Abstract:
A high pressure ball valve seal assembly utilizes primary, secondary, and tertiary seals to withstand debris, caustic fluids, high pressure, and high temperature. The seal assembly comprises first and second inner seats and first and second outer seats which are retained within the valve body. First inner and outer seats are mounted on a first side of a closure member in the valve cavity and second inner and outer seats mounted on a second side of the closure member opposite the first side. A plurality of sealing rings are provided, whereby the sealing rings may be arranged to provide a tertiary upstream seal physically located on the downstream side of the ball valve.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Field of the Invention 
         [0002]    The present invention relates generally to ball valve seal assemblies and, more particularly, to a ball valve tertiary seal assembly. 
         [0003]    Description of the Prior Art 
         [0004]    Ball valves have been used for years and have employed closure members of a generally spherical shape. These members are rotated about one of its axes to align or place out of line the through-port with the flow passages of the body member to establish the open and closed positions of the stopper. The provision of the closure member in spherical form has a number inherent advantages, not the least of which is overall compactness of the valve and that it requires only one quarter turn of the closure member or spherical stopper to move from open to close and from close to open, as distinguished from the gate type valve where the stopper member must be shifted axially to and from closed position. As distinguished from the tapered or conical type of stopper, all difficulties of the “wedging” effect are avoided. 
         [0005]    Ball valves generally provide for a single seal between the ball and the seat on both sides of the ball to provide. The problem of maintaining an effective seal in high pressure ball valves has long been recognized. Prior efforts to solve the problem of maintaining a satisfactory seal in ball valves are shown in Hulsey U.S. Pat. No. 3,504,885 and Grove U.S. Pat. No. 3,339,886 referenced above. 
         [0006]    Independently operable dual seals have also been provided to address this problem. Exemplary U.S. Pat. Nos. 5,338,003, 5,320,327 and US 54942 to John Beson disclose high pressure ball valves having dual, independent seat to ball seals, the dual seal arrangement including a primary seal and a secondary seal, each operating independently, in proper sequence, each acting in the same direction, and each being pressure actuated, with provision for relieving excess fluid pressure. 
         [0007]    Further, an independent tertiary ball valve seal has been utilized in the past but this prior art design requires that the upstream and downstream seal assemblies are different in shape. In this prior art tertiary seal design, the ball valve can be changed from a ball valve with identical primary and secondary seals on both sides of the closure member to a ball valve with primary and secondary seals on one side of the closure member with a tertiary seal on the opposite side of the ball valve. This design would still have one seal to close off flow in the opposite direction. Changing between the two modes of operation is made more difficult due to the requirement of different seal assemblies when the tertiary or third seal is desired. 
         [0008]    It is an objective of the present invention to provide a long-lived multiple seal valve which can be operated with dual seals in either direction or can be changed to provide a tertiary seal without a requirement for different seats on opposite sides of the ball making the ball valve considerably less expensive to manufacture and less complicated to change. 
         [0009]    Consequently, those of skill in the art will appreciate the present invention, which addresses the above problems and other significant problems uncovered by the inventor that are discussed hereinafter. 
       SUMMARY OF THE INVENTION 
       [0010]    It is a general purpose of the present invention to provide an improved seal assembly and method. 
         [0011]    An object of the present invention is to provide an improved upstream sealing assembly and method that may be utilized in ball valve pressure control equipment. 
         [0012]    Another object of the present invention is to provide a multiple seal assembly providing for primary, secondary, and tertiary seals. 
         [0013]    A further object of the present invention is to provide a ball valve seal assembly with an extended service life as compared with conventional ball valves. 
         [0014]    Accordingly, the present invention provides a ball valve may comprise a valve body and a closure member mounted in the valve body. The closure member is round and rotatable between and open and a closed position to open and close a flowpath through the valve body. 
         [0015]    A plurality of seats for the ball valve are provided with a plurality of seal ring grooves. 
