Abstract:
A differential pressure sealing device for use with ball valves that utilizes the pressure of the fluid being communicated in a piping system to increase the sealing force created by the sealing device. Fluid being communicated through a ball valve is provided to a sealing device that includes some type of element for creating a bias force. The pressure of the fluid being communicated increases the sealing pressure created by the sealing device. In this manner, the bias force created in the sealing device benefits from the pressure of the fluid being communicated to enhance the sealing when used with a ball valve or similar component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on and claims priority to U.S. Provisional Patent Application Ser. No. 61/441,796, filed Feb. 11, 2011. 
     
    
     BACKGROUND 
       [0002]    The present disclosure generally relates to a sealing device for use with ball valves. More specifically, the present disclosure relates to a differential pressure sealing device that utilizes the pressure created by the fluid passing through a piping system including a ball valve to pressurize a seating mechanism to aid in the operation of the ball valve. 
         [0003]    Dirty, scaling fluids are fouling-up valves of all types in many industrial applications, including the refining, oil and gas production, geothermal power, chemical, pipeline and mining industries. The main weakness in most valves and in ball valves in particular, is that their seating designs do not keep particles and scale deposits out of the valve seat ring crevices, grooves, and cavities. This is particularly the case in trunnion style ball valves since their seat rings must be able to move axially to allow the line pressure to urge the seat onto the ball. When the seat ring cannot travel back and forth within the body end flange seat ring pocket, the seat cannot properly engage the ball seating surface and the valve cannot shut off, and/or the operating torques become excessive to the point of preventing the operation of the valve with resultant damage to the valve seats and its ball surface. 
         [0004]    Trunnion ball valves, in particular, cannot be reliably used in many services such as with liquids and vapors that cause scale build-ups, and fluids that contain entrained minerals and solid materials such as sand, because such materials pack into the seat ring pocket spaces behind the seat rings of the valve and lock-it-up. 
       SUMMARY 
       [0005]    The present disclosure generally relates to a sealing device for use with ball valves that utilizes the pressure created by the fluid passing through the ball valve to pressurize a sealing ring of a seating mechanism to aid in the operation of the ball valve. 
         [0006]    The sealing system of the present disclosure is particularly desirable for use with trunnion ball valves and provides for excellent shutoff and ease of operation while at the same time eliminating the operational problems caused by sand, scale and debris. The sealing system of the present disclosure includes a two part metal seat ring cartridge that includes a chamber for energizing an axially-dynamic seat ring made by various materials, such as RTFE, peak, metals and ceramics, with a clean pressurizing fluid that is kept at a higher pressure than the pressure that the valve must seal against in the main pipe. Because the pressure behind the dynamic seat ring is higher than in the pipeline, the seating mechanism prevents the ingress of fluid from the main pipe into the seat ring energizing chamber, thus insuring the free axial movement of the seat ring against the sealing ball of the ball valve. 
         [0007]    In one embodiment of the disclosure, the seating member charging chamber can be pressurized by utilizing a spring loaded differential piston device that communicates the pressure in the main pipe to a clean fluid, such as a non-compressible valve sealant. The additional differential force to pressurize the clean sealant insures that the sealing system will always exert a higher pressure on the inside of the seat ring than the pressure of fluid in the pipe which is against the face of the seat ring. The pressure differential across the seat ring provides the force advantage that seals off the valve. The pressure differential also functions to keep any of the fluid the valve is handling from carrying sand, scale or debris into the charging chamber. 
         [0008]    In an alternate configuration, sealant is injected directly into the seating member charging chamber from a small sealant reservoir. The system maintains the sealant at a selected, constant pressure that is sufficiently higher than the pressure in the pipe to provide the force to seal off the valve and to prevent the ingress of any of the process fluid the valve is handling. 
         [0009]    In yet another alternate configuration, the fluid coming from the pipe is filtered and used as the fluid to pressurize the seating member charging chamber. The charging chamber includes an additional spring to generate the pressure differential across the seat ring that is needed to provide shutoff and prevent the ingress of any fluid or contaminate into the chamber from the processed fluid the valve is handling. 
