Patent Publication Number: US-11649901-B2

Title: Sealing high pressure flow devices

Description:
BACKGROUND 
     This technology relates generally to sealing fluid flow passages inside flow control devices, such as those particularly suited for use in high pressure oil and gas production and processing systems. 
     For example, a fluid end is used in many well servicing applications to contain high pressure, often corrosive and/or abrasive, fracturing fluids in the oil and gas industry. A fluid end typically has a manifold body and a number of components mounted and sealed to the body, such as the suction and discharge plugs, suction and discharge valve seats, stuffing box, discharge flange, and suction manifold; with those components either alone or sleeved as are illustratively described herein. Like the valves, operating a fluid end in the harsh oilfield conditions can cause erosion of the body resulting in leakage in a short amount of time. Repairing the body is also cumbersome and disruptive in the oilfield. 
     Improvements are needed in the internal sealing of high pressure flow devices to increase operating life while reducing downtime and operating cost. What is needed is a solution that transfers the erosion (corrosion and abrasion) from the high pressure fluid end body to the component sealed with the body. It is to those improvements that embodiments of this technology are directed as described in the illustrative embodiments and contemplated within the scope of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an isometric depiction of a fluid end known in the art. 
         FIG.  2    is an enlarged depiction of a portion of the fluid end of  FIG.  1   . 
         FIG.  3    is an exploded cross-sectional depiction of an embodiment of a fluid end. 
         FIGS.  4  and  5    are enlarged depictions of portions of the fluid end of  FIG.  3   . 
         FIG.  6    is a cross-sectional depiction of another embodiment of a fluid end. 
         FIG.  7    is an enlarged depiction of a portion of the fluid end of  FIG.  6   . 
         FIG.  8    is cross-sectional depiction of another embodiment of a fluid end. Another embodiment of a stuffing box sleeve is shown installed within the fluid end. 
         FIG.  9    is the cross-sectional view of  FIG.  3    with the components shown installed within the fluid end. A plunger and a plurality of packing seals are also shown installed within the fluid end. 
         FIG.  10    is a front perspective view of another embodiment of a fluid end. 
         FIG.  11    is a front elevational view of the fluid end shown in  FIG.  10   . 
         FIG.  12    is a cross-sectional view of the fluid end shown in  FIG.  11   , taken along line A-A. 
         FIG.  13    an enlarged view of area A from  FIG.  12   . 
         FIG.  14    is an enlarged view of area B from  FIG.  12   . 
         FIG.  15    is a cross-sectional view of another embodiment of a fluid end. 
         FIG.  16    is an enlarged view of area C from  FIG.  15   . 
         FIG.  17    is a front perspective view of another embodiment of a fluid end. 
         FIG.  18    is a rear perspective view of the fluid end shown in  FIG.  17   . 
         FIG.  19    is a cross-sectional view of the fluid end shown in  FIGS.  17  and  18   , taken along line B-B. 
         FIG.  20    is a front perspective view of another embodiment of a sleeve. The sleeve is shown installed within the fluid end shown in  FIG.  19   . 
         FIG.  21    is front elevational view of the sleeve shown in  FIG.  20   . 
         FIG.  22    is a cross-sectional view of the sleeve shown in  FIG.  21   , taken along line C-C. 
     
    
    
     DETAILED DESCRIPTION 
     Initially, this disclosure is by way of example only, not by limitation. The illustrative constructions and associated methods disclosed herein are not limited to use or application for sealing any specific assembly or in any specific environment. That is, the disclosed technology is not limited to use in sealing fluid ends as described in the illustrative embodiments. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, the skilled artisan understands that the principles herein may be applied equally in sealing other types of high pressure flow devices. 
       FIG.  1    is a simplified isometric cross-sectional depiction of a hydraulic fracturing fluid end  200  that is constructed in accordance with previously attempted solutions. The fluid end  200  comprises a housing or fluid end body  201 , which is generally a manifold used to deliver highly-pressurized corrosive and/or abrasive fluids, typically used in hydraulic fracturing processes in the oil and gas industry. Fluid may pass through the fluid end  200  at pressures that range from 5,000-15,000 pounds per square inch (psi). Fluid ends  200  used in high pressure hydraulic fracturing operations typically move fluid at a minimum of 8,000 psi. However, normally, the fluid end  200  will move fluid at pressures around 10,000-15,000 psi. 
     The fluid end body  201  typically has a first conduit  220  and a second conduit  221  formed within the body  201  that intersect to form an internal chamber  222 . The first conduit  220  is typically orthogonal to the second conduit  221 . The first conduit  220  may have aligned first and second sections  223  and  224  that are situated on opposite sides of the internal chamber  222 . The first section  223  may be referred to as a discharge bore, and the second section  224  may be referred to as an intake bore. Likewise, the second conduit  221  may have aligned third and fourth sections  225  and  226  that are situated on opposite sides of the internal chamber  222 . The third section  225  may be referred to as a plunger bore, and the fourth section  226  may be referred to as a suction bore. The sections  223 ,  224 ,  225 , and  226  each may independently interconnect the internal chamber  222  to an external surface  227  of the fluid end  200 . 
