Patent Publication Number: US-11655812-B2

Title: Fluid end assembly

Description:
SUMMARY 
     The invention is directed to a kit comprising a fluid end body, a component, a retainer element, and a fastening system. The body comprises an external surface, and a bore extending through the body and terminating at an opening formed in the external surface. The component is configured for removable installation within the bore, and the retainer element is engagable with the component when the component is installed within the bore. The fastening system is configured to releasably hold the retainer element against the component when the component is installed to within the bore. The bore has no internal threads formed within that portion that surrounds the component when the component is installed within the bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a partially exploded view of a first embodiment of a fluid end of the present invention.  FIG.  1    shows a suction and discharge end of the fluid end. 
         FIG.  2    is a partially exploded view of a plunger end of the fluid end body shown in  FIG.  1   . 
         FIG.  3    is a cross-sectional view of the fluid end shown in  FIG.  1   , taken along line A-A. 
         FIG.  4    is a partially exploded view of a second embodiment of a fluid end.  FIG.  4    shows a suction and discharge end of the fluid end. 
         FIG.  5    is a partially exploded view of a plunger end of the fluid end body shown in  FIG.  4   . 
         FIG.  6    is a cross-sectional view of the fluid end shown in  FIG.  4   , taken along line B-B. 
         FIG.  7    is a partially exploded view of a third embodiment of a fluid end.  FIG.  7    shows a suction and discharge end of the fluid end. 
         FIG.  8    is a partially exploded view of a plunger end of the fluid end body shown in  FIG.  7   . 
         FIG.  9    is a partially exploded view of a fifth embodiment of a fluid end.  FIG.  9    shows a suction and discharge end of the fluid end. 
         FIG.  10    is a partially exploded view of a plunger end of the fluid end body shown in  FIG.  9   . 
         FIG.  11    is a cross-sectional view of the fluid end shown in  FIG.  9   , taken along line C-C. 
         FIG.  12    is a partially exploded view of a sixth embodiment of a fluid end.  FIG.  12    shows a suction and discharge end of the fluid end. 
         FIG.  13    is a cross-sectional view of the fluid end shown in  FIG.  12   , taken along line D-D. 
         FIG.  14    is a partially exploded view of a seventh embodiment of a fluid end.  FIG.  14    shows a suction and discharge end of the fluid end. 
         FIG.  15    is a side elevational view of one of the plurality of studs for use with the fluid ends. 
     
    
    
     DETAILED DESCRIPTION 
     Fluid end assemblies are typically used in oil and gas operations to deliver highly pressurized corrosive and/or abrasive fluids to piping leading to the wellbore. The assemblies are typically attached to power ends run by engines. The power ends reciprocate plungers within the assemblies to pump fluid throughout the fluid end. Fluid may be pumped through the fluid end at pressures that range from 5,000-15,000 pounds per square inch (psi). Fluid used in high pressure hydraulic fracturing operations is typically pumped through the fluid end at a minimum of 8,000 psi; however, fluid will normally be pumped through the fluid end at pressures around 10,000-15,000 psi during such operations. 
     In fluid end assemblies known in the art, the fluid flow passages or bores formed within the fluid end body are typically sealed by inserting a plug into each bore. A large retaining nut is then installed into each bore above the plug. The retaining nuts typically thread into internal threads formed in the walls of each bore. 
     In operation, the high level of fluid pressure pumping throughout the fluid end may cause the retaining nuts to back off or unthread from their installed position. When a retaining nut unthreads from its installed position, the plug it was retaining may be displaced by fluid pressure. Displacement of the plug allows fluid to leak around the plug and erode the walls of the bore. The internal threads formed in the bores for engagement with the retaining nuts are also known to crack over time. Erosion of the bore walls or cracking of the internal threads typically requires repair or replacement of the fluid end. 
     The present invention is directed to a plurality of different fluid ends having bores sealed without threading retaining nuts into the walls of each bore. As a result, the fluid ends of the present invention do not have internal threads formed in their bores proximate the bore openings. Removal of the internal threads eliminates the problems associated with the internal thread failures and the retaining nuts becoming unthreaded from the bores. 
     With reference to  FIGS.  1  and  3   , a first embodiment of a fluid end  100  is shown. The fluid end  100  comprises a fluid end body  102  having a flat external surface  104  and a plurality of first and second bores  106 ,  108  formed adjacent one another therein, as shown in  FIG.  1   . Preferably, the number of first bores  106  equals the number of second bores  108 . More preferably, each first bore  106  intersects its paired second bore  108  within the fluid end body  102  to form an internal chamber  112 , as shown in  FIG.  3   . 
       FIG.  1    shows five first and second bores  106 ,  108 . In alternative embodiments, the number of sets of paired first and second bores in the fluid end body may be greater than five, or less than five. Thus,  FIG.  4    shows a fluid end body that includes three sets of paired first and second bores. Each bore of each set of paired bores  106  and  108  terminates in a corresponding opening  110  formed in the external surface  104 . The bores  106  and  108  and openings  110  exist in one-to-one relationship. A plurality of internally threaded openings  144  are formed in the body  102  and uniformly spaced around each bore opening  110 , as shown in  FIG.  1   . 
     With reference to  FIG.  3   , each second bore  108  may have an intake opening  118  formed proximate the bottom end of the fluid end body  102 . Each intake opening  118  is connected in one-to-one relationship to a corresponding coupler or pipe. These couplers or pipes are fed from a single common piping system (not shown). 
     A pair of valves  120  and  122  are positioned within each second bore  108 . The valves  120 ,  122  route fluid flow within the body  102 . The intake valve  120  blocks fluid backflow through the intake opening  118 . The discharge valve  122  regulates fluid through one or more discharge openings  126 . A plurality of couplers  127  may be attached to each discharge opening  126  for connection to a piping system (not shown), as shown in  FIG.  1   . 