         [0010]    In yet another alternate embodiment, the system utilizes a compatible fluid other than a sealant or the media the valve is handling to pressurize the seat ring. As an example, air, nitrogen, water or steam can be used to charge the seating member charging chamber and power the seat ring. In the case of steam, it will be possible to more efficiently heat a valve seat ring for use in viscous services. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The drawings illustrate the best mode presently contemplated of carrying out the disclosure. In the drawings: 
           [0012]      FIG. 1  is an isometric view illustrating the installation of the sealing system of the present disclosure on a conventional ball valve; 
           [0013]      FIG. 2  is a schematic illustration of a first embodiment of a pressurizing system used to power the seating assembly; 
           [0014]      FIG. 3  is a second embodiment of the pressurizing system used to charge the sealing system of the present disclosure; and 
           [0015]      FIG. 4  is yet another alternate configuration of the pressure system used to power the seating assembly; 
           [0016]      FIG. 5  is a magnified, section view of a first embodiment of the seating mechanism; 
           [0017]      FIG. 6  is a magnified, section view of a second embodiment of the seating mechanism; and 
           [0018]      FIG. 7  is a third embodiment of the sliding seating mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring first to  FIG. 1 , thereshown is a differential pressure sealing device  10  mounted in an operative position to a ball valve assembly  12 . The ball valve assembly  12  includes an outer housing  14  that encloses a rotating ball  16  that is connected to a rotatable stem  18 . The ball  16  includes an open flow passageway  20  that allows a fluid, which may be a liquid or gas, to selectively pass through the ball valve as the ball  16  is rotated in the housing  14 . The ball  16  includes multiple seating surfaces  22 . The ball  16  is rotatable within the outer housing  14  to selectively restrict fluid flow through a piping system  24 . 
         [0020]    The differential pressure sealing device  10  includes a sliding seating mechanism  26  that is mounted within an internal cavity or groove  28  formed in a metallic main body  30 . The main body  30  includes an end flange  32  and an inner flange  34 . The outer flange  32  includes multiple attachment holes  33  that allow the sealing device to be connected to a pipe of a piping system. The inner flange  34  allows the pressure sealing device  10  to be securely attached to the outer housing  14  of the ball valve  12  through a series of connectors  36  and attachment nuts  38 . Thus, as can be seen in  FIG. 1 , the entire pressure sealing device  10  can be attached to a ball valve  12  to improve the sealing ability of the piping system 
         [0021]      FIG. 2  illustrates the installation of the pressure sealing device  10  within a piping system  24 . As described previously, the pressure sealing device  10  includes the sliding seating mechanism  26  that creates a seal with a seating surface  22  formed on the ball  16  of a conventional ball valve. The pressure sealing device  10  forms part of a first embodiment of a sealing system  40  shown in  FIG. 1 . The sealing system  40  includes a pressurizing system  42  that supplies a pressurized fluid, such as a non-compressible valve sealant, to power the sliding seating mechanism  26 . In the embodiment shown in  FIG. 2 , the pressurizing system  42  includes an inlet port  44  and an outlet port  46 . The inlet port  44  is in pressure communication with a pressure sensing port  48  extending through an outer wall  49  of the piping system  24 . The pressure sensing port  48  allows the inlet port  44  to draw a portion of the fluid flowing through the open interior  50  of the piping system  24  into the inlet port  44  through the inlet line  64 . The fluid flowing in the piping system  24  is flowing at a first pressure. The fluid drawn from the piping system  24  and contained within the inlet port  44  contacts a movable pressure wall  52  that is in direct contact with a compressed charging spring  54 . The charging spring  54  is pre-compressed by stationary pegs  51 . The opposite end of the charging spring  54  contacts a moving piston  56  that has an opposite end in fluid communication with a supply a pressurizing fluid, such as a non-compressible sealant, shown in the reservoir  58 . The charging spring  54  exerts a bias force on the piston  56  to preload and pre-pressurize the volume of the pressurizing fluid contained within the reservoir  58 . In the embodiment illustrated, the pressurizing fluid contained within the reservoir  58  is a grease-based valve sealant but could be any other type of fluid, either gas or liquid, that can communicate a pressure from one area to another. A pressure outlet line  60  leads from the outlet port  46  to an inlet port  62  formed in the inner flange  34  of the pressure sealing device  10 . 
         [0022]    As illustrated in  FIG. 2 , the pressure of the fluid within the outlet line  60  is created by a combination of the pressure of the fluid in the inlet line  62 , which corresponds to the pressure of the fluid within the open interior  50 , and the bias force created by the charging spring  54 . In this manner, the pressurizing system  42  of the present disclosure insures that the pressure of the fluid contained within the pressurized outlet line  60  is greater than the pressure of the fluid in the open interior  50  of the piping system  24  and thus in the inlet line  64 . In the embodiment shown in  FIG. 2 , a valve  66  is positioned to allow air to be bled off from the reservoir  58 . Further, the valve  66  also functions as a fill valve that allows the fluid contained within the reservoir  58  to be filled and replenished as needed. 
         [0023]      FIG. 3  illustrates a second embodiment of the pressurizing system  42  that is utilized to create the required fluid pressure within the pressurized outlet line  60 . In the embodiment shown in  FIG. 3 , the pressurizing device includes a jack pump  68  that includes a handle  70 . The handle  70  can be manually moved to create pressure on the hydraulic fluid or sealant contained within the open reservoir  72 . The jack pump  68  includes a pressure gauge  74  that allows an operator to determine the amount of pressure created within the open reservoir  72 . The alternate embodiment of the pressurizing system shown in  FIG. 3  creates the desired amount of fluid pressure within the pressurized outlet line  60 , which in turn leads to the inlet port  62  formed as part of the pressure sealing device  10 . 
         [0024]    The pressurizing system  42  shown in  FIG. 3  can be modified to include a pulsation damper in the outlet line  60  between the jack pump and the inlet port  62 . Pulsation dampers are well-known components that include a bladder that is pre-charged by a supply of gas, such as nitrogen. The pulsation damper can be installed at the discharge side of the jack pump to reduce noise and vibration and create a more constant pressure on the sealing ring. 
         [0025]      FIG. 4  illustrates yet another alternate embodiment of the pressurizing system  42 . In the embodiment shown in  FIG. 4 , the pressurizing system  42  includes an inlet line  64  that receives the fluid flowing within the open interior  50  of the piping system  24 . The fluid flows through the pressure sensing port  48  and into a combination filter and dryer  76 . The filter and dryer cleans and dries the fluid flowing through the piping system  24  such that after being filtered, the fluid from within the piping system flows into a pressurized outlet line  60 . Since the pressurizing system  42  draws a portion of the fluid from the open interior  50  and uses the pressure of this fluid to drive the sliding seating mechanism  26 , the sliding seating mechanism  26  is designed to include a wave spring or coil spring to increase the pressure acting on the sliding seating mechanism  26  above the pressure of the fluid within the piping system  24 . Details of the use of a wave spring or coil spring to increase the pressure on the seat ring will be described in greater detail below with reference to  FIG. 6 . 
         [0026]      FIG. 5  illustrates the detailed configuration of one embodiment of the sliding seating mechanism  26  constructed in accordance with the disclosure. The sliding seating mechanism  26  is formed as part of the pressure seating device  10  and creates a seal against the seating surface  22  of the ball  16 . As described previously, the inner flange  34  includes an inlet port  62  that leads into a fluid passageway  78 . The fluid passageway  78  extends through the solid body  30  of the inner flange  34  and extends into fluid communication with an annular seating member charging chamber  80 . In this manner, the annular charging chamber  80  receives the supply of pressurized fluid from the pressurizing system shown in one of the embodiments of  FIGS. 2-4 . 
         [0027]    The sliding seating mechanism  26  includes a stationary inner ring  82 , a dynamic center sealing ring  84  and a stationary outer ring  86 . In the embodiment illustrated, the center sealing ring  84  is movable relative to the stationary inner ring  82  and the stationary outer ring  86 . The center sealing ring  84  includes an outer sealing surface  88  that is urged into contact with the seating surface  22  of the ball  16 . In the embodiment illustrated in  FIG. 5 , a resilient O-ring  90  is compressed between a shoulder  91  formed in the inner ring  82  and a rear surface  104  of the center sealing ring  84  such that the resilient properties of the O-ring  90  creates a bias force that urges the sealing surface  88  of the center sealing ring  84  into contact with the seating surface  22  of the ball  16 . 
         [0028]    When a supply of pressurized fluid is received within the annular charging chamber  80 , the supply of pressurized fluid is communicated to an open cavity  92  that includes the O-ring  90  through a pressure port  94  formed in the outer ring  86 . The pressure of the fluid flowing into the open cavity  92  creates a sealing force that combines with the bias force to urge the center sealing ring  84  outward and toward the seating surface  22  of the ball  16 . 
         [0029]    A sealing member  96 , such as an O-ring, is positioned within an open cavity  98  to create a fluid-tight seal to prevent the sealant from passing out of the annular charging chamber  80 . A second sealing member  106  prevents the flow of the fluid in the charging chamber  80  from flowing past the inner ring  82 . A sealing gasket  100  is positioned between a back surface  102  of the inner ring  82  to prevent the flow of the fluid contained within the open interior  50  of the piping system from reaching the annular charging chamber  80 . As can be understood in FIG.  5 , the pressurized fluid received at the inlet port  62  exerts a force on the rear surface  104  of the center ring  84  to increase the pressure between the sealing surface  88  and the seating surface  22  of the ball  16 . The pressure of the sealant creates an additional force on the center sealing ring  84  in addition to the bias force created by the O-ring  90 . 
         [0030]    In an alternate, contemplated embodiment shown in  FIG. 6 , the O-ring  90  can be replaced by a wave spring or a coil spring  93 . The use of a wave spring or a coil spring  93  provides another mechanism to create a bias force against the rear surface  104 . As can be understood in  FIGS. 5 and 6 , the force urging the center sealing ring  84  into contact with the ball  16  is created by a combination of the sealing force created by the pressurized fluid entering through the inlet port  62  and the bias force created by the bias member, such as the O-ring  90  or the bias spring  93 . The combination of the two forces is exerted against the rear surface  104 . 
         [0031]    In the embodiments shown in  FIGS. 5 and 6 , the gasket  100  and the sealing member  106  are used to prevent the flow of both the pressurized fluid received at the inlet port  62  and the pressurized liquid in the piping system from flowing past the inner ring  82 . In a contemplated embodiment, the entire inner ring  82  can be welded to the main body  30 , thus eliminating the need for the sealing member  106  and the gasket  100 . 
         [0032]      FIG. 7  illustrates an alternate embodiment of the sliding seating mechanism  26 . In the embodiment shown in  FIG. 7 , the sliding seating mechanism  26  includes the moving center sealing ring  108  having the sealing surface  88 . However, in the embodiment shown in  FIG. 7 , the inner ring is eliminated and instead a lower flange  110  formed as part of the main body  30  is positioned below the moving center ring  108 . The lower flange  110  includes a sealing member  112 . Outer ring  114  includes a sealing O-ring  116  and a rear pressure port  118  that allows fluid to flow from the fluid passageway  78  into contact with rear surface  120  of the center ring  108 . Although not shown, an O-ring or spring could be placed in contact with the rear surface  120  to increase the bias force generated between the sealing surface  88  of the center ring  108  and the sealing surface  22  of the ball. 
         [0033]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.