components are identified by like numerals with a primed (') suffix and new components are identified by new numerals.
In FIGURE 8, counterbore end wall 78' extends further inwardly into main valve body section 12' and the radially outward extending flange is not included on reinforcing ring 100'. Thus, the inner end face or wall 150 of the reinforcing ring abuts counterbore end wall 78' to positively establish an axial innermost or home position therefor.
In addition, third surface 124' of seat ring 102' does not include a stepped area as shown and described above with reference to the preferred embodiment. Rather, the seat ring third surface is continuous over the annular extent thereof and is adapted to directly engage reinforcing ring first surface 110'.
The above two modifications are primarily production oriented. That is, each eliminates a machining step which is otherwise required for reinforcing ring 100' and seat ring 102'.
With continued reference to FIGURE 8, seat ring first or ball engaging surface 120' also has a slightly modified 11338~7 conformation. As shown, the ball engaging surface is designed to have a concave spherical surface concentric with the longltudinal axis of the seat ring itself and a radius equal to the radius of the ball member. Thus, when the valve is S initially assembled, surface 120' will substantially matingly engage the ball member surface and will remain in such substantial mating engagement during rotational flexure of the seat ring.
It is also possible witnin the broad aspects contemplated for the invention that first or ball engaging surface 1~0' may have other radii of curvature, both larger and smaller than the radius of the ball member. Moreover, in some cases it may be desirable to configure the body of seat ring r~ *
102' so that in the free state thereof such as is shown in FIGURE 8, ball engaging surface 120' is rotated slightly outward of the seat ring central opening. With this type of structure, the loci of the radius for surface 120' will form a circle concentric with the seat ring longitudinal axis. The aforementioned possible alterations for the seat ring ball engaging surface do not in any way depart from the overall intent or scope of the invention.
Finally, with regard to FIGURE 8, a groove 1~0 is included in second surface 122' of seat ring 102'. This groove extends inwardly into the seat ring body between the inner and outer diameters thereof, is continuous and extends around the entirety of second surface 122'. Groove 160 is particularly desirable for use with harder seat ring materials such as acetal resins and the like to increase flexi~ility and ~etter accommoàate the desired rotational flexure thereof as previously described. In addition to the particular groove 1~33877 configuration shown, other shapes and/or sizes therefor may be utilized to accommodate still other types of seat ring materials and/or valve parameters. Still further, groove 160 may also be incorporated into seat rings constructed from softer materials if desired to accommodate a particular valve application or design.
Other modifications not specifically shown in the drawings may be readily incorporated into seat ring assemblies B without in any way departing from the overall invention. For example, it is possible to form axial flange 130 of seat ring - - 102 at the inside diameter thereof as opposed to the preferred . ;. .,~ ,. ~, position at the outside diameter. Another example resides in the specific orientation of seat ring second surface 122. As ~-~wy~ = -shown--in the-drawings, this surface tapers inwardly into-tbe seat ring body from the outside diameter toward the inside diameter. This taper angle may be varied as deemed necessary ana/or second surface 122 may be disposed normal to the seat ring axis so as to be generally parallel to the associated valve body shoulder. It may also be desirable to slightly modify the relative dimensional characteristics between the seat rings, reinforcing rings and disc springs to accommodate particular operational requirements.
Still further, and in some applications of the valve, it would be possible to entirely eliminate use of reinforcing rings 100 in seat assemblies B. In that case, forward or inward movement of the seat rings into valve body passageway 20 would be limited by, for example, engagement of the seat ring third surfaces with the end wa~ls of the passageway counterbores. However, elimination of the reinforcing rings will reduce the pressure ratings attributable to the valve due 113387'7 to increased potential for upstream seat ring displacement and/or distortion which could result in damage to the downstream seat. This could be compensated to some extent by modifying the dimensional relationships between other of the remaining components. Nevertheless, the advantageous relationships between the ball member seat rings and disc springs as described above would still be obtained during valve use.