     A plunger  228  reciprocates within the fluid end body  201  to increase the pressure of fluid being discharged from the fluid end  200 . As shown in  FIG.  1   , the plunger  228  may be disposed within the third section  225  of the second conduit  221 . The plunger  228  is disposed within a plunger packing  213 . The plunger packing  213  comprises a plurality of packing seals  219 . The plunger  228  is powered by an engine operatively engaged with the fluid end  200 . In high pressure hydraulic fracturing operations, the engine preferably has a power output of at least 2,250 horsepower. 
     Valve seats  229  are also shown supported within the first conduit  220 . The valve seats  229  may support valves, such as a ball valve, used to control the movement of high pressure fluid within the body  201 . 
     There are sealing areas in the fluid end  200  that experience erosion during operation. For example, a number of components seal to the fluid end body  201 . As discussed above, the sacrificial member for erosion is the fluid end body  201  instead of the less complex and less expensive mating component. 
     For example, the fluid end body  201  defines a discharge opening  202  that opens into the discharge bore  223 . The discharge opening  202  depicted in these embodiments is sealed closed by inserting a closure or discharge plug or cover  204  into the discharge bore  223  and securing it by advancing a threaded retaining nut  206  into the body  201 . The retaining nut  206  may also be referred to as a retainer. The discharge plug  204  supports a seal  208  that seals against the walls of the fluid end body  201  defining the discharge bore  223 .  FIG.  2    is a simplified cross-sectional depiction of the discharge plug  204  that has a groove  207  into which the seal  208  is mounted. 
     In these illustrative embodiments the groove  207  is rectangular but the contemplated embodiments are not so limited. The skilled artisan understands that the configuration of the groove  207  is largely determined by what shape is required to mount the type of seal selected. The groove  207  intersects an outer surface  215  of the discharge plug  204 , permitting the seal  208  to be sized so that a portion not mounted within the groove  207  extends beyond the outer surface  215  to pressingly engage against the walls of the fluid end body  201  defining the discharge bore  223 . In this construction the highly-pressurized corrosive and/or abrasive fluid can be injected between the seal  208  and walls defining the discharge bore  223 , causing erosion of the seal surface formed by the walls defining the discharge bore  223 . 
     Fluid end bodies have conventionally been made of heat-treated carbon steel, so it was not uncommon for the fluid end body  201  to crack before any sacrificial erosion of the body progressed to the point of creating leakage between the discharge plug  204  and the discharge bore  223 . However, progress in the technology has introduced stainless steel body construction resulting in a significantly longer operating life. As a result, this erosion is no longer negligible but is instead a consideration for reducing erosion in modern fluid end construction. One leading source of discharge bore  223  erosion in conventional fluid ends is the seal  208  mounted in the discharge plug  204  and extending therefrom to seal against a sealing surface formed by the fluid end body  201 . The technology disclosed herein is configured to transfer that erosion wear from the fluid end body  201  to the less complex and less expensive discharge plug  204 . 
       FIG.  3    is an exploded cross-sectional depiction of a fluid end  230  having a housing or fluid end body  232 . The fluid end  230  is constructed in accordance with the technology disclosed herein to, in numerous places, transfer the erosion wear from the body to the less complex and less expensive component that is sealed to the body. The fluid end body  232  forms a number of interconnected bores or conduits, including a first conduit  300 . The first conduit  300  comprises a discharge bore  234  and an intake bore  302  positioned on opposite sides of an internal chamber  304 . The discharge bore  234  defines a discharge opening  235  that is similar to the discharge opening  202  in the conventional fluid end  200  depicted in  FIG.  1   . Likewise, the intake bore  302  defines an intake opening  231  formed opposite the discharge opening  235 . The first conduit  300  forms multi-dimensional diameters at different longitudinal locations between the discharge opening  235  and the intake opening  231 . 
     The discharge opening  235  is sealed closed by inserting a closure or discharge plug  236  into the discharge opening  235  and securing it in place by advancing a threaded retaining nut  238 , as shown in  FIG.  9   . Unlike the conventional discharge plug  204  in  FIG.  1   , the discharge plug  236  does not have a seal mounted to it that seals against the walls surrounding the discharge bore  234 . Instead, the discharge plug  236  defines a sealing surface  237  for a seal  242 , shown in  FIG.  4   . The sealing surface  237  is axially spaced between a first surface  251  and an opposite second surface  253  of the plug  236 . The seal  242  is mounted in an endless groove or recess  240  formed in the walls of the fluid end body  232  surrounding the discharge bore  234 , as shown in  FIGS.  3  and  4   . 
