Patent Publication Number: US-8985136-B2

Title: Protective facial sealing arrangement

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure generally relate to fluid flow control devices, such as ball valves and gate valves. 
     BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in finding and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once desired subterranean resources such as oil or natural gas are discovered, drilling and production systems are often used to access and extract the resources. These systems may be located onshore or offshore depending on the locations of the desired resources. And once extracted, the resources are often transported via pipelines to desired locations, such as refineries. The pipelines typically include valves to control the flow of resources through the pipelines. 
     As may be appreciated, valves include a flow control mechanism for selectively allowing flow through the valves. For instance, a ball valve includes a ball that may be rotated between open and closed positions to allow or inhibit flow through a conduit. A gate valve similarly includes a sliding gate having an aperture that may be moved into and out of alignment with the bore of a conduit to allow or inhibit flow. Regardless of the type, a valve usually includes one or more sealing surfaces that inhibit leaking of fluid. But in some instances these sealing surfaces may collect particles from the fluid flowing through the valve, reducing sealing effectiveness and longevity. Damage to seals and sealing surfaces also negatively impact sealing performance of the valve. And while valves may be operated in harsh conditions (e.g., high operating pressure or with significant external forces), these conditions have the potential to cause valves to separate from conduits and leak. 
     SUMMARY 
     Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. 
     Some embodiments of the present disclosure generally relate to components, such as valves, having facial seals and features that protect such seals and sealing surfaces from wear or damage during installation. In one embodiment, a ball valve includes closure members having sealing grooves to receive facial seals for sealing against a fluid conduit. The closure members also include protective ridges that space the facial seals apart from the fluid conduit to protect the seals during installation of the valve in the conduit. The conduit includes recesses that receive the protective ridges as the valve becomes aligned with the fluid conduit, and receipt of the protective ridges in the recesses cause the sealing surfaces of the valve and the conduit to draw together and energize the facial seals. The protective ridge of each closure member may be provided as a single, continuous ridge, as multiple ridges on the closure member, as a series of protrusions on the closure member, or in any other suitable manner. In some embodiments, the valve may include a floating closure member that is allowed to axially translate within the valve body or include a contoured bore that is shaped to deflect particles in a fluid stream away from sealing surfaces. 
     Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a perspective view of a valve having a body disposed between two fluid conduit connectors in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a horizontal cross-section of the valve of  FIG. 1  and depicts certain internal components of the valve in accordance with one embodiment; 
         FIG. 3  is a perspective view of the valve of  FIG. 1  installed in a fluid conduit in accordance with one embodiment; 
         FIG. 4  is a sectional view of closure members of a flow control assembly, the closure members including protective ridges and retained inside the body of the valve of  FIG. 1  by a pair of retaining rings of the body in accordance with one embodiment; 
         FIGS. 5-12  are cross-sections of one embodiment that generally depict functionality of the protective ridges of the closure members during installation of the body in a fluid conduit; 
         FIGS. 13 and 14  are cross-sections showing additional details of the valve of  FIG. 2 , including a seat that seals against one of the closure members when the valve is in a closed position and drives the closure member into a connector of a fluid conduit in accordance with one embodiment; 
         FIG. 15  is a cross-section generally depicting the valve of  FIG. 2  in an open position in which the passage of fluid between the ball and the closure member pushes the closure member into the connector of the fluid conduit in accordance with one embodiment; 
         FIGS. 16 and 17  are cross-sections of a closure member and other components of  FIG. 2 , in which the closure member is depicted as a floating closure member, in accordance with one embodiment, having a shoulder retained in a recess that allows the floating closure member to axially translate with respect to the valve body to maintain sealing engagement between the floating closure member and an adjacent connector of a fluid conduit; 
         FIG. 18  is a cross-section that depicts a bore of the valve of  FIG. 2  that has a shaped profile or contour that deflects particles away from sealing surfaces in accordance with one embodiment; 
         FIG. 19  is a cross-section of the region bound by line  19 - 19  in  FIG. 18  and depicts the creation of a low-pressure region by the shaped bore that draws particles out of an interstice between the closure member and the ball of the flow control assembly in accordance with one embodiment; 
         FIG. 20  is a cross-section similar to that of  FIG. 19  but with a straight bore that does not create the low-pressure region of  FIG. 19  and does not inhibit particle flow toward sealing surfaces; 
         FIG. 21  is a cross-section of a gate valve in accordance with one embodiment having a bore shaped to deflect particles away from a sealing surface. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components. 