The invention has been described with reference to preferred and alternative embodiments. Obviously, modifications and alterations will occur to others upon the reading and understanding of this specification. It is our intention to include all such modifications and alterations --- insofar as they come within the scope of the appended claims or the equivalents thereof.
The details of all portions of the valve illustrated in FIGURES 1 and 3, except for the ball and seat ring assemblies, may be modified as desired and~or necessary to accommodate different types or styles of ball valve constructions. In general, however, and for purposes of describing the subject invention, the valve body includes a generally cylindrical central passageway or axially extending fluid flow opening 20 which is only slightly larger in diameter than ball C. Each of end fittings 14,16 is releasably connected to central body section 12 by a plurality of longitudinally extending tie bolts generally designated 22 (FIGURE 1). The end fittings are also provided with internal threaas 24,26 or any other convenient means to accommodate connecting the valve to an associated fluid system or piping.
The stem and actuating handle assembly 1~ as illustrated includes a stem member 30 having a lower end 32 shaped as shown for sliding receipt in a slot or groove 34 included in the upper end of ball C. This arrangement allows the ball to be rotated between valve opened and closed positions while at the same time permitting the ball to have some freedom of ~ovement for shifting axially in valve body passageway 20 when the valve is in a closed position.
Stem member 30 extends outwardly through an opening 36 in central body section 12. Suitable packing rings 33,40 and 42 are positioned in opening 36 and sealingly engage the opening and stem member 30. As shown, lower packing ring 42 rests upon an inwardly extending flange 44 formed within opening 36. A split thrust washer 46 is positioned below fiange 44 and is clamped thereto by an outwardly extending shoulder or flange 48 formed at the base of stem member 30.
The stem is held in position by a packing gland 50 and a packing nut 52. As shown in FIGURE 1, tightening of packing nut 52 applies pressure to packing rings 38,40,42 to assure a fluid tight seal about the stem.
Although it is possible to actuate the valve stem by 1~ many different types of actuators, including both manual or automatic, a handle member 54 has been shown. This handle is releasably secured to stem member 30 by a nut 56 which clamps the handle to the top of packing nut 52. Cooperating flats 58,60 are advantageously formed in the handle opening and on the exterior of the stem outer end for properly positioning the handle on the stem. Moreover, the position of the handle and, in turn, the position of ball member C are limited by depending stop members 60,62 carried by handle 54. These stop members engage suitable surfaces on central body section 12 to provide fixed stops for the valve in the full opened and full closed positions.
With continued reference to both FIGURES 1 and 3, the ball seat arrangement utilized in the subject invention includes a pair of seat ring assemblies B disposed on opposite sides of bali member C. As shown, the seat ring assemblies are clampingly maintained in position on opposite sides of the ball adjacent opposite ends of the central body section passageway or opening 20. In the preferred embodiment here under discussion, the seat ring assemblies are located substantially equidistantly on diametrically opposite sides of the axis of il3387~7 rotation of the ball member. While the seat ring assemblies could be maintained in position by many different or alternative arrangements, they are shown in the preferred embodiment as being located by shoulders 70,72 defined by end S faces 74,76 of end fittings 14~16, respectively. The inward limit of movement of the seat ring assemblies is defined by a pair of shoulders 78,80 which are formed by the inner end walls of counterbores extending inwardly of valve body passageway or opening 20. Still further, a seal is provided between central body section 12 and end fittings 14,16 by means of O-rings 82,84 which are received in second counterbores 86,88, respectively. Each O-ring is disposed about the outer circumference or outer peripheral surface of a portion of the associated seat ring assembly B.
The structural details of ball valve A described hereinabove are with reference to the preferred valve construction. It will be readily apparent to those skilled in the art, however, that modifications may readily be made thereto to accommodate particular operational needs and/or requirements. Such changes are not deemed to affect the overall intent or scope of the present invention as will be describtd in detail hereinafter.