     Continuing with  FIGS.  1  and  3   , the fluid end  100  further comprises a plurality of sets of components  128  and  130 . The number of sets preferably equals the number of sets of paired first and second bores  106  and  108  formed in the body  102 . The component  128  is positioned within a first bore  106 , and the component  130  is positioned within its paired second bore  108 . In one embodiment, the component  128  is a suction plug and the component  130  is a discharge plug. Each of the components  128  and  130  are substantially identical in shape and construction, and each is sized to fully block fluid flow within the respective bore  106 ,  108 . A seal  136  is positioned around the outer surface of each component  128 ,  130  to block fluid from leaking from the bores  106 ,  108 . 
     Each of the components  128  and  130  comprises a first section  138  joined to a second section  140 . The first section  138  has a footprint sized to cover the bore opening  110  and the second section  140  is configured for removable receipt within one of the bores  106 ,  108 . In one embodiment, the first section  138  is an enlarged plate and the second section  140  is a plug sized to be closely received within one of the bores  106 ,  108 . When the component  128  or  130  is installed within one of the bores  106 ,  108 , the first section  138  engages with the external surface  104  of the body  102 . This engagement prevents longitudinal movement of the second section  140  within the bore  106  or  108  as shown in  FIG.  3   . 
     With reference to  FIG.  1   , the first section  138  may be formed as a circular structure having a plurality of notches  142  cut from its outer periphery. When each of the first sections  138  is engaged with the external surface  104  of the body  102 , each of the notches  142  partially surrounds one of the openings  144  spaced around each bore opening  110 . 
     Continuing with  FIGS.  1  and  3   , once each component  128 ,  130  is installed in the fluid end body  102 , each of the components  128 ,  130  is secured in place by a retainer element  132  in a one-to-one relationship. Each retainer element  132  has a footprint sized to fully cover the first section  138  of the components  128  and  130 . The retainer elements  132  shown in  FIG.  1    are flat and cylindrical. A plurality of openings  146  are formed about the periphery of each retainer element  132 . Each opening  146  is alignable with a corresponding one of the openings  144  in a one-to-one relationship. 
     Each of the retainer elements  132  is secured to the fluid end body  102  using a fastening system  134 . The fastening system comprises a plurality of studs  148 , a plurality of washers  150 , and a plurality of nuts  152 . Each stud  148  is externally threaded adjacent its first end  149 , while each opening  144  has internal threads that mate with those of the stud  148 . Each stud  148  may be threaded into place within a corresponding one of the openings  144 , in a one-to-one relationship. 
     Once a first stud  148  has been installed in the body  102  at its first end  149 , its opposed second end  151  projects from the body&#39;s external surface  104 . When each component  128  is positioned within its bore  106 , each of its notches  142  at least partially surrounds a corresponding one of the studs  148 . Likewise, when each component  130  is positioned within its bore  108 , each of its notches  142  at least partially surrounds a corresponding one of the studs  148 . 
     Each peripheral opening  146  formed in each of the retainer elements  132  is registerable with a corresponding one of the studs  148 . The plurality of washers  150  and nuts  152  may be installed and torqued on each one of the studs  148 . The plurality of washers  150  and nuts  152  hold the retainer element  132  against the first section  138  of the components  128 ,  130  and hold the first section  138  against the external surface  104  of the fluid end body  102 . Because each of the retainer elements  132  is attached to the fluid end body  102  using the fastening system  134 , no external threads are formed on the outer surface of each retainer element  132 . Likewise, no internal threads are formed within the walls of each bore  106 ,  108 . 
     With reference to  FIGS.  2  and  3   , a plunger end  154  of the fluid end  100  is shown. The plurality of first bores  106  terminate at openings  156  formed on the external surface  104  of the plunger end  154 . An internal seat  159  is formed in the walls of each of the bores  106  proximate each of the bore openings  156 . A plurality of threaded openings  161  are formed in each of the internal seats  159 , as shown in  FIG.  2   . 
     A component  158  is positioned within each first bore  106  through each of the openings  156 . Each of the components  158  is tubular and sized to be closely received within each bore  106 . In one embodiment, the components  158  are stuffing box sleeves. 
     With reference to  FIG.  3   , each of the components  158  may have a first section  160  that joins a second section  162  via a tapered section  164 . The first section  160  may have a larger diameter than the second section  162 . When each of the components  158  are installed within each of the bores  106 , the tapered section  164  engages a tapered seat  166  formed in the walls of each bores  106 . This engagement prevents longitudinal movement of each component  158  within each bore  106 . A seal  167  is positioned around the outer surface of the second section  162  of each of the components  158  in order to block fluid from leaking from the bores  106 . 
     Once installed within the body  102 , each component  158  is secured in place by a retainer element  170  in a one-to-one relationship. Each of the retainer elements  170  is sized to be closely received within each bore  106  and engage a top surface  171  of each component  158 , as shown in  FIG.  3   . Each of the retainer elements  170  shown in  FIG.  2    has a cylindrical body and a threaded central opening  172 . A plurality of openings  174  are formed about the periphery of each of the retainer elements  170 . The openings  174  are uniformly spaced around each central opening  172 . 
     A plurality of ports  175  may be formed in an outer surface of each retainer element  170  that are orthogonal to the plurality of openings  174 . At least one seal  176  may also be disposed around the outer surface of each of the retainer elements  170 . The seal  176  helps block fluid from leaking from the bores  106 . 
     Each of the retainer elements  170  is secured to the fluid end body  102  using a fastening system  178 . The fastening system  178  comprises a plurality of threaded screws  180 . The screws  180  are preferably socket-headed cap screws. 
     The fastening system  178  secures each retainer element  170  to each internal seat  159 . When each retainer element  170  is positioned within each bore  106 , each of the peripheral openings  174  is alignable with a corresponding one of the openings  161  in a one-to-one relationship. Each of the screws  180  is registerable within one of the openings  161  in the seat  159  and one of the peripheral openings  174  in the retainer element  170 . 
