Abstract:
A valve plug includes a cylinder, a first plug seat, a second plug seat, and a convoluted portion. The cylinder has a first and second end. The first plug seat is disposed at the first end. The second plug seat is disposed proximal to the second end. The convoluted portion is disposed between the first seat and the second seat. The convoluted portion provides flexibility for the cylinder to flex between the first plug seat and the second plug seat.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a valve. More particularly, the present invention pertains to a globe valve. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is generally well known that valves are important devices for the regulation of the flow of fluids in pipes or other such conduits. As known to those skilled in the art, a valve regulates the rate of fluid flow as the position of the valve plug within the valve is changed by an actuator. Two important features of a valve, such as a globe valve, are that it is generally desirous to be able to fully stop the flow fluid at the closed position and be capable of withstanding the temperatures and chemical influences of the fluid flowing therethrough. In order to properly stop the flow of fluid, it is advantageous for the mating surfaces within the valve to engage with a relatively high degree of precision. Even with this relatively high degree of precision, valves typically include elastomeric seals such as, washers, O-rings or the like to ensure a fluid-tight seal when the valve is positioned in a closed configuration. Typical globe valves are used in numerous applications ranging from simple level control to boiler feed water systems, superheated bypass applications, control of radioactive fluids, caustic or acidic fluids, and the like. Unfortunately, elastomeric materials are not capable of withstanding some of these relatively extreme conditions. In addition, large globe valves such as those having a flow control orifice or port greater than 6-inches in diameter and are known to suffer from seal failures. 
         [0003]    Unfortunately, it is difficult to provide a seal that functions across a range of pressures and temperatures, that is compatible with a variety of fluids, that allows the valve to be opened and closed with minimal effort, and that is sufficiently wear resistant to withstand repeated opening and closing operations. While these issues are historically well known, conventional valves still suffer from one or more of these disadvantages. 
         [0004]    Accordingly, it is desirable to provide a valve that overcomes the disadvantages described herein at least to some extent. 
       SUMMARY OF THE INVENTION 
       [0005]    The foregoing needs are met, to a great extent, by the present invention, wherein in one respect valve is provided that in some embodiments overcomes the disadvantages described herein at least to some extent. 
         [0006]    An embodiment of the present invention pertains to a valve plug. The valve plug includes a cylinder, a first plug seat, a second plug seat, and a convoluted portion. The cylinder has a first and second end. The first plug seat is disposed at the first end. The second plug seat is disposed proximal to the second end. The convoluted portion is disposed between the first seat and the second seat. The convoluted portion provides flexibility for the cylinder to flex between the first plug seat and the second plug seat. 
         [0007]    Another embodiment of the present invention pertains to a trim for a globe valve. The trim includes a cage and a valve plug. The cage has a first cage seat, an opening, and a second cage seat. The first cage seat is disposed proximal to a first end of the cage. The opening is disposed above the first cage seat. The second cage seat is disposed above the opening. The valve plug includes a cylinder, a first plug seat, a second plug seat, and a convoluted portion. The cylinder has a first and second end. The first plug seat is disposed at the first end. The first plug seat is configured to mate with the first cage seat. The second plug seat is disposed proximal to the second end. The second plug seat is configured to mate with the second cage seat. The convoluted portion is disposed between the first seat and the second seat. The convoluted portion provides flexibility for the cylinder to flex between the first plug seat and the second plug seat. 
         [0008]    Yet another embodiment of the present invention relates to a globe valve. The globe valve includes a body, a cage, and a valve plug. The cage is disposed in the body and has a first cage seat, an opening, and a second cage seat. The first cage seat is disposed proximal to a first end of the cage. The opening is disposed above the first cage seat. The second cage seat is disposed above the opening. The valve plug includes a cylinder, a first plug seat, a second plug seat, and a convoluted portion. The cylinder has a first and second end. The first plug seat is disposed at the first end. The first plug seat is configured to mate with the first cage seat. The second plug seat is disposed proximal to the second end. The second plug seat is configured to mate with the second cage seat. The convoluted portion is disposed between the first seat and the second seat. The convoluted portion provides flexibility for the cylinder to flex between the first plug seat and the second plug seat. 
         [0009]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0010]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0011]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a cross-sectional side view of a globe valve according to an embodiment of the invention. 
           [0013]      FIG. 2  is a split cross sectional view of a portion of the globe valve with one half of the view being in a closed conformation and the other half being in an open conformation according to  FIG. 1 . 
           [0014]      FIG. 3  is a detailed cross-sectional view of the globe valve in a partial closed conformation according to  FIG. 1 . 