With reference to FIGURE 2, description will be made of the s~ecific details of seat assemblies B. FIGU~E 2 shows a cross-sectional view of the seat assembly disposed at end fitting 14, it being appreciated that the other assembly is identical thereto unless otherwise specifically noted. Also, ball member C has been deleted for ease of understandin~ and appreciating the seat assembly construction.
113387'7 Each seat assembly is preferably comprised of three components, i.e., a reinforcing ring 100, a seat ring 102 and a frusto-conical disc spring 104. Reinforcing ring 100 has an annular configuration and is desirably constructed from a rigid material such as steel or other suitable metal. In FIGURE 2, reinforcing ring 100 is shown as including a first continuous surface or end face 110 which faces the associated shoulder 70 of end fitting 14. A second continuous surface 112 faces generally toward the ball member (not shown) but is dimensioned to be spaced therefrom in order to prevent any contact or interference therewith. A radially outward extending flange 114 is configured and dimensioned to engage shoulder 78 in cent~al body section passageway 20 to establish a positive forwardmost or home position for the reinforcing ring. The outer circumference or peripheral surface 116 of ring 100 is closely disposed to the side wall of passageway 20.
Referring still to FIGURE 2, it will be seen that seat ring 102 also comprises an annular or ring-like member having a central opening therethrough. A first continuous ball engaging surface 120 initially has a generally frusto-conical conformation concentric with the seat ring itself. A seat ring second surface 122 generally faces the associated shoulder 70 of end fitting 14. A third surface 124 faces reinforcing ring first continuous surface 110 and is conveniently stepped as at area 12~ radially inward from outer peripheral surface 12B.
This stepped area is dimensioned and configured to be received over a portion of the reinforcing ring and engage first continuous surface 110 thereof. As will become more readi~y apparent, surface 110 acts as a bearing surface to provide rigid support for the upstream seat ring during exposure to fluid pressure.
~13387'7 A flange or lip 130 extends axially outward of surface 122 generally at outer peripheral surface 128. This lip or flange is preferably continuous about the seat ring and so located that its radial inner surface generally corresponds to the outside diameter of conical disc spring 104. Flange or lip 130 is beveled at the radial outermost area thereof and is rolied over the radial outer edge of the disc spring in the manner shown. While not necessary, this arrangement advantageously maintains the seat ring and disc spring together as a sub-assembly.
In the preferred arrangement of the invention, seat rings 102 are constructed from a resilient plastic material such as polytetrafluoroethylene or the like. It should be readily appreciated, however, that other types of materials such as acetal resins and the like could also be advantageously utilized. The particular material chosen will, to some extent.
be dependent upon the operating conditions to which the valve is to be subjected. Moreover, various design modifications may be incorporated into the seat assembly components as will be described hereinafter with reference to FIGURE 8.
Frusto-conical disc spring 104 includes an outer end 140 and an inner end 142. The diameter at the outer end is such that a disc spring may be received within the cylindrical cavity defined by the inner wall of seat ring axial flange 130 and second surface 122. The inner diameter of the spring at end 142 is substantially equal to the diameter of the opening through the seat ring.
The spring is selected so that its force is sufficient under partial deflection to continuously urge the seat ring tcward ~he ball and toward bearing engagement with surface 110 11338~q of reinforcing ring 100. The spring must aiso allow stressing or compression thereof toward a flattened condition to accommodate ball shifting in engagement with seat ring first surface 12~. In the preferred embodiment here under discusslon, seat ring second surface 122 is configured so as to partially stress disc spring 104 when the seat ring and disc spring are joined as a sub-assembly. Such stressing is approximately equal to one half of the distance from the free state toward the fully stressed or substantially flattened configuration. However, it should be appreciated that this stressing is not necessary to satisfactory operation of seat assemblies B and the presence or absence thereof is a function of the relative dimensional characteristics between seat ring second surface 122 and disc spring 104.