     The screws  180  may be torqued as desired to tightly attach each of the retainer elements  170  to each internal seat  159  and securely hold each component  158  within each bore  106 . Because each of the retainer elements  170  is attached to the fluid end body  102  using the fastening system  178 , no external threads are formed on the outer surface of each of the retainer elements  170 . Likewise, no internal threads are formed within the walls of each bore  106  on the plunger end  154  of the body  102 . 
     Continuing with  FIGS.  2 - 3   , a plurality of packing seals  181  may be positioned within each of the components  158  and each of the retainer elements  170  to prevent fluid from leaking from the bores  106 . At least one of the packing seals  181  may have a plurality of ports  179  formed in its outer periphery, as shown in  FIG.  2   . The ports  179  provide an exit for fluid trapped within the packing seals  181 . Fluid exiting the ports  179  may exit the retainer element  170  through the ports  175 . 
     A packing nut  182  may also be threaded into the central opening  172  of each of the retainer elements  170  in a one-to-one relationship. The packing nut  182  has a threaded section  183  joined to a body  184 . The body  184  shown in  FIG.  2    is cylindrical. However, the body  184  may also be square or rectangular shaped. A central passage  185  extends through the threaded section  183  and the body  184 . The threaded section  183  of the packing nut  182  is threaded into the central opening  172  of the retainer element  170 . 
     When installed within each of the retainer elements  170 , each of the packing nuts  182  engages with and compresses the packing seals  181  installed within each component  158  and retainer element  170 , as shown in  FIG.  3   . Compression of the packing seals  181  helps prevent fluid from leaking past the seals  181 . A seal  186  may also be positioned within the central passage  185  of each of the packing nuts  182  to further seal fluid from leaking from the bores  106 . 
     A plurality of holes  187  are formed around the outer surface of each of the packing nut bodies  184 . The holes  187  serve as connection points for a spanner wrench that may be used to tightly thread the packing nut  182  into the central opening  172  of each of the retainer elements  170 . 
     A plunger  188  may also be installed within each bore  106  in a one-to-one relationship. When a plunger  188  is installed within a bore  106 , the plunger  188  is positioned within the component  158 , the retainer element  170 , and the packing nut  182 , as shown in  FIG.  3   . Each of the plungers  188  projects from the plunger end  154  of the fluid end body  102  and is attached to a separate power end. As discussed above, the power end reciprocates each of the plungers  188  within the fluid end body  102  so as to pump fluid throughout the body. Each of the plungers  188  may be attached to the power end via a clamp  190  in a one-to-one relationship. 
     Several kits are useful for assembling the fluid end  100 . A first kit comprises a plurality of the components  128  or  130 , a plurality of the retainer elements  132 , and the fastening system  134 . A second kit may comprise the plurality of components  158 , a plurality of the retainer elements  170 , and the fastening system  178 . The second kit may further comprise a plurality of the packing seals  181 , a plurality of the packing nuts  182 , and a plurality of the plungers  188 . Each of the kits may be assembled using the fluid end body  102 . 
     With reference to  FIGS.  4  and  6   , a second embodiment of a fluid end  200  is shown. The fluid end  200  comprises a fluid end body  202  having a flat external surface  204  and a plurality of first and second bores  206 ,  208  formed adjacent one another therein, as shown in  FIG.  4   . Each bore of each set of paired bores  206  and  208  terminates in a corresponding opening  210  formed in the external surface  204 . A plurality of threaded openings  211  are formed in the body  202  and uniformly spaced around each opening  210 . The internal functions of the fluid end  200  are identical to those described with reference to fluid end  100 , shown in  FIG.  3   . 
     The fluid end  200  further comprises a plurality of sets of components  212  and  214 . The number of sets preferably equals the number of set of paired first and second bores  206  and  208  formed in the body  202 . The component  212  is positioned within a first bore  206 , and the component  214  is positioned within its paired second bore  208 . In one embodiment, the component  212  is a suction plug and the component  214  is a discharge plug. 
     Each of the components  212  and  214  is substantially identical in shape and construction, and is sized to fully block fluid flow within the respective bore  206 ,  208 . A seal  216  is positioned around the outer surface of each component  212 ,  214  to block fluid from leaking from the bores  206 ,  208 . 
     As shown in  FIG.  4   , a top surface  213  of each component  212 ,  214  may sit flush with the external surface  204  of the body  202  when installed within a respective bore  206 ,  208 . Each of the components  212  and  214  may engage with internal seats (not shown) formed in the walls of each of the bores  206 ,  208 . Such engagement helps prevent longitudinal movement of the components  212 ,  214  within the respective bore  206 ,  208 . 
     Once installed within the fluid end body  202 , each component  212  and  214  is secured in place by a retainer element  218  in a one-to-one relationship. Each of the retainer elements  218  has a footprint sized to cover a single bore opening  210 . The retainer elements  218  shown in  FIG.  4    are flat and cylindrical. A plurality of openings  220  are formed about the periphery of each retainer element  218 . Each peripheral opening  220  is alignable with a corresponding one of the openings  211  in a one-to-one relationship, as shown in  FIG.  4   . 
     The retainer elements  218  are secured to the external surface  204  of the fluid end body  202  by a fastening system  222 . The fastening system  222  comprises a plurality of externally threaded studs  224 , a plurality of washers  226 , and a plurality of internally threaded nuts  228 . Each stud  224  is externally threaded adjacent its first end  230 , while each opening  211  has internal threads that mate with those of the stud  224 . Each stud  224  may be threaded into place within a corresponding one of the openings  211 , in a one-to-one relationship. 
     Once a first stud  224  has been installed in the body  202  at its first end  230 , its opposed second end  232  projects from the body&#39;s external surface  204 . Each peripheral opening  220  formed in the retainer elements  218  is registerable with a corresponding one of the studs  224 . The plurality of washers  226  and nuts  228  may be installed and torqued on each of the studs  224 . The plurality of washers  226  and nuts  228  hold the retainer elements  218  against the external surface  204  of the fluid end body  202 . Because each of the retainer elements  218  is attached to the fluid end body  202  using the fastening system  222 , no external threads are formed on the outer surface of each retainer element  218 . Likewise, no internal threads are formed within the walls of each bore  206  and  208 . 