           [0015]      FIG. 4  is a detailed cross-sectional view of the globe valve in a fully closed conformation according to  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The present invention provides, in some embodiments, a flexible plug for use in balanced, double-seated globe valve trim and a globe valve with flexible plug. The globe valve is configured to provide control over the flow of fluid therethrough across a relatively wide range of pressures, temperatures, and chemical activity of the fluid. In a particular embodiment, these properties are instilled in the globe valve by virtue of a flexible metal plug that is entirely made from metal and/or includes no elastomeric or polymeric components. The globe valve is configured to provide a fluid-tight seal when positioned in the closed conformation as a result of a double seat with a flexible portion disposed therebetween. In addition to the flexible, all-metal construction, embodiments include some or all of the following features: Pressure balancing for reduced actuator thrust; Exceptional seat leakage tightness (Class V); Capable of continuous high temperature operation; Flexible region of plug capable of infinite cycle life; Employs standard differential angle seats; Available for full range of globe valve trim sizes; Capable of flow under or flow over the web; Simple design with no moving parts; and/or Manufactured with ordinary machining tolerances. 
         [0017]    Embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. Referring now to  FIG. 1 , a balanced, cage style globe valve  10  is illustrated. The globe valve  10  is generally comprised of a body  12 , a bonnet  14 , and trim  16 . The trim  16  contains the internal components of the globe valve  10  that modulate or control fluid flow through the globe valve  10  and includes a flexible plug  18  and a cage  20 . The flexible plug  18  includes a first plug seat  22  and a second plug seat  24 . The cage  20  includes a first cage seat  26  and a second cage seat  28 . Fluid flow through the globe valve  10  is controlled by linear motion of a stem  30  urging the flexible plug  18  along a central longitudinal axis  32 . The stem, in turn, is urged to translate along the central longitudinal axis  32  via the action of an actuator assembly  34 . The actuator assembly  34  may include any suitable conventional actuator assembly. 
         [0018]    The first plug seat  22  and the second plug seat  24  respectively mate with the first cage seat  26  and the second cage seat  28  to provide areas of contact in the cage  20  for the flexible plug  18  to create valve shut-off in order to inhibit fluid flow through globe valve  10 . In various examples, the globe valve  10  may be in a flow-up or flow-down configuration. In a particular example, the globe valve  10  illustrated in  FIG. 1  is shown in a flow-up configuration. The fluid stream flows up through the trim  16  as indicated by a set of flow arrows  40  from an inlet  42 , through the trim  24 , and out an outlet  44 . The force required to move the flexible plug  18  is supplied by an actuator assembly  34  that is directly coupled to the body  12  through the bonnet  14 . The actuation force from the actuator assembly  34  is transferred to the flexible plug  18  through the stem  30  that is rigidly attached to the actuator assembly  34  and the flexible plug  18 . The cage  20  is configured to provide a guide for the flexible plug  18  to slide within. In addition, as further described herein, the cage  20  includes the first cage seat  26  and the second cage seat  28 . The cage  20  is disposed within the body  12  and held in place by a compressive force exerted by the attached bonnet  14 . 
         [0019]    The bonnet  14  is configured to retain pressure of the fluid within the body  12 . The bonnet  14  not only provides a mount for the actuator assembly  34  to the body  12 , compressively retains the cage  20 , but also houses a packing  46  to create a fluid seal around the stem  30 . The bonnet  14  may include any suitable type of bonnet. In a particular example, the bonnet  14  is the bolted-flange type depicted in  FIG. 1  showing a bonnet  14  with a single integral flange or shoulder  48 . 
         [0020]    The balanced-plug globe valve  10  shown in  FIG. 1  allows upstream fluid, and therefore upstream fluid pressure, to pass through a passageway  50  disposed in the flexible plug  18  and thus balance a pressure load on both a top and bottom sides of the flexible plug  18 . This pressure balance nullifies most of the static unbalance force on the flexible plug  18 . The reduced unbalance force permits operation of the globe valve  10  with smaller actuators than those necessary for conventional unbalanced, valve bodies. 
         [0021]    The globe valve  10  shown in  FIG. 1  is illustrated in both an open and closed conformation. That is, the cross sectional view is split along the central longitudinal axis  32  with a view  52  to the left being in the closed conformation and a view  54  to the right being in the open conformation. The views  52  and  54  are shown in greater detail in  FIG. 2 . In  FIG. 2 , the view  52  shows a first seal  56 , a second seal  58  and an opening  60  disposed between the first and second seals  56  and  58 . In this manner, the opening  60  may be completely sealed off in response to the first seal  56  and second seal  58  being sealed. In response to the seal  56  and seal  58  being unsealed, the opening  60  is configured to allow the fluid to flow therethrough. In this regard, the opening  60  may include any suitable passage or passages configured to allow fluid to flow therethrough. In a particular example, the opening  60  may include a screen or mesh-like area at a portion of the cage  20 . In another example, the opening  60  may include one or more holes bored through or formed in the cage  20 . In yet other examples, the opening  60  may include slots or other such conduits for the flow of the fluid through the globe valve  10 . 
         [0022]    Disposed between the first plug seat  22  and the second plug seat  24  is a spring or convolution  70 . The convolution  70  is configured to provide flexibility in the flexible plug  18  between the first plug seat  22  and the second plug seat  24 . As shown, the convolution  70  includes a serpentine wall with material properties that allow the convolution  70  to flex when compressed and then return to a nominal shape when not under a load. This flexibility allows the first seal  56  and the second seal  58  to be formed while accommodating minor irregularities. This action is similar to the role an elastomeric seal plays in a conventional valve. However, in the globe valve  10 , the use of the flexible plug  18  provides for this ability without the disadvantages of elastomeric seals. For example, the convolution  70  may be as heat, radiation, and/or chemical tolerant as the base metal used in the flexible plug  18 . In another example, the convolution  70  may be able to withstand substantially more open/close cycles than an elastomeric seal. These and other advantages may be provided by the convolution  70 . 
         [0023]      FIG. 3  is a detailed cross-sectional view of the globe valve  10  in a partial closed conformation according to  FIG. 1 . As shown in  FIG. 3 , in this partial closed or initial conformation, the first plug seat  22  is brought in contact with the first cage seat  26  to establish the first seal  56 . The convolution  70  includes a spring rate (k) in newton/meters (N/m). Factors that may influence the spring rate of the convolution  70  include the thickness of the materials selected and material properties of those materials including the temperature profile the materials have been subjected to. 
         [0024]    At a stem force from about 0 newtons until the spring rate is overcome, a gap  72  is present. The spring rate and gap  72  determine the amount of compressive force closing the first seal  56 . That is, once a sufficient load is placed on the stem  30  (stem force) to contact the second plug seat with the second cage seat  28 , any additional stem force is essentially not transferred to the first seal  56  but instead, further compresses the second seal  58 . By varying these factors, the spring rate may be configured to provide sufficient force upon the first plug seat  22  to seal the first seal  56 . It is an advantage that the compressive closing force on the first seal  56  can be controlled by modulating the spring rate and the size of the gap  72  at a stem force of about 0 newtons. This relationship is described in the following equation: 
         [0000]      F 1 =kx  eq. 1
 
         [0025]    Where F 1  is the compressive force on the first seal  56 , k is the spring rate (in kilograms(kg)/meter(m)) of the convolution  70 , and x is the length (m) of the gap  72  at the point where the first plug seat  22  and first cage seat  26  make contact and the stem force is 0 newtons. In this manner, a sufficient force to seal the first seal  56  may be applied while minimizing the possibility of over-compressing the first seal  56 . The amount of force used to seal the first seal  56  depends upon a variety of factors such as, for example, a contact area of the first seal  56 , surface finishing and material properties at the contact area, machining tolerances, expected flow rate, pressure, fluid, etc. in the globe valve  10 , empirical data, and the like. 
         [0026]    At this partial close position, in either a flow over or flow under conformation of the flow in the globe valve  10 , the fluid pressures are balanced. For example, in a flow over conformation, fluid entering from below the cage  20  may flow through the passageway  50  such that the pressures on either side of the flexible plug  18  are balanced. In a flow under conformation, the fluid may flow through the gap  72  to flow above the flexible plug  18  and then flow through the passageway  50  to again balance the pressures on the flexible plug  18 . In conventional, single seat valves, actuator loads required to close the valve can become excessive—particularly at larger trim sizes and/or for higher pressure drops across the trim. 
         [0027]      FIG. 4  is a detailed cross-sectional view of the globe valve  10  in a fully closed conformation according to  FIG. 1 . As shown in  FIG. 4 , in this closed conformation, the second plug seat  24  is brought in contact with the second cage seat  28  to establish the second seal  58 . Once this initial contact is made, further compression of the second seal  58  acts to seal the second seal  58 . 
         [0028]    In order to close the second seal  58 , a second force (F 2 ) in addition to F 1  applied to the stem  30 . The amount of force used to seal the second seal  58  depends upon a variety of factors such as, for example, a contact area of the second seal  58 , surface finishing and material properties at the contact area, machining tolerances, expected flow rate, pressure, fluid, etc. in the globe valve  10 , empirical data, and the like. The amount of force used to seal the second seal  58  is described in the following equation: 
         [0000]        F   seal   kx+F   2   eq. 2
 
         [0029]    Where F seal  is the force exerted by the actuator assembly  34  (shown in  FIG. 1 ) and translated via the stem  30  to the flexible plug  18 , k is the spring rate (kg/m) of the convolution  70 , x is the length (m) of the gap  72  at the point where the first plug seat  22  and first cage seat  26  make contact and the stem force is 0 newtons, and F2 is the amount of force configured to seal the second seal  58 . In this manner, a sufficient force to seal the second seal  58  may be applied while minimizing the possibility of over-compressing the second seal  58 . 
         [0030]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.