Disc spring 104 advantageously accommodates generally rotational flexure of the seat ring at least until the spring has been moved to a substantially flattened condition. Such operation provides for improved valve sealing results in a manner to be described. Dependin~ upon the type, size and ~0 style of ball valve involved, conical disc springs 104 may be advantageously constructed from a number of different metals which have spring properties falling within an acceptable range.
Referring to FIGURES 3-7, description will hereinafter be made with reference to operation of the new ball valve and seat assembly. FIGURE 3 shows the valve in a fully assembled valve opened position (no load fluid pressure condition). In this position, the two seat assemblies B have been shifted from the unstressed condition shown in FIGURE 2 to a partially stressed condition. Sizing of ball member C, seat assemblies B
and shoulders 70,72 are such as to provide this relationship at ball valve assembly or make-up.
~33877 More particularly, and with continued reference to FIGURE 3 as well as with reference to FIGURE 4, the seat assemblies are moved such that opposed seat rings 102 are slightly rotatably flexed away from each other generally about their outer peripheries and against disc springs 104 in response to engagement between seat ring first surfaces 120 and ball member C. This action slightly compresses the associated disc springs toward a flattened condition. In the position of FIGURE 3, the disc springs are preferably deflected through approximately half of their remaining travel~ In addition to positioning the ball member, this spring deflection assures a seal force between the two seat rings and ball at first surfaces 120 regardless of how low the system pressure may be.
It also assures that the seat ring disposed adjacent the valve inlet will form a seal with the overall seat load being dependent upon the area of the seat ring outside diameter.
FIGURE 4 shows an enlarged partial view of the downstream seat assembly B which is disposed at end fitting 14 when the valve is in the opened position of FIGURE 3. In this valve position, the upstream seat assembly associated with end fitting 1~ assumes a substantially identical relationship. As there shown, frusto-conical seat ring first or ball engaging surface 120 is in sealing engagement with the surface of the ball member C. The ball slightly deforms a portion of surface 120 so that at least that portion has a concave spherical conformation. Simultaneously, seat ring 102 is rotatably flexed against disc spring 104 so as to slightly compress the disc spring. Because of the rotational flexing in seat ring 102, the surface of seat ring stepped area 126 is moved away from a contacting relationship with reinforcing ring first surface 11~.
~133877 FIGURE 5 shows the valve in a closed position under elevated fluid pressure conditions with the direction of fluid flow being designated by arrow P adjacent the valve inlet.
Depending upon the system pressure, the ball is forced to shift axially of passageway 20 in the direction of fluid flow toward the outlet or downstream seat assembly. As a result of this shifting, the seat ring of the upstream seat assembly will be moved back toward its original unstressed conformation as shown in FIGURE 6 under the influence of the associated disc spring 104. Thus, the upstream seat ring is rotatably flexed or shifted toward the ball as the Dall moves downstream. At the same time, the outlet seat ring is further shifted or rotatably flexed downstream as shown in FIGURE 7 to further compress its associated disc spring. Up to this point, both seat rings are approximately equally flexible with deflection occurring across the full annulus of the seat from the outside diameter to the inside diameter.
Once the inlet seat deflects back to its original unstressed condition, it changes from a flexible to a much more rigid member. In this condition, the surface of seat ring stepped area 126 bears against first surface 110 of the associat:ed reinforcing ring (FIGU~E 6). The aforementioned bearing engagement virtually stops the inlet seat from any further movement toward the ball as the system pressure continues to increase. Conversely, the downstream seat ring assembly remains flexible and continues to rotatably flex until the associated disc spring is moved to its su~stantially fully flattened configuration (FIGURE 7).