       FIG.  4    is a simplified cross-sectional enlargement depicting the construction of the seal  242  positioned within the groove  240  formed in the fluid end body  232 . The groove  240  opens into the discharge bore  234 . The seal  242  in these illustrative embodiments is mounted in the groove  240  to include an outer radial surface, and is thereby supported by the fluid end body  232 . The groove  240  is characterized by a pair of parallel sidewalls  306  joined by a base  308 . The groove  240  opens towards a centerline of the conduit within which it is formed. Alternatively, as shown by groove  266  in  FIGS.  6  and  7   , the groove may open in a direction parallel to a centerline of the conduit within which it is formed. As above, the rectangular shape of the groove  240  is merely illustrative and not limiting of the contemplated embodiments. Any shape necessary to properly mount a desired seal is contemplated, whether the seal is elastomeric, spring, metal, and the like. The groove  240  intersects the discharge bore  234  permitting the seal  242  to be sized so that a portion of the seal  242  not contained in the groove  240  extends beyond the groove  240  and beyond the bore  234  to pressingly seal against the sealing surface  237  defined by the discharge plug  236 , as shown in  FIG.  4   . 
     The seal construction depicted in  FIG.  4    transfers the erosion wear from the fluid end body  232  to the discharge plug  236 . Such transfer of erosion significantly improves fluid end operations because repairs involving the discharge plug  236  are significantly less complex and less expensive than repairs involving the fluid end body  232 , which typically involve weld-repair. Furthermore, weld-repairing the fluid end body  232  makes it susceptible to premature fatigue cracking in the repaired area. Further, even more operating life can be achieved by applying an erosion-resistant surface treatment to the discharge plug  236 , such as a high velocity oxygen fuel (HVOF) treatment, a tungsten carbide coating, material carburizing, and the like. Replacing instead of repairing an eroded discharge plug  236  is typically feasible, making it advantageously possible to repair a leaking valve constructed according to this technology in the field and thereby significantly reducing down time. 
     Returning to  FIG.  3   , another endless groove or recess  241  is formed in the fluid end body  232 . The groove  241  intersects the discharge bore  234  and is configured to mount a seal (not depicted) that extends from the groove  241  to seal against a sealing surface formed by a discharge valve seat, like the valve seat  229  shown in  FIG.  1   . Similarly, another endless groove or recess  243  is formed in the fluid end body  232 . The groove  243  intersects the intake bore  302  and is configured to mount a seal (not depicted) that extends from the groove  243  to seal against a sealing surface formed by a suction valve seat, like the valve seat  229  shown in  FIG.  1   . The grooves  241  and  243  may be shaped identically to the groove  240 . 
     Continuing with  FIG.  3   , the fluid end body  232  includes a second conduit  310 . The second conduit  310  includes a plunger bore  252  and a suction bore  247  positioned on opposite sides of the internal chamber  304 . The suction bore  247  is sealed closed by inserting a closure or suction plug or cover  244  defining a sealing surface  245  and securing it in place by advancing a threaded retaining nut  246  within the body  232 , as shown in  FIG.  9   . Like the discharge plug  236 , the sealing surface  245  is axially spaced between a first surface  255  and an opposite second surface  261  of the suction plug  244 . An endless groove or recess  248  is formed in the walls of the fluid end body  232  defining the suction bore  247 . The groove  248  may be construed identically to the groove  240 . The groove  248  is configured for mounting a seal, like the seal  242  shown in  FIG.  4   . The seal may extend from the groove  248  and seal against the sealing surface  245  of the suction plug  244 . Such positioning transfers the wear from the fluid end body  232  to the suction plug  244  in comparison to previously attempted solutions and in accordance with the embodiments of this technology. 
     Continuing with  FIG.  3   , the plunger bore  252  defines a plunger opening  250 . The plunger bore  252  is sized to closely receive a stuffing box sleeve  254  that is sealed in place by advancing a threaded retaining nut  256 , as shown in  FIG.  9   . Because the sleeve  254  is secured within the fluid end body  232  by a retaining nut  256 , no threads are formed in the sleeve  254  for mating with the fluid end body  232  or other component. Specifically, no threads are formed in an outer surface of the sleeve  254  along a length of the sleeve  254 . 
     The plunger bore  252  includes a first segment  312  and a second segment  314 . The first segment  312  is positioned closer to the internal chamber  304  and the suction bore  247  than the second segment  314 . The second segment  314  has a greater diameter than the first segment  312 . Threads may be formed in the walls of the fluid end body  232  surrounding at least a portion of the second segment  314 . The threads may mate with threads formed on the retaining nut  256 . An endless groove or recess  257  is formed in the walls of the fluid end body  232  surrounding the first segment  312 . The groove  257  is configured to house a seal  260 , as shown in  FIG.  5   . The groove  257  may be identical to the groove  240 . Likewise, the seal  260  may be identical to the seal  242 . 
