Patent Publication Number: US-11644018-B2

Title: Fluid end

Description:
RELATED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. Ser. No. 17/515,707, authored by Thomas et al. and filed on Nov. 1, 2021. Application Ser. No. 17/515,707 is a Continuation of Ser. No. 16/951,741, authored by Thomas and filed Nov. 18, 2020, which has issued as U.S. Pat. No. 11,162,479. 
     Application Ser. No. 16/951,741 claims the benefit of the following provisional patent applications: Ser. No. 62/936,789, authored by Thomas et al. and filed on Nov. 18, 2019; Ser. No. 62/940,513, authored by Thomas et al. and filed on Nov. 26, 2019; Ser. No. 62/953,763, authored by Thomas et al. and filed on Dec. 26, 2019; Ser. No. 62/957,489, authored by Foster et al. and filed on Jan. 6, 2020; Ser. No. 62/959,570, authored by Thomas et al. and filed on Jan. 10, 2020; Ser. No. 62/960,194, authored by Foster et al. and filed on Jan. 13, 2020; Ser. No. 62/960,366, authored by Foster et al. and filed on Jan. 13, 2020; Ser. No. 62/968,634, authored by Foster et al. and filed on Jan. 31, 2020; Ser. No. 62/990,817, authored by Thomas et al. and filed on Mar. 17, 2020; Ser. No. 63/008,036, authored by Thomas et al. and filed on Apr. 10, 2020; Ser. No. 63/018,021, authored by Thomas et al. and filed Apr. 30, 2020; Ser. No. 63/019,789, authored by Thomas et al. and filed on May 4, 2020; Ser. No. 63/027,584, authored by Thomas et al. and filed on May 20, 2020; Ser. No. 63/033,244, authored by Thomas et al. and filed Jun. 2, 2020; Ser. No. 63/040,086, authored by Thomas et al. and filed on Jun. 17, 2020; Ser. No. 63/046,826, authored by Thomas et al. and filed on Jul. 1, 2020; Ser. No. 63/053,797, authored by Thomas et al. and filed on Jul. 20, 2020; Ser. No. 63/076,587, authored by Thomas et al. and filed on Sep. 10, 2020; and Ser. No. 63/089,882, authored by Thomas et al. and filed on Oct. 9, 2020. The entire contents of all of the above listed provisional and non-provisional patent applications are incorporated herein by reference. 
     This application also claims the benefit of the following provisional patent applications: Ser. No. 63/125,459, authored by Thomas et al. and filed on Dec. 15, 2020; Ser. No. 63/148,065, authored by Thomas et al. and filed on Feb. 10, 2021; Ser. No. 63/150,340, authored by Thomas et al. and filed on Feb. 17, 2021; Ser. No. 63/155,835, authored by Thomas et al. and filed on Mar. 3, 2021; Ser. No. 63/168,364, authored by Thomas et al. and filed on Mar. 31, 2021; and Ser. No. 63/283,487, authored by Thomas et al. and filed on Nov. 28, 2021. The entire contents of all of the above listed provisional patent applications are incorporated herein by reference. 
    
    
     BACKGROUND 
     Various industrial applications may require the delivery of high volumes of highly pressurized fluids. For example, hydraulic fracturing (commonly referred to as “fracking”) is a well stimulation technique used in oil and gas production, in which highly pressurized fluid is injected into a cased wellbore. As shown for example in  FIG.  1   , the pressured fluid flows through perforations  10  in a casing  12  and creates fractures  14  in deep rock formations  16 . Pressurized fluid is delivered to the casing  12  through a wellhead  18  supported on the ground surface  20 . Sand or other small particles (commonly referred to as “proppants”) are normally delivered with the fluid into the rock formations  16 . The proppants help hold the fractures  14  open after the fluid is withdrawn. The resulting fractures  14  facilitate the extraction of oil, gas, brine, or other fluid trapped within the rock formations  16 . 
     Fluid ends are devices used in conjunction with a power source to pressurize the fluid used during hydraulic fracturing operations. A single fracking operation may require the use of two or more fluid ends at one time. For example, six fluid ends  22  are shown operating at a wellsite  24  in  FIG.  2   . Each of the fluid ends  22  is attached to a power end  26  in a one-to-one relationship. The power end  26  serves as an engine or motor for the fluid end  22 . Together, the fluid end  22  and power end  26  function as a hydraulic pump. 
     Continuing with  FIG.  2   , a single fluid end  22  and its corresponding power end  26  are typically positioned on a truck bed  28  at the wellsite  24  so that they may be easily moved, as needed. The fluid and proppant mixture to be pressurized is normally held in large tanks  30  at the wellsite  24 . An intake piping system  32  delivers the fluid and proppant mixture from the tanks  30  to each fluid end  22 . A discharge piping system  33  transfers the pressurized fluid from each fluid end  22  to the wellhead  18 , where it is delivered into the casing  12  shown in  FIG.  1   . 
     Fluid ends operate under notoriously extreme conditions, enduring the same pressures, vibrations, and abrasives that are needed to fracture the deep rock formations shown in  FIG.  1   . Fluid ends may operate at pressures of 5,000-15,000 pounds per square inch (psi) or greater. Fluid used in hydraulic fracturing operations is typically pumped through the fluid end at a pressure of at least 8,000 psi, and more typically between 10,000 and 15,000 psi. However, the pressure may reach up to 22,500 psi. The power end used with the fluid end typically has a power output of at least 2,250 horsepower during hydraulic fracturing operations. A single fluid end typically produces a fluid volume of about 400 gallons, or 10 barrels, per minute during a fracking operation. A single fluid end may operate in flow ranges from 170 to 630 gallons per minute, or approximately 4 to 15 barrels per minute. When a plurality of fluid ends are used together, the fluid ends collectively deliver about 4,200 gallons per minute or 100 barrels per minute to the wellbore. 
     In contrast, mud pumps known in the art typically operate at a pressure of less than 8,000 psi. Mud pumps are used to deliver drilling mud to a rotating drill bit within the wellbore during drilling operations. Thus, the drilling mud does not need to have as high of fluid pressure as fracking fluid. A fluid end does not pump drilling mud. A power end used with mud pumps typically has a power output of less than 2,250 horsepower. Mud pumps generally produce a fluid volume of about 150-600 gallons per minute, depending on the size of pump used. 
     In further contrast, a fluid jetting pump known in the art typically operates at pressures of 30,000-90,000 psi. Jet pumps are used to deliver a highly concentrated stream of fluid to a desired area. Jet pumps typically deliver fluid through a wand. Fluid ends do not deliver fluid through a wand. Unlike fluid ends, jet pumps are not used in concert with a plurality of other jet pumps. Rather, only a single jet pump is used to pressurize fluid. A power end used with a jet pump typically has a power output of about 1,000 horsepower. Jet pumps generally produce a fluid volume of about 10 gallons per minute. 
     High operational pressures may cause a fluid end to expand or crack. Such a structural failure may lead to fluid leakage, which leaves the fluid end unable to produce and maintain adequate fluid pressures. Moreover, if proppants are included in the pressurized fluid, those proppants may cause erosion at weak points within the fluid end, resulting in additional failures. 
     It is not uncommon for conventional fluid ends to experience failure after only several hundred operating hours. Yet, a single fracking operation may require as many as fifty (50) hours of fluid end operation. Thus, a traditional fluid end may require replacement after use on as few as two fracking jobs. 
     During operation of a hydraulic pump, the power end is not exposed to the same corrosive and abrasive fluids that move through the fluid end. Thus, power ends typically have much longer lifespans than fluid ends. A typical power end may service five or more different fluid ends during its lifespan. 
     With reference to  FIG.  3   , a traditional power end  34  is shown. The power end  34  comprises a housing  36  having a mounting plate  38  formed on its front end  40 . A plurality of stay rods  42  are attached to and project from the mounting plate  38 . A plurality of pony rods  44  are disposed at least partially within the power end  34  and project from openings formed in the mounting plate  38 . Each of the pony rods  44  is attached to a crank shaft installed within the housing  36 . Rotation of the crank shaft powers reciprocal motion of the pony rods  44  relative to the mounting plate  38 . 
     A fluid end  46  shown in  FIG.  3    is attached to the power end  34 . The fluid end  46  comprises a single housing  48  having a flange  50  machined therein. The flange  50  provides a connection point for the plurality of stay rods  42 . The stay rods  42  rigidly interconnect the power end  34  and the fluid end  46 . When connected, the fluid end  46  is suspended in offset relationship to the power end  34 . 
     A plurality of plungers  52  are disposed within the fluid end  46  and project from openings formed in the flange  50 . The plungers  52  and pony rods  44  are arranged in a one-to-one relationship, with each plunger  52  aligned with and connected to a corresponding one of the pony rods  44 . Reciprocation of each pony rod  44  causes its connected plunger  52  to reciprocate within the fluid end  46 . In operation, reciprocation of the plungers  52  pressurizes fluid within the fluid end  46 . The reciprocation cycle of each plunger  52  is differently phased from that of each adjacent plunger  52 . 
     With reference to  FIG.  5   , the interior of the fluid end  46  includes a plurality of longitudinally spaced bore pairs. Each bore pair includes a vertical bore  56  and an intersecting horizontal bore  58 . The zone of intersection between the paired bores defines an internal chamber  60 . Each plunger  52  extends through a horizontal bore  58  and into its associated internal chamber  60 . The plungers  52  and horizontal bores  58  are arranged in a one-to-one relationship. 
     Each horizontal bore  58  is sized to receive a plurality of packing seals  64 . The seals  64  are configured to surround the installed plunger  52  and prevent high-pressure fluid from passing around the plunger  52  during operation. The packing seals  64  are maintained within the bore  58  by a retainer  65 . The retainer  65  has external threads  63  that mate with internal threads  67  formed in the walls surrounding the bore  58 . In some traditional fluid ends, the packing seals  64  are installed within a removable stuffing box sleeve that is installed within the horizontal bore. 
     Each vertical bore  56  interconnects opposing top and bottom surfaces  66  and  68  of the fluid end  46 . Each horizontal bore  58  interconnects opposing front and rear surfaces  70  and  72  of the fluid end  46 . A discharge plug  74  seals each opening of each vertical bore  56  on the top surface  66  of the fluid end  46 . Likewise, a suction plug  76  seals each opening of each horizontal bore  58  on the front surface  70  of the fluid end  46 . 
     Each of the plugs  74  and  76  features a generally cylindrical body. An annular seal  77  is installed within a recess formed in an outer surface of that body, and blocks passage of high pressure fluid. The discharge and suction plugs  74  and  76  are retained within their corresponding bores  56  and  58  by a retainer  78 , shown in  FIGS.  3 ,  5 , and  6   . The retainer  78  has a cylindrical body having external threads  79  formed in its outer surface. The external threads  79  mate with internal threads  81  formed in the walls surrounding the bore  56  or  58  between the installed plug  74  or  76  and the surface  66  or  70  of the fluid end  46 . 
     As shown in  FIG.  3   , a single manifold  80  is attached to the fluid end  46 . The manifold  80  is also connected to an intake piping system, of the type shown in  FIG.  2   . Fluid to be pressurized is drawn from the intake piping system into the manifold  80 , which directs the fluid into each of the vertical bores  56 , by way of openings (not shown) in the bottom surface  68 . 
     When a plunger  52  is retracted, fluid is drawn into each internal chamber  60  from the manifold  80 . When a plunger  52  is extended, fluid within each internal chamber  60  is pressurized and forced towards a discharge conduit  82 . Pressurized fluid exits the fluid end  46  through one or more discharge openings  84 , shown in  FIGS.  3 - 5   . The discharge openings  84  are in fluid communication with the discharge conduit  82 . The discharge openings  84  are attached to a discharge piping system, of the type shown in  FIG.  2   . 
     A pair of valves  86  and  88  are installed within each vertical bore  56 , on opposite sides of the internal chamber  60 . The valve  86  prevents backflow in the direction of the manifold  80 , while the valve  88  prevents backflow in the direction of the internal chamber  60 . The valves  86  and  88  each comprise a valve body  87  that seals against a valve seat  89 . 
     Traditional fluid ends are normally machined from high strength alloy steel. Such material can corrode quieldy, leading to fatigue cracks. Fatigue cracks occur because corrosion of the metal decreases the metal&#39;s fatigue strength—the amount of loading cycles that can be applied to a metal before it fails. Such cracking can allow leakage that prevents a fluid end from achieving and maintaining adequate pressures. Once such leakage occurs, fluid end repair or replacement becomes necessary. 
     Fatigue cracks in fluid ends are commonly found in areas that experience high stress. For example, with reference to the fluid end  46  shown in  FIG.  5   , fatigue cracks are common at a corner  90  formed in the interior of the fluid end  46  by the intersection of the walls surrounding the horizontal bore  58  with the walls surrounding the vertical bore  56 . A plurality of the corners  90  surround each internal chamber  60 . Because fluid is pressurized within each internal chamber  60 , the corners  90  typically experience the highest amount of stress during operation, leading to fatigue cracks. Fatigue cracks are also common at the neck that connects the flange  50  and the housing  48 . Specifically, fatigue cracks tend to form at an area  92  where the neck joins the housing  48 , as shown for example in  FIGS.  4  and  5   . 
     For the above reasons, there is a need in the industry for a fluid end configured to avoid or significantly delay the structures or conditions that cause wear or failures within a fluid end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an illustration of the underground environment of a hydraulic fracturing operation. 
         FIG.  2    illustrates above-ground equipment used in a hydraulic fracturing operation. 
         FIG.  3    is a left side perspective view of a traditional fluid end attached to a traditional power end. 
         FIG.  4    is a top plan view of the fluid end shown in  FIG.  3   . 
         FIG.  5    is a sectional view of the fluid end shown in  FIG.  4   , taken along line A-A. 
         FIG.  6    is a front perspective view of a fluid end. A plurality of stay rods are attached to the fluid end. 
         FIG.  7    is a rear perspective view of the fluid end shown in  FIG.  6   , but the plurality of stay rods have been removed. 
         FIG.  7 A  is a side elevational view of the fluid end shown in  FIG.  6   , but with another embodiment of intake and discharge manifolds. 
         FIG.  7 B  is a front perspective view of the fluid end shown in  FIG.  7 A . 
         FIG.  8    is a front perspective view of one of the fluid end sections making up the fluid end shown in  FIG.  6   . 
         FIG.  9    is a cross-sectional view of the fluid end section shown in  FIG.  8   , taken along line D-D. 
         FIG.  10    is a perspective view of a first surface of a connect plate used with the fluid end shown in  FIG.  6   . 
         FIG.  11    is a perspective view of a second surface of the connect plate shown in  FIG.  10   . 
         FIG.  12    is an elevational view of the first surface of the connect plate shown in  FIG.  10   . 
         FIG.  13    is an elevational view of the second surface of the connect plate shown in  FIG.  10   . 
         FIG.  14    is a perspective view of a second surface of a housing making up the fluid end section shown in  FIG.  8   . 
         FIG.  15    is an elevational view of the second surface of the housing shown in  FIG.  14   . 
         FIG.  16    is a cross-sectional view of the fluid end and stay rods shown in  FIG.  6   , taken along a plane that includes the line B-B. 
         FIG.  17    is a cross-sectional view of the fluid end and stay rods shown in  FIG.  6   , taken along a plane that includes the line C-C. 
         FIG.  18    is a top plan view of the housing shown in  FIG.  14   . 
         FIG.  19    is an enlarged view of area E shown in  FIG.  9   . 
         FIG.  19 A  is a front perspective view of another embodiment of a fluid end having upper and lower discharge manifolds. 
         FIG.  19 B  is a side elevational view of the fluid end shown in  FIG.  19 A . 
         FIG.  19 C  is a front perspective view of the fluid end shown in  FIG.  19 A  but uses another embodiment of upper and lower discharge manifolds. 
         FIG.  19 D  is a side elevational view of the fluid end shown in  FIG.  19 C . 
         FIG.  19 E  is a front and top perspective view of one of the fluid end sections shown in  FIGS.  19 A and  19 C . 
         FIG.  19 F  is a front and bottom perspective view of the fluid end section shown in  FIG.  19 E . 
         FIG.  19 G  is a cross-sectional view of the fluid end section shown in  FIGS.  19 E and  19 F , taken along line CA-CA. 
         FIG.  19 H  is an enlarged view of area CB shown in  FIG.  19 G  with the addition of arrows indicating fluid flow. 
         FIG.  20    is the cross-sectional view of the fluid end section shown in  FIG.  17    with the upper and lower intake manifolds shown attached to the housing. 
         FIG.  21    is a rear perspective view of the fluid end section shown in  FIG.  20   , but the plunger has been removed. 
         FIG.  22    is a top plan view of a stuffing box shown attached to the housing in  FIG.  20   . 
         FIG.  23    is a perspective view of a first surface of the stuffing box shown in  FIG.  22   . 
         FIG.  24    is an elevational view of the first surface of the stuffing box shown in  FIG.  22   . 
         FIG.  25    is a cross-sectional view of the stuffing box shown in  FIG.  24   , taken along line F-F. 
         FIG.  26    is a cross-sectional view of the stuffing box shown in  FIG.  24   , taken along line G-G. 
         FIG.  27    is a perspective view of a second surface of the stuffing box shown in  FIG.  22   . 
         FIG.  28    is an elevational view of the second surface of the stuffing box shown in  FIG.  22   . 
         FIG.  29    is a cross-sectional view of the stuffing box shown in  FIG.  28   , taken along line H-H. 
         FIG.  30    is a top plan view of a retainer shown attached to the stuffing box in  FIG.  20   . 
         FIG.  31    is a perspective view of a first surface of the retainer shown in  FIG.  30   . 
         FIG.  32    is an elevational view of the first surface of the retainer shown in  FIG.  30   . 
         FIG.  33    is a cross-sectional view of the retainer shown in  FIG.  32   , taken along line I-I. 
         FIG.  34    is a cross-sectional view of the retainer shown in  FIG.  36   , taken along line J-J. 
         FIG.  35    is a perspective view of a second surface of the retainer shown in  FIG.  30   . 
         FIG.  36    is an elevational view of the second surface of the retainer shown in  FIG.  30   . 
         FIG.  37    is a cross-sectional view of the retainer shown in  FIG.  36   , taken along line K-K. 
         FIG.  38    is a top plan view of a plunger packing shown installed within the stuffing box and retainer in  FIG.  20   . 
         FIG.  39    is a perspective view of a first surface of the plunger packing shown in  FIG.  38   . 
         FIG.  40    is an elevational view of the first surface of the plunger packing shown in  FIG.  38   . 
         FIG.  41    is a cross-sectional view of the plunger packing shown in  FIG.  40   , taken along line L-L. 
         FIG.  42    is a perspective exploded view of the plunger packing shown in  FIG.  38   . 
         FIG.  43    is a top plan view of a packing nut shown installed within the retainer in  FIG.  20   . 
         FIG.  44    is a perspective view of a first surface of the packing nut shown in  FIG.  43   . 
         FIG.  45    is an elevational view of the first surface of the packing nut shown in  FIG.  43   . 
         FIG.  46    is a cross-sectional view of the packing nut shown in  FIG.  45   , taken along line M-M. 
         FIG.  47    is a perspective view of a first surface of a retainer shown installed within the housing in  FIG.  20   . 
         FIG.  48    is an elevational view of the first surface of the retainer shown in  FIG.  47   . 
         FIG.  49    is a cross-sectional view of the retainer shown in  FIG.  48   , taken along line N-N. 
         FIG.  50    is the cross-sectional view shown in  FIG.  9   , but the suction valve is spaced from the fluid routing plug. 
         FIG.  51    is the cross-sectional view shown in  FIG.  50   , but the plunger has extended into the housing, the suction valve is sealed against the fluid routing plug, and the discharge valve is spaced from the fluid routing plug. 
         FIG.  52    is a perspective view of a second surface of a fluid routing plug shown installed within the fluid end section in  FIG.  50   . 
         FIG.  53    is a perspective view of a first surface of the fluid routing plug shown in  FIG.  52   . 
         FIG.  54    is an elevational view of the second surface of the fluid routing plug shown in  FIG.  52   . 
         FIG.  55    is a cross-sectional view of the fluid routing plug shown in  FIG.  54   , taken along line O-O. 
         FIG.  56    is an elevational view of the first surface of the fluid routing plug shown in  FIG.  52   . 
         FIG.  57    is a top plan view of the fluid routing plug shown in  FIG.  52   . 