As the downstream seat ring is rotatably flexed, and with the seat ring constructed from polytetrafluoroethylene or the like, ball member C further deforms first or ball engaging surface 120 thereof so that an increasing surface portion assumes a concave spherical conformation. In the preferred structural arrangement here described, substantially all of first surface 120 will matingly engage the ball member when the downstream disc spring is fully stressed. This relationship is shown in FIGURE 7. A lesser amount of deformation in first surface 120 would be present in those cases where the seat ring is constructed from harder materials such as acetal resins and the like. When ball member C has shifted an amount to substantially fully deflect the downstream disc spring, the ball memDer is moved away from all contact by ball engaging surface 120 of the upstream seat ring. A gap x (FIGURES 5 and 6) is formed therebetween and no sealing whatsoever occurs on the upstream side of the ball.
This result minimizes downstream seat loading and wear as well as reducing the turning torque required to rotate ball member C back to the valve opened position. Within the predetermined operational li~,its of the valve, ball engaging surface 120 of the downstream seat ring will not generally be substantially further deformed due to system pressures from the conformation generally shown in FIGURE 7. Substantial further deformation could undesirably cause the downstream seat ring to break down and/or be completely destroyed.
Reinforcing ring 100 associated with the upstream seat assembly prevents failure of the associated seat ring 102 by providing a large bearing surface so that the bearing stress will only be approximately 1 1~2 to 2 times the fluid system pressure. This bearing stress is well within the capabilities of most plastic materials utilized in constructing ball valve 1~3387~7 seat rings. ~oreover, and as the valve approaches the opening point, i.e., when the ball C is rotated from the position shown in FIGURE 5 back to the position shown in FIGURE 3, only seat ring ball engaging surface 120 must span the ball opening.
This greatly reduces the unsupported area and length of the span. First surface 110 of the reinforcing ring also provides support substantially across the entire span of upstream seat ring third surface 124. The combined effect of support across the ball opening and a wide bearing shoulder at seat ring stepped area 126 prevents the upstream or inlet seat ring from distorting. It is essential to prevent such distortion in order to preclude subsequent damage to the downstream seat ring. When an unsupported upstream seat ring deforms into the ball opening, it forms a bulge in a sector of the seat ring.
This bulge, in turn, pushes the ball member off center and forces it to cut or distort the downstream seat. Such downstream seat ring distortion causes it to leak at both high and low pressures.
The ball valve A with seat assemblies B described in detail hereinabove is deemed to provide a substantial improvement over those arrangements previously known in the art. The subject design permits the seat assemblies to be flexible and deflect when acting as a downstream seat but to be rigid when acting as an upstream seat. The assemblies are spring loaded at initial assembly to facilitate sealing at low pressures. The seat ring and ball movements are proportioned to release the upstream seat ring from sealing against the ball at high pressures. The upstream seat is supported by a reinforcing ring during valve opening to prevent distortion.
Also, this reinforcing ring provides a large bearing support 1~3387'7 area to prevent the upstream seat ring from shearing at the valve body shoulder or being otherwise displaced from its proper location within the valve.
FIGURE 8 shows a number of design modifications or features which may be advantageously incorporated into seat assemblies B. Such modifications accommodate component machining and valve use as will become apparent. Moreover, the modifications may be individually adopted to use and are not dependent on each other for successful seat assembly operation. For ease of illustrating these alternative design features, like components are identified by like numerals with a primed (') suffix and new components are identified by new numerals.
In FIGURE 8, counterbore end wall 78' extends further inwardly into main valve body section 12' and the radially outward extending flange is not included on reinforcing ring 100'. Thus, the inner end face or wall 150 of the reinforcing ring abuts counterbore end wall 78' to positively establish an axial innermost or home position therefor.
In addition, third surface 124' of seat ring 102' does not include a stepped area as shown and described above with reference to the preferred embodiment. Rather, the seat ring third surface is continuous over the annular extent thereof and is adapted to directly engage reinforcing ring first surface 110'.
The above two modifications are primarily production oriented. That is, each eliminates a machining step which is otherwise required for reinforcing ring 100' and seat ring 102'.