     Continuing with  FIG.  3   , the stuffing box sleeve  254  is characterized by a tubular sleeve. The sleeve  254  comprises a first portion  316  joined to a second portion  318 . The first and second portions  316  and  318  each have a cylindrical shape, such that the sleeve  254  may be considered primarily cylindrical. The first portion  316  has an outer diameter, D 1 . The second portion  318  has an outer diameter, D 2 . The diameter D 2  is greater than the diameter D 1 . The diameter D 2  is also greater than a maximum diameter of the groove  257 . The sleeve  254  is installed within the plunger bore  252  such that the first portion  316  is closely received within the first segment  310  and the second portion  318  is closely received within the second segment  314 , as shown in  FIG.  9   . The difference between the diameters D 1  and D 2  and the diameters of the plunger bore  252  prevent further movement of the sleeve  254  into the fluid end body  232 , as shown in  FIG.  9   . 
     Continuing with  FIGS.  3  and  9   , the diameter D 1  is constant along at least a portion of the length of the first portion  316  of the sleeve  254 . The diameter D 1  may be constant along the entire length of the first portion  316 , with the exception of a tapered surface  319  between the first portion  316  and a first surface  322  of the sleeve  254 . No grooves are formed in the outer surface of the first portion  316  for housing a seal. Rather, the outer surface of the first portion  316  has a sealing surface  259  for the seal  260 , as shown in  FIG.  5   . 
     The diameter D 2  is constant along at least a portion of the length of the second portion  318 . The diameter D 2  may be constant along the entire length of the second portion  318 , with the exception of one or more grooves formed in the outer surface of the second portion  318  for housing a seal or receiving lubrication. The area of the outer surface of the sleeve  254  having the one or more grooves may be referred to as a third portion of the sleeve  254 . An inner diameter of the third portion may be the same as the inner diameter of the second portion  318 . 
       FIG.  5    is a simplified cross-sectional depiction of the body  232  having the groove  257 . Again, the groove  257  intersects the plunger bore  252  permitting a portion including an outer radial surface of a radial seal  260  to be mounted in the groove  257 . Another portion of the seal  260  not mounted in the groove  257  extends from the groove  257  to pressingly seal against the sealing surface  259  of the sleeve  254 . Although in these depicted embodiments a radial seal is used, the contemplated embodiments are not so limited. The skilled artisan readily understands that other types of seals could be used instead of or in addition to the radial seal depicted, such as axial seals, crush seals, and the like. 
     Turning back to  FIGS.  3  and  9   , the first and second portions  316  and  318  of the sleeve  254  define a central passage  320 . The central passage  320  interconnects a first and second outer surface  322  and  324  of the sleeve  254 . The first outer surface  322  may be joined to the first portion  316  of the sleeve  254 . The first outer surface  322  may be joined to the outer surface of the first portion  316  via the tapered surface  319 . The second outer surface  324  may be joined the second portion  318  or the third portion of the sleeve  254 . The retaining nut  256  may engage the second surface  324  of the sleeve  254 , as shown in  FIG.  9   . 
     Continuing with  FIG.  3   , the first portion  316  has an inner diameter, D 3 . The second portion  318  has an inner diameter, D 4 . The diameter D 4  is greater than the diameter D 3 . The diameter D 3  may be constant along the length of the first portion  316 , and the diameter D 4  may be constant along the length of the second portion  318 , and if included, the third portion. An inner surface of the second portion  318  may transition to an inner surface of the first portion  316  at a right angle, such that an internal seat  326  is formed within the second portion  318 . The transition between the inner surface of the second portion  318  and the inner surface of the first portion  316  may be referred to as a first transition. 
     Similarly, an outer surface of the first portion  316  is joined to an outer surface of the second portion  318  at a right angle. In alternative embodiments, the first portion may be joined to the second portion by a tapered portion, as shown for example in  FIG.  8   . The transition between the outer surface of the first portion  316  and the outer surface of the second portion  318  may be referred to as a second transition. The first and second transitions may also be referred to as a fourth portion of the sleeve  254 . 
     Continuing with  FIG.  9   , the plunger packing  213 , including the plurality of packing seals  219 , is installed within the second portion  318  of the sleeve  254  such that the plunger packing  213  abuts the internal seat  326 . No portion of the plunger packing  213  is installed within the first portion  316  of the sleeve  254 , as shown in  FIG.  9   . A portion of the plunger packing  213  may also be installed within the third portion of the sleeve  254 . The plunger  228  is disposed within at least a portion of the sleeve  254  and the plunger packing  213 . 