         FIG.  58    is a cross-sectional view of the fluid routing plug shown in  FIG.  57   , taken along line P-P. 
         FIG.  59    is an enlarged view of area Q shown in  FIG.  57   . 
         FIG.  60    is the top plan view of the fluid routing plug shown in  FIG.  57   , but the plug has been slightly rotated. 
         FIG.  61    is a cross-sectional view of the fluid routing plug shown in  FIG.  60   , taken along line R-R. 
         FIG.  62    is a cross-sectional view of the fluid routing plug shown in  FIG.  60   , taken along line S-S. 
         FIG.  63    is a cross-sectional view of the fluid routing plug shown in  FIG.  60   , taken along line T-T. 
         FIG.  64    is an enlarged view of the fluid routing plug shown in  FIG.  60   . 
         FIG.  65    is the cross-sectional view shown in  FIG.  50   . 
         FIG.  66    is an enlarged view of area U shown in  FIG.  65   . 
         FIG.  67    is an enlarged view of area V shown in  FIG.  65   . 
         FIG.  68    is an enlarged view of area W shown in  FIG.  65   . 
         FIG.  69    is an enlarged view of area X shown in  FIG.  65   . 
         FIG.  70    is an enlarged view of area Y shown in  FIG.  65   . 
         FIG.  71    is an enlarged view of area Z shown in  FIG.  65   . 
         FIG.  72    is a top plan view of a suction valve shown installed within the housing in  FIG.  50   . 
         FIG.  73    is a perspective view of a second surface of the suction valve shown in  FIG.  72   . 
         FIG.  74    is an elevational view of the second surface of the suction valve shown in  FIG.  72   . 
         FIG.  75    is a perspective view of a first surface of the suction valve shown in  FIG.  72   . 
         FIG.  76    is a cross-sectional view of the suction valve shown in  FIG.  74   , taken along line AA-AA. 
         FIG.  77    is a top plan view of a suction valve guide shown installed within the housing shown in  FIG.  50   . 
         FIG.  78    is a perspective view of a first surface of the suction valve guide shown in  FIG.  77   . 
         FIG.  79    is an elevation view of the first surface of the suction valve guide shown in  FIG.  77   . 
         FIG.  80    is a cross-sectional view of the suction valve guide shown in  FIG.  79   , taken along line AB-AB. 
         FIG.  81    is a perspective view of a second surface of the suction valve guide shown in  FIG.  77   . 
         FIG.  82    is an elevational view of the second surface of the suction valve guide shown in  FIG.  77   . 
         FIG.  83    is a perspective view of the suction valve guide shown in  FIG.  77    engaged with the suction valve shown in  FIG.  72   . A spring is shown positioned between the suction valve guide and the suction valve. 
         FIG.  84    is a top plan view of the suction valve guide, suction valve, and spring shown in  FIG.  83   . 
         FIG.  84 A  is a top plan view of another embodiment of a suction valve guide. 
         FIG.  84 B  is a perspective view of the first surface of the suction valve guide shown in  FIG.  84 A . 
         FIG.  84 C  is an elevational view of the first surface of the suction valve guide shown in  FIG.  84 A . 
         FIG.  84 D  is a cross-sectional view of the suction valve guide shown in  FIG.  84 C , taken along line CC-CC. 
         FIG.  84 E  is a perspective view of the second surface of the suction valve guide shown in  FIG.  84 A . 
         FIG.  84 F  is an elevational view of the second surface of the suction valve guide shown in  FIG.  84 A . 
         FIG.  84 G  is a top plan view of another embodiment of a suction valve guide. 
         FIG.  84 H  is a perspective view of the first surface of the suction valve guide shown in  FIG.  84 G . 
         FIG.  84 I  is an elevational view of the first surface of the suction valve guide shown in  FIG.  84 G . 
         FIG.  84 J  is a cross-sectional view of the suction valve guide shown in  FIG.  84 I , taken along line CD-CD. 
         FIG.  84 K  is a perspective view of the second surface of the suction valve guide shown in  FIG.  84 G . 
         FIG.  84 L  is an elevational view of the second surface of the suction valve guide shown in  FIG.  84 G . 
         FIG.  84 M  is a perspective view of the first surface of another embodiment of a suction valve guide. 
         FIG.  84 N  is a cross-sectional view of the suction valve guide shown in  FIG.  84 M . 
         FIG.  84 O  is a cross-sectional view of another embodiment of a suction valve guide. 
         FIG.  84 P  is a perspective and exploded view of the first surface of the suction valve guide shown in  FIG.  84 O . 
         FIG.  84 Q  is a cross-sectional view of another embodiment of a suction valve guide. 
         FIG.  84 R  is a perspective and exploded view of the first surface of the suction valve guide shown in  FIG.  84 Q . 
         FIG.  85    is a top plan view of a discharge valve shown installed within the housing in  FIG.  50   . 
         FIG.  86    is a perspective view of a second surface of the discharge valve shown in  FIG.  85   . 
         FIG.  87    is an elevational view of the second surface of the discharge valve shown in  FIG.  85   . 
         FIG.  88    is a perspective view of a first surface of the discharge valve shown in  FIG.  85   . 
         FIG.  89    is a cross-sectional view of the discharge valve shown in  FIG.  87   , taken along line AC-AC. 
         FIG.  90    is a top plan view of a discharge valve guide shown installed within the housing in  FIG.  50   . 
         FIG.  91    is a perspective view of a first surface of the discharge valve guide shown in  FIG.  90   . 
         FIG.  92    is an elevation view of the first surface of the discharge valve guide shown in  FIG.  90   . 
         FIG.  93    is a cross-sectional view of the discharge valve guide shown in  FIG.  92   , taken along line AD-AD. 
         FIG.  94    is a cross-sectional view of the discharge valve guide shown in  FIG.  92   , taken along line AE-AE. 
         FIG.  95    is a perspective view of a second surface of the discharge valve guide shown in  FIG.  90   . 
         FIG.  96    is a perspective cut-away view of a first surface of the fluid end section shown in  FIG.  8   . 
         FIG.  97    is an enlarged view of area AF shown in  FIG.  96   . 
         FIG.  98    is a perspective view of the discharge valve guide shown in  FIG.  90    engaged with the discharge valve shown in  FIG.  85   . A spring is shown positioned between the discharge valve guide and the discharge valve. 
         FIG.  99    is a top plan view of the discharge valve guide, discharge valve, and spring shown in  FIG.  98   . 
         FIG.  99 A  is a top plan view of another embodiment of a discharge valve guide. 
         FIG.  99 B  is a perspective view of the second surface of the discharge valve guide shown in  FIG.  99 A . 
         FIG.  99 C  is an elevational view of the second surface of the discharge valve guide shown in  FIG.  99 A . 
         FIG.  99 D  is a cross-sectional view of the discharge valve guide shown in  FIG.  99 C , taken along line CE-CE. 
         FIG.  99 E  is a perspective view of the first surface of the discharge valve guide shown in  FIG.  99 A . 
         FIG.  99 F  is an elevational view of the first surface of the discharge valve guide shown in  FIG.  99 A . 
         FIG.  100    is the cross-sectional view of the fluid end section shown in  FIG.  9   . 
         FIG.  100 A  is a perspective view of a second surface of another embodiment of a fluid routing plug. 
         FIG.  100 B  is a perspective view of a first surface of the fluid routing plug shown in  FIG.  10 A . 
         FIG.  100 C  is an elevational view of the second surface of the fluid routing plug shown in  FIG.  100 A . 
         FIG.  100 D  is a cross-sectional view of the fluid routing plug shown in  FIG.  100 C , taken along line JA-JA. 
         FIG.  100 E  is a cross-sectional view of the fluid routing plug shown in  FIG.  100 C , taken along line JB-JB. 
         FIG.  100 F  is the cross-sectional view of the fluid end section shown in  FIG.  9   , but the fluid routing plug from  FIG.  100 A  is shown installed within the housing. 
         FIG.  100 G  is an enlarged view of area JC from  FIG.  100 F . 
         FIG.  101    is a perspective view of a first surface of another embodiment of a fluid routing plug. 
         FIG.  102    is an elevational view of the first surface of the fluid routing plug shown in  FIG.  101   . 
         FIG.  103    is a cross-sectional view of the fluid routing plug shown in  FIG.  102   , taken along line AG-AG. 
         FIG.  104    is a top plan view of the fluid routing plug shown in  FIG.  101   . 
         FIG.  105    is a perspective view of a second surface of the fluid routing plug shown in  FIG.  101   . 
         FIG.  106    is an elevational view of the second surface of the fluid routing plug shown in  FIG.  101   . 
         FIG.  107    is a cross-sectional view of the fluid routing plug shown in  FIG.  106   , taken along line AH-AH. 
         FIG.  108    is the cross-sectional view of the fluid end section shown in  FIG.  50   , but the fluid routing plug from  FIG.  101    is shown installed within the housing. 
         FIG.  109    is the cross-sectional view of the fluid end section shown in  FIG.  51   , but the fluid routing plug from  FIG.  101    is shown installed within the housing. 
         FIG.  110    is a top plan view of another embodiment of a suction and discharge valve. 
         FIG.  111    is a perspective view of a second surface of the suction and discharge valve shown in  FIG.  110   . 
         FIG.  112    is an elevational view of a second surface of the suction and discharge valve shown in  FIG.  110   . 
         FIG.  113    is a perspective view of a first surface of the suction and discharge valve shown in  FIG.  110   . 
         FIG.  114    is a cross-sectional view of the suction and discharge valve shown in  FIG.  112   , taken along line AI-AI. 
         FIG.  115    is the cross-sectional view of the fluid end section shown in  FIG.  65   , but another embodiment of a fluid routing plug is shown installed within the housing. 
         FIG.  116    is an enlarged view of area AJ shown in  FIG.  115   . 
         FIG.  117    is an enlarged view of area AK shown in  FIG.  115   . 
         FIG.  118    is the cross-sectional view of the fluid end section shown in  FIG.  65   , but another embodiment of a fluid routing plug is shown installed within the housing. 
         FIG.  119    is an enlarged view of area AL shown in  FIG.  118   . 
         FIG.  120    is an enlarged view of area AM shown in  FIG.  118   . 
         FIG.  121    is a top plan view of another embodiment of a fluid routing plug. 
         FIG.  122    is a perspective view of a second surface of the fluid routing plug shown in  FIG.  121   , with a plurality of second fluid passages formed within the plug shown by phantom lines. 
         FIG.  123    is an elevational view of the second surface of the fluid routing plug shown in  FIG.  121   , with a plurality of second fluid passages formed within the plug shown by phantom lines. 
         FIG.  124    is a cross-sectional view of the fluid routing plug shown in  FIG.  123   , taken along line AN-AN. 
         FIG.  125    is a cross-sectional view of the fluid routing plug shown in  FIG.  121   , taken along line AO-AO. 
         FIG.  126    is the top plan view of the fluid routing plug shown in  FIG.  121   , with the plurality of second fluid passages formed within the plug shown by phantom lines. 
         FIG.  127    is an elevational view of a first surface of the fluid routing plug shown in  FIG.  121   , with a plurality of second fluid passages formed within the plug shown by phantom lines. 
         FIG.  128    is a perspective view of the first surface of the fluid routing plug shown in  FIG.  121   . 
         FIG.  128 A  is a perspective view of a second surface of another embodiment of a fluid routing plug. 
         FIG.  128 B  is an elevational view of the second surface of the fluid routing plug shown in  FIG.  128 A . 
         FIG.  128 C  is a cross-sectional view of the fluid routing plug shown in  FIG.  128 A , taken along line KA-KA. 
         FIG.  128 D  is a top plan view of the fluid routing plug shown in  FIG.  128 A . 
         FIG.  128 E  is a perspective-view of a first surface of the fluid routing plug shown in  FIG.  128 A . 
         FIG.  128 F  is an elevational view of the first surface of the fluid routing plug shown in  FIG.  128 A . 
         FIG.  128 G  is a cross-sectional view of the fluid routing plug shown in  FIG.  128 D , taken along line KB-KB. 
         FIG.  129    is a top plan view of another embodiment of a fluid routing plug. 
         FIG.  130    is an elevational view of a second surface of the fluid routing plug shown in  FIG.  129   . 
         FIG.  131    is a cross-sectional view of the fluid routing plug shown in  FIG.  130   , taken along line AP-AP. 
         FIG.  131 A  is a perspective view of the first surface of another embodiment of a fluid routing plug. 
         FIG.  131 B  is a cross-sectional view of the fluid routing plug shown in  FIG.  131 C , taken along line CF-CF. 
         FIG.  131 C  is an elevational view of the first surface of the fluid routing plug shown in  FIG.  131 A . 
         FIG.  131 D  is a cross-sectional view of the fluid routing plug shown in  FIG.  131 C , taken along line CG-CG. 
         FIG.  131 E  is a top plan view of the fluid routing plug shown in  FIG.  131 A . 
         FIG.  131 F  is a perspective view of the second surface of the fluid routing plug shown in  FIG.  131 A . 
         FIG.  131 G  is an elevational view of the second surface of the fluid routing plug shown in  FIG.  131 A . 
         FIG.  131 H  is a cross-sectional view of the fluid routing plug shown in  FIG.  131 E , taken along line CH-CH. 
         FIG.  131 I  is the cross-sectional view of the fluid routing plug shown in  FIG.  131 B  having a pair of inserts installed therein. 
         FIG.  131 J  is a perspective and exploded view of the first surface of the fluid routing plug shown in  FIG.  131 I . 
         FIG.  131 K  is a perspective and exploded view of the second surface of the fluid routing plug shown in  FIG.  131 I . 
         FIG.  131 L  is a perspective view of a first surface of another embodiment of a fluid routing plug. 
         FIG.  131 M  is a cross-sectional view of the fluid routing plug shown in  FIG.  131 N , taken along line CJ-CJ. 
         FIG.  131 N  is an elevational view of the first surface of the fluid routing plug shown in  FIG.  131 L . 
         FIG.  131 O  is a top plan view of the fluid routing plug shown in  FIG.  131 L . 
         FIG.  131 P  is a cross-sectional view of the fluid routing plug shown in  FIG.  131 O , taken along line CK-CK. 
         FIG.  131 Q  is the top plan view of the fluid routing plug shown in  FIG.  131 O  having a pair of seals installed therein. 
         FIG.  131 R  is the cross-sectional view of the fluid routing plug shown in  FIG.  131 Q . 
         FIG.  131 S  is a cross-sectional view of an alternative embodiment of a fluid end section having the fluid routing plug shown in  FIG.  131 L  installed therein. 
         FIG.  131 T  is a cross-sectional view of another embodiment of a fluid routing plug. 
         FIG.  132    is a perspective view of a first surface of another embodiment of a fluid end section having another embodiment of a housing. 
         FIG.  133    is a cross-sectional view of the fluid end section shown in  FIG.  132   , taken along a plane positioned on line AQ-AQ. 
         FIG.  134    is a top plan view of a retainer shown attached to the housing in  FIG.  132   . 
         FIG.  135    a perspective view of a second surface of the retainer shown in  FIG.  134   . 
         FIG.  136    is an elevational view of the first surface of the retainer shown in  FIG.  134   . 
         FIG.  137    is a cross-sectional view of the retainer shown in  FIG.  135   , taken along line AR-AR. 
         FIG.  138    is a perspective view of a first surface of the housing shown in  FIG.  132   . 
         FIG.  139    is an enlarged view of area AS shown in  FIG.  138   . 
         FIG.  139 A  is a front perspective view of another embodiment of a fluid end section. 
         FIG.  139 B  is a rear perspective view of the fluid end section shown in  FIG.  139 A . 
         FIG.  139 C  is a cross-sectional view of the fluid end section shown in  FIG.  139 A , taken along line CL-CL. 
         FIG.  139 D  is a cross-sectional view of the fluid end section shown in  FIG.  139 A , taken along line CM-CM. A pair of stay rods are shown attached to the fluid end section. 
         FIG.  140    is a sectional view of another embodiment of a fluid end section. 
         FIG.  141    is a sectional view of the fluid end section shown in  FIG.  140   , taken along a different axis. 
         FIG.  142    is a top plan view of a first section of the housing shown in  FIG.  140   . 
         FIG.  143    is a perspective view of a first surface of the first section shown in  FIG.  142   . 
         FIG.  144    is an elevational view of the first surface of the first section shown in  FIG.  142   . 
         FIG.  145    is a cross-sectional view of the first section shown in  FIG.  144    taken along line AT-AT. 
         FIG.  146    is a perspective view of a second surface of the first section shown in  FIG.  142   . 
         FIG.  147    is an elevational view of the second surface of the first section shown in  FIG.  142   . 
         FIG.  148    is a cross-sectional view of the first section shown in  FIG.  147   , taken along line AU-AU. 
         FIG.  149    is a perspective view of a first surface of a second section of a housing shown in  FIG.  140   . 
         FIG.  150    is an elevational view of the first surface of the second section shown in  FIG.  149   . 
         FIG.  151    is a cross-sectional view of the second section shown in  FIG.  150   , taken along line AV-AV. 
         FIG.  152    is a cross-sectional view of the second section shown in  FIG.  150   , taken along line AW-AW. 
         FIG.  153    is a sectional view of another embodiment of a fluid end section. 
         FIG.  154    is a perspective view of a first surface of a housing of the fluid end section shown in  FIG.  153   . 
         FIG.  155    is a top plan view of the housing shown in  FIG.  154   . 
         FIG.  156    is an elevational view of the first surface of the housing shown in  FIG.  154   . 
         FIG.  157    is a side elevational view of the housing shown in  FIG.  154   . 
         FIG.  158    is a side elevational view of the fluid end section shown in  FIG.  153   . 
         FIG.  159    is a cross-sectional view of the fluid end section shown in  FIG.  158   , taken along line AX-AX. 
         FIG.  160    is a sectional view of the fluid end section shown in  FIG.  153   , taken along a different axis. 
         FIG.  161    is an enlarged view of area AY shown in  FIG.  160   . 
         FIG.  162    is an elevational view of a first surface of another embodiment of a stuffing box of the fluid end section in  FIG.  153   . 
         FIG.  163    is a perspective view of the first surface of the stuffing box shown in  FIG.  162   . 
         FIG.  164    is a top plan view of the stuffing box shown in  FIG.  162   . 
         FIG.  165    is a cross-sectional view of the stuffing box shown in  FIG.  162   , taken along line AZ-AZ. 
         FIG.  166    is a perspective view of a second surface of another embodiment of a fluid end section. 
         FIG.  167    is a cross-sectional view of the fluid end section shown in  FIG.  166   , taken along a plane positioned on line BA-BA. 
     
    
    
     DETAILED DESCRIPTION 
     Turning now to the non-prior art figures,  FIGS.  6  and  7    show a fluid end  100 . The fluid end  100  may be attached to the traditional power end  34 , shown in  FIG.  3   . Alternatively, the fluid end  100  may be attached to various embodiments of power ends, such as the modular power end described in U.S. Provisional Patent Application Ser. No. 63/053,797, authored by Thomas et al. and filed on Jul. 20, 2020. 
     Unlike the traditional fluid end  46 , shown in  FIG.  3   , the fluid end  100  comprises a plurality of fluid end sections  102  rather than a single housing  48 . The fluid end sections  102  are positioned in a side-by-side relationship. Preferably, the fluid end  100  comprises five fluid end sections  102 . However, more or less fluid end sections  102  may be used. Forming the fluid end  100  out of multiple fluid end sections  102  allows a single fluid end section  102  to be replaced, if needed. In contrast, the entire housing  48  in traditional fluid ends  46  may need to be replaced if only a portion of the housing  48  fails. 
     Turning to  FIGS.  8  and  9   , each fluid end section  102  comprises a horizontally positioned housing  104  having a generally cylindrical cross-sectional shape, as shown in  FIG.  8   . In alternative embodiments, each fluid end section may have a generally rectangular cross-sectional shape. In Unlike the traditional fluid end  46  shown in  FIGS.  3  and  5   , each housing  104  does not include a vertical bore intersecting a horizontal bore to form an internal chamber. Rather, each housing  104  only has a single horizontally positioned bore  106 , as shown in  FIG.  9   . Removing the internal chamber found in traditional fluid ends from the housing  104  removes common stress points from the housing  104 . 
     Eliminating the intersecting bore also reduces the cost of manufacturing the fluid end  100  as compared to traditional fluid ends. The time required to manufacture the fluid end  100  is greatly reduced without the need for machining an intersecting bore, and the fluid end  100  may be manufactured on a lathe instead of a machining center. The fluid end  100  may also be manufactured out of lower strength and less costly materials since it does not include the high stress areas found in traditional fluid ends. Each housing  104  may be manufactured out of high strength alloy steel, such as carbon steel. In alternative embodiments, each housing  104  may be manufactured out of stainless steel. 