     With reference to  FIGS.  5 - 6   , a plunger end  234  of the fluid end  200  is shown. The plurality of first bores  206  terminate at openings  236  formed on the external surface  204  of the plunger end  234 . The plunger end  234  of the fluid end body  202  is similar to the plunger end  154  of fluid end body  102 , shown in  FIGS.  2 - 3   , except that an internal seat  159  is not formed within each bore  206 . Instead, a plurality of internally threaded openings  238  are formed in the external surface  204  of the fluid end body  202  that are uniformly spaced around each bore opening  236 . 
     A component  240  is positioned within each first bore  206  through each of the openings  236  in a one-to-one relationship. Each of the components  240  is tubular and sized to be closely received within each bore  206 . In one embodiment, the components  240  are stuffing box sleeves. 
     With reference to  FIG.  6   , each of the components  240  may have a first section  242  that joins a second section  244  via a tapered section  246 . The first section  242  may have a larger diameter than the second section  244 . When each of the components  240  are installed within each of the bores  206 , the tapered section  246  engages a tapered seat  248  formed in the walls of each bore  206 . This engagement prevents longitudinal movement of each component  240  within each bore  206 . A seal  250  is positioned around the outer surface of the second section  244  of each of the components  240  to block fluid from leaking from the bores  206 . 
     Once installed within the body  202 , a top surface  252  of each of the components  240  may sit flush with the external surface  204  of the body  202 . Each of the components  240  is secured in place within each bore  206  by a retainer element  254  in a one-to-one relationship. The retainer elements  254  shown in  FIG.  5    have a cylindrical body and a threaded central opening  256 . A plurality of openings  258  are formed about the periphery of each of the retainer elements  254 . The openings  258  are uniformly spaced around each central opening  256 . 
     The retainer elements  254  are secured to the external surface  204  of the fluid end body  202  using a fastening system  260 . The fastening system  260  comprises a plurality of threaded screws  262 . The screws  262  are preferably socket-headed cap screws. When each retainer element  254  is positioned over each bore opening  236 , each of the peripheral openings  258  is alignable with a corresponding one of the openings  238  in a one-to-one relationship. Each of the screws  262  is registerable within one of the openings  238  in the body  202  and one of the peripheral openings  258  in each of the retainer elements  254 . 
     The screws  262  may be torqued as desired to tightly attach each of the retainer elements  254  to the body  202  and securely hold each of the components  240  within each bore  206 . Because each of the retainer elements  254  is attached to the fluid end body  202  using the fastening system  260 , no external threads are formed on the outer surface of each retainer element  254 . Likewise, no internal threads are formed within the walls of each bore  206  on the plunger end  234  of the body  202 . 
     Similar to the plunger end  154  shown in  FIG.  2   , a plurality of packing seals  264  may be positioned within each of the components  240 . A packing nut  266  may thread into the central opening  256  of each retainer element  254  and compress the packing seals  264 . A seal  267  may also be positioned within each packing nut  266 . Additionally, a plurality of plungers  268  may be disposed within each component  240 , retainer element  254 , and packing nut  266 . Each of the plungers  268  may be attached to a power end via a clamp  270 . 
     In alternative embodiments, the components  212 ,  214 , and  240  may not be flush with the external surface  204  of the body  202  when installed in the respective bores  206 ,  208 . In such case, a flange or ledge may be formed on each of the retainer elements  218  or  254  on its side facing the component  212 ,  214 , or  240 . The flange or ledge may be installed within the bores  206 ,  208  so that it tightly engages the top surface  213  or  252  of the components  212 ,  214 , or  240 . 
     Likewise, if the components  212 ,  214 , or  240  project from the external surface  204  of the body  202  when installed within the respective bores  206 ,  208 , the retainer elements  218  or  254  can be modified to accommodate the component  212 ,  214 , or  240 . For example, a cut-out may be formed in the retainer element  218  or  254  for closely receiving the portion of the component  212 ,  214 , or  240  projecting from the body  202 . The area of the retainer element  218  or  254  surrounding the cut-out will engage the external surface  204  of the body  202 . 
     Several kits are useful for assembling the fluid end  200 . A first kit comprises a plurality of the components  212  or  214 , a plurality of retainer elements  218 , and the fastening system  222 . A second kit may comprise the plurality of components  240 , a plurality of the retainer elements  254 , and the fastening system  260 . The second kit may further comprise a plurality of packing seals  264 , a plurality of packing nuts  266 , and a plurality of plungers  268 . Each of the kits may be assembled using the fluid end body  202 . 
     Turning now to  FIG.  7   , a third embodiment of a fluid end  300  is shown. The fluid end  300  comprises a fluid end body  302  having a flat external surface  304  and a plurality of first and second bores  306 ,  308  formed adjacent one another therein. Each bore of each set of paired bores  306  and  308  terminates in a corresponding opening  310  formed in the external surface  304 . A plurality of threaded openings  311  are formed in the body  302  and uniformly spaced around each bore opening  310 . The internal functions of the fluid end  300  are identical to those described with reference to fluid end  100 , shown in  FIG.  3   . 
     The fluid end  300  further comprises a plurality of sets of components  312  and  314 . The number of sets preferably equals the number of set of paired first and second bores  306  and  308  formed in the body  302 . The component  312  is positioned within a first bore  306 , and the component  314  is positioned within its paired second bore  308 . In one embodiment, the component  312  is a suction plug and the component  314  is a discharge plug. A seal  315  is positioned around each of the components  312 ,  314  to block fluid from leaking from the respective bores  306 ,  308 . 
     The components  312  and  314  have the same shape and construction as the components  212  and  214  shown in  FIGS.  4  and  6   . Each of the components  312  and  314  may engage with internal seats (not shown) formed in the walls of each of the bores  306 ,  308 . Such engagement helps prevent longitudinal movement of the components  312 ,  314  within the respective bores  306 ,  308 . 