       FIG.  6    depicts another embodiment of a fluid end  330  comprising a fluid end body  332 . A number of additional endless grooves or recesses are formed in the fluid end body  332  for mounting various seals to transfer the wear away from the body  332  to the mating component in accordance with embodiments of this technology. For example, a groove  266  is formed in the fluid end body  332  intersecting a discharge bore  334 . Consistent with this whole description, the groove  266  permits mounting an axial seal  268 , shown in  FIG.  7   . The seal  268  is configured to extend from the groove  266  to seal against a leading face of a discharge plug, like the discharge plug  236  shown in  FIG.  3   .  FIG.  7    is a simplified enlarged depiction of the fluid end body  332  having the groove  266  into which the axial seal  268  is mounted. In these illustrative embodiments the seal  268  is configured to extend beyond the walls defining the discharge bore  334  to seal against a discharge plug  236  as it is urged downward by advancing a retaining nut, like the retaining nut  238 , shown in  FIG.  3   . 
     Importantly, the simplified seal construction depicted in  FIG.  7    and elsewhere is in no way limiting of the contemplated embodiments and scope of the claimed technology. In alternative embodiments a radial seal or a crush seal and the like can be employed to transfer the erosion wear from the fluid end body  232  or  332  to the mating component. A crush seal refers to a seal construction that acts at least to some degree both axially and radially. For example, a groove  272  having only two walls is shown in  FIG.  6   . The walls of the groove  272  extend concentrically around a plunger bore  336 . A stuffing box sleeve may be formed to have side walls that fully overlies the groove  272  when it is positioned in the plunger bore  336 , as shown for example in  FIG.  15   . This allows the seal to act as a crush seal because it seals axially and radially against the installed sleeve. 
     Returning to  FIG.  6   , the fluid end body  332  may have other surfaces forming endless grooves or recesses for mounting various other seals. For example, a groove  270  is formed in a suction bore  338  for mounting a seal that is configured to seal against a sealing surface of a suction plug, like the suction plug  244  shown in  FIG.  3   . In the same way the fluid end body  332  can have grooves  274  and  276  for mounting seals that are configured to seal against sealing surfaces of a discharge valve seat and a suction valve seat, respectively. Likewise, the fluid end body  332  can have a groove  278  for mounting a seal that is configured to seal against a suction manifold (not depicted). What&#39;s common in any event is the seal construction of this technology transfers the seal wear from the fluid end body  332  to the less complex and less expensive mating component that is attached to the fluid end body  332 . 
       FIG.  8    depicts another embodiment of a fluid end  340  having a fluid end body  342 . The fluid end  340  is generally identical to the fluid end  330 , but includes another embodiment of a plunger bore  344 . The plunger bore  344  is similar to the plunger bore  252 , but is sized to receive another embodiment of a stuffing box sleeve  346 . The stuffing box sleeve  346  is identical to the stuffing box sleeve  254  with a few exceptions. 
     The stuffing box sleeve  346  comprises a first portion  348  joined to a second portion  350  by a tapered portion  352 . The first portion  348  is installed within a first segment  354  of the plunger bore  344  and the second portion  350  is installed within a second segment  356  of the plunger bore  344 . A groove  358  is formed in the walls of the fluid end body  342  surrounding the first segment  354 . The groove  358  may be identical to the groove  257 . A seal  360  is shown installed within the groove  358  and engaging an outer sealing surface of the first portion  348 . A seal  362  may also be installed within a groove  364  formed in an outer surface of the second portion  350  of the sleeve  346 . Such area of the sleeve  346  may be referred to as a third portion of the sleeve  346 . 
     As the stuffing box sleeve  346  is inserted into the plunger bore  344 , air pressure forms in a space defined in the clearance gap between the outer diameter of the stuffing box sleeve  346  and the walls of the fluid end body  342  defining the plunger bore  344  and between the seal  360  and the seal  362  at the opposing end of the stuffing box sleeve  346 . The air pressure exerts a force urging the stuffing box sleeve  346  out of the plunger bore  344 , complicating manufacture and degrading the seal integrity at the lower end of the stuffing box sleeve  346 . A breather opening  284  can be formed between that space and ambient space above the stuffing box sleeve  346  to vent the air pressure. 
       FIG.  8    also depicts a conventional construction of the seal  362  that is mounted in the groove  364  formed by the stuffing box sleeve  346  and extends from that groove  364  to seal against the walls of the fluid end body  342  defining the plunger bore  344 . The contemplated embodiments can include combinations of the conventional construction and the construction of this technology where other matters come into play. 
       FIG.  8    also depicts employing the open-cylinder-shaped stuffing box sleeve  346  and securing it in place by advancing a retaining nut, like the retaining nut  256  shown in  FIG.  3   . That construction is illustrative and in no way limiting of the contemplated technology. 
     Other configurations can be employed as well. For example, the skilled artisan understands that a conventional stuffing box can be employed that combines a stuffing box sleeve and a retaining nut, unitarily, into one component. In other conventional constructions, a stuffing box may be used in combination with a seal carrier insert that mates with the stuffing box and provides the groove for mounting the seal. In yet other contemplated embodiments, a stuffing box sleeve can be modified to a construction combining a substantially cylindrical-shaped stuffing box to which is mated a seal surface insert that provides the sealing surface. 