         [0016]    The ball valve is selectively configurable in a first configuration or a second configuration. 
         [0017]    The first configuration comprises a first group of sealing rings mounted in selected of the plurality of seal ring grooves to form bi-directional primary seals and bi-directional secondary seals, wherein a respective secondary seal is activated upon leakage of a respective primary seal. 
         [0018]    The second configuration comprises a second group of sealing rings mounted in selected of the plurality of seal ring grooves to form bi-directional primary seals, a secondary seal and a tertiary seal, wherein the tertiary seal is activated upon leakage of the secondary seal. In one embodiment, only two sealing rings are changed between the first configuration and the second configuration. 
         [0019]    The plurality of seats may comprise a first inner seat mounted in the valve body that engages a first side of the closure member, a second inner seat mounted in the valve body that engages a second side of the closure member, a first outer seat mounted in the valve body that engages a first side of the closure member, and a second outer seat mounted in the valve body that engages a second side of the closure member. 
         [0020]    In one preferred embodiment, the first inner seat is axially moveable with respect to an axis of the flowpath, the second inner seat is axially moveable with respect to an axis of the flowpath, the first outer seat is axially moveable with respect to an axis of the flowpath, and the second outer seat is axially moveable with respect to an axis of the flowpath. 
         [0021]    The plurality of seal ring grooves are disposed in the first inner seat, the second inner seat, the first outer seat, and the second outer seat. 
         [0022]    The valve may further comprise a peripheral seal ring groove formed on an outer periphery of at least one of the first inner seat or the second inner seat so that presence of at least one seal ring within the peripheral seal ring is consistent with the second configuration. 
         [0023]    The valve may further comprise a peripheral seal ring groove formed on an outer periphery of at least one of the first outer seat or the second outer seat so that absence of at least one seal ring within the peripheral seal ring is consistent with the second configuration. 
         [0024]    In one embodiment, a plurality of seal rings are mountable in selectable of the seal ring grooves. In a first selective configuration of the plurality of seal rings, the first inner seat and the second inner seat are each operable to form a primary seal with the closure member, the first outer seat and the second outer seat are each operable to form a secondary seal with the closure member. 
         [0025]    In a second selective configuration of the plurality of seal rings, the first inner seat and the second inner seat are each operable to form a primary seal with the closure member. The first outer seat is operable to form a secondary seal and the second outer seat is operable to form a tertiary seal that is energized by upstream pressure when leakage occurs in the primary seal of the first inner seat and the secondary seal of the first outer seat. 
         [0026]    The valve may further comprise a peripheral seal ring groove formed on an outer periphery of at least one of the first inner seat or the second inner seat so that absence of at least one seal ring within the peripheral seal ring groove is consistent with the first selective configuration of the plurality of seal rings. 
         [0027]    The valve may further comprise a peripheral seal ring groove formed on an outer periphery of at least one of the first outer seat or the second outer seat so that presence of at least one seal ring within the peripheral seal ring groove is consistent with the first 
         [0028]    In one embodiment, a method for making a ball valve may comprise providing a valve body and providing a closure member mounted in the valve body. 
         [0029]    Other steps may comprise providing a plurality of seats, and providing that a first configuration of sealing rings mounted on the plurality of seats form bi-directional primary seals and bi-directional secondary seals, wherein a respective secondary seal is activated upon leakage of a respective primary seal. 
         [0030]    Another step may comprise providing that a second configuration of sealing rings mounted on the plurality of seats form bi-directional primary seals, a secondary seal and a tertiary seal, wherein the tertiary seal is activated upon leakage of the secondary seal. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0031]    For a further understanding of the nature and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements may be given the same or analogous reference numbers and wherein: 
           [0032]      FIG. 1  is a top conceptual view, partially in cross-section, of a ball valve with a primary seal engaged in accord with one possible embodiment of the present invention. 