     Once installed within the body  302 , a top surface  313  of each of the components  312 ,  314  may sit flush with the external surface  304  of the body  302 . Each of the components  312 ,  314  is secured within each respective bore  306 ,  308  by a retainer element  316 . Each of the retainer elements  316  shown in  FIG.  7    is a large rectangular plate having a footprint sized to cover a plurality of adjacent bore openings  310  at one time. A plurality of openings  318  are formed in each retainer element  316  that are alignable with a corresponding one of the openings  311  in a one-to-one relationship. 
     Each of the retainer elements  316  is secured to the external surface  304  of the fluid end body  302  by a fastening system  320 . The fastening system  320  comprises a plurality of externally threaded studs  322 , a plurality of washers  324 , and a plurality of internally threaded nuts  326 . The fastening system  320  secures each of the retainer elements  316  on the fluid end body  302  in the same way as described with reference to the fastening system  222  used with the fluid end  200 . 
     Because each of the retainer elements  316  is attached to the fluid end body  302  using the fastening system  320 , no external threads are formed in the retainer element  316 . Likewise, no internal threads are formed within the walls of each bore  306  and  308 . 
     When the retainer elements  316  are installed on the fluid end body  302 , the edges of the retainer element  316  may extend far enough so as to sit flush with the edges of the fluid end body  302 . In alternative embodiments, the retainer element  316  may have different shapes or sizes. For example, the retainer element  316  may be large enough so as to cover an entire side surface of the fluid end body  302 . Alternatively, the retainer elements  316  may have rounded edges, as shown in  FIG.  8   . 
     Turning to  FIG.  8   , a plunger end  330  of the fluid end  300  is shown. The plurality of first bores  306  terminate at openings  332  formed on the external surface  304  of the plunger end  330 . A plurality of internally threaded openings  334  are formed in the external surface  304  that are uniformly spaced around each bore opening  332 . 
     A component  336  is positioned within each first bore  306  through each of the openings  332 . Each of the components  336  is tubular and sized to be closely received within each bore  306 . In one embodiment, the components  336  are stuffing box sleeves. The components  336  have the same shape and construction as the components  240 , shown in  FIGS.  5 - 6   . 
     Once installed within the body  302 , a top surface  346  of each of the components  336  may sit flush with the external surface  304  of the body  302 . Each of the components  336  is secured within each bore  306  by a single retainer element  348 . The retainer element  348  shown in  FIG.  8    is a large oval plate having a footprint sized to cover a plurality of adjacent bore openings  332  formed on the plunger end  330  of the fluid end body  302 . A plurality of openings  350  are formed in the retainer element  348  that are alignable with a corresponding one of the openings  334  in a one-to-one relationship. 
     In alternative embodiments, the retainer element  348  may have different shapes or sizes. For example, the retainer element  348  may be large enough so as to cover an entire side surface of the fluid end body  302 . Alternatively, the retainer element  348  may have squared edges, as shown in  FIG.  7   . 
     The retainer element  348  is secured to the external surface  304  of the fluid end body  302  by a fastening system  352 . The fastening system  352  comprises a plurality of screws  354 . The fastening system  352  secures the retainer element  348  on the fluid end body  302  in the same way as described with reference to the fastening system  260  used with the fluid end  200  and shown in  FIGS.  5 - 6   . 
     Because the retainer element  348  is attached to the fluid end body  302  using the fastening system  352 , no external threads are formed in the retainer element  348 . Likewise, no internal threads are formed within the walls of each bore  306 . 
     A central threaded opening  356  is formed in the center of each grouping of openings  350  in the retainer element  348 . The openings  356  are alignable with each bore opening  332  in a one-to-one relationship. A single packing nut  358  may thread into each central opening  356 . A seal  359  may be positioned within each packing nut  358 . 
     Similar to the plunger end  234  shown in  FIGS.  5 - 6   , a plurality of packing seals  360  may be positioned within each component  336 . Each of the packing nuts  358  may compress the packing seals  360  when installed within the retainer element  348 . A plurality of plungers  362  may be disposed within each component  336 , the retainer element  348 , and each packing nut  358 . Each of the plungers  362  may be connected to a power end via a clamp  364 . A cross-sectional view of the fluid end  300  looks identical to the cross-sectional view of the fluid end  200 , shown in  FIG.  6   . 
     Several kits are useful for assembling the fluid end  300 . A first kit comprises a plurality of the components  312  or  314 , a retainer element  316 , and the fastening system  320 . A second kit may comprise a plurality of the components  336 , a retainer element  348 , and the fastening system  352 . The second kit may further comprise a plurality of the packing seals  360 , a plurality of the packing nuts  358 , and a plurality of the plungers  362 . Each of the kits may be assembled using the fluid end body  302 . 
     With reference to  FIGS.  9  and  11   , a fourth embodiment of a fluid end  400  is shown. The fluid end  400  comprises a fluid end body  402  having a flat external surface  404  and a plurality of first and second bores  406 ,  408  formed adjacent one another therein, as shown in  FIG.  9   . Each bore of each set of paired bores  406  and  408  terminates in a corresponding opening  410  formed in the external surface  404 . A plurality of threaded openings  411  are formed in the body  402  and uniformly spaced around each opening  410 . The internal functions of the fluid end  400  are identical to those described with reference to fluid end  100 , shown in  FIG.  3   . 
     The fluid end  400  further comprises a plurality of sets of components  412  and  414 . The number of sets preferably equals the number of set of paired first and second bores  406  and  408  formed in the body  402 . The component  412  is positioned within a first bore  406 , and the component  414  is positioned within its paired second bore  408 . In one embodiment, the component  412  is a suction plug and the component  414  is a discharge plug. A seal  415  is positioned around the outer surface of each of the components  412 ,  414  to block fluid from leaking from the respective bores  406 ,  408 . 