     Returning momentarily to  FIGS.  3  and  9   , the sleeve  254  also protects the walls of the fluid end body  232  surrounding the plunger bore  252  from erosion by providing an inner surface against which the plunger packing  213  seals. That, again, by design transfers the wear from the fluid end body  232  to the less complex and less expensive sleeve  254 . 
     With reference to  FIGS.  10 - 14   , another embodiment of a fluid end  400  is shown. The fluid end  400  comprises a fluid end body  402  releasably attached to a connect plate  404 . The fluid end  400  is constructed similar to those embodiments described in United States Patent Publication No. 2019/0178243, in the name of Nowell et al., the entire contents of which are incorporated herein by reference. The fluid end body  402  and attached connect plate  404  may be referred to herein as the fluid end body or housing  406 . 
     With reference to  FIG.  12   , a first conduit  408  and a second conduit  410  are formed in the housing  406 . The conduits  408  and  410  intersect to form an internal chamber  412 . As shown in  FIGS.  10  and  11   , a plurality of the first and second conduits  408  and  410  are formed in the fluid end  400  and positioned in a side-by-side relationship. The first conduit  408  includes a discharge bore  414  and an intake bore  416  positioned on opposite sides of the internal chamber  412 . The second conduit  410  includes a plunger bore  418  and a suction bore  420  positioned on opposite sides of the internal chamber  412 . 
     Continuing with  FIG.  12   , a discharge plug  422  is installed within the discharge bore  414  and a suction plug  424  is installed within the suction bore  420 . The plugs  422  and  424  are retained within the housing  406  using a plurality of retainers  426 . Each retainer  426  is secured to the housing  406  using a fastening system  428 , like that described in United States Patent Publication No. 2020/0300240, authored by Nowell et al., the entire contents of which are incorporated herein by reference. 
     Like the discharge and suction plugs  236  and  244  shown in  FIG.  3   , no grooves are formed in the outer surface of the plugs  422  and  424  for housing a seal. Instead, an endless groove  430  is formed in the walls of the housing  406  surrounding the discharge bore  414  for housing a seal  432 . Likewise, an endless groove  434  is formed in the walls of the housing  406  surrounding the suction bore  420  for housing a seal  436 . During operation, the seals  432  and  436  engage an outer sealing surface of the plugs  422  and  424 . Over time, the seals  432  and  436  wear against the outer sealing surface of the plugs  422  and  424 . If the outer surface of the plugs  422  and  424  begins to erode, the plugs  422  and  424  may be removed and replaced with a new plug. 
     Turning to  FIG.  14   , the groove  434  is characterized by two side walls  440  joined by a base  442 . The groove  240 , shown in  FIG.  4   , has two side walls  306  joined to the base  308  at a right angle or with small radius corners. For example, the radius corners may be approximately 0.015 inches. In contrast, the groove  434 , shown in  FIG.  14   , has side walls  440  joined to the base  442  via much larger radius corners  444 . The radius is approximately 0.150 inches. The larger radius corners  444  make the groove  434  have a rounded cross-sectional shape. In operation, the larger radius corners  444  help relieve stress in the walls surrounding the groove  434 , helping to increase the life of the fluid end  400 . In alternative embodiments, the radius corners may be even larger in size, such that the groove has the shape of a half circle. In further alternative embodiments, the walls forming the groove may have multiple sections with different radii. 
     Continuing with  FIG.  12   , a stuffing box sleeve  446  is installed within the plunger bore  418 . The stuffing box sleeve  446  is generally identical to the stuffing box sleeve  254 , shown in  FIG.  3   , with a few exceptions. The sleeve  446  comprises a first portion  448  joined to a second portion  450 . The first and second portions  448  and  450  each have a cylindrical shape, such that the sleeve  446  may be considered primarily cylindrical. The first portion  448  has an outer diameter, D 1 . The second portion  450  has an outer diameter, D 2 . The diameter D 2  is greater than the diameter D 1 . The diameter D 2  is also greater than a maximum diameter of a groove  452  formed in the walls surrounding the plunger bore  418 . The sleeve  446  is installed within the plunger bore  418  such that the first portion  448  is installed within a first segment  454  of the plunger bore  418  and the second portion  450  is installed within a second segment  456  of the plunger bore  418 . The difference between the diameters D 1  and D 2  and the diameters of the plunger bore  418  prevent further movement of the sleeve  446  into the housing  406 . 
     Continuing with  FIG.  12   , the diameter D 1  is constant along at least a portion of the length of the first portion  448  of the sleeve  446 . The diameter D 1  may be constant along the entire length of the first portion  448 , with the exception of a tapered surface  472 , shown in  FIG.  13   . No grooves are formed in the outer surface of the first portion  448  for housing a seal. Rather, the outer surface of the first portion  448  serves as a sealing surface for a seal  458 , as shown in  FIG.  13   . 