With continued reference to FIGURE 8, seat ring first or ball engaging surface 120' also has a slightly modified 11338~7 conformation. As shown, the ball engaging surface is designed to have a concave spherical surface concentric with the longltudinal axis of the seat ring itself and a radius equal to the radius of the ball member. Thus, when the valve is S initially assembled, surface 120' will substantially matingly engage the ball member surface and will remain in such substantial mating engagement during rotational flexure of the seat ring.
It is also possible witnin the broad aspects contemplated for the invention that first or ball engaging surface 1~0' may have other radii of curvature, both larger and smaller than the radius of the ball member. Moreover, in some cases it may be desirable to configure the body of seat ring r~ *
102' so that in the free state thereof such as is shown in FIGURE 8, ball engaging surface 120' is rotated slightly outward of the seat ring central opening. With this type of structure, the loci of the radius for surface 120' will form a circle concentric with the seat ring longitudinal axis. The aforementioned possible alterations for the seat ring ball engaging surface do not in any way depart from the overall intent or scope of the invention.
Finally, with regard to FIGURE 8, a groove 1~0 is included in second surface 122' of seat ring 102'. This groove extends inwardly into the seat ring body between the inner and outer diameters thereof, is continuous and extends around the entirety of second surface 122'. Groove 160 is particularly desirable for use with harder seat ring materials such as acetal resins and the like to increase flexi~ility and ~etter accommoàate the desired rotational flexure thereof as previously described. In addition to the particular groove 1~33877 configuration shown, other shapes and/or sizes therefor may be utilized to accommodate still other types of seat ring materials and/or valve parameters. Still further, groove 160 may also be incorporated into seat rings constructed from softer materials if desired to accommodate a particular valve application or design.
Other modifications not specifically shown in the drawings may be readily incorporated into seat ring assemblies B without in any way departing from the overall invention. For example, it is possible to form axial flange 130 of seat ring - - 102 at the inside diameter thereof as opposed to the preferred . ;. .,~ ,. ~, position at the outside diameter. Another example resides in the specific orientation of seat ring second surface 122. As ~-~wy~ = -shown--in the-drawings, this surface tapers inwardly into-tbe seat ring body from the outside diameter toward the inside diameter. This taper angle may be varied as deemed necessary ana/or second surface 122 may be disposed normal to the seat ring axis so as to be generally parallel to the associated valve body shoulder. It may also be desirable to slightly modify the relative dimensional characteristics between the seat rings, reinforcing rings and disc springs to accommodate particular operational requirements.
Still further, and in some applications of the valve, it would be possible to entirely eliminate use of reinforcing rings 100 in seat assemblies B. In that case, forward or inward movement of the seat rings into valve body passageway 20 would be limited by, for example, engagement of the seat ring third surfaces with the end wa~ls of the passageway counterbores. However, elimination of the reinforcing rings will reduce the pressure ratings attributable to the valve due 113387'7 to increased potential for upstream seat ring displacement and/or distortion which could result in damage to the downstream seat. This could be compensated to some extent by modifying the dimensional relationships between other of the remaining components. Nevertheless, the advantageous relationships between the ball member seat rings and disc springs as described above would still be obtained during valve use.