     The components  412  and  414  have substantially the same shape and construction as the components  212  and  214  shown in  FIGS.  4  and  6   . However, in contrast to the components  212 ,  214 , each of the components  412  and  414  is joined to a single retainer element  416 . 
     The components  412 ,  414  may be welded or fastened to the center of the back surface of each retainer element  416 . Alternatively, each of the components  412  or  414  and a corresponding retainer element  416  may be machined as a single piece, as shown in  FIG.  11   . Each of the retainer elements  416  secures each of the components  412 ,  414  within the respective bores  406 ,  408 . The retainer elements  416  also prevent the components  412 ,  414  from moving longitudinally within the respective bores  406 ,  408 . 
     A plurality of openings  418  are formed about the periphery of each retainer element  416 . Each peripheral opening  418  is alignable with a corresponding one of the openings  411  in a one-to-one relationship, as shown in  FIG.  9   . 
     The retainer elements  416  are secured to the external surface  404  of the body  402  using a fastening system  420 . The fastening system  420  comprises a plurality of externally threaded studs  422 , a plurality of washers  424 , and a plurality of internally threaded nuts  426 . The fastening system  420  secures the retainer elements  416  to the fluid end body  402  in the same way as described with reference to the fastening system  222  used with the fluid end  200 . 
     Because the retainer elements  416  are attached to the fluid end body  402  using the fastening system  420 , no external threads are formed in the retainer elements  416 . Likewise, no internal threads are formed within the walls of each bore  406  and  408 . 
     Turning now to  FIGS.  10 - 11   , a plunger end  430  of the fluid end  400  is shown. The plurality of first bores  406  terminate at openings  432  formed on the external surface  404  of the plunger end  430 . A plurality of internally threaded openings  434  are formed in the external surface  404  that are uniformly spaced around each bore opening  432 . 
     A component  436  is positioned within each first bore  406  through each of the openings  432 . Each of the components  436  is tubular and sized to be closely received within each bore  406 . In one embodiment, the components  436  are stuffing box sleeves. The components  436  have substantially the same shape and construction as the components  240 , shown in  FIGS.  5 - 6   . However, in contrast to the components  240 , each of the components  436  is joined to a single retainer element  438 . 
     The components  436  may be welded or fastened to the center of the back surface of each retainer element  438 . Alternatively, each of the components  436  and a corresponding retainer element  438  may be machined as a single piece, as shown in  FIG.  11   . Each of the retainer elements  438  secures each of the components  436  within the bores  406 . The retainer elements  438  also prevent the components  436  from moving longitudinally within the bores  406 . 
     A threaded central opening  440  is formed within each retainer element  438 . A plurality of threaded openings  442  are formed about the periphery of each of the retainer elements  438  and are uniformly spaced around each central opening  440 . Each peripheral opening  442  is alignable with a corresponding one of the openings  434  in a one-to-one relationship, as shown in  FIG.  10   . 
     The retainer elements  438  are secured to the external surface  404  of the body  402  using a fastening system  444 . The fastening system  444  comprises a plurality of screws  446 . The fastening system  444  secures the retainer elements  438  to the fluid end body  402  in the same way as described with reference to the fastening system  260  used with the fluid end  200  and shown in  FIGS.  5 - 6   . 
     Because the retainer elements  438  are attached to the fluid end body  402  using the fastening system  444 , no external threads are formed in the retainer elements  416 . Likewise, no internal threads are formed within the walls of each bore  406  on the plunger end  430  of the body  402 . 
     Like the plunger end  330  of fluid end  300 , the fluid end  400  may also comprise a plurality of packing seals  448 , a plurality of packing nuts  450 , each housing a seal  454 , and a plurality of plungers  456 . Each plunger  456  may be connected to a power end via a clamp  458 . 
     Several kits are useful for assembling the fluid end  400 . A first kit comprises a plurality of the components  412  or  414 , a plurality of the retainer elements  416 , and the fastening system  420 . A second kit may comprise a plurality of the components  436 , a plurality of the retainer elements  438 , and the fastening system  444 . The second kit may further comprise a plurality of the packing seals  448 , a plurality of the packing nuts  450  and a plurality of the plungers  456 . Each of the kits may be assembled using the fluid end body  402 . 
     With reference to  FIGS.  12 - 13   , a fifth embodiment of a fluid end  500  is shown. The fluid end  500  comprises a fluid end body  502  having a flat external surface  504  and a plurality of first and second bores  506 ,  508  formed adjacent one another therein, as shown in  FIG.  12   . Each bore of each set of paired bores  506  and  508  terminates in a corresponding opening  510  formed in the external surface  504 . A plurality of threaded openings  511  are formed in the body  502  and uniformly spaced around each opening  510 . The internal functions of the fluid end  500  are identical to those described with reference to fluid end  100 , shown in  FIG.  3   . 
     The fluid end  500  further comprises a plurality of sets of components  512  and  514 . The number of sets preferably equals the number of set of paired first and second bores  506  and  508  formed in the body  502 . The component  512  is positioned within a first bore  506 , and the component  514  is positioned within its paired second bore  508 . In one embodiment, the component  512  is a suction plug and the component  514  is a discharge plug. The components  512  and  514  have the same shape and construction as the components  212  and  214  shown in  FIGS.  4  and  6   . A seal  516  is positioned around the outer surface of each component  512 ,  514  to block fluid from leaking from the bores  506 ,  508 . 
     As shown in  FIG.  12   , a top surface  513  of each of the components  512 ,  514  may sit flush with the external surface  504  of the body  502  when installed within a respective bore  506 ,  508 . Each of the components  512  and  514  may engage with internal seats (not shown) formed in the walls of each of the bores  506 ,  508 . Such engagement helps prevent longitudinal movement of the components  512 ,  514  within the respective bore  506 ,  508 . 