     Turning now to the drawings, a valve  10  is illustrated in  FIGS. 1 and 2  by way of example. The depicted valve  10  is a ball valve and is described as such below for the sake of explanation. But it will be appreciated that many of the features detailed herein may be used with other valves, such as gate valves and check valves to name only two. The valve  10  includes a body  12  that houses internal flow control components and is disposed between fluid conduit connectors  14  and  16 . Blind hubs  18  are attached with clamps  20  to the connectors  14  and  16 . These blind hubs  18  may be removed to allow the connectors  14  and  16  to be connected as part of a pipeline or other fluid conduit (e.g., by welding the connectors  14  and  16  to two sections of pipe). 
     Opposite sides of the body  12  include a cover  22  and a trunnion  24 . A flow control assembly  28  is disposed in a cavity  32  of the body  12 . The flow control assembly  28  includes a ball  30  that may be turned by a stem  26  and pivot about the trunnion  24  to move between open and closed positions. The ball  30  is disposed between two closure members  36 , which may also be referred to as facial sealing rings  36 . As described in greater detail below, the closure members  36  include shoulders  34  retained in the body  12  by retaining rings  38  of the body. The retaining rings  38  may be attached to the central portion of the body in any suitable manner, such as with cap screws. 
     In at least some embodiments, and as presently depicted, the valve  10  is a cartridge valve in which the body  12  and its internal components may be installed in a fluid conduit by inserting the body  12  transverse to the flow axis of the fluid conduit between the connectors  14  and  16  and fastening flanges  40  of these connectors to the body  12  (e.g., with cap screws). Similarly, the body  12  may be removed from the fluid conduit—which allows inspection or replacement of internal valve components—by unfastening the body  12  from the flanges  40  and sliding it out from between the flanges. It will also be appreciated that, in those embodiments in which the connectors  14  and  16  are fastened to the body  12  with cap screws, the retaining rings  38  may include holes (as generally depicted in  FIG. 4 ) to allow the cap screws inserted through the flanges  40  to pass through the retaining rings  38  and into the central portion of the body  12 . 
     The valve  10  includes various seals to control flow and inhibit leaking. For instance, the valve  10  includes facial seals  42  (e.g., lip seals) for sealing the closure members  36  to the end faces of the connectors  14  and  16 . The flow control assembly  28  also includes seats  44  and seals  48  on the ball  30 . The ball  30  may be rotated into a closed position (depicted in  FIG. 2 ) through keyed engagement of the stem  26  in recess  50  and pivoting of the ball  30  about the trunnion  24  in recess  52  to move the bore  54  of the ball  30  out of alignment with the bores  56  and  58  of the connectors  14  and  16 ). In this closed position, the seats  44  seal against the closure members  36  and cooperate with the ball  30  to inhibit flow through the valve  10 . 
     As depicted in  FIG. 2 , the connectors  14  and  16  include flanges  60  on ends opposite the body  12 . These flanges  60  facilitate connection to blind hubs  18  via clamps  20 . But the flanges  60  may be also connected as part of a fluid conduit as depicted in  FIG. 3  in accordance with one embodiment. As shown in  FIG. 3 , the connectors  14  and  16  are coupled via flanges  60  to two sections  62  of a fluid conduit, such as a pipeline. In the present embodiment, the flanges  60  are welded to flanges  64  of the two sections  62 . But the connectors  14  and  16 , with or without flanges  60 , may be coupled as part of a fluid conduit in any other suitable manner. Indeed, the connectors  14  and  16  may be an integral part of a fluid conduit in some embodiments (e.g., the connectors  14  and  16  may consist of flanges or end faces of sections of a fluid conduit). 