           [0033]      FIG. 2  is a top conceptual view, partially in cross-section, of a ball valve with a secondary seal engaged in accord with one possible embodiment of the present invention. 
           [0034]      FIG. 3  is a top conceptual view, partially in cross-section, of a ball valve with a tertiary seal engaged in accord with one possible embodiment of the present invention. 
       
    
    
       [0035]    While the present invention will be described in connection with presently preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents included within the spirit of the invention. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    Referring now to the drawings and more particularly to  FIG. 1 , there is shown a view of ball valve  100  in the closed position. In one embodiment, ball valve  100  can be a trunnion mounted ball valve arrangement and may or may not comprise an explosion proof valve. However, the teachings provided for herein may apply to other ball valve arrangements. 
         [0037]    Spherical or ball closure member  10  is mounted within valve cavity or chamber  32  defined by valve body  30 . First inner seat  20  and first outer seat  50  are mounted on a first side of closure member  10 . Second inner seat  70  and second outer seat  60  are mounted on a second side of closure member  10  opposing the first side of closure member  10 . Stem  8  rotates closure member  10  a quarter turn between an open position and a closed position with respect to bore  40 . 
         [0038]    Upstream stepped interior  106  defines a stepped interior surface of cavity  32  within valve body  30 . Stepped interior  106  supports first inner seat  20  and first outer seat  50  in position with respect to each other and closure member  10 . Downstream stepped interior  102  also supports second inner seat  70  and second outer seat  60  against closure member  10  within valve chamber  32 . Upstream interior  106  and downstream interior  102  are preferably mirror images of each other. 
         [0039]    In  FIGS. 1 &amp; 2 , the arrangement of first inner seat  20  and first outer seat  50  with respect to each other and valve body  30  can be a mirror image of second outer seat  60  and second inner seat  70  with respect to each other and valve body  30 . Various fastening arrangements may be utilized consistent with the teachings herein to secure the inner and outer seats within valve cavity  32 . In one embodiment, the upstream and downstream seats can be but do not necessarily have to be interchangeable and can be but do not necessarily have to be mirror images of each other. 
         [0040]    First inner seat  20  and first outer seat  50  move axially parallel to bore axis  16  independently of each other. Movement is made with respect to valve element  10  and body  32  within upstream flow path  13 . Similarly, both second inner seat  70  and second outer seat  60  are independently axially movable within downstream flowpath  15 . Therefore, with the embodiment of  FIG. 1 , ball valve assembly  100  can provide for both selective upstream and/or downstream sealing to provide bi-directional sealing consistent with the teachings provided herein. This redundant sealing technology whereby the outer seats provide redundant backup sealing enables ball valve  100  to offer a longer service life. 
         [0041]    In general operation, ball valve sealing assembly  100  provides for primary seal  22  as upstream pressure  90  pushes against first inner seat end  18  forcing first inner seat sealing face  21  against first sealing side  12  of closure member  10  when closure member  10  is in the closed position. It will be noted that seal element  22  or other seal elements may be of many different types including but not limited to metal to metal seals, corrosive resistant alloy welded inlay, various shaped seals, elastomeric seals, and/or other sealing materials. 
         [0042]    In this embodiment, first sealing O-ring  28  is mounted within groove  27  and makes sealing contact with stepped interior  106  as pressure pushes against first inner seat  20 . Spring or springs  4  act against first inner seat shoulder  3  to bias first inner sealing face  21  into contact with closure member  10  to provide an initial seal. Increased upstream pressure increases the sealing force at sealing face  21 . Therefore, upstream fluid and the upstream fluid pressure  90  is contained to flow passage  13 . As pressure decreases, the sealing force decreases. Thus, wear may be decreased as compared to valves that do not provide this option. 