     Once installed within the fluid end body  502 , each component  512  and  514  is secured in place by a retainer element  518  in a one-to-one relationship. Each of the retainer elements  518  has a footprint sized to cover a single bore opening  510 . The retainer elements  518  shown in  FIG.  12    are flat and cylindrical and each have a central threaded opening  519 . A plurality of openings  520  are formed about the periphery of each retainer element  518  and are uniformly spaced around each central opening  519 . Each peripheral opening  520  is alignable with a corresponding one of the openings  511  in a one-to-one relationship, as shown in  FIG.  12   . 
     The retainer elements  518  are secured to the external surface  504  of the fluid end body  504  by a fastening system  522 . The fastening system  522  comprises a plurality of externally threaded studs  524 , a plurality of washers  526 , and a plurality of internally threaded nuts  528 . The fastening system  522  secures the retainer elements  518  to the fluid end body  502  in the same way as described with reference to the fastening system  222  used with the fluid end  200  shown in  FIGS.  4  and  6   . 
     Each central opening  519  formed in each retainer element  518  is alignable with each corresponding bore opening  510  in a one-to-one relationship. A retaining nut  530  may thread into each central opening  519  to cover each bore opening  510 . Using a threaded retaining nut  530  with the retainer element  518  allows access to each bore opening  510  without having to remove the retainer elements  518  from the fluid end body  502 . 
     While the fluid end  500  uses a threaded retaining nut  530 , the retaining nut  530  is not threaded into the walls of the bores  506 ,  508 . Thus, any failures associated with the retaining nut  530  may be experienced in the retainer element  518 , which is easily replaceable. This similar configuration is used on the plunger end  234  of the fluid end  200  shown in  FIGS.  5 - 6   . Such configuration is shown again on a plunger end  532  of the fluid end body  502  in  FIG.  13   . 
     A kit is useful for assembling the fluid end  500 . The kit may comprise a plurality of the components  512  or  514 , a plurality of the retainer elements  518 , and the fastening system  522 . The kit may further comprise a plurality of retaining nuts  530 . The kit may be assembled using the fluid end body  502 . 
     Turning now to  FIG.  14   , a sixth embodiment of a fluid end  600  is shown. The fluid end  600  comprises a fluid end body  602  having a flat external surface  604  and a plurality of first bores (not shown) and second bores  608  formed adjacent one another therein. Each bore of each set of paired bores terminates in a corresponding opening  610  formed in the external surface  604 . A plurality of threaded openings  611  are formed in the body  602  and uniformly spaced around each opening  610 . The internal functions of the fluid end  600  are identical to those described with reference to fluid end  100 , shown in  FIG.  3   . 
     The fluid end  600  further comprises a plurality of sets of components  614 . The component  614  is positioned within a second bore  608 . The components positioned within each first bore are not shown in  FIG.  14   . However, such components are identical in shape and construction to the components  614 . 
     The number of sets of components preferably equals the number of set of paired first bores (not shown) and second bores  608  formed in the body  602 . In one embodiment, the component positioned within a first bore is a suction plug, and the component  614  is positioned within its paired second bore  608  is a discharge plug. The components  614  have a substantially similar shape and construction as the components  212  and  214  shown in  FIGS.  4  and  6   , except that a threaded hole  616  is formed in a top surface  613  of each component  614 . A seal  618  is positioned around the outer surface of each component  614  to block fluid from leaking from the bores  608 . 
     The top surface  613  of each component  614  may sit flush with the external surface  604  of the body  602  when installed within a bore  608 . Each of the components  614  may engage with internal seats (not shown) formed in the walls of each of the bores  608 . This engagement helps prevent longitudinal movement of the components  614  within the bore  608 . Likewise, the components positioned within the first bores (not shown) may engage internal seats formed within the walls of the first bores. 
     Once installed within the fluid end body  602 , each component  614  is secured by a retainer element  620  in a one-to-one relationship. Likewise, the components positioned within the first bores (not shown) are each secured by one of the retainer elements  620 . Each of the retainer elements  620  has a footprint sized to cover a single bore opening  610 . The retainer elements  620  shown in  FIG.  14    are flat and cylindrical and each have a central threaded opening  622 . A plurality of openings  624  are formed about the periphery of each retainer element  620  and are uniformly spaced around each central opening  622 . Each peripheral opening  624  is alignable with a corresponding one of the openings  611  in a one-to-one relationship. 
     The retainer elements  620  are secured to the external surface  604  of the fluid end body  602  by a fastening system  626 . The fastening system  626  comprises a plurality of externally threaded studs  628 , a plurality of washers (not shown), and a plurality of internally threaded nuts  630 . The fastening system  626  secures the retainer elements  620  to the fluid end body  602  in the same way as described with reference to the fastening system  222  used with the fluid end  200  shown in  FIGS.  4  and  6   . 
     The fastening system  626  may further comprise a plurality of eye bolts  632 , a plurality of handles  634 , and a cable  636 . Each eye bolt  632  has external threads  638  formed on its first end and an eye  640  formed on its opposite second end. The threaded end  638  of each eye bolt  632  threads into each hole  616  formed in each component  614  in a one-to-one relationship. Once installed within each hole  614 , the eye  640  of each eyebolt  632  projects through the central opening  622  formed in each retainer element  620 . 
     Each of the handles  634  has a threaded section  642  joined to a cylindrical body  644 . A central passage  646  extends through the threaded section  642  and the body  644 . Each of the threaded sections  642  may be installed within the central opening  622  of each of the retainer elements  620  such that each eyebolt  632  is disposed within the central passage  646 . Once one of the handles  634  is installed in a retainer element  620 , the eye bolt  632  projects from the handle  634 . The handle  634  helps support the eye bolt  632  and provides a grip to assist in installation or removal of a retainer element  620  on the fluid end body  602 . 
     The cable  636  may be disposed through each eye  640  of each eye bolt  632 . Each of the eye bolts  632  may be oriented to facilitate the passage of the cable  636  through each eye  640 . The ends of the cable  636  may be attached to the external surface  604  of the fluid end body  602  using eye bolts  650  and clamps  652 . The cable  636  is preferably made of a stirr and tough material, such as high-strength nylon or steel. 