     Continuing with  FIGS.  8  and  9   , each housing  104  comprises a first outer surface  108  joined to an opposed second outer surface  110  by an intermediate outer surface  112 . The horizontal bore  106  extends through the housing  104  along a central longitudinal axis  114  and interconnects the opposed first and second outer surfaces  108  and  110 , as shown in  FIG.  9   . Each housing  104  is of single piece construction. 
     Since each housing  104  only has a single horizontal bore  106 , fluid must be routed throughout the housing  104  differently from how fluid is routed throughout a traditional fluid end housing  48 . As will be described in more detail herein, a fluid routing plug  116 , shown in  FIGS.  52 - 64   , is installed within each housing  104  and is configured to route fluid throughout the housing  104 . 
     With reference to  FIGS.  6 ,  7 , and  10 - 16   , each housing  104  is supported on a single connect plate  118  in a one-to-one relationship. A plurality of sets of stay rods  120 , shown in  FIG.  6   , are used to attach each connect plate  118  to a power end. The connect plates  118  may each be attached to the corresponding stay rods  120  prior to attaching a housing  104  to a corresponding connect plate  118 . Because the housings  104  are each attached to a connect plate  118 , the fluid end  100  does not include a flange like the flange  50  formed in the fluid end  46  shown in  FIG.  3   . In an alternative embodiment, multiple housings may be attached to a single, larger connect plate. In such embodiment, the stay rods are likewise attached to the single, larger connect plate. 
     The stay rods  120  shown in  FIG.  6    are configured for use with a modular power end, like that shown in in U.S. Provisional Patent Application Ser. No. 63/053,797, authored by Thomas et al. and filed on Jul. 20, 2020. A spacer  122  is installed on each stay rod  120  and is configured to engage with a front surface of the power end. In alternative embodiments, the stay rods may be configured like the stay rods  42  shown in  FIG.  3   . 
     With reference to  FIGS.  10 - 13   , each connect plate  118  has a generally rectangular shape and has opposed first and second surfaces  124  and  126 . A plurality of first passages  128  are formed around the outer periphery of each connect plate  118 . Each first passage  128  interconnects the first and second surfaces  124  and  126  of the connect plate  118  and is configured for receiving a stay rod  120 . Each stay rod  120  extends through a corresponding passage  128  in a one-to-one relationship. 
     The connect plate  118  shown in  FIGS.  10 - 13    has four first passages  128 . Likewise, four stay rods  120  are shown attached to each connect plate  118  in  FIG.  6   . In alternative embodiments, the connect plate may have more than four or less than four first passages, as long as the amount of first passages corresponds with the number of stay rods being used with each connect plate. 
     Once each stay rod  120  is installed in a connect plate  118 , a first end  130  of each stay rod  120  projects from the first surface  124  of the connect plate  118 , as shown in  FIG.  16   . A nut  132  and a washer  134  are installed on the projecting first end  130  of each stay rod  120  in a one-to-one relationship. The nut  132  is turned until it tightly engages a corresponding washer  134  and the first surface  124  of the connect plate  118 , thereby securing the connect plate  118  to the stay rods  120 . 
     With reference to  FIGS.  6 , and  14 - 16   , a plurality of notches  136  are formed around the periphery of the housing  104  at its second surface  110 , as shown in  FIGS.  14  and  15   . When the housing  104  is attached to the connect plate  118 , each notch  136  partially surrounds one of the first passages  128  in a one-to-one relationship. The notches  136  provide space to access the washer  134  and nut  132  during operation. 
     Continuing with  FIGS.  10 - 13   , a central bore  138  is formed in each connect plate  118  and interconnects the first and second surfaces  124  and  126 . The central bore  138  is configured for receiving a stuffing box  140 , as described in more detail later herein. A plurality of second passages  142  are formed in the connect plate  118  and surround the central bore  138 . Each second passage  142  interconnects the first and second surfaces  124  and  126  of the connect plate  118 . The second passages  142  are configured to align in a one-to-one relationship with a plurality of first threaded openings  144  formed in the second surface  110  of each housing  104 , as shown in  FIGS.  14  and  15   . 
     Each housing  104  is attached to the first surface  124  of a corresponding connect plate  118  using a fastening system  146 . The fastening system  146  comprises a plurality of studs  148 , a plurality of washers  150 , and a plurality of nuts  152 , as shown in  FIGS.  7  and  17   . A first end  154  of each stud  148  is configured to mate with a corresponding one of the first openings  144  formed in the housing  104 . The second passages  142  formed in the connect plate  118  subsequently receive the plural studs  148  projecting from the housing  104 . 
     When the housing  104  and the connect plate  118  are brought together, a second end  156  of each stud  148  projects from the second surface  126  of the connect plate  118 . A washer  150  and a nut  152  are subsequently installed on the second end  156  of each stud  148 , in a one-to-one relationship. The nut  152  is turned until it tightly engages the washer  150  and the second surface  126  of the connect plate  118 , thereby securing the housing  104  and the connect plate  118  together. 
     In  FIGS.  10 - 15   , the housing  104  and connect plate  118  each have eight corresponding first openings  144  and second passages  142 . In alternative embodiments, more than eight or less than eight corresponding openings and second passages may be formed in the housing and connect plate. In such embodiments, the fastening system may comprise the same number of studs, washers, and nuts as there are openings and passages. In further alternative embodiments, the fastening system may comprise different types of fasteners, such as socket-headed screws. In even further alternative embodiments, the connect plate  118  may be integral with the housing  104 , as shown for example in  FIGS.  139 A- 139 D . 
     Continuing with  FIGS.  10 - 15   , a pair of third passages  158  are formed in the connect plate  118  on opposite sides of the central bore  138 . The third passages  158  are alignable with a pair of pin holes  160  formed in the second surface  110  of the housing  104 . Each third passage  158  and each corresponding pin hole  160  is configured to receive a dowel pin in a one-to-one relationship. The dowel pins are used to help align the housing  104  on the connect plate  118  during assembly. A threaded hole  162  may also be formed in a top surface  164  of each connect plate  118 , as shown in  FIGS.  10  and  11   . The threaded hole  162  is configured for receiving a lifting eye (now shown) used to lift and support the connect plate  118  during assembly. 
     In alternative embodiments, the connect plate may have various shapes and sizes other than those shown in  FIGS.  10 - 13   . For example, the connect plate may be shaped like the various embodiments disclosed in U.S. Provisional Patent Ser. No. 63/053,797, authored by Thomas et al. and filed on Jul. 20, 2020. 
     Turning back to  FIGS.  6  and  7   , in contrast to the traditional fluid end  46 , shown in  FIG.  3   , the fluid end  100  is configured to receive fluid from two manifolds, rather than just one. The fluid end  100  comprises an upper intake manifold  166  and a lower intake manifold  168 . Each manifold  166  and  168  is in fluid communication with each fluid end section  102 . Using two different manifolds  166  and  168  allows different types of fluid to be delivered to each fluid end section  102 . For example, fluid having a higher level of proppant may be delivered via the upper intake manifold  166 , while fluid having a zero to minimal level of proppant may be delivered via the lower intake manifold  168 . 
     Continuing with  FIGS.  6  and  7   , the upper and lower intake manifolds  166  and  168  are joined to the fluid end sections  102  via a plurality of conduits  159 . Each conduit  159  is positioned directly below the corresponding manifold  166  and  168  and extends along a straight line between the fluid end section  102  and the corresponding manifold  166  and  168 . Thus, each conduit  159  and corresponding manifolds  166  and  168  have a “T” shape. 
     Turning to  FIGS.  7 A and  7 B , an alternative embodiment of an upper and lower intake manifold  161  and  163  is shown. The upper and lower intake manifolds  161  and  163  are joined to the fluid end sections  102  via a plurality of conduits  165 . The conduits  165  have an elbow shape. The elbow shape of the conduits  165  causes the corresponding manifolds  161  and  163  to be spaced farther away from a discharge manifold  167 , than the manifolds  166  and  168 . Providing more space between the intake manifolds  161  and  163  and the discharge manifold  167  provides more space for maintenance to different areas of the fluid end  100 , when needed. 
     Turning back to  FIG.  9   , an upper and lower intake bore  170  and  172  are formed within the housing  104 . Each bore  170  and  172  interconnects the intermediate outer surface  112  and the horizontal bore  106 . The upper and lower intake bores  170  and  172  shown in  FIG.  9    are collinear. In alternative embodiments, the upper and lower intake bores may not be collinear. 
     With reference to  FIGS.  6 - 9   , the upper intake bore  170  is in fluid communication with the upper intake manifold  166 , and the lower intake bore  172  is in fluid communication with the lower intake manifold  168 . In operation, fluid may be delivered into the housing  104  through both the upper and lower intake bores  170  and  172 . In alternative embodiments, only one intake bore may be formed in the housing and only one intake manifold may be attached to the housing. 
     Continuing with  FIGS.  6 - 9   , the fluid end  100  further comprises a plurality of discharge conduits  174 . Each discharge conduit  174  is attached to one of the fluid end sections  102  in a one-to-one relationship. A discharge manifold  176  interconnects each of the discharge conduits  174 , as shown in  FIGS.  6  and  7   . In alternative embodiments, the discharge conduits and discharge manifold may be formed as a single unit, like the discharge manifold  167 , shown in  FIGS.  7 A and  7 B . 
     Continuing with  FIG.  9   , a discharge bore  178  is formed in the housing  104  and interconnects the intermediate surface  112  and the horizontal bore  106 . The discharge bore  178  is positioned between the first surface  108  of the housing  104  and the intake bores  170  and  172 . The discharge bore  178  is in fluid communication with the discharge conduit  174 . In operation, fluid to be pressurized enters the housing  104  through the upper and lower intake bores  170  and  172 . Pressurized fluid exits the housing  104  through the discharge bore  178 . 
     With reference to  FIG.  18   , the discharge bore  178  has an oval cross-sectional shape, as shown by a discharge bore opening  180 . The opening  180  has a length A and a width B. The discharge bore  178  is formed within the housing  104  such that the width B extends along an axis that is parallel to the longitudinal axis  114  of the housing  104 . During operation, high fluid pressure within the discharge bore  178  may cause the walls along the length A to compress, causing the discharge bore  178  to have a more circular cross-sectional shape. Providing room for the walls surrounding the discharge bore  178  to compress, helps reduce stress in the housing  104  and increase fluid flow. In alternative embodiments, the discharge bore may have a circular cross-sectional shape. 
     Continuing with  FIG.  19   , a counterbore  173  is formed within the housing  104  immediately above the opening  180  of the discharge bore  178 . The discharge bore  178  opens into the counterbore  173 . The counterbore  173  has a circular cross-sectional shape, as shown by the opening  175  in  FIG.  18   . A portion of the discharge conduit  174  is installed within the counterbore  173  through its opening  175 . A seal  182  is interposed between the walls of the housing  104  surrounding the discharge bore  178  and an outer surface of the discharge conduit  174 . The seal  182  is installed within a groove  184  formed in the walls of the housing  104 . The seal  182  may be identical to the second seal  376 , described with reference to  FIGS.  65  and  70   . In alternative embodiments, the seal may be identical to the first seal  374 , described with reference to  FIGS.  65  and  71   . 
     The groove  184  is characterized by two sidewalls  185  joined to a base  183 . The sidewalls  185  may join the base  183  via radius corners or at a 90 degree angle. No grooves are formed in the outer surface of the discharge conduit  174  for housing a seal. In operation, the seal  182  wears against the outer surface of the discharge conduit  174 . If the outer surface of the discharge conduit  174  begins to erode, allowing fluid to leak around the seal  182 , the discharge conduit  174  may be replaced with a new discharge conduit  174 . 
     The discharge bore  178  shown in  FIG.  9    interconnects a top surface  113  of the intermediate surface  112  of the housing  104  and the horizontal bore  106 . Likewise, the discharge conduits  174  shown in  FIGS.  6 ,  7 , and  9    are attached to the top surface  113  of the intermediate surface  112  of each housing  104 . In operation, any gas trapped within the housing  104  rises towards the top of the housing  104 . Placing the discharge bore  178  and conduit  174  at the top of the housing  104  allows the gases to naturally escape. Additionally, any wear caused to the components by the rising gas will primarily be imposed on the discharge conduit  174 , rather than the housing  104 . The discharge conduit  174  and corresponding discharge piping  176  are easily replaced, if needed. 
     In alternative embodiments, the discharge bore may interconnect a bottom or side surface of the intermediate surface and the horizontal bore, and the discharge conduit may be attached to the corresponding surface of the housing. In further alternative embodiments, the discharge bore may interconnect the first outer surface of the housing and the horizontal bore, and the discharge conduit may be attached to the first outer surface of the housing. 
     With reference to  FIGS.  6 ,  18  and  19   , a rectangular flange  171  is formed around each discharge conduit  174 . Each rectangular flange  171  is attached to the housing  104  using a plurality of threaded studs  186  and nuts  187 , as shown in  FIGS.  6  and  19   . A plurality of threaded openings  188  are formed in the housing  104  for receiving the studs  186 , as shown in  FIG.  18   . The openings  188  are positioned in a rectangular pattern around the discharge bore opening  180 . Such pattern helps maximize the surface area of the intermediate surface  112  of the housing  104 , helping to reduce the size and weight of the housing  104 . 
     With reference to  FIGS.  7  and  18   , the intake manifolds  166  and  168  each comprise a plurality of rectangular flanges  189  joined to a plurality of conduits  191  in a one-to-one relationship, as shown in  FIG.  7   . Each rectangular flange  189  is attached to the housing  104  using a plurality of threaded studs  190  and nuts  193 , as shown in  FIG.  7   . A plurality of threaded openings  192  are formed in the housing  104  for receiving the studs  190 , as shown in  FIG.  18   . The openings  192  are positioned in a rectangular pattern around the intake bores  170  and  172  to maximize surface area of the housing  104 . In alternative embodiments, the discharge conduits and intake manifolds may be attached to the housing using different types of fasteners, such as socket-headed screws. 
     Continuing with  FIG.  18   , the intermediate surface  112  of the housing  104  includes a first portion  194  joined to a second portion  196  by a first tapered portion  198 . The second portion  196  is joined to a third portion  200  by a second tapered portion  202 . The first portion  194  is joined to the first surface  108  and the third portion  200  is joined to the second surface  110 . 
     The second portion  196  has a smaller diameter than both the first and third portions  194  and  200 . Providing the second portion  196  with a smaller diameter helps remove unnecessary weight from the housing  104 . The third portion  200  may have a slightly larger diameter than the first portion  194 . The first, second, and third portions  194 ,  196 , and  200  are generally cylindrical. Thus, the housing  104  may be characterized as being primarily cylindrical. In alternative embodiments, the housing may be uniform in diameter throughout its intermediate surface. In further alternative embodiments, the housing may have various diameters throughout its intermediate surface other than those shown in  FIG.  18   . 
     Continuing with  FIG.  18   , a threaded hole  204  is formed in the top surface  113  of the intermediate surface  112 . The threaded hole  204  is positioned at the center of gravity of the housing  104  when the housing  104  is fully loaded with the components described herein. The threaded hole  204  is configured to receive a lifting eye (not shown) used to lift and support the housing  104  during assembly and maintenance, as shown in  FIG.  9   . 
     With reference to  FIGS.  19 A- 19 H , an alternative embodiment of a fluid end  99  is shown. The fluid end  99  is generally identical to the fluid end  100  but includes an alternative embodiment of fluid end sections  101  and utilizes upper and lower discharge manifolds  109  and  111 . The fluid end section  101  is generally identical to the fluid end section  102 , shown in  FIG.  8   , but includes an alternative embodiment of a fluid end housing  103 . 
     Continuing with  FIGS.  19 E- 19 H , the fluid end housing  103  is generally identical to the fluid end housing  104  shown in  FIGS.  8  and  9    but includes a second discharge bore. The housing  103  comprises an upper discharge bore  105  and a lower discharge bore  107 . The upper and lower discharge bores  105  and  107  are vertically aligned and collinear, as shown in  FIGS.  19 G and  19 H . In alternative embodiments, the discharge bores  105  and  107  may be positioned at a non-zero angle relative to one another or may be laterally offset from one another. 
     Continuing with  FIGS.  19 G and  19 H , the upper discharge bore  105  is generally identical to the discharge bore  178 , shown in  FIG.  9   ; however, the discharge bore  105  may not include the counterbore  173  or the radial seal groove  184 . Instead, a seal groove  131 , also shown in  FIGS.  19 E and  19 F , is formed in the outer surface of the housing  103  for receiving a seal (not shown). A corresponding seal groove is formed on a bottom surface of a manifold or discharge conduit for receiving the seal. The seal installed within the seal groove  131  acts as a face real rather than a radial seal, like the seal  182 , shown in  FIG.  9   . 
     The lower discharge bore  107  is identical to the upper discharge bore  105  but is formed in the opposite side of the housing  103 . In operation, fluid exits the housing  103  through both the upper and lower discharge bores  105  and  107 , as shown by arrows  97  in  FIG.  19 H . 
     Using the two discharge bores  105  and  107  instead of a single discharge bore balances the flow of fluid around the inner components of housing  103  as fluid exits the fluid routing plug  116  and flows into the bores  105  and  107 . Specifically, fluid flow is balanced around the discharge valve  294 , the discharge valve guide  531  and its corresponding seal  520 , discussed later herein. The balanced flow of fluid applies a more even load to these components during operation. The more evenly applied load results in more even wear and an increased life span of such components. 
     Turning back to  FIGS.  19 A and  19 B , the upper and lower discharge bores  105  and  107  are each in fluid communication with corresponding upper and lower discharge manifolds  109  and  111 . The manifolds  109  and  111  are each formed as a single unit, like the discharge manifold  167 , shown in  FIGS.  7 A and  7 B . 
     Turning to  FIGS.  19 C and  19 D , another embodiment of upper and lower manifolds  115  and  117  are shown. The manifolds  115  and  117  are identical to the discharge manifold  176 , shown in  FIGS.  6 ,  7 ,  8 , and  9   . Like the manifold  176 , the upper and lower manifolds  115  and  117  each comprise a plurality of discharge conduits  119  attached to a corresponding one of housings  103  in a one-to-one relationship. 
     The discharge conduits  119  are generally identical to the discharge conduits  174 , shown in  FIG.  9   . However, the discharge conduits  119  are not installed within the counterbore  173  and instead abut the outer surface of the housing  103  and aligns with the corresponding discharge bore  105  or  107 . The discharge conduits  119  are attached to the housing  103  in the same manner as the discharge conduits  174 . Fluid is prevented from leaking between the bore  105  or  107  and the conduits  119  or the manifolds  109  and  111  by the face seal installed within the seal groove  131 , shown in  FIGS.  19 G and  19 H . 
     With reference to  FIGS.  20 - 29   , each fluid end section  102  further comprises a stuffing box  140  attached to the second outer surface  110  of the housing  104 . The stuffing box  140  has a generally cylindrical shape and comprises a first outer surface  206  joined to an opposed second outer surface  208  by an intermediate outer surface  210 . The intermediate surface  210  includes a cylindrical first portion  212  joined directly to a cylindrical second portion  214 . The first portion  212  is positioned adjacent the first surface  206  and has a reduced diameter from that of the second portion  214 . A threaded hole  215  is formed in a top surface of the second portion  214 . The threaded hole  215  is configured to receive a lifting eye (not shown) used to lift and support the stuffing box  140  during assembly and maintenance. 
     A central passage  216  interconnects the stuffing box&#39;s first and second outer surfaces  206  and  208 . The walls surrounding the central passage  216  include a first section  218  joined to a second section  220  by a tapered shoulder  222 , as shown in  FIGS.  25 ,  26 , and  29   . The second section  220  has a larger diameter than that of the first section  218 . As described in more detail herein, the second section  220  and the tapered shoulder  222  are configured for receiving a plunger packing  224 , as shown in  FIGS.  20  and  21   . 
     Continuing with  FIGS.  23 - 29   , a plurality of passages  226  are formed around the periphery of the second portion  214  of the stuffing box  140 . Each passage  226  interconnects the second surface  208  of the stuffing box  140  and a base  228  of the second portion  214 . The passages  226  are formed parallel to the central passage  216 . 