The invention has been described with reference to preferred and alternative embodiments. Obviously, modifications and alterations will occur to others upon the reading and understanding of this specification. It is our intention to include all such modifications and alterations --- insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a ball valve of the type including a valve body having a generally cylindrical fluid flow passageway, a ball member disposed in said passageway mounted for selective rota-tion between valve opened and valve closed positions with said ball member being shiftable generally axially in said passage-way at least when said valve is in said closed position under fluid pressure conditions, a pair of annular seat rings disposed in said passageway on opposite sides of said ball member between said ball member and associated valve body shoulders, radial inward extending seat ring retaining surfaces disposed in said passageway adjacent said ball member on opposite sides thereof engaged by annular seat ring forward face portions to limit axial movement of said seat rings into said passageway, and an annular disc spring interposed between each seat ring and the associated of said shoulders for continuously urging a ball member engaging surface on each seat ring toward sealing engage-ment with said ball member and wherein each disc spring has a generally frusto-conical configuration in its unstressed condi-tion with the smaller diameter end thereof pointing toward said ball member, the improvement comprising:
said annular seat rings each including a base area adjacent the radial outermost portions thereof axially dimensioned for retaining receipt between the associated seat ring retaining surface and valve body shoulder, said seat rings each being further configured so that the radial inner portion thereof is spaced from the associated valve body shoulder; said disc springs having at least radial portions thereof from the smaller diameter ends toward the larger diameter ends spaced from said valve body shoulders axially inward into said passageway; said seat ring retaining surfaces each having a radial width dimension greater than one half the radial extent of the forward face portion of the associated seat ring; said seat rings each being rotation-ally flexible generally about said base area thereof between a first generally rigid position with said seat ring forward face portion engaging the associated seat ring retaining surface over the coextensive radial extents thereof and a second gener-ally rigid position with the associated disc spring stressed toward the associated valve body shoulder to a substantially flattened condition; said seat rings being axially spaced apart from each other in said passageway so that said ball member engaging surfaces thereof are in normal positions sealingly engaging said ball member with said seat rings rotationally flexed from said first positions toward said second positions so that each seat ring forward face portion is slightly arcuately moved about said base area from the associated retaining surface at least over a portion of the coextensive radial widths thereof and wherein said disc springs are partially stressed toward a flattened condition for continuously urging said ball member engaging surfaces toward engagement with said ball member; and, one of said seat rings adapted to be further rotationally flexed toward said second position while the other of said seat rings is simultaneously rotationally flexed toward said first position in response to ball member shifting in said passageway toward said one seat ring when said ball member is in said valve closed position under fluid pressure conditions, the ball member engaging surface of said other seat ring being in a non-contact-ing relationship with said ball member when said one seat ring is moved to said second position.
said annular seat rings each including a base area adjacent the radial outermost portions thereof axially dimensioned for retaining receipt between the associated seat ring retaining surface and valve body shoulder, said seat rings each being further configured so that the radial inner portion thereof is spaced from the associated valve body shoulder; said disc springs having at least radial portions thereof from the smaller diameter ends toward the larger diameter ends spaced from said valve body shoulders axially inward into said passageway; said seat ring retaining surfaces each having a radial width dimension greater than one half the radial extent of the forward face portion of the associated seat ring; said seat rings each being rotation-ally flexible generally about said base area thereof between a first generally rigid position with said seat ring forward face portion engaging the associated seat ring retaining surface over the coextensive radial extents thereof and a second gener-ally rigid position with the associated disc spring stressed toward the associated valve body shoulder to a substantially flattened condition; said seat rings being axially spaced apart from each other in said passageway so that said ball member engaging surfaces thereof are in normal positions sealingly engaging said ball member with said seat rings rotationally flexed from said first positions toward said second positions so that each seat ring forward face portion is slightly arcuately moved about said base area from the associated retaining surface at least over a portion of the coextensive radial widths thereof and wherein said disc springs are partially stressed toward a flattened condition for continuously urging said ball member engaging surfaces toward engagement with said ball member; and, one of said seat rings adapted to be further rotationally flexed toward said second position while the other of said seat rings is simultaneously rotationally flexed toward said first position in response to ball member shifting in said passageway toward said one seat ring when said ball member is in said valve closed position under fluid pressure conditions, the ball member engaging surface of said other seat ring being in a non-contact-ing relationship with said ball member when said one seat ring is moved to said second position.
2. The improvement as defined in claim 1 wherein said seat ring retaining surfaces are defined by first radial sur-faces included on a pair of reinforcing rings separately posi-tioned in said passageway on opposite sides of said ball member with said first radial surfaces facing toward the associated one of said valve body shoulders, said reinforcing rings further including locating means for obtaining positive loca-tion therefor in said passageway and a second surface generally facing said ball member being at all times in a spaced relation-ship therefrom.