     Certain details of the body  12  and the closure members  36  may be better understood by reference to  FIG. 4 . This sectional view depicts the closure members  36  and the body  12  without other elements of the valve  10  for the sake of clarity. The retaining rings  38  may be attached to the central portion of the valve body  12  with cap screws through the smaller holes of the retaining rings depicted in  FIG. 4  to retain the closure members  36  within the body. And the body  12  may be coupled to the flanges  40  by cap screws that pass through the larger holes of the retaining rings  38  also shown in  FIG. 4 . 
     The outer surfaces of the closure members or facial sealing rings  36  include sealing grooves  68  and  70 . In the present embodiment, the sealing grooves  68  are configured to receive the facial seals  42  and the sealing grooves  70  may receive additional seals, such as o-rings. Once the body  12  is installed in a fluid conduit, the closure members  36  seal against the fluid conduit (e.g., along end faces of connectors  14  and  16 ) with the seals in the sealing grooves  68  and  70 . But the sealing efficiency of such a seal depends on its condition and the condition of the surface it seals against—a damaged seal or sealing surface may allow fluid to leak from the conduit. And such seals and sealing surfaces may be easily damaged. Left unchecked, the sliding installation of the body  12  into the fluid conduit (e.g., between pipe flanges, like flanges  40 ) may cause the facial seals  42  or other seals in the closure members  36  to rub against the fluid conduit, causing friction that may wear or even damage the seals. And hard contact between the fluid conduit and other portions of the body  12  may mar or otherwise damage the sealing surfaces. 
     To reduce premature wear and unintended damage, the outer faces of the closure members  36  include protective ridges  72  that extend outwardly beyond seals installed in the sealing grooves  68  and  70 . The protective ridges  72  provide frictional surfaces that reduce the possibility of damage to the seals in the sealing grooves  68  and  70  or to the sealing surfaces by facilitating separation of these seals (and the rest of the outer faces of the closure members  36 ) apart from the fluid conduit (e.g., the flanges  40 ) during installation or removal of the body  12 . In the present embodiment, the protective ridges  72  are circular ridges that circumscribe and are provided radially outward from the sealing grooves  68  and  70  on the outer faces of the closure members  36 . But the protective ridges  72  may take other forms. For instance, rather than unbroken ridges that circumscribes the sealing grooves  68  and  70 , the protective ridges  72  may be provided as multiple protrusions on the outer face of each closure member  36 . And whether provided as a single ridge or a series of ridges, each protective ridge  72  need not be circular in arrangement (or provided in any other particular geometric shape). 
     Operation of the protective ridges  72  in protecting facial seals of the closure members  36  may be better understood with reference to  FIGS. 5-12 , which generally depict installation of the body  12 , along with the closure members  36  and facial seals  42 , in a fluid conduit (e.g., between a pair of flanges  40 ). Although certain features depicted in  FIG. 2  have been omitted from these figures for the sake of explanation, it will be appreciated that such features may be included in an actual implementation. Further, these figures generally depict movement of the body  12  and a closure member  36  along an end face of the fluid conduit (connector  14  in the illustrated embodiment). But it will also be appreciated that the opposite closure member  36  would move along an opposite end face of the fluid conduit (e.g., of connector  16 ), and that the protective ridges  72  on both closure members  36  act similarly to that described below. 
     In the present embodiment, the end faces of the flanges  40  include mating recesses  78  for receiving the protective ridges  72 . The recesses  78  may be of any shape or configuration that allows the protective ridges  72  to be received in the recesses  78 . For example, in an embodiment having circular protective ridges  72 , the recesses  78  are also circular. As the body  12  begins to be moved into position between the flanges  40  of the fluid conduit ( FIG. 5 ), the protective ridges  72  engage the flanges  40  to maintain separation between the rest of the body  12  and the flanges  40 . As the body  12  is moved downward in the present figures, the body  12  and the closure member  36  slide along in spaced relation to the end face of the flange  40  (noting again that the other closure member  36  would slide along in spaces relation to the other flange  40  in a similar manner). As generally depicted in  FIGS. 6-8 , the protective ridges  72  of the closure members  36  maintain spacing of the facial seals  42  and the body  12  apart from the flanges  40  during installation of the body  12  to reduce friction on the seals  42  and to reduce the likelihood of damage to the seals  42  or the corresponding sealing surfaces. This spacing or separation is maintained until the protective ridges  72  are landed in the mating recesses  78  of the end faces of flanges  40 . 