     Turning back to  FIGS.  14  and  15   , a plurality of second threaded openings  230  are formed in the second surface  110  of the housing  104 . The openings  230  surround the opening of the horizontal bore  106 . The second openings  230  are surrounded by the first openings  144  used with the connect plate  118 . 
     Continuing with  FIGS.  20  and  21   , the walls surrounding the horizontal bore  106  adjacent the second surface  110  of the housing  104  are sized to receive the first portion  212  of the stuffing box  140 . The first portion  212  is installed within the horizontal bore  106  such that the base  228  of the second portion  214  abuts the second surface  110  of the housing  104 . A portion of the second portion  214  is disposed within the central bore  138  formed in the connect plate  118 . The stuffing box  140  is aligned on the housing  104  such that the passages  226  align with the second openings  230  in a one-to-one relationship. 
     With reference to  FIGS.  20 ,  21 , and  30 - 37   , the stuffing box  140  is attached to the housing  104  using a retainer  232  and a fastening system  234 . The retainer  232  has a generally cylindrical shape and comprises opposed first and second outer surfaces  236  and  238  joined by an intermediate surface  240 . A central passage  242  interconnects the first and second outer surfaces  236  and  238 . At least a portion of the central passage  242  has internal threads  244 . A plurality of side passages  246  are formed in the retainer  232 . Each passage  246  interconnects the central passage  242  and the intermediate surface  240 . The passages  246  provide a pathway for lubricating oil to be introduced to the horizontal bore  106  during operation. The oil lubricates the moving parts within the housing  104  during operation. 
     Continuing with  FIGS.  30 - 37   , a plurality of passages  248  are formed in the retainer  232  and surround the central passage  242 . Each passage  248  interconnects the first and second outer surfaces  236  and  238 . The first surface  236  of the retainer  232  is positioned on the second surface  208  of the stuffing box  140  such that the passages  248  align with the passages  226  formed in the stuffing box  140 , in a one-to-one relationship. 
     A pair of dowel pin holes  241  are formed in the second surface  208  of the stuffing box  140 , as shown in  FIGS.  27  and  28   . A corresponding pair of dowel pin holes  243  are formed in the first surface  236  of the retainer  232 , as shown in  FIGS.  31  and  32   . The holes  241  and  243  are configured for receiving a dowel pin. The dowel pin aligns the retainer  232  on the stuffing box  140  during assembly. 
     Turning back to  FIGS.  20  and  21   , the fastening system  234  secures both the retainer  232  and the stuffing box  140  to the housing  104 . The fastening system  234  comprises a plurality of studs  250 , nuts  252 , and washers  254 . A first end  256  of each stud  250  mates with one of the second openings  230  in the housing  104  in a one-to-one relationship. The passages  226  in the stuffing box  140  and the passages  248  in the retainer  232  subsequently receive the plural studs  250  projecting from the housing  104 . 
     A second end  258  of each stud  250  projects from the second surface  238  of the retainer  232 . The projecting second end  258  of each stud  250  receives a washer  254  and a nut  252 . The nut  252  is turned until it tightly engages the washer  254  and the second surface  238  of the retainer  232 , thereby securing the retainer  232  and the stuffing box  140  together. The retainer  232 , in turn, holds the stuffing box  140  against the housing  104 . The stuffing box  140  and the retainer  232  may be attached to and removed from the housing  104  without removing the connect plate  118 . 
     When the first portion  212  of the stuffing box  140  is installed within the housing  104 , a seal  260  is interposed between the walls of the housing  104  and outer surface of the first portion  212 . The seal  260  is installed within a groove  262  formed in the walls of the housing  104 . The seal  260  may be identical to the first seal  374 , described with reference to  FIGS.  65  and  71   . In alternative embodiments, the seal may be identical to the second seal  376 , described with reference to  FIGS.  65  and  70   . 
     The groove  262  is characterized by two sidewalls  264  joined by a base  266 , as shown in  FIG.  21   . The sidewalls  264  may join the base  266  via radius corners or at a 90 degree angle. No grooves are formed in the first portion  212  of the stuffing box  140  for housing a seal. The seal  260  wears against the outer surface of the first portion  212  during operation. If the outer surface of the first portion  212  begins to erode, allowing fluid to leak around the seal  260 , the stuffing box  140  may be replaced with a new stuffing box  140 . 
     When the stuffing box  140  is attached to the housing  104  using the fastening system  234 , a first end  256  of the studs  250  may be installed within the housing  104  such that they extend past the seal  260 , as shown in  FIG.  20   . An edge of the studs  250  may not be purposely aligned with an edge of the seal  260  in order to prevent areas of high stress from being aligned with one another in the housing  104 , potentially causing a stress riser. 
     Continuing with  FIGS.  20 ,  21 , and  38 - 42   , a plunger packing  224  is installed within the central passage  216  of the stuffing box  140 . The plunger packing  224  engages the tapered shoulder  222  and is positioned within the second section  220  of the central passage  216 , as shown in  FIGS.  20  and  21   . A portion of the plunger packing  224  may extend into the central passage  242  of the retainer  232 . The plunger packing  224  has a central passage  268  that aligns with the central passages  216  and  242  when the plunger packing  224  is installed within the stuffing box  140  and the retainer  232 . In alternative embodiments, the plunger packing may be sized to not extend into the retainer. 
     The plunger packing  224  comprises a pair of outer ring seals  270  and  271  and at least one inner ring seal  272 . The outer ring seals  270  and  271  may be made of metal while the inner ring seals  272  may be made of an elastomer material. The outer ring  270  has a tapered outer surface  274  that is sized to engage the tapered shoulder  222  formed in the central passage  216 . The tapered engagement helps reduce stress in the stuffing box  140  during operation. In alternative embodiments, the walls surrounding the central passage of the stuffing box may include an annular shoulder rather than a tapered shoulder. In such embodiment, the plunger packing may have a flat outer ring configured to mate with the annular shoulder. A plurality of holes  275  are formed in the outer ring  271 . The holes  275  are in fluid communication with the side passages  246  formed in the retainer  232  in order to deliver lubricating oil to the housing  104 . 
     With reference to  FIGS.  20 ,  21 , and  43 - 46   , a packing nut  276  is installed within the retainer  232  and engages the plunger packing  224 . The packing nut  276  comprises a first surface  278  joined to an opposed second surface  280  by an intermediate surface  282 . A central passage  284  extends through the packing nut  276  and interconnects the opposed first and second surfaces  278  and  280 . A plurality of side holes  286  are formed in the packing nut  276  and interconnect the central passage  284  and the intermediate surface  282 . The holes  286  are configured for engaging a tool used to grip the packing nut  276 . 
     Continuing with  FIGS.  43 - 46   , external threads  288  are formed in a portion of the intermediate surface  282  of the packing nut  276 . The external threads  288  are configured to mate with the internal threads  244  formed within the retainer  232 , as shown in  FIGS.  20  and  21   . The mating threads  288  and  244  are buttress threads. The buttress threads are configured to handle a large amount of load using a low number of threads. Using a low number of threads allows the packing nut  276  to be quickly removed or installed within the retainer  232 . In alternative embodiments, the packing nut and retainer may mate using traditional threads. 
     When the packing nut  276  is installed within the retainers  232 , the first surface  278  of the packing nut  276  engages an outer ring seal  270  of the plunger packing  224 . Such engagement compresses the plunger packing  224 , creating a tight seal. After the packing nut  276  has been installed within a retainer  232 , the central passage  284  within the packing nut  276  is aligned with the central passage  268  in the plunger packing  224 . 
     Continuing with  FIGS.  20  and  21   , when the stuffing box  140  and the retainer  232  are attached to the housing  104 , the central passages  216  and  242  align with the horizontal bore  106 . Likewise, the central passages  268  and  284  in the installed plunger packing  224  and packing nut  276  align with the horizontal bore  106 . Thus, the central passages  216 ,  242 ,  268 , and  284  may be considered an extension of the horizontal bore  106 . A plunger  290  is disposed with the installed plunger packing  224  and the packing nut  276 , as shown in  FIG.  20   . In operation, the plunger  290  reciprocates within the horizontal bore  106  in order to pressurize fluid contained with the housing  104 . 
     With reference to  FIGS.  20 ,  21 , and  47 - 49   , the horizontal bore  106  is sealed at the first surface  108  of the housing  104  by a retainer  300 . The retainer  300  has a first surface  302  joined to an opposed second surface  304  by an outer intermediate surface  306 . A cutout  308  is formed in the second surface  304  for receiving a portion of a discharge valve guide  298 . A central passage  310  is formed in the retainer  300  and interconnects the first surface  302  and the cutout  308 . The walls surrounding the central passage  310  have a polygonal shape. The polygonal shape is configured to mate with a tool used to grip the retainer  300 . 
     The intermediate surface  306  of the retainer  300  has external threads  312  that mate within internal threads  314  formed in the walls surrounding the horizontal bore  106  adjacent the first surface  108  of the housing  104 , as shown in  FIGS.  20  and  21   . The mating threads  312  and  314  are buttress threads. The buttress threads are configured to handle a large amount of load using a low number of threads. Using a low number of threads allows the retainer  300  to be quickly removed from or installed within the housing  104 . In alternative embodiments, the retainer may mate with the housing using traditional threads. In further alternative embodiments, the retainer may be secured to the housing using a fastening system, as shown for example in  FIG.  132   . 
     Turning now to  FIGS.  50  and  51   , the fluid routing plug  116  is installed within a medial section of the horizontal bore  106 . The fluid routing plug  116  is configured to engage with a suction valve  292  on one side and a discharge valve  294  on the opposite side. In operation, the suction and discharge valves  292  and  294  move axially along an axis that is parallel to or aligned within the central longitudinal axis  114  of the housing  104 , shown in  FIG.  9   , as the valves  292  and  294  move at alternating times between an open and closed position. In the closed position, the valves  292  and  294  are pressed against the fluid routing plug  116 , preventing fluid from exiting the plug  116 . In the open position, the valves  292  and  294  are spaced from the fluid routing plug  116 , allowing fluid to flow from the plug  116 . 
     As will be described in more detail herein, axial movement of the suction valve  292  is limited by a suction valve guide  296  installed within the housing  104 . Likewise, axial movement of the discharge valve  294  is limited by the discharge valve guide  298  installed within the housing  104 . 
     Turning now to  FIGS.  52 - 64   , the fluid routing plug  116  comprises a body  316  having opposed first and second outer surfaces  318  and  320  joined by an intermediate outer surface  322 . The first outer surface  318  may also be referred to as the suction side of the fluid routing plug  116 . The second outer surface  320  may also be referred to as the discharge side of the fluid routing plug  116 . A central longitudinal axis  324  extends through the body  316  and both surfaces  318  and  320 , as shown in  FIG.  55   . 
     A plurality of first fluid passages  326  are formed within the body  316  and interconnect the intermediate surface  322  and the first surface  318 . The first fluid passages  326  interconnect the intermediate surface  322  and the first surface  318  by way of an axial-blind bore  328 , as shown in  FIG.  55   . The blind bore  328  extends along the central longitudinal axis  324  of the body  316 . The first fluid passages  326  each open into the blind bore  328  via a plurality of openings  330 . A longitudinal axis  332  of each first fluid passage  326  intersects the central longitudinal axis  324  of the body  316 , as shown in  FIG.  58   . 
     The fluid routing plug  116  shown in  FIGS.  52 - 64    has four first fluid passages  326  formed in its body  316 . The first fluid passages  326  are equally spaced around the body  316 . In alternative embodiments, more than four or less than four first fluid passages may be formed in the body and may be equally or unequally spaced apart from one another. 
     Continuing with  FIG.  55   , the first fluid passages  326  extend between the intermediate surface  322  and the blind bore  328  at a non-right angle relative to the central longitudinal axis  324 —the acute angle facing the second surface  320  of the body  316 . Forming the first fluid passages  326  at such angle reduces the amount of stress in the fluid routing plug  116  as fluid flows through the first fluid passages  326 . Forming the first fluid passages  326  at such an angle also helps direct fluid flow towards the blind bore  328  and the first surface  318 . 
     With reference to  FIGS.  57  and  59   , the first fluid passages  326  have an oval cross-sectional shape, as shown by an opening  334  of each first fluid passage  326  on the intermediate surface  322 . Each opening  334  has a length A and a width B, as shown in  FIG.  59   . The first fluid passages  326  are formed in the body  316  such that the length A extends along an axis that is parallel to the central longitudinal axis  324  of the body  316 . Orienting the first fluid passages  326  as such helps reduce the amount of stress in the body  316  as fluid flows through the first fluid passages  326  and helps maximize the rate of fluid flow through the passages  326 . In alternative embodiments, the first fluid passages may have a different cross-sectional shape, such as a circular or oblong shape. In further alternative embodiments, the first fluid passages may be shaped like the first fluid passages  910 , shown in  FIGS.  121  and  124   . 
     With reference to  FIGS.  60 - 63   , the fluid routing plug  116  further comprises a plurality of second fluid passages  336  formed in the body  316 . The second fluid passages  336  each have a circular cross-sectional shape and interconnect the first and second surfaces  318  and  320  of the body  316 . In alternative embodiments, the second fluid passages may have a different cross-sectional shape, such as an oval or oblong shape. 
     Unlike the first fluid passages  326 , the second fluid passages  336  do not intersect an axially blind bore. Rather, each second fluid passage  336  extends between the first and second surface  318  and  320  along a straight-line path. The second fluid passages  336  and the first fluid passages  326  do not intersect and are positioned offset from one another, as shown in  FIG.  58   . Positioning the first and second passages  326  and  336  offset from one another helps minimize the stress in the fluid routing plug  116  during operation. The fluid routing plug  116  shown in  FIGS.  52 - 64    has twelve second fluid passages  336  formed in its body  316 . In alternative embodiments, more or less than twelve second fluid passages may be formed in the body. 
     Each second fluid passage  336  extends between the first and second surfaces  318  and  320  along a different axis, as shown in  FIGS.  60 - 63   . Each axis is positioned at a non-zero angle relative to the central longitudinal axis  324  of the body  316 . Forming each second passage  336  along a different axis helps alleviate stress in the fluid routing plug  116  during operation and helps maximize the rate of fluid flow through the second passages  336 . 
     Turning back to  FIGS.  53 ,  55 , and  56   , the first surface  318  of the body  316  includes an outer rim  338  joined to a tapered wall  340 . The outer rim  338  may taper slightly between the intermediate surface  322  and the tapered wall  340 , as shown in  FIG.  55   . Such taper provides more surface area for the tapered wall  340  without increasing the length of the intermediate surface  322 . The tapered wall  340  extends between an entrance  342  of the blind bore  328  and the outer rim  338  at an angle of at least 30 degrees relative to the central longitudinal axis  324  of the body  316 . Preferably, the tapered wall  340  is formed at an angle of 45 degrees relative to the central longitudinal axis  324  of the body  316 , as is shown in  FIG.  55   . As will be described in more detail later herein, the tapered wall  340  forms a cavity  344  within the first surface  318  of the body  316  that is sized to receive a sealing element  346  of the suction valve  292 , as shown in  FIGS.  72 - 76   . 
     Continuing with  FIGS.  53  and  56   , the second fluid passages  336  open on the outer rim  338  of the first surface  318 , as shown by the openings  348 . The second fluid passages  336  are formed within the body  316  such that the openings  348  are positioned in groups  350  around the outer rim  338 . The first surface  318  shown in  FIG.  59    comprises four groups  350  of openings  348 , each group  350  comprising three openings  348 . Adjacent openings  348  within each group  350  are equally spaced. The spacing between the nearest openings  348  of adjacent groups  350  exceeds the spacing between adjacent openings  348  within a single group  350 . Spacing the openings  348  in groups  350  helps achieve the ideal velocity of fluid flow through the fluid routing plug  116  and allows the second fluid passages  336  to be offset from the first fluid passages  326 , as shown in  FIG.  58   . In alternative embodiments, the openings may be spaced in differently sized groups or different patterns than that shown in  FIG.  56   . 
     With reference to  FIGS.  52 ,  54 , and  55   , the second surface  320  of the body  316  comprises an outer rim  352  joined to a central base  354  by a tapered wall  356 . The tapered wall  356  extends between the central base  354  and the outer rim  352  at an angle of at least 30 degrees relative to the central longitudinal axis  324  of the body  316 . Preferably, the tapered wall  356  is formed at an angle of 45 degrees relative to the central longitudinal axis  324  of the body  316 , as is shown in  FIG.  55   . As will be described in more detail later herein, the tapered wall  356  forms a cavity  358  within the second surface  320  of the body  316  that is sized to receive a sealing element  360  of the discharge valve  294 , as shown in  FIGS.  85 - 89   . 
     Continuing with  FIGS.  52 ,  54 , and  55   , a blind bore  362  is formed in the center of the central base  354 . The walls surrounding the blind bore  362  may be configured to mate with a tool used to grip the fluid routing plug  116 . For example, the walls surrounding the blind bore  362  may be threaded. The second fluid passages  336  open on the central base  354  of the second surface  320 , as shown by the openings  364  in  FIGS.  52  and  54   . The second fluid passages  336  are formed within the body  316  such that the openings  364  surround the opening of the blind bore  362 . The openings  364  shown in  FIG.  54    are all equally spaced from one another around the opening of the blind bore  362 . In alternative embodiments, the openings of the second fluid passages on the central base may not all be equally spaced apart from one another. 
     Continuing with  FIG.  55   , in order to provide space for the openings  364  on the second surface  320 , the tapered wall  356  has a greater diameter than the tapered wall  340  formed in the first surface  318 . Thus, as will be described in more detail herein, the sealing element  360  of the discharge valve  294  is larger in size than the sealing element  346  of the suction valve  292 , as shown in  FIGS.  72 - 76  and  85 - 89   . 
     Turning back to  FIGS.  50  and  51   , the fluid routing plug  116  is installed within the horizontal bore  106  such that the first fluid passages  326  are in fluid communication with the upper and lower intake bores  170  and  172 . The upper and lower intake bores  170  and  172  direct fluid into the first fluid passages  326  of the fluid routing plug  116 . The first fluid passages  326  direct the fluid into the blind bore  328  and towards the first surface  318  of the fluid routing plug  116 . 
     When the plunger  290  is retracted from the housing  104 , the fluid flowing through the first fluid passages  326  forces the suction valve  292  to move axially away from the first surface  318 . Such position is considered an open position of the suction valve  292 . When the suction valve  292  is spaced from the first surface  318 , fluid flows out of the blind bore  328 , through the gap between the first surface  318  and the suction valve  292 . From there, the fluid flows around the suction valve  292  and the suction valve guide  296  and into the horizontal bore  106 . A first fluid flow path for the fluid to be pressurized is shown by the arrows  366  in  FIG.  50   . 
     With reference to  FIG.  51   , as the plunger  290  extends into the horizontal bore  106 , the plunger  290  forces fluid in the horizontal bore  106  back towards the fluid routing plug  116 . Pressurized fluid forced back towards the fluid routing plug  116  by the plunger  290  forces the suction valve  292  to seal against the first surface  318 , sealing the entrance  342  of the blind bore  328 . Such position is considered a closed position of the suction valve  292 . Once the entrance  342  of the blind bore  328  is sealed, the only place for fluid to flow is through the openings  348  of the second fluid passages  336  on the outer rim  338  of the first surface  318 . 
     Fluid flows into the openings  348  on the first surface  318  and through the second passages  336  towards the second surface  320  of the fluid routing plug  116 . The pressurized fluid at the second surface  320  forces the discharge valve  294  to move axially away from the second surface  320 , unsealing the openings  364  of the second fluid passages  336 . Such position is considered an open position of the discharge valve  294 . Pressurized fluid is then allowed to flow around the discharge valve  294  and into the discharge bore  178 . A second fluid flow path for the pressurized fluid is shown by the arrows  368  in  FIG.  51   . 
     When the plunger  290  retracts from the housing  104 , the fluid pressure on the back side of the discharge valve  294  is greater than the fluid pressure within the fluid routing plug  116 . Such pressure differential causes the discharge valve  294  to seal against the second surface  320 , sealing the openings  364  of the second fluid passages  336 . Such position is considered the closed position of the discharge valve  294 . 
     Turning to  FIG.  64   , the intermediate surface  322  of the fluid routing plug  116  varies in diameter throughout its length and generally decreases in size from its second surface  320  to its first surface  318 . The intermediate surface  322  comprises a first sealing surface  370  positioned adjacent the first surface  318  and a second sealing surface  372  positioned adjacent the second surface  320 . The first and second sealing surfaces  370  and  372  each extend around the entire intermediate surface  322  in an endless manner and surround the longitudinal axis  324  of the body  316 . The first and second sealing surfaces  370  and  372  shown in  FIG.  64    are annular. In alternative embodiments, the first and second sealing surfaces may have non-annular shape, such as an oval shape. 