3. The improvement as defined in claim 2 wherein said passageway is counterbored a predetermined axial distance from each of said shoulders with each counterbore having an inner end wall, said locating means comprising said reinforcing rings having at least a portion thereof received against the end wall of the associated counterbore.
4. The improvement as defined in claim 3 wherein each reinforcing ring includes a radially outward extending flange dimensioned to engage the end wall of the associated counterbore and each seat ring further includes a stepped area in the forward face portion thereof, said reinforcing ring first surface being receivable in said stepped area.
5. The improvement as defined in claim 1 wherein the surface of each seat ring facing the associated one of said valve body shoulders includes a relief groove extending there-around to facilitate ease of seat ring rotational flexure between said first and second positions.
6. The improvement as defined in claim 1 wherein said disc springs are partially stressed greater than one half the dis-tance to the flattened condition when said seat rings are in said normal position.
7. The improvement as defined in claim 6 wherein the disc spring associated with said other seat ring is partially stressed approximately one half the distance to the flattened condition in said other seat ring first position.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10296279A | 1979-12-12 | 1979-12-12 | |
| US102,962 | 1979-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1133877A true CA1133877A (en) | 1982-10-19 |
Family
ID=22292629
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA362,710A Expired CA1133877A (en) | 1979-12-12 | 1980-10-17 | Ball valve and seat assembly |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5694071A (en) |
| CA (1) | CA1133877A (en) |
| DE (1) | DE3042818A1 (en) |
| GB (1) | GB2065276A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4602762A (en) * | 1982-02-16 | 1986-07-29 | Whitey Co. | Ball valve and seat assembly |
| US4410165A (en) * | 1982-02-16 | 1983-10-18 | Whitey Co. | Ball valve and seat assembly |
| US4671308A (en) * | 1982-10-14 | 1987-06-09 | Whitey Co. | Fire-safe ball valve |
| AU565423B2 (en) * | 1982-10-14 | 1987-09-17 | Whitey Co. | Fire-safe ball valve |
| GB8430368D0 (en) * | 1984-11-30 | 1985-01-09 | Southerton Ltd James | Valves |
| JPH0559061U (en) * | 1991-04-18 | 1993-08-03 | 株式会社ケイヴイシー | Ball valve |
| DE19520900A1 (en) * | 1995-06-01 | 1996-12-12 | Rautenkranz Int Hermann | Shut=off valve for pipe |
| DE60023733T2 (en) * | 1999-11-23 | 2006-07-27 | Swagelok Co., Solon | BALL VALVE SEAT SEAL |
| EP1643173B1 (en) * | 1999-11-23 | 2007-01-24 | Swagelok Company | Ball valve seat seal |
| US6695285B1 (en) | 1999-11-23 | 2004-02-24 | Swagelok Company | Ball valve seat seal |
| CN101984277A (en) * | 2010-12-02 | 2011-03-09 | 福建高中压阀门科技有限公司 | Automatic compensation device for ball valve seal |
| US11131404B2 (en) * | 2015-11-16 | 2021-09-28 | Hayward Industries, Inc. | Ball valve |
| FR3081200B1 (en) * | 2018-05-18 | 2021-07-23 | Sogefi Air & Cooling | SEAL, ESPECIALLY FOR A ROTARY BALL VALVE |
| DE102018117240A1 (en) | 2018-07-17 | 2020-01-23 | Illinois Tool Works Inc. | Coolant valve for a vehicle |
-
1980
- 1980-10-17 CA CA362,710A patent/CA1133877A/en not_active Expired
- 1980-11-13 DE DE19803042818 patent/DE3042818A1/en not_active Withdrawn
- 1980-11-17 JP JP16181980A patent/JPS5694071A/en active Pending
- 1980-12-11 GB GB8039654A patent/GB2065276A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2065276A (en) | 1981-06-24 |
| JPS5694071A (en) | 1981-07-30 |
| DE3042818A1 (en) | 1981-06-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |