Abstract:
A positive displacement pump fluid end with multiple fluid chambers and each fluid chamber comprising a valve body, valve seal, seat, spring, and external guide. External top male stem guide is integral to the fluid end discharge cover or the suction valve spring retainer. Female guide is internal and integral with the valve body. When the valve opens hydrodynamic forces and moments align the valve to prevent rotation. An embodiment features tapered male and female guide members to further assist in correct alignment of the valve with the seat. Various additional embodiments assist in venting any trapped fluids between the male and female portions of the guide.

Description:
FIELD OF THE INVENTION 
     The invention generally concerns high-pressure plunger-type pumps useful, for example, in oil well hydraulic fracturing. More specifically, the invention relates to valves suitable for rapid open-close cycling when pumping abrasive fluids, such as sand slurries at high pressures. 
     BACKGROUND OF THE INVENTION 
     Engineers typically design high-pressure oil field plunger pumps in two sections; the (proximal) power section and the (distal) fluid section. The power section usually comprises a crankshaft, reduction gears, bearings, connecting rods, crossheads, crosshead extension rods, etc. The power section is commonly referred to as the power end by the users and hereafter in this application. The fluid section is commonly referred to as the fluid end by the users and hereafter in this application. Commonly used fluid sections usually comprise a plunger pump housing having a suction valve in a suction bore, a discharge valve in a discharge bore, an access bore, and a plunger in a plunger bore, plus high-pressure seals, retainers, etc.  FIG. 1  is a cross-sectional schematic view of a typical fluid end showing its connection to a power end by stay rods.  FIG. 1  also illustrates a fluid chamber which is one internal section of the housing containing the valves, seats, plungers, plunger packing, retainers, covers, and miscellaneous seals previously described. A plurality of fluid chambers similar to that illustrated in  FIG. 1  may be combined, as suggested in the Triplex fluid end housing schematically illustrated in  FIG. 2 . It is common practice for the centerline of the plunger bore and access bore to be collinear. Typically in the prior art, the centerlines of the plunger bore, discharge bore, suction bore, and access bore are all arranged in a common plane. The spacing of the plunger bores, plungers, plunger packing, and plunger gland nut within each fluid chamber is fixed by the spacing of the crank throws and crank bearings on the crankshaft in the power end of the pump. 
     Valve terminology varies according to the industry (e.g., pipeline or oil field service) in which the valve is used. In some applications, the term “valve” means just the valve body, which reversibly seals against the valve seat. In other applications, the term “valve” includes components in addition to the valve body, such as the valve seat and the housing that contains the valve body and valve seat. A valve as described herein comprises a valve body and a corresponding valve seat, the valve body typically incorporating an elastomeric seal within a peripheral seal retention groove. 
     Valves can be mounted in the fluid end of a high-pressure pump incorporating positive displacement pistons or plungers in multiple cylinders. Such valves typically experience high pressures and repetitive impact loading of the valve body and valve seat. These severe operating conditions have in the past often resulted in leakage and/or premature valve failure due to metal wear and fatigue. In overcoming such failure modes, special attention is focused on valve sealing surfaces (contact areas) where the valve body contacts the valve seat intermittently for reversibly blocking fluid flow through a valve. 
     Valve sealing surfaces are subject to exceptionally harsh conditions in exploring and drilling for oil and gas, as well as in their production. For example, producers often must resort to “enhanced recovery” methods to insure that an oil well is producing at a rate that is profitable. And one of the most common methods of enhancing recovery from an oil well is known as fracturing. During fracturing, cracks are created in the rock of an oil bearing formation by application of high hydraulic pressure. Immediately following fracturing, a slurry comprising sand and/or other particulate material is pumped into the cracks under high pressure so they will remain propped open after hydraulic pressure is released from the well. With the cracks thus held open, the flow of oil through the rock formation toward the well is usually increased. 
     The industry term for particulate material in the slurry used to prop open the cracks created by fracturing is the propend. And in cases of very high pressures within a rock formation, the propend may comprise extremely small aluminum oxide spheres instead of sand. Aluminum oxide spheres may be preferred because their spherical shape gives them higher compressive strength than angular sand grains. Such high compressive strength is needed to withstand pressures tending to close cracks that were opened by fracturing. Unfortunately, both sand and aluminum oxide slurries are very abrasive, typically causing rapid wear of many component parts in the positive displacement plunger pumps through which they flow. Accelerated wear is particularly noticeable in plunger seals and in the suction (i.e., intake) and discharge valves of these pumps. 
     A valve (comprising a valve body and valve seat) that is representative of an example full open design valve and seat for a fracturing plunger pump is schematically illustrated in  FIG. 3 .  FIG. 4  shows how sand and/or aluminum oxide spheres may become trapped between seating surface of valve body and seating surface of valve seat as the suction valve closes during the pump&#39;s pressure stroke. 
     The valve of  FIG. 3  is shown in the open position.  FIG. 4  shows how accelerated wear begins shortly after the valve starts to close due to back pressure. For valve, back pressure tends to close the valve when downstream pressure exceeds upstream pressure. For example, when valve is used as a suction valve, back pressure is present on the valve during the pump plunger&#39;s pressure stroke (i.e., when internal pump pressure becomes higher than the pressure of the intake slurry stream. During each pressure stroke, when the intake slurry stream is thus blocked by a closed suction valve, internal pump pressure rises and slurry is discharged from the pump through a discharge valve. For a discharge valve, back pressure tending to close the valve arises whenever downstream pressure in the slurry stream (which remains relatively high) becomes greater than internal pump pressure (which is briefly reduced each time the pump plunger is withdrawn as more slurry is sucked into the pump through the open suction valve). 
     When back pressure begins to act on a valve, slurry particles become trapped in the narrow space that still separates the sealing surfaces of the valve body and seat. This trapping occurs because the valve is not fully closed, but the valve body&#39;s elastomeric seal has already formed an initial seal against the valve seat. The narrow space shown in  FIG. 4  between metallic sealing surfaces of the valve body and valve seat is typically about 0.040 to about 0.080 inches wide; this width (being measured perpendicular to the sealing surfaces of the valve body and seat) is called the standoff distance. The size of the standoff distance is determined by the portion of the valve body&#39;s elastomeric seal that protrudes beyond the adjacent valve body sealing surfaces to initially contact, and form a seal against, the valve seat. As schematically illustrated in  FIG. 4 , establishment of this initial seal by an elastomeric member creates a circular recess or pocket that tends to trap particulate matter in the slurry flowing through the valve. 
     Formation of an initial seal as a valve is closing under back pressure immediately stops slurry flow through the valve. Swiftly rising back pressure tends to drive slurry backwards through the now-sealed valve, but since back-flow is blocked by the initial valve sealing, pressure builds rapidly on the entire valve body. This pressure acts on the area of the valve body circumscribed by its elastomeric seal to create a large force component tending to completely close the valve. For example, a 5-inch valve exposed to a back pressure of 15,000 pounds per square inch will experience a valve closure force that may exceed 200,000 pounds. 
     The large valve closure force almost instantaneously drives the affected valve, whether suction or discharge, to the fully closed position where the metal sealing surface of the valve body contacts the corresponding metal sealing surface of the valve seat. As the valve body moves quickly through the standoff distance toward closure with the valve seat, the elastomeric seal insert is compressed, thus forming an even stronger seal around any slurry particles that may have been trapped between the seal insert and the valve seat. 
     Simultaneously, the large valve closure force acting through the standoff distance generates tremendous impact energy that is released against the slurry particles trapped between the metallic sealing surfaces of the valve body and the valve seat. As shown in  FIG. 4 , the slurry particles that are trapped between approaching valve seating surfaces are crushed. 
     In addition to the crushing action described above, slurry particles are also dragged between the valve sealing surfaces in a grinding motion. This grinding action occurs because valve bodies and seats are built with complementary tapers on the sealing surfaces to give the valve a self-alignment feature as the valve body closes against the seat. As the large valve closing force pushes the valve body into closer contact with the seat, the valve body tends to slide down the sealing surface taper by a very small amount. Any crushed slurry particles previously trapped between the sealing surfaces are then ground against these surfaces, resulting in extreme abrasive action. 
     Extrusion of the elastomeric valve insert seal is also a major factor influencing the performance of valves and seats for high-pressure oil field plunger pumps when pumping sand slurries.  FIG. 3  schematically illustrates a cross-section of a typical high-pressure pump valve comprising a valve seat with a corresponding valve body having a peripheral elastomeric valve insert seal. As the valve of  FIG. 3  closes,  FIG. 4  schematically shows that the elastomeric seal in a peripheral seal retention groove contacts the valve seat while the valve body&#39;s impact area is still separated from the valve seat by a gap (identified herein as the extrusion gap). Trapped sand or propend particles from the pumped fluid are schematically illustrated in the extrusion gap in  FIG. 4 .  FIGS. 5A and 5B  also show the trapped sand or propend particles in the extrusion gap, as well as a portion of the peripheral elastomeric seal that has extruded into the gap. Extrusion of the peripheral elastomeric seal into the gap typically occurs due to high back pressure acting on the seal. High back pressure also tends to quickly close the valve body against the valve seat, thus closing the gap. But particulate matter in the pumped fluid that is trapped in the gap between the impact area of the valve body and the valve seat may prop the gap open. 
     During valve closure the elastomeric seal typically seals against the valve seat slightly before contact of the valve body impact area and the valve seat. Extrusion of seal elastomer into the extrusion gap thus begins while the valve body impact area is approaching the valve seat. If the extrusion gap is prevented from completely closing by trapped particulate matter, seal extrusion becomes more severe as back pressure on the valve increases (see  FIGS. 5A and 5B ). Such extrusion leads to weakening and tearing of the seal elastomer, causing extrusion damage (see  FIG. 6 ), seal failure and premature valve failure. 
     Typically the motion of the valve body is controlled by valve guide legs attached to the bottom or upstream side of the valve body as shown in  FIG. 3 . Unfortunately these guide legs are another source of accelerated valve and seat failure when pumping high sand slurry concentrations.  FIG. 7A  illustrates an old style valve design, circa 1970, in which the valve legs are forged into the upstream side of the valve body; typical of a Mission Service Master I design.  FIG. 7B  illustrates the slurry flow patterns around the leg; as can be seen in the figure, the downstream side of the legs generates considerable turbulence in the flow. The swirling turbulence in the sand slurry used in typical fracturing work results in sever abrasion of the metal valve body and the elastomeric insert seal, which quickly damages the seal, resulting in seal failure. Once the seal fails on the valve insert, the high pressure fluid on the downstream side of the valve escapes through the seal failure to the low pressure upstream side of the valve. Travelling from the very high pressure to the very low pressure side of the valve results in extreme velocities of the sand slurry, which rapidly erodes the metal valve body and the guide legs in the slurry&#39;s path; many times destroying the entire valve leg. Engineers typically recognize the beginning of this failure by four (4) erosion marks behind each leg on worn valves removed from the pump just prior to catastrophic failure in which one or more of the valve legs are completely destroyed by the high pressure erosion. The abraded seal and erosion of the metal valve body are also illustrated in  FIG. 7B . 
     The development of the Roughneck valve design, circa 1983, and later the Mission Service Master II valve or the Novatech valve shown in  FIG. 8A  greatly improved the flow behind the legs. These designs featured streamlined legs which were achieved by inertia welding an investment guide leg casting to the valve body forging. The streamlined legs and the open area below the valve body and downstream of the guide legs eliminated much of the turbulence behind the guide legs. However in severe pumping environments with high pump rates and high slurry concentrations the problem described in the previous paragraph still existed as evidenced by the four (4) erosion marks and destroyed guide legs.  FIG. 8B  is a picture a state of the art valve damaged by seal failure and severe erosion behind the guide legs. 
     The most obvious solution to the problem described above is the removal of the guide legs and somehow guide the motion of the valve by other means. Top stem valves, illustrated in  FIGS. 9A, 9B, and 10 , attempt this solution. A similar top Stem Valve is illustrated in U.S. Pat. No. 6,698,450. However top stem design valves are inherently unstable in the open position. Once pushed off center by hydraulic flow as illustrated in  FIG. 11A , the forces on the valve tend to push the valve further off center. As the valve continues its cyclic repeating opening and closing, the sliding forces cause rapid and accelerating wear on the top stem guide. 
     The problem of instability is best visualized by comparing a top stem guided valve to the arrow of a weather vane. A weather vane rotates around a pivot point. On a weather vane stabilizing moment is generated by the aerodynamic force on the tail fin multiplied by the moment arm measured from the pivot point to center of the aerodynamic force. This stabilizing force is countered by a destabilizing moment generated by the aerodynamic force on the arrow tip at the front of the vane multiplied by the moment arm measured from the pivot point to center of the force on the arrow. The weather vane always points into the direction of the flow (wind) because there is always more moment or stabilizing force from the tail fins behind the pivot point than moment in front of the pivot point. If the pivot point were moved to the very front or tip of the arrow, then the vane would be extremely stable. Conversely, if the pivot point were moved to the extreme rear of the arrow the vane would be extremely unstable in a fluid flow. Furthermore, if the vane pivots at the rear and as a consequence the vane moves off center to the flow, the vane will move 180 degrees in the flow. Analogizing this to valve in fluid flow, without guidance, the valve would tumble and never close properly. 
     While weather vanes typically use fins to stabilize the vane, conical or cylindrical surfaces at the rear of the vane would function similarly to fins on a typical weather vane. Valves do not have vanes parallel to flow as do weather vanes; however valves do have conical and cylindrical surfaces with the axis of these surfaces parallel to the flow. The bottom conical valve surface can function to stabilize the valve in fluid flow depending on the location of the pivot point. Compare the bottom surface of a similar body, the Apollo Space Capsules. These capsules have a similar shaped body to a valve without guide legs. 
       FIG. 10  is a partial cross-section schematically illustrating discharge valve body in its closed position (i.e., with peripheral elastomeric seal held in symmetrical contact with valve seat by discharge valve spring). Note that top guide stem of discharge valve body is aligned in close sliding contact with top valve stem guide. 
       FIG. 11A  illustrates flow around the discharge valve when the valve is in the fully open position, immediately after first opening of the valve. However there are hydrodynamic forces on the valve from the flow which is making a significant change in direction in order to exit through the discharge manifold. These forces quickly move the valve to a position illustrated in  FIG. 11B . As shown in  FIG. 11B , the valve moves downstream in the flow however the valve&#39;s movement is limited by the valve stem guide in which the valve&#39;s top stem translates. The valve in turn rotates around the pivot point which is the circumferential edge at the bottom of the valve guide. Because the pivot point is above the area on which the hydrodynamic forces act, the valve is continuously pushed off center.  FIG. 11C  is the side view of the valve illustrating the area of the valve on which the hydrodynamic forces act, where A1 is the side area of the valve subjected to hydrodynamic forces that would stabilize the valve and A2 is the side area of the valve subjected to forces that would destabilize the valve in fluid flow around the valve. Because the pivot point is above the area on which the hydrodynamic forces act, the valve is continuously pushed off center. The destabilizing moment is equal to the product of the side area of the valve, A2, multiplied by the length of the destabilizing arm or Arm 2 which is measured from the centroid of the area CT2 to the pivot point. As there is no area, A1, above the pivot point, CT1 does not exist, then the stabilizing arm length Arm 1 equals zero and the product of A1 times Arm 1 equals zero; the stabilizing moment then also equals zero. Thus top stem guided valves act similar to a weather vane in which the pivot point is positioned at the rear of the vane. Expressed mathematically:
 
 A 1×Arm 1=0 &lt;A 2×Arm 2.
 
       FIG. 11D  schematically illustrates how misalignment of top guide stem is possible with excessive wear of top valve stem guide. Such excessive wear can occur because discharge valve body, including top guide stem, is typically made of steel that has been carburized to a hardness of about 60 Rockwell C. In contrast, the wall of top valve stem guide, which is shown in  FIG. 11  as being formed within discharge cover, is typically made of mild alloy steel with a hardness of about 30 Rockwell C. Thus the softer wall of stem guide is worn away by sliding contact with the harder guide stem. This wear is accelerated by side loads on valve body that result when fluid flowing past the valve body changes its direction of flow into the discharge manifold. Analogous side loads would be present on a suction valve when fluid flowing past the valve body changes its direction of flow into the plunger cavity. 
     Eventually, top valve stem guide can be worn sufficiently to allow discharge valve leakage due to significant asymmetric contact of elastomeric seal with valve seat as schematically illustrated in  FIG. 12 . This problem of stem guide wear is typically addressed in practice through use of a replaceable bushing having a modified top valve stem guide (see the schematic illustration in  FIG. 13 ). Bushing is commonly made of a plastic such as urethane, or a wear and corrosion-resistant metal such as bronze. Such bushings require periodic checking and replacement, but these steps may be overlooked by pump mechanics until a valve fails prematurely. 
     When the open valve is badly misaligned and the valve guide is badly worn there are not aligning forces available to properly align the valve as it closes. Thus the valve will close against the seat in a miss-aligned or cocked position as shown in  FIG. 12 . In this position, the side of the cocked valve leaves an extrusion gap that results in shorten valve insert seal life. The cocked valve also results in uneven loading of the metal valve body against the seating surface of the seat resulting in accelerated metal wear on the valve body and seat. 
     SUMMARY OF THE INVENTION 
     The present invention addresses both the problem of premature valve failures in high pressure fracturing pumps due to turbulent flow around the guide legs and instability in top stem guided valves. The present invention features a conical shape on the upstream side of the valve body for improved flow. Elimination of guide legs prevents turbulence that damages the valve insert seal. Rather than guide the valve with external lower guides or upper stem guides, the valve of the present invention is internally guided by a female guide internal to the valve body. As said valve translates between the closed and open position, an external male guide member acting against the female guide member functions to guide and stabilize the valve. Male guide member is integral to either the discharge cover or suction valve spring retainer members of the fluid end. Valves of the present invention are most often fitted in plunger pumps, however said valves may also be used in all positive displacement pumps fitted with a reciprocating plunger, piston, or diaphragm. 
       FIG. 14A  schematically illustrates a cross-section of a right-angular plunger pump with valves of the present invention.  FIG. 14B  schematically illustrates area “B-B” of  FIG. 14A  and the discharge valve, seat, spring, and valve guide of the present invention with the valve in the closed position. Valve body is guided by an inverted male top stem in which the stem is integral with the suction valve spring retainer or the discharge cover. The present invention includes a valve guide internal to the valve body which is a blind hole on the downstream side of the valve body. When the valve first opens during normal cyclic operation, the valve is forced against the stem by hydrodynamic forces from the pumped fluid as shown in  FIG. 15A .  FIG. 15A  also shows the valve attempting to rotate around the pivot point. However unlike top stem guided valves previously described the pivot point on the valve of the present invention is located well below the center of area on which the hydrodynamic forces act as shown in  FIG. 15B , where A3 is the side area of the valve subjected to hydrodynamic forces that would stabilize the valve and A4 is the side area of the valve subjected to forces that would destabilize the valve in fluid flow around the valve. The stabilizing moment is calculated by multiplying the length of the stabilizing arm, Arm 3 by the area above the pivot point, A3. The stabilizing arm is the distance from the pivot point to the centroid CT3 of the area A3. The destabilizing moment is the product of the destabilizing area A4 multiplied by the length of the destabilizing arm, Arm 4, which is measured from the pivot point to the centroid CT4 of the area A4.  FIG. 15B  illustrates that the stabilizing moment is greater than the destabilizing moment when the valve of the present invention first opens or:
 
 A 3×Arm 3 &gt;A 4×Arm4.
 
Compared to the unstable valve of  FIGS. 11B and 11C , the valve of  FIGS. 15A and 15B  has a stabilizing moment that exceeds the destabilizing moment.
 
       FIG. 15A  illustrates some initial rotation of the valve around the pivot point when the valve first opens, however the rotation ceases as the valve opens to the fully open position, thus further increasing the hydrodynamic forces on the valve and increasing the stabilizing moment. As the valve fully opens as illustrated in  FIG. 16A , the stabilizing moment as shown in  FIG. 16B  increases compared to the destabilizing moments. When the valve is fully open the valve is now correctly aligned and the valve&#39;s centerline is parallel with the seat centerline. In  FIG. 16B  area A5 is the side area of the valve subjected to hydrodynamic forces that would stabilize the valve and A6 is the side area of the valve subjected to forces that would destabilize the valve in fluid flow around the valve. The stabilizing moment, calculated by multiplying the length of the stabilizing arm, Arm 5 by the area above the pivot point A5, increases. The stabilizing arm Arm 5 is the distance from the pivot point to the centroid CT5 of the area A5. The destabilizing moment is the product of the destabilizing area A6 multiplied by the length of the destabilizing arm, Arm 6, which is measured from the pivot point to the centroid CT6 of the area A6.  FIG. 16B  illustrates that the stabilizing moment is greater than the destabilizing moment when the valve of the present invention reaches the fully open position, expressed mathematically:
 
 A 5×Arm 5 &gt;&gt;A 6×Arm 6.
 
     Note that the net stabilizing moment is now greater than the net stabilizing moment of the valve of  FIGS. 15A and 15B . When the valve of  FIG. 16B  closes all fluid flow has abated, thus non-symmetrical forces to move the valve out-of-alignment with the seat are eliminated; the valve then closes in alignment with the seat. 
     Because of the solid particles in slurry fluids, there must be sufficient clearance between the guide members of any valve assembly. Without sufficient clearance, solid particles become trapped and lodged between the guide members of the assembly. These trapped particles can then hold the valve open and prevent closure which would then prevent the pump from pumping. This clearance results in some misalignment between the valve and seat regardless of design. In the present invention, this misalignment can be minimized by utilizing tapered male and female components of the guide assembly as illustrated in  FIGS. 17, 18A and 18B .  FIG. 17  illustrates the present invention with tapered male and female guide members and the valve in the closed position. The amount of clearance between the male and female guide components illustrated in  FIG. 17  is typical of the clearance between guide members of valve designs of the prior art. When the valve of  FIG. 17  opens as illustrated in  FIG. 18A , the tapered male and female guide members move act to move the valve into closer alignment with the male guide member and the seat. Any misalignment between the valve and seat is corrected by the converging tapered male and female guide components. Should solid particles become trapped between the mating tapered surfaces as the valve reaches the full open valve position, the large force from the full compressed spring will force the valve closed freeing any trapped particles as the space opens between the tapered surfaces. 
     As illustrated in  FIG. 18B  area A7 is the side area of the valve subjected to hydrodynamic forces that would stabilize the valve and A8 is the side area of the valve subjected to forces that would destabilize the valve in fluid flow around the valve. The stabilizing moment, calculated by multiplying the length of the stabilizing arm Arm 7 by the area above the pivot point A7, increases. The stabilizing arm is the distance from the pivot point to the centroid CT7 of the area A7. The destabilizing moment is the product of the destabilizing area A8 multiplied by the length of the destabilizing arm, Arm 8, which is measured from the pivot point to the centroid CT8 of the area A8.  FIG. 18B  illustrates that the net stabilizing moment is greater than the net stabilizing moments of valves of  FIGS. 15B and 16B . The greater net stabilizing moment is expressed mathematically:
 
 A 7×Arm 7 &gt;&gt;&gt;A 8×Arm8.
 
     The combination of the low pivot point and the tapered male and female components of the present invention serve to keep the valve from rotating and keep the valve in proper alignment through the opening and closing movement of the valve during normal pumping operations. 
     An alternate embodiment of the invention features an internal guide bushing made from a low friction material such as Nylon or other plastic materials. The guide bushing may be cast-in-place in the valve body as described in the applicants U.S. Pat. No. 7,168,440. The guide bushing further may contain flutes or longitudinal grooves on the internal portion of the guide to relieve any trapped fluids that would impede the opening or closing of the valve. Flutes or grooves further prevent sand particles from becoming wedged between the male and female portion of the guide and thus preventing the valve from normal opening or closing operation. 
     In a further embodiment of the invention, the stem guide may also contain a coaxial hole vented to relieve any trapped fluids that would impede the opening or closing of the valve. In a further embodiment of the invention, a conical spring is fitted around a boss at the base of the stem guide and also fitted inside an integral ring on top of the valve. The close fit of the conical spring serves to provide support for the guidance for the reciprocal motion of the valve of this invention along a predetermined axis. Conical spring provides a biasing force to force said valve toward a closed position with said valve seat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional schematic view of a typical plunger pump fluid section showing its connection to a power section by stay rods. 
         FIG. 2A  is an exterior view of the fluid end housing shown in a sectional view in  FIG. 1 ;  FIG. 2B  is the front projected view of the fluid end housing of  FIG. 2A ;  FIG. 2C  is the top projected view of the fluid end housing of  FIG. 2A ; and  FIG. 2D  is the rear projected view of the fluid end housing of  FIG. 2A . 
         FIG. 3  schematically illustrates a cross-section of a typical high-pressure pump valve comprising a valve body and a corresponding valve seat. 
         FIG. 4  schematically illustrates the formation of an extrusion gap as the valve of  FIG. 3  closes. 
         FIG. 5A  schematically illustrates extrusion of seal elastomer into the extrusion gap shown in  FIG. 4 , the gap being held open by particulate matter trapped between the valve body impact area and the valve seat. 
         FIG. 5B  schematically illustrates an enlargement of the area indicated in  FIG. 5A . 
         FIG. 6  schematically illustrates seal extrusion damage caused by tearing of the extruded seal as shown in  FIGS. 5A and 5B . 
         FIG. 7A  schematically illustrates a valve body design in which the legs are forged into the main valve body. 
         FIG. 7B  schematically illustrates the valve of  FIG. 7A  and the flow turbulence around the guide legs. 
         FIG. 8A  schematically illustrates the current state of the art valve design in which the guide legs are a streamlined investment casting to provide improved fluid flow. 
         FIG. 8B  is a picture of an actual valve of a design schematically illustrated in  FIG. 8A  and the erosion damage due to turbulent fluid flow. 
         FIG. 9A  schematically illustrates a cross-section of a right-angular plunger pump having a top stem guided suction valve and a top stem guided discharge valve. 
         FIG. 9B  schematically illustrates the sectional view labeled B-B in  FIG. 9A . 
         FIG. 10  is a partial cross-section schematically illustrating detail of the top stem guided discharge valve of  FIGS. 9A and 9B . 
         FIG. 11A  schematically illustrates flow around a discharge valve with the valve in the full open position. 
         FIG. 11B  schematically rotation of the discharge valve body of  FIG. 11A . 
         FIG. 11C  schematically illustrates a side view of  FIG. 11B  and the moment applied to the valve by the flow. 
         FIG. 11D  schematically illustrates extreme rotation of the valve of  FIG. 11B  due to worn valve guide. 
         FIG. 12  schematically illustrates improper closure of the discharge valve of  FIG. 10  due to unstable misalignment and rotation of the valve. 
         FIG. 13  schematically illustrates a replaceable bushing in a modification of the top valve stem guide shown in  FIG. 10 . 
         FIG. 14A  schematically illustrates a cross-section of a right-angular plunger pump with a fluid chamber having a top stem internally guided suction and discharge valves of the present inventions. 
         FIG. 14B  schematically illustrates an enlargement of Area “B-B” of  FIG. 14A  according to the present invention. 
         FIG. 15A  schematically illustrates the valve of  FIG. 14B  in the partially opened position in which the valve begins to rotate around the pivot point between the female valve guide integral with the valve body and the male valve guide integral with the discharge cover. 
         FIG. 15B  schematically illustrates a side view of  FIG. 15A  and the moments applied to the valve by the flow. 
         FIG. 16A  schematically illustrates the valve of  FIG. 14B  in the fully opened position and the valve rotated around the pivot point to a position in which the centerline of the valve is aligned with the centerline of the seat. 
         FIG. 16B  schematically illustrates a side view of  FIG. 16A  and the moments applied to the valve by the flow. 
         FIG. 17  schematically illustrates an alternate embodiment of the valve of  FIG. 14B  with a tapered female valve guide integral with the valve body and a tapered male valve guide integral with the discharge cover. 
         FIG. 18A  schematically illustrates the valve of  FIG. 17  in the fully opened position and the tapered surfaces of the female and male guides are mated in which the centerline of the valve is collinear with the centerline of the seat. 
         FIG. 18B  schematically illustrates a side view of  FIG. 18A  and the moments applied to the valve by the flow. 
         FIG. 19A  schematically illustrates an alternate embodiment of a top stem internally guided valve body with an internal guide in which the female portion of the guide has a wear bushing with fluted grooves made according to the present invention. 
         FIG. 19B  schematically illustrates the sectional view labeled B-B in  FIG. 19A . 
         FIG. 20  schematically illustrates an alternate embodiment of a top stem internally guided valve body with an internal guide in which the male portion of the guide is internally vented to relieve trapped fluids between the male guide and the bottom of the female guide. 
         FIG. 21  schematically illustrates an alternate embodiment of a top stem internally guided valve body with an internal guide wherein guidance is enhanced with the addition of close fitting conical spring. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 14A  schematically illustrates a cross-section of a right-angular plunger pump fluid end housing  12 , with a fluid chamber  1 , having internally guided suction and discharge valves of the present inventions. Fluid Chamber  1  has discharge fluid chamber  2  and a suction chamber  3 , wherein discharge fluid chamber  2  contains a discharge seat  250 , discharge valve and seal assembly  230 , discharge cover  211 , male stem guide  271 , and a discharge spring  241 . Suction fluid chamber  3  contains a suction seat  350 , suction valve and seal assembly  330 , suction valve spring retainer  311 , suction male stem guide  371 , and a suction spring  341 . Fluid chamber  1  also contains a plunger  14 . Discharge fluid chamber  2  is connected to adjacent discharge fluid chambers by a discharge manifold  13 . 
       FIG. 14B  schematically illustrates an embodiment of the present invention. Discharge valve assembly  210  is positioned in the discharge fluid chamber  2 , which is one of multiple chambers inside fluid end housing  12 . A valve body and seal assembly  230  comprising a top stem internally guided valve body  260  having a elastomeric seal insert  269 . Valve body and seal assembly  230  are components of a valve and seat assembly  220  which is composed of seat  250  and valve body and seal assembly  230 . Similarly the complete discharge valve assembly  210  includes discharge cover  211 , valve spring  241 , and valve and seat assembly  220 . Valve body  260  has a downstream portion  264  substantially conical in shape and a top or upstream side with an internal stem guide section  261  which is composed of a cylindrical section  263  and a lower section  262 . Discharge Cover  211  has an integral male stem guide  271  which has a cylindrical section  273  and a lower section  272  at the bottom of stem guide  271 . Seat  250  has venturi throat section  251  for improved flow and reduced fluid turbulence. 
       FIG. 17  schematically illustrates an embodiment of a valve body and seal assembly  230 ′ comprising a top stem internally guided valve body  260 ′ having an elastomeric seal or insert  269 . Valve body and seal assembly  230 ′ are components of a valve and seat assembly  220 ′ which is composed of seat  250  and valve body and seal assembly  230 ′. Similarly the complete discharge valve assembly  210 ′ includes discharge cover  211 ′, valve spring  241 , and valve and seat assembly  220 ′. Valve body  260 ′ has a downstream portion  264  substantially conical in shape and a top or upstream side with an internal stem guide section  261 ′ which is composed of a tapered section  263 ′ and a lower stem seat section  262 ′. Discharge Cover  211 ′ has an integral male stem guide  271 ′ which has a tapered body section  273 ′ and a lower complementary seating section  272 ′ at the bottom of stem guide  271 ′, wherein the complementary seating section  272 ′ mates with the stem seat section  262 ′ when the valve stem is in the fully seated position. Seat  250  has venturi throat section  251  for improved flow and reduced fluid turbulence. Fluid End housing  12 , fluid chamber  2 , and discharge manifold  13  are unchanged from previous embodiments of this application. 
       FIGS. 19A and 19B  schematically illustrates an embodiment of a valve body and seal assembly  230 ″ comprising a top stem internally guided valve body  260 ″ having an elastomeric seal or insert  269  and a female guide member  281 . Valve and seat assembly  220 ″ is composed of seat  250  and valve body and seal assembly  230 ″. Similarly the complete discharge valve assembly  210 ″ includes discharge cover  211 , valve spring  241 , and valve and seat assembly  220 ″. A guide bushing  281  made of a low friction material is pressed or molded into valve body  260 ″. Guide bushing  281  contains two or more longitudinal grooves  282 . Guide bushing  281  also contains two or more crests or flats  283  which form the inner most surface of the guide bushing  281 . Flat surface  283  slides against male stem guide  271 . Discharge Cover  211  is unchanged from the embodiment shown in  FIGS. 14A, and 14B  with the same male stem guide  271  which has a cylindrical section  273  and a lower section  272  at the bottom of stem guide  271 . Valve body  260 ″ has only minor changes from valve body  260  of the embodiment shown in  FIGS. 14A and 14B . Lower section  262 ″ is coincidental to lower section  262  of valve body  260  except for the larger major diameter of the conical section  262 ″. The major diameter of the lower section  262 ″ is coincidental with the bottom of cylindrical section  263 ″. Seat  250  has venturi throat section  251  for improved flow and reduced fluid turbulence. Fluid End housing  12 , fluid chamber  2 , and discharge manifold  13  are unchanged from previous embodiments of this application. 
       FIG. 20  schematically illustrates an embodiment of a valve body and seal assembly  230  comprising a top stem internally guided valve body  260  having an elastomeric seal or insert  269 . Valve and seat assembly  220  is composed of seat  250  and valve body and seal assembly  230 . Similarly the complete discharge valve assembly  210 ′″ includes discharge cover  211 ″, valve spring  241 , and valve and seat assembly  220 . Discharge Cover  211 ″ has a male guide stem  271 ″ which has a cylindrical section  273 , a lower section  272 ″ at the bottom of stem  271 ″, a coaxial vent hole  276  and a least one radial hole  277 . Valve body  260  of  FIG. 22  are identical to the valve body  220  illustrated in  FIGS. 14A and 14B  with the same or similar downstream portion  264  substantially conical in shape and a top or upstream side with an internal stem guide section  261  which is composed of a cylindrical section  263  and a lower section  262 . Seat  250  has venturi throat section  251  for improved flow and reduced fluid turbulence. Fluid End housing  12 , fluid chamber  2 , and discharge manifold  13  are unchanged from previous embodiments of this application. 
       FIG. 21  schematically illustrates an embodiment of a valve body and seal assembly  230 ′″ comprising a top stem internally guided valve body  260 ′″ having an elastomeric seal or insert  269 . Valve and seat assembly  220 ′ is composed of seat  250  and valve body and seal assembly  230 ′″. Similarly the complete discharge valve assembly  210 ″″ includes discharge cover  211 ′″, a conical valve spring  242 , and valve and seat assembly  220 ′″. Discharge Cover  211 ′″ has a male guide stem  271 ′″ which has a tapered section  273 ′ and a lower section  272 ′″ at the bottom of stem guide  271 ′″, a coaxial vent hole  276  and a least one radial hole  277 . Radial hole  277  is located in a substantially cylindrical boss  278  at base of tapered section  271 ′″. Valve body  260 ′″ has a downstream portion  264  substantially conical in shape and a top or upstream side with an internal stem guide section  261 ′ which is composed of a tapered section  263 ′ and a lower section  262 ′. Valve body  260 ′″ has an integral ring  265  on the top portion of valve body  260 ′″; said ring  265  being located at or near outer most substantially cylindrical surface  267  of valve body  260 ′″. Boss  278  may be conical to aid in installation of spring  242  over said boss  278 . Conical spring  242  has an inside surface  243  that fits around boss  278  of discharge cover  211 ′″. Conical Spring  242  also has a large end with an outside surface  244  that fits against inside surface  266  of ring  265  that is integral to valve body  260 ′″. In some embodiments, spring  242  is fitted with a small interference fit around boss  278  and inside valve body ring  267 . With said interference fit, said spring  242  functions as a guide that augments the guidance of the reciprocal motion of the valve  230 ′″ of this invention. In the preferred embodiment the interference fit of said spring around boss  278  and inside valve body ring  278  ranges between 0.00 and 0.06 inches measured on the diameter. 
     Seat  250  illustrated in  FIG. 21  has venturi throat section  251  for improved flow and reduced fluid turbulence. Fluid End housing  12 , fluid chamber  2 , and discharge manifold  13  are unchanged from previous embodiments of this application.