     The landing of a protective ridge  72  in a recess  78  is generally illustrated in  FIGS. 9-12 , and it is noted that the protective ridge of the other closure member  36  would be landed in a mating recess  78  of the other flange  40  in a similar manner. As the protective ridge  72  approaches alignment with the recess  78 , the protective ridge begins to engage the recess  78  and reduce the separation of the end face of the flange  40  and the facial seal  42 . As the protective ridge  72  is landed in the recess  78 , the sealing surfaces of the closure member  36  and the flange  40  engage one another and the facial seal  42  is energized. In this arrangement, the protective ridges  72  keep the sealing surfaces apart for most of the transverse distance traveled by the body during installation in the fluid conduit and reduce wear and damage on the facial seals  42  and the sealing surfaces of the closure member  36  and the flanges  40 . And while such a protected facial sealing arrangement that spaces a facial seal from a fluid conduit during installation is described above in the context of a ball valve, it will be appreciated that the same arrangement can be applied in other components. For example, protective features like the ridges  72  can be used with other types of valves (e.g., gate valves) or in any other components (e.g., flow meters) intended to be installed in, and facially seal against, a fluid conduit. 
     As pressure within the valve  10  increases, or as external forces act on the valve  10  or the fluid conduit in which it is installed, the conduit (e.g., flanges  40  of the connectors  14  and  16 ) can separate from the body  12  and the adjacent closure members  36 . And such deflection of the flanges  40  from the seals on the outer surfaces of the closure members or facial sealing rings  36  could impair the ability of the seals to maintain sealing engagement with the flanges  40  and cause leaks from the fluid conduit. But in some embodiments, including the one depicted in  FIGS. 13-17 , the valve  10  improves facial sealing between the valve and the fluid conduit by providing the closure member  36  as an adaptive, floating closure member that is allowed to axially translate with respect to the body  12  along the fluid conduit axis to compensate for flange or conduit deflection. And pressure provided by fluid entering the valve  10  from the fluid conduit maintains positive pressure on the closure member  36  to maintain sealing engagement during such separation of the flange from the valve. 
     As discussed in greater detail below with respect to  FIGS. 16 and 17 , the shoulders  34  of the closure members  36  are received in oversized recesses in the body  12  that allow translation of the closure members  36  along a flow path of the valve. But first referring to  FIGS. 13 and 14 , when the valve  10  is closed the seats  44  seal against sealing surfaces  94  on the inner parts of the closure members  36 . As shown in  FIG. 14 , a fluid path or passage  82  between the seat  44  and the ball  30  allows fluid to enter a region behind the seat  44  along rear surfaces  84  and  86  and the pressure of this fluid applies a force to the seat  44  toward the sealing surface  94  of the closure member  36 . The pressure of fluid at the front surface  88  of the seat  44  similarly applies a contrary force away from the sealing surface  94 . 
     But while the pressure of the fluid acting on the front and back of the seat  44  may be equal, the area over which this pressure acts is not. Particularly, in the present embodiment the projected area of the rear surfaces  84  and  86  on which the pressurized fluid acts (generally represented by arrow  90  and measured in a plane orthogonal to the axis of translation of the closure member  36 ) is greater than the projected area of the front surface  88  on which the pressurized fluid acts (generally represented by arrow  92  and again measured in a plane orthogonal to the axis of translation of the closure member  36 ). Consequently, the net force on the seat  44  from the pressurized fluid is directed toward the closure member  36 —the pressure pushes the seat  44  into the closure member  36  and the closure member  36  into the fluid conduit (e.g., flange end  40  of connector  14 ). In those embodiments in which the closure member  36  is a floating closure member, the fluid pressure on the seat  44  drives axial translation of the closure member  36  toward the fluid conduit to maintain proper sealing engagement with the fluid conduit when it deflects away from the body  12 . 