         [0043]    Turning now to  FIG. 2 , in this embodiment, if primary seal  22  is damaged as indicated by X  53  will first outer seat  50  become energized by the pressure indicated by arrows  91  and engage closure member  10  to form a secondary seal. When primary seal  22  is damaged, upstream pressure  90  flows past seal  22  as indicated by arrows  91  through flow passage  38 . The pressure that bleeds between first inner seat  20  and first sealing side  12  pushes first inner seat  20  axially backwards as indicated by arrow  26 . The fluid travels through channel  38  between first inner seat  20  and first outer seat  50 . The pressure behind first outer seat end  59  urges first outer seal element  51  against first sealing side  12  in the direction of arrow  56  to create secondary seal  52 . As the upstream pressure increases, the seal force at  52  increases. Likewise, as the force decreases, then less force is applied. In this way, wear at  52  is decreased when less sealing force is required. 
         [0044]    Secondary seal  52  uses a new seat and a new area of first sealing side  12  to seal against producing another positive upstream seal for ball valve  100 . This action prolongs the effective seal of ball valve  100 . Although primary seal  22  is damaged, first inner seat  20  and first inner sealing face  22  now acts as a wiper ring to keep line debris away from secondary seal  52  and further reduces the chances of subsequent seal failure. First outer sealing ring  58  is provided within outer groove  57  so that all the upstream pressure remains in channel  38  to act on the surface of first outer seat end  59  to pressure activate seal  52  and prevents leakage past outer seat  50  into valve cavity  32 . 
         [0045]    In  FIGS. 1 &amp; 2 , the arrangement of first inner seat  20  and first outer seat  50  with respect to each other and valve body  30  is a mirror image of second outer seat  60  and second inner seat  70  with respect to each other and valve body  30  as discussed hereinbefore. The valve is bi-directional because the primary and secondary seats on both sides of closure element  10  are substantially the same and operate in the same way. 
         [0046]    However, in the configuration of  FIG. 3 , when the tertiary sealing mechanism is utilized, three of the four seats operate to seal in one direction and only a primary seal would operate in the opposite way. Accordingly, the valve is still bi-directional but has a preferred direction so that the preferred orientation allows use of all three sets of seals on the upstream side. 
         [0047]    Turning now to  FIG. 3 , ball valve  100  is shown with tertiary upstream seal  66  engaged and pressure activated in accord with one possible embodiment of the present invention. In this case, leakage occurs past seal  22  and  52  as indicated by the crosses  53  and  57 . Accordingly, pressure as indicated by arrows  36  flows into cavity  32 . Assuming the pressure in cavity  32  is greater than the downstream pressure, then tertiary seal  66  is activated. 
         [0048]    Tertiary seal  66  which provides the third back up seal for upstream pressure is created by modifying the arrangement of the downstream sealing members. Second inner seat  70  and second outer seat  60  are duplicates of those shown in  FIGS. 1 and 2  and may be duplicates of the corresponding upstream seats. However, sealing ring  68  is removed from second outer seat groove  82 . Seal ring  69  is placed within second inner seat groove  84  on the downstream side of ball valve  100 . Second inner seat groove  84  is formed on a periphery of the second inner seat and may be referred to as a peripheral seal ring groove herein. A corresponding inner seat groove may be formed on a periphery of the first inner seat. After the sealing rings are mounted as indicated in  FIG. 3 , second outer seat  60  then acts as a third or tertiary seal backup to operation of first inner and outer seats  20  and  50 . 
         [0049]    In one embodiment, third sealing ring  69 , as well as sealing rings  28 ,  58 , and  78  are comprised of an elastomeric material or other suitable O-ring material. The material for the O-rings and/or other types of sealing members can be selected based on the pressure, temperature, and expected fluids. However, other types of sealing elements could be utilized in place of O-rings. 