     In operation, the eyebolts  632  and cable  636  tether each of the retaining elements  620  and components  614 , in case of failure of the retainer elements  620 , a portion of the fastening system  626 , or the fluid end body  602 . When a failure occurs, the large pressure in the fluid end body  602  will tend to force the components  614  out of their respective bores  608  with a large amount of energy. The cable  636  helps to retain the components  614  within the bores  608  in the event of a failure. The cable  636  also helps to retain the retainer elements  620  in position in the event of a failure. The fastening systems  134 ,  222 ,  320 ,  420 , and  522  used with fluid ends  100 ,  200 ,  300 ,  400 , and  500  may also be configured for use with the eye bolts  632 , handles  634  and cable  636 . 
     In alternative embodiments, the handles  634  may not be used. A single eye bolt  632  may also be formed integral with a single component  614 . A single cable  636  may also be used through each of the eyebolts  632 . Each cable  636  would independently attach to the external surface  604  of the fluid end body  602 . 
     Several kits are useful for assembling the fluid end  600 . A first kit comprises a plurality of the components  614 , a plurality of the retainer elements  620 , and the fastening system  626 . The kit may be assembled using the fluid end body  602 . 
     With reference to  FIGS.  1 - 14   , a single fluid end body may use any combination of the kits described herein. The fluid end bodies, components, and retainer elements described herein are preferably made of high strength steel. 
     While the fluid end bodies  102 ,  202 ,  302 ,  402 , and  502  shown in  FIGS.  1 - 13    are substantially rectangular in shape, the kits described herein may also be used with any shape of a fluid end body, such as that shown in  FIG.  14   . Likewise, the retainer elements described herein may vary in shape and size, as desired. For example, the circular retainer elements described herein may be square or rectangular shaped. 
     The fastening systems  134 ,  222 ,  320 ,  420 , and  522  described herein each use eight studs around each bore opening. In alternative embodiments, more than eight studs or less than eight studs may be used to secure each retainer element over each bore opening. For example,  FIG.  14    only shows six studs securing each retainer element  620  over each bore opening  610 . Likewise, fewer than 16 or more than 16 screws may be used with the fastening systems  178 ,  260 ,  352 , and  444 . The number of peripheral openings formed in each retainer element described herein may correspond with the number of openings formed around each bore opening in each fluid end body and the number of studs or screws being used. 
     The fastening systems described herein reduce the amount of torque required to secure each retainer element to the fluid end bodies. Rather than having to torque one large retaining nut, the torque is distributed throughout the plurality of studs, nuts, or screws. Decreasing the amount of torque required to seal the bores increases the safety of the assembly process. 
     Turning to  FIG.  15   , a stud  700  is shown. The stud  700  may be used with the fastening systems  134 ,  222 ,  320 ,  420 ,  522 , and  626  shown in  FIGS.  1 ,  4 ,  7 ,  9 ,  11 , and  14   . For exemplary purposes, the stud  700  will be described with reference to fluid end  100 , shown in  FIG.  1   . 
     The stud  700  has a first threaded section  702  and an opposite second threaded section  704 . The threaded sections  702  and  704  are joined by an elongate, cylindrical body  706 . The first threaded section  702  is configured for threading into one of the plurality of threaded openings  144  formed in the fluid end body  102 . The second threaded section  704  is configured for threading into the threaded opening formed in one of the nuts  152 . 
     The first section  702  may have fewer threads than that of the opening  144 . For example, if the opening  144  has 18 internal threads, the first section  702  of the stud  700  may only have 16 external threads. This configuration ensures that all of the threads formed on the first section  702  will be engaged and loaded when the first end  702  is threaded into the opening  144 . Engaging all of the threads helps increase the fatigue life of the first end  702  of the stud  700 . Likewise, the second section  704  may have fewer external threads than there are internal threads formed in the nut  152 . The stud  700  may also be subjected to shot peening on its non-threaded sections prior to its use to help reduce the possibility of fatigue cracks. The stud  700  may have a smooth outer surface prior to performing shot peening operations. 
     The body  706  of the stud  700  comprises a first section  708  and a second section  710 . The first section  708  has a smaller diameter than the second section  710 . The retainer element  132  is primarily held on the first section  708  of the stud  700 . The diameter of the second section  710  is enlarged so that it may center the washer  150  on the stud  700 . 
     The diameter of the second section  710  is configured so that it is only slightly smaller than the diameter of the central opening of the washer  150 . This sizing allows the washer  150  to closely receive the second section  710  of the stud  700  when the washer  150  is positioned on the stud  700 . When the washer  150  is positioned on the second section  710 , the washer  150  is effectively centered on the stud  700 . The washer  150  is also effectively centered against the nut  152 , once the nut  152  is installed on the stud  700 . 
     Without placing the washer  150  on the second section  710 , the washer may have to be manually centered on the stud  700  prior to installing the nut  152 . If the washer  150  is not properly centered on the stud  700  or against the nut  152 , it may be difficult to effectively torque or un-torque the nut  152  from the stud  700 , depending on the type of washer used. 
     The plurality of washers used with each fastening system  134 ,  222 ,  320 ,  420 ,  522 , and  626  shown in  FIGS.  1 ,  4 ,  7 ,  9 ,  11 , and  14    may be configured to allow a large amount of torque to be imposed on the nuts used with the washers without using a reaction arm. Instead, the washer itself may serve as the counterforce needed to torque a nut onto a stud. Not having to use a reaction arm increases the safety of the assembly process. The nuts used with the fastening systems  134 ,  222 ,  320 ,  420 ,  522 , and  626  may also comprise a hardened inner layer to help reduce galling between the threads of the nuts and studs during the assembly process. An example of the above described washers, nuts, and methods are described in Patent Cooperation Treaty Application Serial No. PCT/US2017/020548, authored by Junkers, et al., the entirety of which is incorporated herein by reference. 
     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.