     The valve  10  may also be configured to provide positive pressure on the closure member  36  when the valve is in an open position, as depicted in  FIG. 15 . Particularly, when the valve  10  is open, fluid is allowed to enter between the closure member  36  and the ball  30  through a fluid passage or interstice  96 . The pressure of the fluid between the ball  30  and the closure member  36  applies a force on the closure member  36  toward the fluid conduit (connector  14  in  FIG. 15 ). And with the ability of the closure member  36  to axially translate within the body  12 , this force on the closure member  36  may maintain proper sealing engagement with the fluid conduit even when the end of the conduit deflects away from the body  12 . 
     Additional details about the axial translation of the floating closure members  36  are depicted in  FIGS. 16 and 17  in accordance with one embodiment. As shown in  FIG. 16 , the shoulder  34  of the closure member  36  is received in a recess  102  in the body  12 . The recess  102  has an axial width  104  that is greater than the axial width  106  of the shoulder  34 , thus allowing the shoulder  34  to translate within the recess  102 . The amount by which the width  104  exceeds the width  106  may vary between different embodiments based on operating considerations (e.g., expected maximum deflections of flanges  40  from the valve  10 ). In one embodiment, the width  104  is 0.5 millimeters greater than the width  106  to allow a 0.5 millimeter range of axial motion of the closure member  36 . But in other embodiments, the width  104  may exceed the width  106  by other amounts (e.g., 0.3 millimeters, 0.7 millimeters, 1.0 millimeters, 2.0 millimeters, or even greater amounts) to provide corresponding ranges of motion for the closure members. The closure member  36  may also include a radial seal  108  that seals against the body  12  while accommodating axial translation of the closure member  36 . 
     In  FIG. 16 , the shoulder  34  is positioned at an intermediate location in the recess  102  and the closure member  36  is depicted as in tight contact with the fluid conduit (here represented as connector  14 ) at an interface  112 . Upon deflection of the fluid conduit away from the valve body  12  to create a gap  116  ( FIG. 17 ) between the conduit and the retaining ring  38  of the body  12 , the closure member  36  can translate axially to the left (with surface  110  of the shoulder approaching the retaining ring  38 ) to maintain tight contact at the interface  112  of the closure member  36  and the fluid conduit. In some embodiments, both closure members  36  are adaptive, floating closure members. 
     While the presently disclosed use of a floating closure member  36  may be beneficial in other contexts, the use of a floating closure member  36  may be particularly beneficial in a compact, cartridge valve arrangement in which lighter structures are employed to reduce mass but result in larger deformations under load conditions. Thus, the inclusion of a floating closure member  36  in some embodiments allows the valve  10  to compensate for separation between the fluid conduit and the valve without increasing the thickness of the valve and conduit or incurring greater bolting requirements. 
     Additionally, it is noted that valves are often used to control the flow of fluids including particles (e.g., slurries or other abrasive fluids including particles of sand or of some other solid). These particles may negatively impact seals and sealing surfaces, causing deterioration in valve sealing performance over the life of a valve. Additionally, the design of some valves can trap such particles near sealing surfaces, further interfering with sustained operation of the valves. But in some embodiments, such as that depicted in  FIGS. 18 and 19 , the valve  10  includes features that deflect particles away from sealing surfaces. These features may also promote flushing of particles from the sealing surfaces. 
     As depicted in  FIG. 18 , a bore of the valve  10 , including bores  118  of the closure members  36  and the bore  54  of the ball  30 , is a contoured bore shaped to deflect particles away from sealing surfaces. More specifically, the bores  54  and  118  include particle-deflection features  120  and  122 . These features  120  and  122  are provided in the form of raised deflectors or lips  120  and  122  on the bores, though other embodiments could include different deflecting features. The bores  54  and  118  may also include recesses  124  and  126  adjacent to the lips  120  and  122 . In the presently depicted embodiment, the bore  54  of the ball  30  is a symmetric, polycylindrical bore having a straight bore portion  128  in the middle of the ball  30  between other straight bore portions defined by the recesses  126 . The straight portions may be connected to one another in any desired fashion, such as by conical tapers between the recesses  126  and the straight bore portion  128 . 