         [0050]    Sealing ring  69  is positioned around second inner seat  70  in groove  84 . Upstream pressure  90  being greater than the downstream pressure in flowpath  15  activates second outer seat  60  and maintains the integrity of second outer seat seal  66  as discussed herein. Assuming leakage past first inner and outer seats  20  and  50 , then first inner seat  20  and first outer seat  50  will be urged away from closure member  10  as shown by arrows  26  and  56 . Pressure will flow past first inner seat  20  and first outer seat  50  into surrounding closure member in cavity  32  as depicted by arrows  36  before bleeding through channel  85 , past empty groove  82 , whereby the pressure created will push against second outer end  96  to activate tertiary seal  66  with second outer sealing element  61  and second sealing side  14 . Seal ring  69  prevents leakage to the downstream side of the valve and maintains the upstream pressure at end  96  of second outer seat  60  so that second outer seat  60  is urged in the direction of arrow  63 . 
         [0051]    Springs  94  bias second outer seat  60  into contact with second sealing side  14  to provide an initial seal and/or additional sealing force. Tertiary seal  66  also assures that any overpressure from thermal expansion will always vent back upstream rather than downstream as with conventional ball valve arrangements. Upstream pressure urges third sealing ring  68  to engage second inner seat  60  in the direction of arrow  63  to prevent the pressure from bleeding out downstream. As upstream pressure is increased, then second outer seat  60  is pushed with greater force against closure member  10 . 
         [0052]    If upstream pressure is reversed, valve  100  is bi-directional. In this embodiment with ball valve  100  being configured for use with tertiary seal  66 , second inner seat  70  will form a primary seal  76  if downstream pressure is exerted through flowpath  15  forcing second inner sealing element  71  against second sealing face  14 . The pressure would work at surface  72  to urge second inner element  70  towards closure element  10  in the direction of arrow  63 . Springs  92  operate to at least form a first seal. In other words, operation of second inner seal to provide a primary seal is the same as discussed with respect to first inner seal forming a primary seal. 
         [0053]    While the operation of the third or tertiary seal has been described with the valve remaining closed, the operation due to opening and closing the valve is also a possibility. Essentially, the tertiary seal is activated if the pressure in valve cavity  32  is greater than the pressure in downstream flowpath  15 . Each time valve  100  is opened, the valve cavity is exposed to pressure in the upstream and/or downstream flow lines. Accordingly, if pressure in the valve cavity is the upstream high pressure, and after the valve closes then the downstream pressure decreases, tertiary seal  66  is activated. Accordingly, both the primary seal and the tertiary seal may be simultaneously operational. While the primary seal upstream is normally exposed to more debris and so forth, it is possible that the tertiary seal could fail prior to failure of the primary seal. Accordingly, the term tertiary seal as used herein refers to a third seal or third level of sealing rather than necessarily any particular order of operation of the seals or importance of the seal. All seals are important with redundancy being provided in one embodiment at up to three levels and in another embodiment at up to two levels bi-directionally. In one embodiment, the secondary seals operate after leakage of the primary seal. However, the tertiary seal may operate before the secondary seal and/or with the secondary seal. 
         [0054]    In the embodiment shown in  FIG. 3 , ball valve assembly  100  can provide for both selective upstream and/or downstream sealing to provide bi-directional sealing consistent with the teachings provided herein. This redundant sealing technology enables the ball valve to offer a longer service life than other ball valves taught by the associated prior art. 
         [0055]    Accordingly, the seal rings may be provided in two configurations utilizing the same seats in both configurations. It is not necessary to change the seats. Most of the O-rings can be used in both configurations but in one embodiment one O-ring is changed. As well, most O-ring grooves are used in both configurations. In one simple non-limiting embodiment, the difference between the first configuration and the second configuration is an O-ring is removed from one groove and a different O-ring is placed in another groove without need to change the seats. In this way, in one configuration, the valve is bi-directional with primary and secondary seals. In another configuration only the primary seals are bi-directional. However in one direction secondary and tertiary seals are provided. 
         [0056]    Accordingly, because many varying and different embodiments may be made within the scope of the inventive concept(s) herein taught, and because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative of a presently preferred embodiment and not in a limiting sense.