     The diameter D 2  is constant along at least a portion of the length of the second portion  450 . The diameter D 2  may be constant along the entire length of the second portion  450 , with the exception of one or more grooves formed in the outer surface of the second portion  450  for housing a seal or for providing space for lubrication to be delivered to the interior of the housing  406 . The outer surface of the sleeve  446  having the one or more grooves may be referred to as a third portion of the sleeve  446 . An inner diameter of the third portion may be the same as the inner diameter of the second portion  450 , with the exception of one or more lubrication holes. 
     The second portion  450  may further comprise one or more passages  451  interconnecting the inner and outer surfaces of the second portion  450 , as shown in  FIG.  12   . The one or more passages  451  are in fluid communication with a lube port  453  formed in the housing  406 . During operation, lubrication is delivered to the interior of the sleeve  446  via the lube port  453  and the one or more passages  451 . 
     The first and second portions  448  and  450  of the sleeve  446  define a central passage. The central passage interconnects a first and second outer surface  460  and  462  of the sleeve  446 . The first outer surface  460  may be joined to the first portion  448  of the sleeve  446 . The first surface  460  may join the outer surface of the first portion  448  via the tapered surface  472 , shown in  FIG.  13   . The second outer surface  462  may be joined the second portion  450  or the third portion of the sleeve  446 . A retainer  464  may engage the second surface  462  of the sleeve  446  and secure the sleeve  446  within the plunger bore  418 . The retainer  464  shown in  FIG.  12    is secured to the housing  406  using a fastening system, like that shown in United States Patent Publication No. 2020/0300240, authored by Nowell et al. In alternative embodiments, the retainer  464  may thread into the walls of the housing  406 . 
     Continuing with  FIG.  12   , the first portion  448  has an inner diameter, D 3 . The second portion  450  has an inner diameter, D 4 . The diameter D 4  is greater than the diameter D 3 . An inner surface of the second portion  450  may transition to an inner surface of the first portion  448  at a right angle, such that an internal seat  466  is formed within the second portion  450 . The transition between the inner surface of the second portion  450  and the inner surface of the first portion  448  may be referred to as a first transition. 
     Turning to  FIG.  13   , the inner surface of the first portion  448  may have a slightly convex portion  468  joined to a straight portion  470 . The convex portion  468  may extend between the internal seat  466  and the straight portion  470 . Because the first portion  448  includes the convex portion  468 , the first portion  448  may also have an inner diameter, D 5 . The diameter D 3  is greater than the diameter D 5 . The convex portion  468  helps increase the wall thickness of the first portion  448 , which helps alleviate stress within the sleeve  446  during operation. In alternative embodiments, the inner surface of the first portion  448  may be shaped like the sleeve  254  shown in  FIG.  3   . The outer surface of the first portion  448  may also include the tapered surface  472  adjacent the first surface  460 . 
     Continuing with  FIG.  12   , an outer surface of the first portion  448  is joined to an outer surface of the second portion  450  at a right angle. In alternative embodiments, the first portion may be joined to the second portion by a tapered portion, as shown for example in  FIG.  8   . The transition between the outer surface of the first portion  448  and the outer surface of the second portion  450  may be referred to as a second transition. The first and second transitions may also be referred to as a fourth portion of the sleeve  446 . 
     Continuing with  FIGS.  12  and  13   , the groove  452  is formed in the walls surrounding the first segment  454  of the plunger bore  418 . The groove  452  is identical to the groove  434 . In alternative embodiments, the grooves  434  and  452  formed in the fluid end  400  may be shaped like any one of the other grooves described herein. 
     Turning to  FIGS.  15  and  16   , another embodiment of a fluid end  500  is shown. The fluid end  500  is identical to the fluid end  400 , with the exception of its plunger bore  502 . A groove  504  formed in the walls surrounding a first segment  506  of the plunger bore  502  only has two side walls  508  and  510 , as shown in  FIG.  16   . The side walls  508  and  510  may intersect at a right angle or a radius corner. 
     Another embodiment of a stuffing box sleeve  512  is shown installed within the plunger bore  502 . The sleeve  512  is identical to the sleeve  446 , but may have a shorter first portion  514  and a longer second portion  516 . When the sleeve  512  is installed within the plunger bore  502 , a base  518  of the second portion  516  forms a third wall of the groove  504 . A seal  520  installed within the groove  504  may be identical to the seal  454 , shown in  FIG.  13   . During operation, the seal  520  wears against an outer sealing surface of the first portion  514  of the sleeve  512 . 