     Moreover, by allowing the lips  120  and  122  to rise from the recesses  124  and  126 , the recesses  124  and  126  of the present embodiment enable the flow bore of the valve to be maintained at a generally constant diameter. That is, although the lips  120  and  122  and the recesses  124  and  126  cause minor variation in the diameter of the bore through the valve  10 , the diameters of the bore at the crests of the lips  120  and  122  are the same as the diameters  130  and  132  of the bores  56  and  58 , as well as the diameter  134  of the bore portion  128  of the ball  30 . 
     The lips  120  and  122  function to deflect particles of a particle-laden fluid away from sealing surfaces of valve  10 . As depicted in  FIG. 19 , as fluid flows from left to right the lip  120  deflects particles, as generally represented by arrow  140 , toward the center of the fluid stream and away from the sealing surface  94  of the closure member  36 . This deflection itself reduces the ingress of particles from the fluid stream into the space between the closure member  36  and the ball  30  and creates a protective fluid envelope along the bore near sealing surface  94 . 
     Additionally, in the presently depicted embodiment the deflection of particles away from the sealing surface  94  by the lip  120  creates a Venturi effect (or a depressurization of fluid) in the bore in a low-pressure region  142  (compared to other regions in fluid stream in the valve) beyond the lip  120  and radially inward from an interstice or space  146  between the closure member  36  and the ball  30 . The lower pressure in the region  142  draws fluid and particles out of the space  146  (as generally represented by arrow  144 ), in essence gently flushing particles from this space and cleaning the sealing surfaces (e.g., surface  94 ). This is in contrast to a valve depicted in  FIG. 20  as having straight bores  150  and  152  without fluid deflection features, which instead do not inhibit the entry of particles from the fluid stream into the space  146  (as generally represented by arrow  154 ). The other lips  120  and  122  of  FIGS. 18 and 19  may operate similarly to the lip described above, depending of course on the direction of flow through the valve  10 . 
     While the fluid-deflecting and cleaning features disclosed above are described in the context of a ball valve  10 , these features may be used in other types of valves as well (e.g., gate valves or check valves). Indeed, any valve with sealing surfaces close to a bore of the valve to be used to control the flow of particle-laden fluids may benefit from the present techniques. For instance,  FIG. 21  depicts one embodiment of a gate valve  158  including such features. 
     The gate valve  158  includes a body  160  having a bore  162 . A flow control assembly  164  is provided to selectively interrupt flow through the valve  158  by moving a gate  166  transverse to the bore  162  to open and close the valve. Seats  168  of the flow control assembly  164  include seals  170  near the valve bore to seal against the gate  166 . Bores of the seats  168  include lips  174  and recesses  178 , while a bore  172  of the gate  166  includes lips  176  and recesses  180 . These lips and recesses may operate similarly to those described above with respect to ball valve  10 . More specifically, these features may deflect particles in a fluid stream toward the center of the fluid stream and away from sealing surfaces (e.g., away from the seals  170 ), and may create Venturi effects near the lips that draw particles out of interstices between the seats  168  and the gate  166 . Also, the recesses  178  and  180  facilitate maintenance of a generally constant-diameter flow bore in which the diameters of the bores at the crests of the lips  174  and  176  are equal to the diameter  186  of the bore  162  and the diameter  188  of a straight portion  182  in the middle of the gate  166 . 
     Technical effects of some of the presently disclosed embodiments include improved longevity, increased pressure tolerances, and reduced leaking in valves. As described above, in some embodiments the inclusion of protective ridges on closure members of a valve reduces wear and damage to certain seals and sealing surfaces. Further, the inclusion of a floating closure member in some embodiments allows a valve to compensate for flange or conduit deflection away from the valve and maintain sealing. And in some embodiments fluid deflection features in valve bores route damaging particles away from sealing surfaces. Various embodiments of the present technique may include one or more of these features, or of other features described above. 
     While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.