     The first sealing surface  370  has a smaller diameter than the second sealing surface  372 . As will be described in more detail herein, the first and second sealing surfaces  370  and  372  are configured to engage a first and second seal  374  and  376  installed within the housing  104 , as shown in  FIGS.  70  and  71   . 
     Continuing with  FIG.  64   , the intermediate surface  322  of the fluid routing plug  116  further comprises a first bevel  378  positioned between the opening  334  of the first fluid passages  326  and the first sealing surface  370 . The first bevel  378  extends around the entire intermediate surface  322  in an endless manner and surrounds the longitudinal axis  324  of the body  316 . The first bevel  378  shown in  FIG.  64    is annular. In alternative embodiments, the first bevel may have a non-annular shape, such as an oval shape. 
     A maximum diameter of the first bevel  378  is greater than the diameter of the first sealing surface  370 . The maximum diameter of the first bevel  378  is positioned adjacent the openings  334  of the first fluid passages  326  and a minimum diameter of the first bevel  378  is positioned adjacent the first sealing surface  370 . As will be described in more detail later herein, the first bevel  378  corresponds with a first beveled surface  380  formed in the housing  104 , as shown in  FIGS.  65  and  69   . 
     The intermediate surface  322  also comprises a second bevel  382  positioned between the second sealing surface  372  and the openings  334  of the first fluid passages  326 . The second bevel  382  extends around the entire intermediate surface  322  in an endless manner and surrounds the longitudinal axis  324  of the body  316 . The second bevel  382  shown in  FIG.  64    is annular. In alternative embodiments, the first bevel may have non-annular shape, such as an oval shape. 
     A maximum diameter of the second bevel  382  is positioned adjacent the second sealing surface  372  and a minimum diameter of the second bevel  382  is positioned adjacent the openings  334  of the first fluid passages  326 . The second sealing surface  372  and the maximum diameter of the second bevel  382  both have a greater diameter than the maximum diameter of the first bevel  378  and the diameter of the first sealing surface  370 . 
     As will be described in more detail later herein, the second bevel  382  corresponds with a second beveled surface  384  formed in the housing  104 , as shown in  FIGS.  65  and  68   . A small transition bevel  386  may extend between the second sealing surface  372  and the second bevel  382 . However, the transition bevel  386  does not engage the second beveled surface  384 , as shown in  FIG.  68   . The transition bevel  386  helps reduce friction between the fluid routing plug  116  and the housing  104  during installation. 
     As described above, the first and second bevels  378  and  382  are positioned between the first and second sealing surfaces  370  and  372 . The first and second bevels  378  and  382  help alleviate stress in the fluid routing plug  116  during operation. In alternative embodiments, the intermediate surface may only include a single bevel positioned between the first and second sealing surfaces. 
     Continuing with  FIG.  64   , the various diameters of the intermediate surface  322  are shown in more detail. The first sealing surface  370  has a diameter D 1 . The maximum diameter of the first bevel  378  has a diameter D 2 . The maximum diameter of the second bevel  382  has a diameter D 3 , and the second sealing surface  372  has a diameter D 4 . As described above in detail, D 4  is greater than D 3 , D 3  is greater than D 2 , and D 2  is greater than D 1 . 
     With reference to  FIG.  65   , in addition to being shaped to alleviate stress, the intermediate surface  322  is shaped to allow for easy installation of the fluid routing plug  116  within the horizontal bore  106 . The fluid routing plug  116  is installed into the horizontal bore  106  at the first outer surface  108  of the housing  104 . The fluid routing plug  116  is installed with the first surface  318  entering the horizontal bore  106  before the second surface  320 . The fluid routing plug  116  is pushed into the horizontal bore  106  until the first sealing surface  370  engages the first seal  374  and the second sealing surface  372  engages the second seal  376 . 
     The first sealing surface  370  and first bevel  378  have smaller diameters than the second seal  376  and the second beveled surface  384 . Thus, clearance exists between these features as the fluid routing plug  116  is installed into the horizontal bore  106 . Providing such clearance during installation avoids unnecessary wear to both the housing  104  and fluid routing plug  116  during installation. 
     With reference to  FIGS.  65  and  67   , once the fluid routing plug  116  is installed within the housing  104 , an annular chamber  388  is formed between the walls of the housing  104  and the intermediate surface  322 . The intake bores  170  and  172  open into the chamber  388 . Only a couple of the openings  334  of the first fluid passages  326  may align with the intake bores  170  and  172 . Alternatively, the fluid routing plug  116  may be installed within the housing  104  such that none of the openings  334  directly align with the intake bores  170  and  172 . The chamber  388  provides a pathway for fluid from the intake bores  170  and  172  to flow around the fluid routing plug  116  and into the openings  334  of the first fluid passages  326 . The chamber  388  also provides space for proppant or other debris to collect during operation. 
     Continuing with  FIG.  67   , the walls of the housing  104  surrounding the horizontal bore  106  immediately adjacent the intake bores  170  and  172  are beveled, as shown by bevels  390  and  392 . The bevels  390  and  392  help reduce stress in the housing  104  during operation and increase the size of the annular chamber  388 . In alternative embodiments, the bevels  390  and  392  may be larger than those shown in  FIG.  67    in order to increase the size of the chamber  388 , as shown for example in  FIG.  100 F . Similarly, the walls of the housing  104  surrounding the horizontal bore  106  immediately adjacent the discharge bore  178  are also beveled, as shown by the bevel  394  in  FIG.  66   . The bevel  394  reduces stress in the housing  104  during operation and helps direct fluid into the discharge bore  178 . 
     Continuing with  FIGS.  65  and  68   , the second bevel  382  and the second beveled surface  384  are shown in more detail. The second beveled surface  382  is positioned between the second seal  376  and the intake bores  170  and  172 . The second beveled surface  384  has an annular shape and surrounds the horizontal bore  106  in an endless manner. In alternative embodiments, the second beveled surface may have a shape that conforms to the shape of the second bevel formed in the fluid routing plug. 
     When the fluid routing plug  116  is installed within the horizontal bore  106 , the second bevel  382  seats against the second beveled surface  384 , as shown in  FIG.  68   . The bevels  382  and  384  meet at a non-right angle. Such angle reduces stress in the fluid routing plug  116  and the housing  104  during operation. The bevels  382  and  384  remain engaged during the forward and backwards stroke of the plunger  290 . 
     Turning to  FIGS.  65  and  69   , the first bevel  378  and the first beveled surface  380  are shown in more detail. The first beveled surface  380  is positioned between the intake bores  170  and  172  and the first seal  374 . The first beveled surface  380  has an annular shape and surrounds the horizontal bore  106  in an endless manner. In alternative embodiments, the first beveled surface may have a shape that conforms to the shape of the first bevel formed in the fluid routing plug. 
     In contrast to the second bevel  382 , the first bevel  378  is sized to be spaced from the first beveled surface  380  when the fluid routing plug  116  is initially installed within the housing  104 , as shown by a gap  398 . The gap  398  provides space for the fluid routing plug  116  to expand during operation. 
     As the plunger  290  retracts backwards away from the housing  104 , a significant amount of load is applied to the second bevel  382 . The applied load causes the fluid routing plug  116  to slightly compress, forcing the intermediate surface  322  at the first bevel  378  to expand outwards. As the first bevel  378  expands, it eventually engages with the first beveled surface  380 . Upon engaging the first beveled surface  380 , the load being applied to the second bevel  382  is shared with the first bevel  378 , thereby decreasing the load applied to the second bevel  382 . Without the gap  398 , the fluid routing plug  116  would not have room to expand, potentially causing damage to the fluid routing plug  116  and the housing  104  over time. 
     As the plunger  290  extends forward into the housing  104 , the first bevel  378  will return to its un-expanded state, re-creating the gap  398 . The gap  398  will repeatedly be created and closed during operation as the plunger  290  reciprocates. In addition to providing space for the fluid routing plug  116  to expand, the gap  398  also provides a gas and fluid relief area during the forward stroke of the plunger  290 . 
     Continuing with  FIGS.  68  and  69   , because the second bevel  382  carries the majority of the load experienced by the fluid routing plug  116  during operation, the second bevel  382  is longer than the first bevel  378 . In alternative embodiments, the first bevel may be longer than that shown in  FIG.  69    or be equal in length to the second bevel. In such embodiments, the first beveled surface formed in the housing may correspond with the chosen size of the first bevel. In further alternative embodiments, the first bevel may be sized to mate with the first beveled surface when the fluid routing plug is first installed within the housing. 
     With reference to  FIGS.  65 ,  70 , and  71   , in order to prevent fluid from leaking around the fluid routing plug  116  during operation, the first and second seals  374  and  376  are positioned between the sealing surfaces  370  and  372  and the walls of the housing  104  surrounding the horizontal bore  106 . 
     The first seal  374  is positioned within a first annular groove  400  formed in housing  104  and surrounding the horizontal bore  106  in an endless manner. The first groove  400  is positioned between the intake bores  170  and  172  and the second outer surface  110  of the housing  104 , as shown in  FIG.  65   . The first groove  400  is characterized by two sidewalls  402  joined by a base  404 , as shown in  FIG.  71   . The sidewalls  402  may join the base  404  via radius corners or at a 90 degree angle. In alternative embodiments, the first groove may have a non-concentric shape that corresponds with the shape of the first sealing surface. 
     The second seal  376  is positioned within a second annular groove  406  formed in the housing  104  and surrounding the horizontal bore  106  in an endless manner. The second groove  406  is positioned between the discharge bore  178  and the intake bores  170  and  172 , as shown in  FIG.  65   . The second groove  406  is characterized by two sidewalls  408  joined by a base  410 . The sidewalls  408  may join the base  410  via radius corners or at a 90 degree angle. In alternative embodiments, the second groove may have a non-concentric shape that corresponds with the shape of the second sealing surface. 
     The second groove  406  has a larger diameter than that of the first groove  400  due to the diameter of the horizontal bore  106  at each groove, as shown in  FIG.  65   . Likewise, the second seal  376  has a larger diameter than that of the first seal  374 . Because the first and second grooves  400  and  406  are formed in the housing  104 , no grooves are formed in the intermediate surface  322  of the fluid routing plug  116  for receiving a seal. 
     When the fluid routing plug  116  is installed within the horizontal bore  106 , the first and second seals  374  and  376  tightly engage the corresponding first and second sealing surfaces  370  and  372 , as shown in  FIGS.  70  and  71   . During operation, the first and second seals  374  and  376  wear against the first and second sealing surfaces  370  and  372 . If the first or second sealing surface  370  or  372  begins to erode, allowing fluid to leak around the fluid routing plug  116 , the plug  116  may be removed and replaced with a new plug  116 . The first or second seal  374  or  376  may also be replaced with a new seal, if needed. 
     The first groove  400  shown in  FIG.  71    is wider than the second groove  406  shown in  FIG.  70   . As described below, each groove  400  and  406  is sized to correspond with the size of the seal installed within the groove. In alternative embodiments, the first and second grooves may be wider or narrower than those shown in the figures in order to accommodate the size of the seal installed within the groove. 
     As discussed above, the fluid routing plug  116  may repeatedly stretch and contract in response to the changing fluid pressure. For example, when the plunger  290  is retracted out of the housing  104 , the fluid pressure at the first surface  318  is equal or approximately equal to the pressure of fluid delivered to the housing  104  from the intake manifolds  166  and  168 . Such fluid pressure may be around 100-200 psi, for example. When the plunger  290  extends into the housing  104 , the fluid at the first surface  318  may be pressurized to around 10,000 psi, for example. 
     The first seal  374 , being positioned adjacent the first surface  318  of the fluid routing plug  116  experiences the constant change in fluid pressure. In contrast, the second seal  376 , being positioned adjacent the second surface  320 , experiences more static fluid pressure. The fluid pressure at the second surface  320  of the fluid routing plug  116  may remain at or close to 10,000 psi, for example. 
     Continuing with  FIGS.  70  and  71   , because the first seal  374  experiences more pressure fluctuations during operation than the second seal  376 , the first seal  374  may be more robust than the second seal  376 . For example, the first seal  374  is larger than the second seal  376  and has a generally square cross-sectional shape, while the second seal  376  has a circular cross-sectional shape. The first seal  374  may also have a higher durometer value than the second seal  376 . As described below, both seals  374  and  376  are bi-directional seals. In alternative embodiments, the second seal may be of the same construction as the first seal. 
     Continuing with  FIG.  71   , the first seal  374  is shown engaged with both side walls  402  of the first groove  400 . In operation, as the plunger  290  extends into the housing  104 , pressurized fluid pushes against the right side of the first seal  374 , helping to activate the first seal  374  and create a tight seal between the first seal  374  and the first sealing surface  370 . As the plunger  290  retracts from the housing  104  and the fluid pressure drops, the fluid pressure is greater on the left side of the first seal  374 . Thus, the fluid pressure may push against the left side of the first seal  374 , helping to activate the first seal  374 . Therefore, in operation, the first seal  374  may move slightly between its left and right side. 
     Continuing with  FIG.  70   , the second seal  376  is shown engaged with both side walls  408  of the second groove  406 . In operation, pressurized fluid within the housing  104  helps to activate the second seal  376 , thereby creating a tight seal between the second seal  376  and the second sealing surface  372 . Because the second seal  376  experiences primarily static fluid pressure, the second seal  376  may not move within the second groove  406 , as much as the first seal  374  moves within the first groove  400 . 
     Continuing with  FIGS.  70  and  71   , the first seal  374  also takes up approximately 97% of the open volume within the first groove  400 . Likewise, the second seal  376  takes up almost 97% of the open volume within the second groove  406 . Normally, seals are configured to take up around 70% of the open volume within the groove the seal is installed within. The remaining open volume provides space for the seal to expand and move. However, in operation, fluid and proppants can fill the open volume and wear against the groove, eventually causing the walls of the groove to erode. If the walls of the groove are damaged, the housing  104  may need to be replaced. 
     By sizing the grooves  400  and  406  so that the seals  374  and  376  take up almost all of the open volume within the corresponding grooves  400  and  406 , there is less room for fluid or proppants to fill any open space within the grooves. Specifically, fluid and proppants are prevented from entering any open volume on the back side of the seals  374  and  376 , thereby protecting the first and second grooves  400  and  406  from erosion. In alternative embodiments, the first seal may take less volume of the first groove than is shown in  FIG.  70   . Likewise, in alternative embodiments, the second seal may take up less volume of the second groove than is shown in  FIG.  71   . The other grooves formed in the housing and described herein may also be configured so that the corresponding seals take up approximately 97% of the open volume within the groove. 
     Continuing with  FIG.  71   , the first sealing surface  370  may extend up to immediately adjacent the first surface  318  of the body  316 . A first portion  412  of the intermediate surface  322  between the first bevel  378  and the first sealing surface  370  faces the housing  104  walls. A very small gap exists between the first portion  412  and the housing  104 . The gap may be as small as 0.001 inches in width. Such gap provides clearance to reduce friction between the fluid routing plug  116  and the housing  104  during installation and operation. Such gap also provides space for excess proppant to collect during operation. 
     Continuing with  FIG.  70   , a second portion  416  of the intermediate surface  322  between the second sealing surface  372  and the second surface  320  may face the walls of the housing  104 . A third portion  418  of the intermediate surface  322  between the second sealing surface  372  and the transition bevel  386  may also face the walls of the housing  104 . Like the first portion  412 , a very small gap exists between the second and third portions  416  and  418  and the housing  104 . The gaps may be as small as 0.001 inches in width. Such gaps provide clearance to reduce friction between the fluid routing plug  116  and the housing  104  during installation and operation. Such gaps also provide space for excess proppant to collect during operation. 
     Turning back to  FIG.  65   , as discussed above, the walls of the housing  104  surrounding the horizontal bore  106  are sized to allow for easy installation of the fluid routing plug  116 . The second groove  406  has a diameter D 1 . A maximum diameter of the second beveled surface  384  has a diameter D 2 . A maximum diameter of the first beveled surface  380  has a diameter D 3 , and the first groove  400  has a diameter D 4 . The diameter D 4  is greater than the diameter D 3 . The diameter D 3  is greater than the diameter D 2 , and the diameter D 2  is greater than the diameter D 1 . 
     With reference to  FIGS.  72 - 76  and  85 - 89   , the suction and discharge valves  292  and  294  are generally identical, with the exception that the discharge valve  294  may be larger in size than the suction valve  292 . As discussed above, the suction and discharge valves  292  and  294  each have a sealing element  346  and  360 . The sealing elements  346  and  360  each include a sealing surface  420  and  422  that tapers at an angle that matches the angle of the tapered wall  340  and  356  of the fluid routing plug  116 . Thus, the sealing surfaces  420  and  422  each taper at an angle of 30 or 45 degrees. Preferably, the tapered walls  340  and  356  and the sealing surfaces  420  and  422  both taper at an angle of 45 degrees. 
     Forming the mating tapered walls  340  and  356  and sealing surfaces  420  and  422  at 45 degrees provides more surface area for the valves  292  and  294  to seal against the fluid routing plug  116 . Providing more sealing surface area or a larger “strike face” helps distribute the forces applied to the valves  292  and  294  and the fluid routing plug  116 , thereby providing more evenly distributed sealing. Providing more evenly distributed sealing prevents certain areas from wearing faster than others, helping to increase the life of the parts. 
     Each valve  292  and  294  also has an outer sealing diameter A and an inner sealing diameter B, as shown in  FIGS.  72  and  85   . The ratio of the outer sealing diameter A to the inner sealing diameter B is preferably 1.55 or greater. This ratio helps increase the life of the valves  292  and  294  and reduce any turbulent fluid flow during operation. The valves  292  and  294  and the fluid routing plug  116  are configured so that no portion of the valves  292  and  294  enters the first or second fluid passages  326  and  336  during operation. Additionally, no portion of the valve  292  enters the blind bore  328  during operation. Rather, the suction valve  292  is configured only to cover the entrance  342  of the blind bore  330  on the first surface  318 , and the discharge valve  294  is configured only to cover the openings  364  of the second fluid passages  336  on the second surface  320 . 
     Continuing with  FIGS.  72 - 76   , the suction valve  292  is shown in more detail. The suction valve  292  comprises the sealing element  346  joined to a stem  424 . When the suction valve  292  is installed within the horizontal bore  106 , the stem  424  extends along an axis that is parallel to or aligned with central the longitudinal axis  114  of the housing  104 . 
     The sealing element  346  comprises opposed first and second surfaces  426  and  428  joined by the sealing surface  420 . A groove  430  is formed in the sealing surface  420  adjacent the first surface  426 , as shown in  FIG.  76   . A seal  432  is installed within the groove  430 . The groove  430  is characterized by a first sidewall  434  joined to a second sidewall  436 . The sidewalls  434  and  436  may be joined by an inner groove  438 . The groove  430  is sized to correspond with the inward facing surface of the seal  432 . An outward facing surface of the seal  432  comprises a convex surface  440  joined to a concave surface  442 . The seal  432  is preferably made of a polyurethane compound. In alternative embodiments, the seal may be made of a different elastomer material. 
     When the suction valve  296  seals against the first surface  318  of the fluid routing plug  116 , the seal  432  and a portion of the sealing surface  420  mate with the tapered wall  340 , as shown in  FIG.  51   . The seal  432  is shaped so that the convex surface  440  displaces into, or toward, the concave surface  442  as the seal  432  engages the tapered wall  340 . This relative movement allows the shear forces to be dissipated, increasing the life of the seal  432  and the suction valve  292 . If the seal  432  becomes worn and no longer seals properly, the seal  342  may be removed and replaced with a new seal  432 . In alternative embodiments, the seal and groove may have various shapes and sizes, as desired. In further alternative embodiments, the sealing surface may not include a groove and corresponding seal. 
     Continuing with  FIG.  76   , the second surface  428  of the sealing element  346  is sized to cover the entrance  342  of the blind bore  328 , as shown in  FIG.  51   . A cutout  444  is formed within the second surface  428 . The cutout  444  creates a small cavity within the second surface  428 . The cavity provides space for fluid to collect and apply pressure to the suction valve  292 . Such pressure helps force the suction valve  292  to move axially to an open position. 
     Continuing with  FIGS.  75  and  76   , the stem  424  projects from the first surface  426  of the sealing element  346 . An annular void  446  is formed in the first surface  426  and surrounds the stem  424 . The first surface  426  further includes a ring-shaped outer rim  448  that surrounds the annular void  446  and the stem  424 . The outer rim  448  joins the sealing surface  420 . The annular void  446  reduces weight within the suction valve  292  and helps orient the valve&#39;s center of gravity during operation. 
     An annular groove  450  is formed in the outer rim  448 . The groove  450  is configured for receiving a bottom portion of a spring  452 , as shown in  FIG.  83   . As described below, a top portion of the spring  452  engages with the suction valve guide  296 , as shown in  FIGS.  83  and  84   . The spring  452  biases the suction valve  292  in the closed position. Positioning the spring  452  on the outer rim  448  helps to stabilize the suction valve  292  during operation. 
     With reference to  FIGS.  77 - 82   , the stem  424  is configured to move axially within the suction valve guide  296 . The suction valve guide  296  may also be referred to as a cage for the suction valve  292 . The suction valve guide  296  comprises a body  454  having opposed first and second surfaces  456  and  458 . A central passage  460  is formed within the body  454  and interconnects the first and second surfaces  456  and  458 . A plurality of legs  462  extend out from the body  454  adjacent its first surface  456  and project downward towards its second surface  458 . The suction valve guide  296  shown in  FIGS.  77 - 82    has six evenly spaced legs  462  formed around its body  454 . In alternative embodiments, more or less than six legs may be formed on the body and may be non-uniformly spaced. 
     The legs  462  gradually decrease in thickness from the body  454  to a bottom surface  464  of each leg  462 . The bottom surface  464  of each leg  462  is extremely thin so that the legs  462  do not block or interfere with the openings  348  of the second fluid passages  336  on the first surface  318 , as shown in  FIG.  50   . 
     Continuing with  FIGS.  77 - 82   , an outer surface of each leg  462  includes a bevel  466 . The bevels  466  are configured to engage a corresponding bevel  468  formed in the walls of the housing  104 , as shown in  FIGS.  50  and  51   . The suction valve guide  296  is inserted into the horizontal bore  106  until the bevels  466  and  468  engage, allowing the guide  296  to bottom out on the walls of the housing  104 . Once the bevels  466  and  468  are engaged, the suction valve guide  296  is held against the walls of the housing  104  by the spring  452  and fluid pressure. 
     When the suction valve guide  296  is in its installed position, the bottom surface  464  of each of the legs  462  hovers just above the first surface  318  of the fluid routing plug  116 , leaving a gap between the legs  462  and the plug  116 . The bottom surfaces  464  do not directly contact the fluid routing plug  116  in order to prevent the suction valve guide  296  from applying load to the plug  116  during operation. 
     Continuing with  FIG.  80   , a tubular insert  470  is installed within the central passage  460  of the body  454 . The insert  470  may be press-fit within the passage  460 . The insert  470  extends the length of the central passage  460  and is formed from a more wear resistant material than the suction valve guide  296 . For example, the insert  470  may be made of tungsten carbide, while the suction valve guide  296  may be made of high strength alloy steel. The stem  424  is installed within the insert  470  and reciprocates within the insert  470  during operation, as shown in  FIGS.  50  and  51   . Any fluid contained within the insert  470  drains from the opening of the central passage  460  on the first surface  456  of the body  454 . 
     During operation, the stem  424  may wear against the insert  470  as it reciprocates. The insert  470  helps decrease the rate of wear and helps the stem to wear evenly against the insert. Forming only the insert  470  out of a wear resistant material helps reduce the cost of the other parts, which do not experience as much wear during operation. 
     Turning to  FIGS.  83  and  84   , the spring  452  is interposed between the suction valve  292  and the suction valve guide  296 . The spring  452  is held between the outer rim  448  of the suction valve  292  and an inner surface  472  of the legs  462 . At least a portion of the spring  452  surrounds the body  454  of the suction valve guide  296 . As the suction valve  292  moves to an open position, the spring  452  compresses between the suction valve  292  and the suction valve guide  296 . 
     With reference to  FIGS.  84 A- 84 F , another embodiment of a suction valve guide  451  is shown. The suction valve guide  451  is like the suction valve guide  296  but does not include the plurality of spaced apart legs  462 . Instead, the suction valve guide  451  comprises a thin-walled skirt  453  surrounding a plurality of support legs  455 . Three support legs  455  are shown in the figures. In alternative embodiments, the suction valve guide  451  may comprise more than three support legs or less than three support legs. 
     Continuing with  FIGS.  84 A- 84 F , the suction valve guide  451  comprises a body  457  having opposed first and second surfaces  459  and  461 . A central passage  463  is formed within the body  457  and interconnects the first and second surfaces  459  and  461 . While not shown, the tubular insert  470 , shown in  FIG.  80   , may be installed within the central passage  463 . 
     The plurality of support legs  455  extend out from the body  457  adjacent its first surface  459  and project downward towards its second surface  461 . The skirt  453  surrounds a lower portion of the support legs  455  and extends slightly past second surface  461  of the body  457 , as shown in  FIG.  84 D . The skirt  453  comprises a tapered upper section  465  joined to a cylindrical lower section  467 . A plurality of large flow ports  469  are formed between adjacent support legs  455  and between the first surface  459  of the body  457  and the tapered upper section  465  of the skirt  453 , such that fluid may pass between the body  457  and the interior of the skirt  453 . 
     Turning back to  FIG.  19 G , the suction valve guide  451  is shown installed within the housing  103 . When installed, the tapered section  465  of skirt  453  engages the beveled surface  468 . The cylindrical section  467  engages and covers the wall of the housing  103  between the fluid routing plug  116  and the beveled surface  468 . By covering the wall of the housing  103  in this area, the skirt  453  acts as a shield for the wall, helping to reduce any wear and erosion to this area of the housing  103 . All fluid flow is diverted through the flow ports  469  of the suction valve guide  451 , which can be easily replaced, if needed. 
     With reference to  FIGS.  84 G- 84 L , another embodiment of a suction valve guide  471  is shown. The suction valve guide  471  is identical to the suction valve guide  451  but does not include any support legs  455 . Instead, the guide  471  comprises a skirt  473  joined to a body  479  by a plurality of support arms  481 . The arms  481  only extend between the body  479  and the skirt  473 . In contrast, the legs  455 , shown in  FIG.  84 B , extend between the body  457  and the skirt  453  and down the interior of the skirt  453 . By removing the legs  455 , the open area within the interior of the skirt  453  is enlarged, providing more area for fluid flow. 
     Continuing with  FIGS.  84 G- 84 L , the skirt  473  is identical to the skirt  453  and comprises a tapered upper section  483  and a cylindrical lower section  485 . The suction valve guide  471  further comprises a plurality of flow ports  487 . The body  479  of the valve guide  471  and the flow ports  487  are identical to those used with the valve guide  451 . 
     With reference to  FIGS.  84 M and  84 N , another embodiment of a suction valve guide  501  is shown. The suction valve guide  501  is identical to the suction valve guide  471  but a material  503  has been added to the interior cylindrical section  485  of the skirt  473 . The material  503  is configured to reduce wear and prevent erosion of the skirt  473  during operation. For example, the material  503  may comprise a hardened material, such as sprayed carbide, or other hardened materials known in the art. In alternative embodiments, the material  503  may comprise an elastomer configured to absorb fluid flow energy. In further alternative embodiments, the material  503  may comprise Teflon or other slick, smooth, slippery surface configured to reduce friction between fluid flow and the interior of the skirt  473 . 
     With reference to  FIGS.  84 O and  84 P , another embodiment of a suction valve guide  511  is shown. The suction valve guide  511  is identical to the suction valve guide  471  but a hardened wear ring  513  has been installed within the interior of the cylindrical section  485  of the skirt  473 . The wear ring  513  is preferably made of a harder material than that of the skirt  473 . During operation, the wear ring  513  prevents wear and erosion to the interior of the skirt  473 . In alternative embodiments, the wear ring  513  may be configured to cover more interior areas of the suction valve guide  511 . 
     The wear ring  513  may be press-fit into the interior of the skirt  473  or may be attached by other means known in the art, such as welding. The wear ring  513  may also be configured to be easily removed and replaced with a new wear ring  513 , if needed. 
     With reference to  FIGS.  84 Q and  84 R , another embodiment of a suction valve guide  521  is shown. The suction valve guide  521  is identical to the suction valve guide  471  but comprises a skirt  523  having a cylindrical section  525  that is a separate piece from a tapered section  527  and the rest of the valve guide  521 . The cylindrical section  525  is separated from the tapered section  527  at a separation point  529 , as shown in  FIG.  84 Q . When the suction valve guide  521  is installed within a housing, the cylindrical section  525  abuts the tapered section  527  of the skirt  523 . 
     The cylindrical section  525  is preferably formed from a different material than of the tapered section  527 . For example, the cylindrical section  525  may be formed of or sprayed with a hardened material, such as tungsten carbide, while the rest of the valve guide  521  may be formed of carbon steel. 
     In operation, the hardened cylindrical section  525  of the skirt  523  is resistant to erosion, extending the life of the skirt  523 . The cylindrical section  525 , being a separate piece from the rest of the suction valve guide  521 , may also be easily removed and replaced with a new cylindrical section  521 , if needed. 
     With reference to  FIGS.  85 - 89   , the discharge valve  294  is shown in more detail. As discussed above, the discharge valve  294  is constructed identically to the suction valve  292 , with the exception that the discharge valve  294  may be larger in size. The discharge valve  294  shown in  FIGS.  85 - 89   , for example, has a larger sealing surface  422  and a longer stem  474  than the suction valve  292 . When the discharge valve  294  is installed within the horizontal bore  106 , the stem  424  extends along an axis that is parallel to or aligned with the central longitudinal axis  114  of the housing  104 . A seal  475  is installed within a groove  477  formed in the sealing surface  422  and is configured to engage with the tapered wall  356  formed in the second surface  320  of the fluid routing plug  116 . A bottom surface  476  of the discharge valve  294  is sized to cover the central base  354 , as shown in  FIG.  50   . 
     With reference to  FIGS.  90 - 95   , the stem  474  formed on the discharge valve  294  is configured to move axially within the discharge valve guide  298 . The discharge valve guide  298  may also be referred to as a cage for the discharge valve  294 . The discharge valve guide  298  comprises a body  478  having opposed first and second surfaces  480  and  482  joined by an intermediate surface  484 . The intermediate surface  484  includes a front portion  486 , a medial portion  488 , and a rear portion  490 . The medial portion  488  has a larger diameter than both the front and rear portions  486  and  490 . The front portion  486  has a slightly larger diameter than the rear portion  490 . 
     Continuing with  FIGS.  90 - 95   , a blind bore  492  is formed in the first surface  480  and extends into the front portion  486  of the body  478 . The blind bore  492  is configured to receive a tool used to grip the discharge valve guide  298 . The front portion  486  is sized to be received within the cutout  308  formed in the retainer  300 , as shown in  FIGS.  50  and  51   . When the discharge valve guide  298  and the retainer  300  are engaged, the blind bore  492  opens into the central passage  310  formed in the retainer  300 . 
     A central passage  494  is formed in the body  478  and opens on the second surface  482 , as shown in  FIGS.  93  and  94   . The central passage  494  opens in the body  478  into an axially blind counterbore  496 . A plurality of relief ports  498  are formed in the body  478 . Each relief port  498  interconnects the counterbore  496  and a base  500  of the medial portion  488 , as shown in  FIG.  94   . 
     Continuing with  FIGS.  93  and  94   , a tubular insert  502  is installed within the central passage  494 . The insert  502  is identical to the insert  470 , with the exception that the insert  502  may be larger than the insert  470 . During operation, the stem  474  moves axially within the insert  502  installed within the central passage  494 . Any fluid within the insert  502  drains from the body  478  through the counterbore  496  and the relief ports  498 . 
     Continuing with  FIGS.  90 - 92   , a plurality of legs  504  project from the medial portion  488  and extend towards the second surface  482  of the body  478 . The discharge valve guide  298  shown in  FIGS.  90 - 95    comprises five legs  504 . The legs  504  are positioned on the body  478  so as to leave a large space  506  between at least two adjacent legs  504 . Other than the space  506 , the legs  504  are equally spaced from one another. The space  506  is intended to align with the discharge bore  178 , thereby preventing any legs  504  from blocking the discharge bore  178  during operation. Providing the space  506  therefore allows fluid to flow freely between the discharge valve  294  and the discharge bore  178  without significant obstructions. The space  506  also helps minimize wear applied to the legs  504  by the flowing fluid over time. In alternative embodiments, the body may have more or less than five legs as be spaced, as desired, as long as the legs are positioned on the body so as to leave a large space between at least two of the legs. 
     With reference to  FIG.  90   , each of the legs  504  has a thicker upper portion  508  and thinner lower portion  510 . The thicker upper portion  508  provides strength to the legs  504  while the lower portion  510  is thinned in order to provide more room for fluid flow around the legs  504 . The upper portion  508  also includes a tapered inner surface  512 . Tapering the inner surface  512  of the legs  504  provides strength and alleviates stress in the legs  504  during operation. 
     Continuing with  FIGS.  90 - 95   , when the discharge valve guide  298  is installed within the horizontal bore  106 , a bottom surface  514  of each leg  504  engages the outer rim  352  of the second surface  320  of the fluid routing plug  116 , as shown in  FIGS.  50  and  51   . The discharge valve guide  298  is held against the fluid routing plug  116  by the retainer  300 . Such engagement helps keep the second bevel  382  of the fluid routing plug  116  seated against the second beveled surface  384 , as shown in  FIGS.  65  and  68   . 
     Continuing with  FIGS.  93  and  95   , a dowel pin  516  is installed within a blind bore  517  formed in the medial portion  488  of the body  478 . The dowel pin  516  is configured to be received within a dowel pin hole or groove  518  formed in the walls of the housing  104  surrounding the horizontal bore  106 , as shown in  FIGS.  96  and  97   . The discharge valve guide  298  is installed within the horizontal bore  106  such that the dowel pin  516  is positioned within the dowel pin hole  518 . Such positioning ensures that the space  506  between the pair of legs  504  aligns with the discharge bore  178 , thus preventing any legs  504  from blocking the discharge bore  178  during operation. 
     Continuing with  FIGS.  96  and  97   , a seal  520  is interposed between the intermediate surface  484  of the body  478  and the walls of the housing  104 . The seal  520  may be identical to the second seal  376  shown in  FIGS.  65  and  70   . In alternative embodiments, the seal may be identical to the first seal  374  shown in  FIGS.  65  and  71   . The seal  520  is installed within a groove  522  formed in the housing  104 . The groove  522  is characterized by two sidewalls  524  joined to abase  526 . The sidewalls  524  may join the base  526  via radius corner or at a 90 degree angle. During operation, the seal  520  wears against the outer intermediate surface  484  of the discharge valve guide  298 . If the intermediate surface  484  begins to erode, allowing fluid to leak around the seal  520 , the discharge valve guide  298  may be removed and replaced with a new discharge valve guide  298 . 
     With reference to  FIGS.  98  and  99   , a spring  528  is installed between the discharge valve  294  and the discharge valve guide  298 . A bottom portion of the spring  528  sits in a groove  530 , shown in  FIG.  89   , formed in an outer rim  532  of the discharge valve  294 . A top portion of the spring  528  engages a ledge  534  formed in the base  500  of the medial portion  488  of the discharge valve guide  298 . During operation, the spring  528  compresses against the ledge  534  of the medial portion  488 . 
     With reference to  FIGS.  99 A- 99 F , another embodiment of a discharge valve guide  531  is shown. The discharge valve guide  531  is generally identical to the discharge valve guide  298  but only includes a pair of legs  533  instead of the five legs  504 , shown in  FIG.  91   . Each leg  533  is wider than the individual legs  504  such that each leg  533  spans about a quarter of the circumference of a body  535  of the valve guide  531 . Each leg  533  is positioned opposite the other leg  533 . A large space  537  exists between each leg  533 , as shown in  FIGS.  99 B and  99 E . 
     A plurality of relief ports  539  are formed in the body  535  between each leg  533 . The relief ports  539  are generally identical to the relief ports  498 , shown in FIG.  94 , but have wider openings. The remaining features of the discharge valve guide  531  are identical to those on the discharge valve guide  298 . 
     With reference to  FIGS.  19 G and  19 H , the discharge valve guide  531  is shown installed within the housing  103 . The guide  531  is installed such that each space  537  aligns within each of the discharge bores  105  and  107 , providing a clear pathway for fluid flow. 
     Turning to  FIG.  100   , the components installed within the housing  104  are installed through the first surface  108 , starting with the suction valve guide  296 . The diameter of the installed components slightly increases from the second surface  320  to the first surface  318 . For example, the suction valve guide  296  has smaller outer diameters than the fluid routing plug  116 , and the fluid routing plug  116  has smaller outer diameters than the discharge valve guide  298 . The discharge valve guide  298  has smaller outer diameters than the retainer  300 . 
     Likewise, the diameters of the walls surrounding the horizontal bore  106  generally increase from the second surface  110  to the first surface  108 . As shown in  FIG.  100   , a diameter D 4  of the horizontal bore  106  is greater than a diameter D 3  of the horizontal bore  106 . The diameter D 3  of the horizontal bore  106  is greater than a diameter D 2  of the horizontal bore  106 . The diameter D 2  of the horizontal bore  106  is greater than a diameter D 1  of the horizontal bore  106 . Such construction allows the components to be installed without engaging the walls of the housing  104  until the component is at its intended installed position. The seals  374 ,  376 , and  520  may be installed within the housing  104  prior to installing the other components described above. 
     Turning to  FIGS.  100 A- 100 E , another embodiment of a fluid routing plug  550  is shown. The fluid routing plug  550  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  550  is identical to the fluid routing plug  116 , with a few exceptions. The fluid routing plug  550  comprises a body  552  having a first outer surface  554  joined to a second outer surface  556  by an intermediate outer surface  558 . The second surface  556  of the fluid routing plug  550  generally identical to the second surface  320  of the fluid routing plug  116 , but a central base  560  formed in the second surface  556  is spaced from an edge  562  of a tapered wall  564  formed in the second surface  556 . The central base  560  is spaced from the tapered wall  564  such that a throat  566  is formed between the central base  560  and the tapered wall  564 . 
     Continuing with  FIGS.  100 A- 100 D , a blind hole  568  is formed in the central base  560  and a plurality of openings  570  corresponding to a plurality of second fluid passages  572  open on the central base  560  and surround the blind hole  568 . In operation, fluid exiting the openings  570  flows into the throat  566  before pushing against the discharge valve  294  engaged with the second surface  556 . Allowing fluid to gather in the throat  566  before contacting the discharge valve  294  helps the fluid to contact more surface area of the discharge valve  294 , instead of having a plurality of single points of contact from each second fluid passage opening. Allowing the fluid to contact more surface area of the discharge valve  294  helps reduce wear to the valve over time. 
     Continuing with  FIGS.  10 E and  100 F , the intermediate surface  558  of the fluid routing plug  550  is identical to the intermediate surface  322  formed on the fluid routing plug  116 . However, the intermediate surface  558  may include a cutout  576  adjacent the second surface  556 . The cutout  576  provides space for fluid or proppant to collect during operation, as shown in  FIG.  100 F . The cutout  576  also helps reduce friction during installation of the fluid routing plug  550  within the housing  104 . A small gap  578  may also exist between the walls of the housing  104  and the intermediate surface  558  between a second sealing surface  580  and the cutout  576 , as shown in  FIG.  100 F . The gap  578  helps the seal  376  breath during operation. 
     Continuing with  FIG.  100 B , the first surface  554  of the fluid routing plug  550  is identical of the first surface  318  of the fluid routing plug  116 , with the exception of its outer rim  582 . The outer rim  582  is flat and wider than the outer rim  338 , shown in  FIG.  55   . Because the outer rim  582  is wider, a plurality of openings  584  for the second fluid passages  572  may have a slightly larger diameter than the openings  348 , shown in  FIG.  56   . Likewise, the openings  570  may also have a slightly larger diameter than the openings  364  shown in  FIG.  54   . Providing a slightly larger diameter for the second fluid passages  572  helps reduce fluid velocity through the fluid routing plug  550  during operation. Reducing fluid velocity within the fluid routing plug  550  helps reduce wear to the fluid routing plug  550  over time. 
     Turning to  FIGS.  101 - 109   , another embodiment of a fluid routing plug  600  is shown. The fluid routing plug  600  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  600  is identical to the fluid routing plug  116 , with a few exceptions. The fluid routing plug  600  comprises a body  602  having a first outer surface  604  joined to a second outer surface  606  by an intermediate outer surface  608 . In contrast to the fluid routing plug  116 , the first and second surfaces  604  and  606  of the fluid routing plug  600  are configured so that each surface  604  and  606  has identically sized tapered walls  610  and  612 , as shown in  FIG.  103   . Because the tapered walls  610  and  612  are the same size, a suction valve  614  and a discharge valve  616  used with the fluid routing plug  600  may be identical in size, as shown in  FIGS.  108  and  109   . 
     Using the same size suction and discharge valves  614  and  616  helps equalize the forces applied to the fluid routing plug  600  and the valves  614  and  616  during operation, helping to reduce any wear to the parts over time. Making the suction and discharge valves  614  and  616  identical also makes replacing the valves  614  and  616  during operation easier. 
     Continuing with  FIGS.  103 ,  105 , and  106   , the tapered wall  612  formed in the second surface  606  extends between an outer rim  618  and an annular groove  620  formed in the center of the second surface  606 . The annular groove  620  may be considered a central base formed in the second surface  606 . The groove  620  surrounds a blind bore  622  formed in the center of the second surface  606 . The blind bore  622  is identical to the blind bore  362  formed in the fluid routing plug  116 , as shown in  FIG.  55   . 
     The groove  620  is characterized by two parallel sidewalls  624  joined by a base  626 . The sidewalls  624  each extend at a non-zero angle relative to a central longitudinal axis  628  of the body  602 . Because the sidewalls  624  of the groove  620  extend at an angle, the base  626  of the groove  620  extends at a non-zero angle relative to the central longitudinal axis  628  of the body  602 . Preferably, the base  626  extends at approximately the same angle as the tapered wall  612  so that the base  626  and the tapered wall  612  are in a generally parallel relationship. The tapered wall  612  shown in  FIG.  103    extends at a 45 degree angle relative to the central longitudinal axis  628 . 
     An annular inner edge  638  of the tapered wall  612  is joined to the outer sidewall  624  of the groove  620  at a right angle. The diameter of the inner edge  638  of the tapered wall  612  is the same size as a diameter of an entrance  630  of an axially blind bore  632  formed in the first surface  604 , as shown in  FIG.  103   . In alternative embodiments, the groove formed in the second surface and the inner edge of the tapered wall may not have an annular shape. 
     Continuing with  FIGS.  103 ,  105 , and  106   , a plurality of second fluid passages  634  are formed in the body  602 . The second fluid passages  634  are identical to the second fluid passages  336  formed in the fluid routing plug  116 , shown in  FIGS.  52 - 64   , with the exception of the positioning of their openings  636  on the second surface  606 . Each second fluid passage  634  opens on the base  626  of the groove  620  formed in the second surface  606 . Thus, the openings  636  are axially spaced from the inner edge  638  of the tapered wall  612 . Because the sidewalls  624  of the groove  620  are formed at an angle, the inner edge  638  of the tapered wall  612  slightly overlaps the openings  636 , as shown in  FIG.  106   . By positioning the openings  636  in an axially spaced relationship with the inner edge  638  of the tapered wall  612 , the size of the tapered wall  612  can be decreased without decreasing the size of the openings  636 . The annular groove  620  also functions as a throat, similar to the throat  566  formed in the fluid routing plug  550 . 
     Because the tapered wall  612  is decreased in size from the tapered wall  356  shown in  FIG.  55   , the outer rim  618  on the second surface  606  is wider than the outer rim  352 . The outer rim  618  also tapers between the intermediate surface  608  and the tapered wall  612 , as shown in  FIGS.  103  and  104   . Such taper increases the length of the tapered wall  612  without increasing the length of the intermediate surface  608 . 
     Continuing with  FIGS.  101 - 107   , the first surface  604  is identical to the first surface  318  shown in  FIGS.  53 ,  55 , and  56   , with the exception of its outer rim  640 . Instead of tapering like the outer rim  338 , shown in  FIG.  55   , the outer rim  640  is flat. The outer rim  640  is flat in order to slightly decrease the size of the tapered wall  610  to match the size of the tapered wall  612 . The intermediate surface  608  of the fluid routing plug  600  is identical to that of the fluid routing plug  116 , shown in  FIG.  64   . A plurality of first fluid passages  642  formed in the body  602  are identical to the first fluid passages  326 , shown in  FIGS.  55 ,  57 , and  59   . The second fluid passages  634  open on the outer rim  640  of the first surface  604 , as shown by the openings  644 . The openings  644  are positioned in groups  645 , in the same manner as the second fluid passages  336  formed in the fluid routing plug  116 , as shown in  FIG.  56   . The openings  636  on the second surface  606  may remain spaced in groups  645 , as shown in  FIG.  106   . 
     With reference to  FIGS.  108  and  109   , the fluid routing plug  600  routes fluid throughout the housing  104  in the same manner as the fluid routing plug  116 . The suction valve guide  296  is shown engaged with suction valve  614 . Another embodiment of a discharge valve guide  647  is shown engaged with the discharge valve  616 . 
     The discharge valve guide  647  is identical to the discharge valve guide  298 , shown in  FIGS.  90 - 95   , with a few exceptions. A counterbore  649  formed in the guide  647  is larger than the counterbore  496 . The counterbore  649  is larger in order to accommodate the shorter stem  646  of the discharge valve  616 . An insert  651  installed within the discharge valve guide  647  is the same size as the insert  470  installed within the suction valve guide  296 . 
     With reference to  FIGS.  110 - 114   , as discussed above, in contrast to the valves  292  and  294 , the valves  614  and  616  are identical in size and shape. The valves  614  and  616  are generally identical to the valves  292  and  294 , with a few exceptions. Each valve  614  and  616  comprises a sealing element  652  joined to a stem  646 . The stem  646  projects from a first surface  650  of the sealing element  652 . 
     An annular cutout  648  is formed within a medial portion of the stem  646 . The cutout  648  provides space for fluid or proppants to collect during operation. Providing such space prevents the fluid and proppants from rubbing against the inserts  470  and  502 . The suction and discharge valves  292  and  294  may be configured to include an annular cutout within their stems  424  and  474 . 
     Continuing with  FIGS.  110 - 114   , the sealing element  652  further includes a second surface  668  joined to the first surface  650  by a sealing surface  658 . A groove  656  is formed in the sealing surface  658  for housing a seal  654 . The groove  656  is identical to the groove  430 , shown in  FIG.  76   . An outward facing surface of the seal  654  comprises a sidewall  660  joined to a tapered base  662 . In operation, the tapered base  662  engages the tapered walls  610  and  612  of the fluid routing plug  600 . The sidewall  660  may compress creating a tight seal. 
     The first surface  650  of the sealing element  652  includes an outer rim  664 . An outer ledge  666  surrounds the outer rim  664 . A bottom portion of a spring engages the outer rim  664  and is held in place by the outer ledge  666 . While not shown, a cutout may be formed in the second surface  668  of the sealing element  652 , like the cutout  444 , shown in  FIG.  76   . 
     One or more kits may be useful in assembling the fluid end section  102 . A kit may comprise a plurality of housings  104  and a plurality of the corresponding fluid routing plugs  116 ,  550 , or  600 . The kit may also comprise a plurality of suction valves  292  or  614 , discharge valves  294  or  616 , suction valve guides  296 , discharge valve guides  298  or  657 , springs  452  and  528 , retainer  300 , stuffing box  140 , retainer  232 , plunger packing  224 , packing nut  276 , fastening system  234 , discharge conduit  174 , and the various seals described herein. The kit may also comprise the intake manifolds  166  and  168 , pipe system  176 , connect plate  118 , fastening system  146  and stay rods  120 . The kit may also comprise other various features described herein for use with the fluid end  100 . Unless specifically described herein, the various components of the fluid end  100  may be made of high strength alloy steel, such as carbon steel or stainless steel. 
     With reference to  FIGS.  115 - 117   , an alternative embodiment of a fluid routing plug  700  is shown. The fluid routing plug  700  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  700  is identical to the fluid routing plug  116 , with the exception of the shape of its first and second bevels  702  and  704 . When the fluid routing plug  700  is first installed within the horizontal bore  106 , the second bevel  704  only partially engages a second beveled surface  706 , as shown in  FIG.  116   . The bevels  704  and  706  mate at a second bevel mating surface  708  and a second beveled surface mating surface  710 . Below the mating surfaces  708  and  710 , the second bevel  704  and the second beveled surface  706  have mating angles that are not equal, causing a gap  712  to exist between the bevels  704  and  706 . Specifically, the second bevel  704  may have a slightly convex shape so that portions of the second bevel  704  don&#39;t match the flat shape of the second beveled surface  706 . 
     The width of the gap  712  gradually increases between the mating surfaces  708  and  710  and a bottom portion  714  of the second bevel  704  and a bottom portion  716  of the second beveled surface  706 . Thus, the width B of the gap  712  is wider than the width A of the gap  712 . Because the second bevel  704  has a slightly convex shape, the angle between the mating surfaces  708  and  710  is different from the angle between the bottom portions  714  and  716 . 
     Turning to  FIG.  117   , the first bevel  702  and the first beveled surface  718  are shown in more detail. Like the second bevel  704 , the first bevel  702  may only partially engage a first beveled surface  718 . The bevels  702  and  718  mate at a first bevel mating surface  720  and a first beveled surface mating surface  722 . Below the mating surfaces  720  and  722 , the first bevel  702  and the first beveled surface  718  have mating angles that are not equal, causing a gap  724  to exist between the bevels  702  and  718 . Specifically, the first bevel  702  may have a slightly convex shape so that portions of the first bevel  702  do not match the flat shape of the first beveled surface  718 . 
     The width of the gap  724  gradually increases between the mating surfaces  720  and  722  and a bottom portion  726  of the first bevel  702  and a bottom portion  728  of the first beveled surface  718 . Thus, the width B of the gap  724  is wider than the width A of the gap  724 . Because the first bevel  702  has a slightly convex shape, the angle between the mating surfaces  720  and  722  is different from the angle between the bottom portions  726  and  728 . 
     The width of the gaps  712  and  724  has been exaggerated in  FIGS.  116  and  117    for illustration purposes. In reality, portions of the gaps  712  and  724  may be approximately 0.002 inches in width, for example. However, the gaps  712  and  724  may be wider or smaller depending on the materials and forces used. 
     As discussed above, in operation, the fluid pressure applied to the fluid routing plug  700  will cause the plug  700  to compress and expand as the plunger  290  retracts from the housing  104 . As the fluid routing plug  700  starts to expand, the bottom portion  714  of the second bevel  704  will move to engage the bottom portion  714  of the second beveled surface  706 , causing the bottom portions  714  and  716  to mate. Likewise, the bottom portion  726  of the first bevel  702  will move to engage the bottom portion  728  of the first beveled surface  718 . Such movement of the fluid routing plug  700  distributes the load applied to the fluid routing plug  700  through the length of the first and second bevels  702  and  704 . 
     With reference to  FIGS.  118 - 120   , an alternative embodiment of a fluid routing plug  800  is shown. The fluid routing plug  800  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  800  is identical to the fluid routing plug  700 , with the exception of the shape of its first and second bevels  802  and  804 . Like the fluid routing plug  700 , the second bevel  804  is sized to leave a gap  806  between the second bevel  804  and a second beveled surface  808  when the fluid routing plug  800  is first installed within the housing  104 . In contrast to the gap  712 , an angle formed between the mating surfaces  810  and  812  and bottom portions  814  and  816  of the second bevel  804  and second beveled surface  808  remains the same. Thus, an area A of the gap  806  has the same angle as an area B of the gap  806 . 
     Likewise, the first bevel  802  is shaped so that an angle formed between the first bevel  802  and a first beveled surface  820  stays relatively the same between mating surfaces  822  and  824  and bottom portions  826  and  828 . Thus, the width A of the gap  818  has approximately the same angle as the width B of the gap  818 . 
     The width of the gaps  806  and  818  has been exaggerated in  FIGS.  119  and  120    for illustration purposes. In reality, portions of the gaps  806  and  818 , for example, may be approximately 0.002 inches in width. However, the gaps  806  and  818  may be wider or smaller depending on the materials and forces used. 
     As discussed above, the first and second bevels  802  and  804  expand during operation. Such movement of the fluid routing plug  800  distributes the load applied to the fluid routing plug  800  through the length of the first and second bevels  802  and  804 . 
     In alternative embodiments, the first bevel may be configured to have a gap that increases in size, as shown in  FIG.  117   , while the second bevel may be configured to have a gap that increases by a different amount, as shown in  FIG.  119   , and vice versa. In further alternative embodiments, the width of the gap may be of various shapes and sizes depending on the materials used and forces involved. In even further alternative embodiments, the intermediate surface of the fluid routing plug may include any combination of the different bevel constructions described herein. 
     Turning to  FIGS.  121 - 128   , another embodiment of a fluid routing plug  900  is shown. The fluid routing plug  900  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  900  is identical to the fluid routing plug  116 , with a few exceptions. The fluid routing plug  900  comprises a body  902  having a first outer surface  904  joined to a second outer surface  906  by an intermediate outer surface  908 . A plurality of first fluid passages  910  are formed in the body  902  and interconnect the intermediate surface  908  and the first surface  904  by way of an axially blind bore  912 , as shown in  FIG.  124   . 
     In contrast to the first fluid passages  326 , shown in  FIGS.  55  and  58   , a longitudinal axis  914  of each first fluid passage  910  does not intersect a central longitudinal axis  916  of the body  902 , as shown in  FIG.  125   . Rather, the first fluid passages  910  are formed such that the longitudinal axis  914  of each passage  910  is offset from the central longitudinal axis  916  of body  902 . The offset configuration of the first fluid passages  910  encourages a vortex type flow of fluid about the central longitudinal axis  916 , thereby reducing fluid turbulence during operation. In alternative embodiments, the longitudinal axis  914  of each first fluid passage  910  may intersect the longitudinal axis  916  of the body  902 . 
     A plurality of openings  918  formed on the intermediate surface  908  for the first fluid passages  910  are similar to the openings  334 , shown in  FIGS.  57  and  59   , but have a more oblong shape, as shown in  FIG.  121   . The oblong shape shown in  FIG.  121    has opposed first and second ends  920  and  922 . The second end  922 , which is closer to the second surface  906 , is slightly wider than the first end  920 . The unequal size of the ends  920  and  922  helps direct fluid along the offset longitudinal axis  914  of the first fluid passages  910 . The unequal size of the ends  920  and  922  also helps increase the wall thickness in certain areas of the body  902  between the first fluid passages  910  and a plurality of second fluid passages  924 . 
     In alternative embodiments, the opposed ends of the openings may be identical in size or may be shaped identical to the openings  334 , shown in  FIGS.  57  and  59   . The opening  918  of the first fluid passage  910  shown in  FIG.  121    extends along an axis that is parallel to the longitudinal axis  916  of the body  902 . In alternative embodiments, the openings of the first fluid passages may extend at a non-zero angle relative to the longitudinal axis  916  of the body  902 , as shown for example by the openings  972  shown in  FIG.  128 D . The angle at which the first fluid passages  910  are formed in the body  902  may vary, as desired, in order to increase the wall thickness within the body  902  and reduce stress in the body  902  during operation. 
     Continuing with  FIGS.  122  and  126   , each of the second fluid passages  924  formed in the body  902  interconnects the first and second surfaces  904  and  906 . The second fluid passages  924  are identical to the second fluid passages  336 , shown in  FIGS.  60 - 63   , but the second fluid passages  924  are slightly pivoted from the position of the second fluid passages  336 . Each second fluid passage  924  is pivoted so that it has a compound angle with respect to the central longitudinal axis  916 , as shown in  FIGS.  122 ,  123     126 , and  127 . Meaning, each second fluid passage  924  extends such that it has two different angles relative to the central longitudinal axis  916 —up-and-down, and side-to-side. Like the first fluid passages  910 , forming the second fluid passages  924  at such angles encourages a vortex type flow of fluid about the central longitudinal axis  916 , thereby reducing fluid turbulence during operation. 
     Continuing with  FIGS.  124 ,  127 , and  128   , the first surface  904  of the fluid routing plug  900  may be identical to the first surface  318 , shown in  FIGS.  53 ,  55 , and  56   . However, an outer rim  926  of the first surface  904  may be flat rather than tapered. The second surface  906  of the fluid routing plug  900  is identical to the fluid routing plug  116 , but a central base  928  formed in the second surface  906  may be slightly set back within the body  902 , as compared to the central base  354 , shown in  FIGS.  54  and  55   . An outer rim  930  on the second surface  906  may be slightly wider than the outer rim  352 , shown in  FIGS.  54  and  55   . The intermediate surface  908  of the fluid routing plug  900  may be identical to the intermediate surface  322  of the fluid routing plug  116 . Alternatively, the intermediate surface may be identical to those formed on the fluid routing plug  700  or  800 . 
     In alternative embodiments, the first and second surfaces  904  and  906  of the fluid routing plug  900  may be configured so that its tapered walls  932  and  934  are the same size, like the fluid routing plug  600 . In further alternative embodiments, the first and second surfaces of the fluid routing plug  900  may be identical to the first and second surfaces of the fluid routing plug  116 . 
     Turning to  FIGS.  128 A- 128 G , another embodiment of a fluid routing plug  950  is shown. The fluid routing plug  950  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  950  is identical to the fluid routing plug  900 , with a few exceptions. The fluid routing plug  950  comprises a body  962  having a first outer surface  964  joined to a second outer surface  952  by an intermediate outer surface  966 . In contrast to the fluid routing plug  900 , the second surface  952  of the fluid routing plug  950  is formed identically to the second surface  856  of the fluid routing plug  850 , shown in  FIGS.  100 A- 100 E . A central base  954  formed in the second surface  952  is spaced from an edge  956  of a tapered wall  958  such that a throat  960  is formed within the second surface  952 . The throat  960  serves the same purpose as the throat  566  formed in the fluid routing plug  550 . 
     Continuing with  FIG.  128 A- 128 G , a plurality of first fluid passages  968 , shown in  FIG.  128 G , and a plurality of second fluid passages  970 , shown in  FIG.  128 A , are formed in the body  962 . The first and second fluid passages  968  and  970  are identical to the first and second passages  910  and  924  formed in the fluid routing plug  900 . However, as discussed above, an opening  972  of the first fluid passages  968  may extend along a non-zero angle relative to a central longitudinal axis  974  of the body  962 , as shown in  FIG.  128 D . In alternative embodiments, the openings  972  may be identical to the openings  918 , shown in  FIG.  121   . Like the fluid routing plug  900 , the angle at which the first fluid passages  968  are formed in the body  962  may vary, as desired, in order to increase the wall thickness within the body  962  and reduce stress in the body  962  during operation. 
     In alternative embodiments, the first and second surfaces  964  and  952  of the fluid routing plug  950  may be configured like the fluid routing plug  600 . In further alternative embodiments, the first and second surfaces of the fluid routing plug  950  may be identical to the first and second surfaces of the fluid routing plug  116 . 
     Turning to  FIGS.  129 - 131   , another embodiment of a fluid routing plug  1000  is shown. The fluid routing plug  1000  may be installed within the housing  104  in place of the fluid routing plug  116 . The fluid routing plug  1000  is identical to the fluid routing plug  116  but includes a first and second annular recess  1002  and  1004  formed in its intermediate surface  1001 . The first annular recess  1002  is positioned between a first bevel  1006  and a first sealing surface  1008 . The second annular recess  1004  is positioned between a second sealing surface  1010  and a second bevel  1012 . 
     When the fluid routing plug  1000  is installed within the horizontal bore  106 , a small annular space exists between the wall of the housing  104  and each recess  1002  and  1004 . The space provides relief areas for excess fluid or proppant to collect during operation. The first and second recesses  1002  and  1004  may also be formed in the intermediate surfaces of the fluid routing plugs  550 ,  600 ,  700 ,  800 ,  900 , and  950 . 
     With reference to  FIGS.  131 A- 131 K , another embodiment of a fluid routing plug  901  is shown. The fluid routing plug  901  is generally identical to the fluid routing plug  550 , shown in  FIG.  100 A- 100 E  but includes modified first and second surfaces  903  and  905 . The first surface  903  comprises a recessed area  907  positioned between the opening of an axially blind bore  909  and a tapered surface  911 . The recessed area  907  is configured to receive a hardened insert  913 , shown in  FIG.  131 I . 
     Similarly, the second surface  905  comprises a recessed area  915  positioned between openings  917  of the second fluid passages  919  and a tapered surface  921 . The recessed area  915  is configured to receive a hardened insert  923 . The inserts  913  and  923  are sized to form an extension of the tapered surfaces  911  and  921 , as well as not block fluid flow through the plug  901 . The hardened inserts  913  and  923  help reduce wear to the plug  901  over time due to repeated contact of the intake and discharge valves  292  and  294 . 
     With reference to  FIGS.  131 L- 131 S , another embodiment of a fluid routing plug  931  is shown. The fluid routing plug  931  is generally identical to the fluid routing plug  550 , shown in  FIG.  100 A- 100 E  but has an alternative embodiment of an intermediate surface  933 . First and second grooves  935  and  937  are formed in the intermediate surface  933  adjacent the corresponding first and second surfaces  939  and  941 . The grooves  935  and  937  are configured to receive a first and second seal  943  and  945 , as shown in  FIGS.  131 Q and  131 R . The seals  943  and  945  may be generally identical to the seals  374  and  376 , shown in  FIGS.  70  and  71   . However, the seals  943  and  945  may have a smaller diameter than the seals  374  and  376 . 
     Continuing with  FIG.  131 S , the fluid routing plug  931  is used with an alternative embodiment of a housing  947 . The housing  947  does not include any grooves for housing seals that engage with the fluid routing plug  931 . Instead, the seals  943  and  945  installed within the fluid routing plug  931  engage the flat walls of the housing  947 . The area of the housing walls engaged with the seals  943  and  945  are characterized as sealing surfaces. In some embodiments, the sealing surfaces may be sprayed with a hardened material to help reduce wear and erosion. 
     In alternative embodiments, a first groove for housing a seal may be formed in the fluid routing plug and a second groove for housing a seal may be formed in the walls of the housing, and vice versa. In such embodiment, a first sealing surface is formed on the fluid routing plug and a second sealing surface is formed on a wall of the housing, or vice versa. 
     With reference to  FIG.  131 T , another embodiment of a fluid routing plug  951  is shown. The fluid routing plug  931  is a combination of the new features added to the fluid routing plugs  901  and  931 . The fluid routing plug  951  comprises recessed areas  953  and  955  for hardened inserts  957  and  959 . The fluid routing plug  951  also comprises first and second grooves  961  and  963  for housing first and second seals  965  and  967 . 
     In alternative embodiments, the first and second surfaces of each of the fluid routing plugs  550 ,  600 ,  700 ,  800 ,  900 ,  950 ,  901 ,  931 , and  951  may each be sized to engage with identically sized suction and discharge valves  292 ,  294 ,  614  or  616 , as discussed with regard to fluid routing plug  600 . In further alternative embodiments, the first and second surfaces of each of the fluid routing plugs  550 ,  600 ,  700 ,  800 ,  900 ,  950 ,  901 ,  931 , and  951  may be sized to engage with differently sized suction and discharge valves  292 ,  294 ,  614  or  616 . In such embodiment, the valves  292 ,  294 ,  614  or  616  may be sized as desired, as long as the ratio of the outer sealing diameter A to the inner sealing diameter B of each valve is preferably 1.55 or greater, as discussed with regard to  FIGS.  72  and  85   . The desired size of the valve may vary depending on the desired fluid velocity within the corresponding fluid routing plug. 
     With reference to  FIGS.  132  and  133   , another embodiment of a fluid end section  1100  is shown. The fluid end section  1100  is similar to the fluid end section  102  but comprises another embodiment of a housing  1102 . The housing  1102  is similar to the housing  104 , with the exception of its first surface  1104 . Rather than having a retainer threaded into its first surface  1104 , like the housing  104 , a retainer  1106  is attached to the first surface  1104  of the housing  1102  using a fastening system  1108 . 
     With reference to  FIGS.  134 - 137   , the retainer  1106  comprises a first surface  1110  joined to a second surface  1112  by an intermediate surface  1114 . A central passage  1116  is formed in the retainer  1106  and interconnects the first and second surfaces  1110  and  1112 . The walls surrounding the central passage  1116  are threaded. A plurality of passages  1118  are formed in the retainer  1106  and surround the central passage  1116 . Each passage  118  interconnects the first and second surfaces  1110  and  1112  of the retainer  1106 . 
     With reference to  FIG.  138   , a plurality of threaded openings  1120  are formed in the first surface  1104  of the housing  1102 . The openings  1120  surround an opening of a horizontal bore  1122  formed in the housing  1102 . The passages  1118  formed in the retainer  1106  are alignable with the openings  1120  in a one-to-one relationship. A dowel pin groove  1124  is also formed in the housing  1102  adjacent the opening of the horizontal bore  1122 , as shown in  FIG.  139   . The dowel pin groove  1124  is configured to receive a dowel pin installed within the retainer  1106 . The dowel pin helps properly align the retainer  1106  on the first surface  1104  of the housing  1102 . 
     Turning back to  FIGS.  132  and  133   , the fastening system  1108  comprises a plurality of studs  1126 , washers  1128 , and nuts  1130 . A first end  1132  of each stud  1126  mates with one of the openings  1120  formed in the housing  1102 , in a one-to-one relationship. The passages  1116  formed in the retainer  1106  subsequently receive the plural studs  1126  projecting from the first surface  1104  of the housing  1102 . 
     When the housing  1102  and the retainer  1106  are brought together, a second end  1134  of each stud  1126  projects from the first surface  1110  of the retainer  1106 . A washer  1128  and a nut  1130  are subsequently installed on the second end  1134  of each stud  1126 , in a one-to-one relationship. The nut  1130  is turned until it tightly engages the washer  1128  and the first surface  1110  of the retainer  1106 , thereby securing the housing  1102  and the retainer  1106  together. Rather than applying a single large torque to a single retainer, the fastening system  1108  contemplates distribution of smaller torques among a plurality of studs  1126  and nuts  1130 . 
     A retainer nut  1136  is threaded into the central passage  1116  formed in the retainer  1106 . The shape and construction of the retainer nut  1136  is identical to the shape and construction of retainer  300  shown in  FIGS.  47 - 49   . Rather than remove all of the nuts  1130  and washers  1128 , the operator can simply remove the retainer nut  1136 . When the retainer nut  1136  is removed, the operator can access the interior of the housing  1102  through the central passage  1116  of the retainer  1106 . Should any fatigue failures occur between the retainer  1106  and the retainer nut  1136 , the retainer  1106  and/or retainer nut  1136  may be removed and replaced with a new retainer  1106  or retainer nut  1136 . 
     Continuing with  FIG.  133   , another embodiment of a fluid routing plug  1138  is shown installed within the housing  1102 . The walls surrounding the horizontal bore  1122  formed in the housing  1102  are configured to mate with the fluid routing plug  1138 . Fluid is routed throughout the fluid routing plug  1138  and the housing  1102  in the same manner as the fluid routing plug  116  and the housing  104 , shown in  FIGS.  50  and  51   . The fluid routing plug  1138  is described in more detail in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020, the entire contents of which are incorporated herein by reference. 
     In alternative embodiments, one of the other fluid routing plugs described herein or described in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020, may be installed within the housing  1102 . In such embodiments, the housing  1102  may be configured to receive the chosen fluid routing plug. 
     Continuing with  FIGS.  132  and  133   , the stuffing box  140  and corresponding components are shown attached to a second surface  1140  of the housing  1102 . The connect plate  118  is also shown attached to the housing  1102  in  FIG.  132   . A plurality of notches are not shown formed in the housing  1102  adjacent its second surface  1140 . In alternative embodiments, the housing  1102  may include a plurality of notches, like the notches  136  shown in  FIG.  6   . 
     With reference to  FIGS.  139 A- 139 D , another embodiment of a fluid end section  1500  is shown. The fluid end section  1500  is generally identical to the fluid end section  102 , shown in  FIGS.  7 A and  7 B  but its housing  1502  has an integrally formed connect plate  1504 . Thus, the connect plate  1504  forms an extension of the housing  1502 , such that it functions as a flange on the housing  1502 . A plurality of openings  1506  are formed in the connect plate  1504  for receiving the stay rods  120 , as shown in  FIG.  139 D . The stay rods  120  are attached to the connect plate  1504  in the same manner as they are attached to the connect plate  118 , shown in  FIG.  16   . 
     With reference to  FIGS.  140  and  141   , another embodiment of a fluid end section  1200  is shown. The fluid end section  1200  comprises another embodiment of a housing  1202 . The housing  1202  is generally identical to the housing  1102  but comprises a first section  1204  joined to a second section  1206  by a fastening system  1208 . A discharge bore  1210  is formed in the first section  1204  and a pair of intake bores  1212  and  1214  are formed in the second section  1206 , as shown in  FIG.  140   . The first section  1204  joins the second section  1206  between the discharge bore  1210  and the intake bores  1212  and  1214 . 
     With reference to  FIGS.  142 - 148   , the first section  1204  comprises a first surface  1216  joined to a second surface  1218  by an intermediate surface  1220 . A horizontal bore  1222  extends through the first section  1204  and interconnects the first and second surfaces  1216  and  1218 . Internal threads  1217  are formed in the walls of the first section  1204  surrounding the horizontal bore  1222  adjacent the first surface  1216 , as shown in  FIGS.  143  and  145   . 
     The intermediate surface  1220  of the first section  1204  includes a first portion  1224  joined to a second portion  1226 . The second portion  1226  has a reduced diameter from that of the first portion  1224  and is positioned adjacent the second surface  1218  of the first section  1204 . A plurality of passages  1223  are formed in the first section  1204  and surround the horizontal bore  1222 . Each passage  1223  interconnects the first surface  1216  and a base  1219  of the first portion  1224 . 
     With reference to  FIGS.  149 - 152   , the second section  1206  comprises a first surface  1228  joined to a second surface  1230  by an intermediate surface  1232 . A horizontal bore  1234  extends through the second section  1206  and interconnects the first and second surfaces  1228  and  1230 . A counterbore  1235  is formed in the first surface  1228  of the second section  1206  that is sized to fittingly receive the second portion  1226  of the first section  1204 . A plurality of threaded openings  1233  are formed in the first surface  1228  of the second section  1206  and surround the horizontal bore  1234 . The openings  1233  are alignable with the passages  1223 , in a one-to-one-relationship. 
     Turning back to  FIG.  140   , when the second portion  1226  is installed within the counterbore  1235 , the base  1219  of the first portion  1224  abuts the first surface  1228  of the second section  1206 . A seal  1238  is interposed between an outer surface of the second portion  1226  and the walls of the second section  1206  surrounding the counterbore  1235 . The seal  1238  is installed within a groove  1240  formed in the walls of the second section  1206  surrounding the counterbore  1235 , as shown in  FIGS.  149  and  152   . The seal  1238  and groove  1240  may be identical to the seal  376  and the groove  406 , shown in  FIG.  70   . 
     Continuing with  FIG.  141   , the fastening system  1208  comprises a plurality of studs  1242 , nuts  1244 , and washers  1246 . The fastening system  1208  attaches the first section  1204  to the second section  1206  in the same fashion as the fastening system  1108  attaches the retainer  1106  to the housing  1102 , shown in  FIG.  133   . A first end  1248  of each stud  1242  is configured to mate with the openings  1233  formed in the first surface  1228  of the second section  1206 , in a one-to-one relationship. The passages  1223  formed in the first section  1204  subsequently receive the plurality of studs  1242  projecting from the first surface  1228 . A nut  1244  and washer  1246  are subsequently installed on a second end  1250  of each stud  1242  and is turned until the first section  1204  and the second section  1206  are secured together. 
     In operation, the second section  1206  experiences higher fluid pressure and therefore more stress than the first section  1204 . Thus, the first section  1204  may be made of a lower strength and less costly material than the second section  1206 . If any failures occur in the first section  1204  during operation, the first section may be removed and replaced with a new first section  1204 . Likewise, if any failures occur in the second section  1206  during operation, the second section can be removed and replaced with a new second section  1206 . 
     Continuing with  FIGS.  140  and  141   , the stuffing box  140  and corresponding components are shown attached to the second surface  1230  of the second section  1206 . The fluid routing plug  1138  is shown installed within both the first and second sections  1204  and  1206 . The walls surrounding the aligned horizontal bores  1222  and  1234  are configured to mate with the fluid routing plug  1138 . Fluid is routed throughout the fluid routing plug  1138  and the first and second sections  1204  and  1206  in the same manner as the fluid routing plug  116  and the housing  104 , shown in  FIGS.  50  and  51   . 
     In alternative embodiments, one of the other fluid routing plugs described herein or described U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020, may be installed within the first and second sections  1204  and  1206 . In such embodiments, the first and second sections  1204  and  1206  may be configured to receive the chosen fluid routing plug. 
     With reference to  FIG.  153   , another embodiment of a fluid end section  1300  is shown. The fluid end section  1300  comprises another embodiment of a housing  1302 . The housing  1302  comprises a first surface  1304  joined to a second surface  1306  by an intermediate surface  1308 . A horizontal bore  1305  is formed in the housing  1302  and interconnects the first and second surfaces  1304  and  1306 . 
     With reference to  FIGS.  154 - 157   , the intermediate surface  1308  of the housing  1302  includes a first portion  1310  joined to a second portion  1312 . The second portion  1312  has a reduced diameter from that of the first portion  1310  and includes the second surface  1306  of the housing  1302 . The first portion  1310  includes varying diameter sections and has an asymmetrical cross-sectional shape, as shown in  FIGS.  156  and  159   . The varying diameter sections and asymmetrical shape are due to portions of the first portion  1310  being removed. Portions of the first portion  1310  have been removed in order to remove excess weight from the housing  1302 , thereby making the housing  1302  easier to move during assembly. 
     With reference to  FIGS.  160  and  161   , the second portion  1312  of the housing  1302  is sized to receive another embodiment of a stuffing box  1314 . A tapered wall  1316  is formed in the second portion  1312  that extends between the horizontal bore  1305  and the second surface  1306 . 
     With reference to  FIGS.  162 - 165   , the stuffing box  1314  is identical to the stuffing box  140  but has a first portion  1318  joined to a second portion  1320  by a tapered portion  1322 . A plurality of passages  1324  formed in the second portion  1312 . Each passage  1324  interconnects a second surface  1319  of the stuffing box  1314  and the tapered portion  1318 . The tapered portion  1318  conforms to the tapered wall  1316  formed in the second surface  1306  of the housing  1302 . The stuffing box  1314  is attached to the housing  1302  in the same manner as the stuffing box  140 , shown in  FIGS.  20  and  21   . 
     Continuing with  FIG.  160   , another embodiment of a connect plate  1326  is attached to the housing  1302 . A central bore  1328  formed in the connect plate  1326  is sized to receive the second portion  1312  of the housing  1302  and at least a portion of the stuffing box  1314 . The connect plate  1326  is attached to the housing  1302  in the same manner as the connect plate  118 , shown in  FIG.  17   . The connect plate  1326  is shown and described in more detail in U.S. Provisional Patent Application Ser. No. 63/053,797, authored by Thomas et al. and filed on Jul. 20, 2020. 
     Turning back to  FIG.  153   , a discharge bore  1329  formed in the housing  1302  interconnects a bottom surface  1330  of the intermediate surface  1308  and the horizontal bore  1305 . Likewise, a discharge conduit  1332  is shown attached to the bottom surface  1330  of the housing  1302 . In alternative embodiments, the discharge bore may interconnect a top surface of the housing and the horizontal bore, like the discharge bore  178  shown in  FIG.  9   . In such embodiment, the discharge conduit is attached to the top surface of the housing, like the discharge conduit  174 , shown in  FIG.  9   . 
     Continuing with  FIG.  153   , another embodiment of a fluid routing plug  1334  is shown installed within the housing  1302 . The walls surrounding the horizontal bore  1305  formed in the housing  1302  are configured to mate with the fluid routing plug  1334 . Fluid is routed throughout the fluid routing plug  1334  and the housing  1302  in the same manner as the fluid routing plug  116  and the housing  104 , shown in  FIGS.  50  and  51   . The fluid routing plug  1334  is described in more detail in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020. 
     In alternative embodiments, one of the other fluid routing plugs described herein or described in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020, may be installed within the housing  1302 . In such embodiment, the housing  1302  may be configured to receive the chosen fluid routing plug. 
     With reference to  FIGS.  166  and  167   , another embodiment of a fluid end section  1400  is shown. The fluid end section  1400  comprises a housing  1402  having a first surface  1406  joined to a second surface  1406  by an intermediate surface  1408 . The housing  1402  further comprises an elongate plunger housing  1410  joined to the second surface  1406  of the housing  1402 . A horizontal bore  1412  is formed in the housing that interconnects the first surface  1404  and terminal end  1414  of the plunger housing  1410 . Only one intake bore  1416  is shown in the housing  1402 . In alternative embodiments, the housing  1402  may include a second intake bore. 
     Continuing with  FIG.  167   , the plunger housing  1410  is used in place of the stuffing box  140 , shown in  FIGS.  20  and  21   . The plunger housing  1410  is sized to receive an elongate plunger  1418 . Fluid is routed throughout the housing  1402  in the same manner as the housing  104 , shown in  FIGS.  50  and  51   , but the plunger  1418  has a much longer plunger stroke. 
     Continuing with  FIG.  167   , another embodiment of a fluid routing plug  1420  is shown installed within the housing  1402 . The walls surrounding the horizontal bore  1412  formed in the housing  1402  are configured to mate with the fluid routing plug  1420 . Fluid is routed throughout the fluid routing plug  1420  and the housing  1402  in the same manner as the fluid routing plug  116  and the housing  104 , shown in  FIGS.  50  and  51   . The fluid routing plug  1420  is described in more detail in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020. 
     In alternative embodiments, one of the other fluid routing plugs described herein or described in U.S. patent application Ser. No. 16/951,605, authored by Thomas et al. and filed on Nov. 18, 2020, may be installed within the housing  1402 . In such embodiment, the housing  1402  may be configured to receive the chosen fluid routing plug. 
     The housings described herein have various embodiments of suction valves, discharge valves, suction valve guides, and discharge valve guides. One of skill in the art will appreciate that these components may have various shapes and sizes depending on the construction of the housing and various components. 
     While not shown herein, in an alternative embodiment, the fluid end  100  described herein may be formed as a single housing having a plurality of horizontal bores formed therein and positioned in a side-by-side relationship. The housing may be attached to a single, large connect plate. In further alternative embodiments, the single housing described above may be broken up into one or more sections have two or more horizontal bores formed therein. Such housings may be attached to one or more connect plates. 
     One of skill in the art will further appreciate that various features of the fluid routing plugs, housings, and other components described herein may be modified or changed, as desired. While not specifically shown in a figure herein, various features from one or more of the fluid routing plugs described herein may be included in another one of the plugs. Likewise, various features from one or more of the different housings described herein may be included in another one of the housings. 
     The concept of a “kit” is described herein due to the fact that fluid ends are often shipped or provided unassembled by a manufacturer, with the expectation that a customer will use components of the kit to assemble a functional fluid end. Alternatively, some components are replaced during operation. Accordingly, certain embodiments within the present disclosure are described as “kits,” which are unassembled collections of components. The present disclosure also describes and claims assembled apparatuses and systems by way of reference to specified kits, along with a description of how the various kit components are actually coupled to one another to form the apparatus or system. 
     The term “means for routing fluid” refers to the various fluid routing plugs described herein and structural equivalents thereof. The term “means for regulating fluid flow” refers to the various suction and discharge valves and suction and discharge valve guides described herein and structural equivalents thereof. A “means for pressurizing fluid” refers to the fluid end and the various embodiments of housings and components installed within or attached to the various housings described herein and structural equivalents thereof. 
     As used herein, “modular” means an apparatus that is comprised of a plurality of components joined together to form a complete apparatus. Such components may be removable and replaceable with like components, if needed. For example, in some embodiments of the fluid end  100  described herein, the fluid end  100  comprises a plurality of fluid end sections  102  joined together to form the fluid end  100 . Each fluid end section  102  may be removed and replaced with a new fluid end section  102 , if needed. 
     The various features and alternative details of construction of the apparatuses described herein for the practice of the present technology will readily occur to the skilled artisan in view of the foregoing discussion, and it is to be understood that even though numerous characteristics and advantages of various embodiments of the present technology have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the technology, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present technology to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. Changes may be made in the construction, operation and arrangement of the various parts, elements, steps and procedures described herein without departing from the spirit and scope of the invention as described in the following claims.