     Turning to  FIGS.  17 - 22   , another embodiment of a fluid end  600  is shown. The fluid end  600  comprises a housing  602  having an external surface  604  and internal chamber  606 , as shown in  FIG.  19   . The housing  602  is shaped similar to that shown in  FIG.  1   , in that it is of single-piece construction and includes a flanged portion  608 . The flanged portion  608  is configured to receive a plurality of stay rods used to attach the fluid end  600  to a power end. First and second intersecting conduits  610  and  612  are formed in the housing  602 . The first conduit  610  has first and second sections  614  and  616 , each of which independently interconnects the internal chamber  606  and the external surface  604  of the housing  602 . The second conduit  612  has third and fourth sections  618  and  62 o, each of which independently interconnects the internal chamber  606  and the external surface  604 . 
     Continuing with  FIGS.  19 - 22   , the fluid end  600  uses another embodiment of a sleeve  622 . The sleeve  622  is of single-piece construction and comprises opposed first and second surfaces  624  and  626  joined by an outer intermediate surface  628 . In contrast to the other sleeve embodiments disclosed herein, the outer intermediate surface  628  of the sleeve  622  has a constant outer diameter along the entire length of the sleeve  622 . 
     The sleeve  622  defines a central passage  63 o and has an internal shoulder  632  formed therein. The internal shoulder  632  is positioned closer to the first surface  624  than the second surface  626  of the sleeve  622 . A plunger packing  634  is installed within the sleeve  622  through the second surface  626  until it abuts the internal shoulder  632 . The plunger packing  634  comprises a plurality of packing seals  635 . 
     Similar to the other sleeve embodiments disclosed herein, no grooves are formed in the outer intermediate surface  628  of the sleeve  622  for housing a seal. Likewise, no threads are formed in the outer intermediate surface  628  for engaging the housing  602  or another component. The sleeve  622  may be made of steel, and not be coated with any abrasive material. If the sleeve  622  begins to erode over time, the sleeve  622  may be removed and replaced with a new sleeve. 
     Continuing with  FIG.  19   , an endless groove  636  is formed within the walls of the housing  602  surrounding the third section  618 . The groove  636  is positioned closer to the internal chamber  606  than the external surface  604  of the housing  602  and may be shaped like any of the endless grooves disclosed herein. An annular seal  638  is installed within the groove  636 . When the sleeve  622  is installed within the third section  618 , the seal  638  engages the outer intermediate surface  628  of the sleeve  622 . Over time, the seal  638  wears against the intermediate surface  628  of the sleeve  622 . If the sleeve  622  begins to erode, it can be removed and replaced with a new sleeve. 
     The housing  602  further comprises an internal shoulder  640  formed within the third section  618  between the groove  636  and the internal chamber  606 . Axial movement of the sleeve  622  within the third section  618  is prevented by engagement of the first surface  624  of the sleeve  622  with the internal shoulder  640 . When installed within the third section  618 , no portion of the sleeve  622  projects from the external surface  604  of the housing  602 . 
     The sleeve  622  is held within the third section  618  by a retainer  650 . The retainer  650  has a threaded outer surface  652  and defines a threaded central opening  654 . The threaded outer surface  652  mates with internal threads  656  formed in the walls of the housing  602 . When the retainer  650  is installed within the housing  602  a first surface  658  of the retainer  650  abuts the second surface  626  of the sleeve  622 , but the retainer  650  does not engage the plunger packing  634 . 
     Continuing with  FIG.  19   , a packing nut  660  having a threaded outer surface  662  is installed within the retainer  650 . The threaded outer surface  662  of the packing nut  660  mates with the threaded central opening  654  of the retainer  650 . The packing nut  660  is turned within the retainer  650  until a first surface  664  of the packing nut  660  engages and compresses the plunger packing  634 . A reciprocating plunger  670  is disposed within the packing nut  660 , retainer  650 , plunger packing  634 , and the sleeve  622 . 
     In alternative embodiments, the housing  602  may be configured to use one of the other embodiments of retainers disclosed herein. The other components installed within the housing  602  and shown in  FIG.  19    are similar to those disclosed herein. 
     In alternative embodiments, the sleeve may have different shapes and sizes but still function to form a second sidewall of the groove. In further alternative embodiments, the suction and discharge plugs may be configured to form one of the sidewalls of a two-walled groove formed in the housing. 
     Summarizing, this technology contemplates a high pressure fluid flow apparatus constructed of a body defining a flow passage, a closure mounted to the body, and a means for sealing between the body and the closure. For purposes of this description and meaning of the claims the term “closure” means a component that is attached or otherwise joined to the body to provide a high-pressure fluid seal between the body and the closure. In some embodiments such as the described fluid end embodiments “closure” encompasses nonmoving components joined to the body to seal an opening such as but not limited to the discharge plug, suction plug, discharge valve seat, suction valve seat, stuffing box sleeve, discharge flange, suction manifold, and the like. The term “means for sealing” means the described structures and structural equivalents thereof that mount a seal to a body instead of a mating closure to transfer the wear in comparison to previously attempted solutions from the body to the closure. “Means for sealing” expressly does not encompass previously attempted solutions that mount a seal to the closure to extend therefrom and seal against the body. 
     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.