SEMI-LINEAR FLUID END FOR PUMPS

Abstract

A pump including a fluid end having a housing and at least one plunger that reciprocates along a cylinder bore includes a discharge valve received along the cylinder bore and positioned in-line with the plunger and a suction valve in communication with the cylinder bore. The cylinder bore is accessible through a front access port formed in the housing and is configured to enable removal of the plunger and valves from the front side of the cylinder bore through the front access port. A cover assembly can be positioned within or over the front access port to enclose and seal the front access port.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of U.S. Provisional Application No. 63/758,455, filed Feb. 14, 2025, titled “SEMI-LINEAR FLUID END FOR PUMPS,” the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to pumping systems, assemblies, apparatuses, and methods, and more particularly, to pumping systems including fluid ends configured to facilitate access to and servicing of the operating components thereof, and which can enable the use of lower cost materials for such components

BACKGROUND

Pumping systems may be used in a variety of applications, including being used to transfer a fluid having a first pressure from one location to another location at a second pressure greater than the first pressure. For example, in industrial applications such as in oil field and other applications, high pressure pumps can be used in hydraulic fracturing systems to increase a fluid pressure of a working fluid (e.g., fracturing fluid, slurry, etc.) for injection into an underground formation through one or more wellbores. The injected fracturing fluid is at a higher pressure than the fracture pressure of the subterranean formation such that the fluid creates fractures therein. The fractures increase a permeability of the subterranean formation so that formation fluids (such as oil, gas, water, etc.) may more easily escape the subterranean formation and flow to the surface via the wellbore(s). A proppant (such as sand or other solids) may be mixed with the fracturing fluid prior to injecting the fracturing fluid downhole, and when injected, may flow into the fractures in the subterranean formation to hold the fractures open after the hydraulic fracturing operation has ended.

Conventional high pressure pumps as generally used in hydraulic fracturing operations typically include a “valve-over-valve” configuration with a vertical bore for suction and discharge valves and a horizontal bore for the reciprocating plunger. The intersection of these bores are subjected to high stress due to the high cycle rate pumping of the fracturing fluid and the impact of sand, rocks, or debris during normal operations, which may induce a fatigue initiation site, and further can facilitate wear and corrosion of the cross-bore, leading to the need to use more expensive materials at the cross-bore portions of the fluid ends and the valves. In addition, servicing of the valves is done by accessing the valves through the vertical bore and the horizontal bore, and since the seats of the valves are press fit into the bores to ensure retention thereof, and further are subject to high pressures during operation of the pump, extraction of the seats for servicing can be dangerous, generally requiring exertion of an extremely high force against the seat, which can cause the seat and extraction tool to jump when the seat releases due to the high amount of stored energy of the extraction process.

Accordingly, it can be seen that a need exists for pumping systems and components thereof and methods of use, assembly, and/or repair of such pumping systems, which address the foregoing and other related and unrelated problems in the art.

SUMMARY

Briefly described, the present disclosure is generally directed to pumping systems and related components thereof, and to methods of assembly, use and accessing the operating components of such pumping systems. In embodiments, the pumping systems and methods of the present disclosure can include high-power pumps such as used in the oil and gas industry where the operating conditions and fluids may present a particularly harsh environment, and which are configured to facilitate access to and easy replacement of operating components and assemblies of the pumps, such valves, a plunger or piston, a packing seal, and other components subjected to damage, deformation, wear, and/or leakage during operation of the pumps.

According to some embodiments, the pump can comprise a high-power pump such as a hydraulic fracturing pump having a fluid end and a power end. In embodiments, the fluid end may include a fluid end block or housing at least partially defining a fluid end bore through which a fluid is pumped. In embodiments, the fluid end will further include one or more cylinder bores extending through the fluid end block or housing. In embodiments, each of the cylinder bores can extend from a first end located at a first or rear side of the housing of the fluid end to a second end located at a second or front side of the housing. In embodiments, the first and second ends of the cylinder bores can terminate at rear and front access ports formed through the rear and front sides of the housing, respectively, which front and rear access ports can be configured to enable access to and removal of various operative components of the fluid end (e.g., valves, a plunger or piston seals, and/or other components). In addition, each cylinder bore can at least partially define a flow passage for along which the fluid is pumped and can include a chamber in fluid communication with a fluid intake and a fluid outlet.

In embodiments, a plunger can be received within each cylinder bore, and is reciprocated along the cylinder bore to draw a fluid into a fluid intake and along a fluid passage into the chamber and pump the fluid under pressure from the chamber and through the fluid outlet to a discharge manifold for the fluid end. The plunger can have a plunger body with a first or proximal end that can project outwardly from the cylinder bore through the rear side of the housing, and a first end moveable into the chamber to force the fluid from the chamber and through the fluid outlet for discharge.

In some embodiments, a packing seal can be positioned along the cylinder bore, adjacent the first end of the fluid end, for forming a fluid seal about the end of the plunger. In embodiments, the first end of the cylinder bore adjacent the packing seal can be enclosed with a cover assembly, with a packing nut, or otherwise sealed/enclosed. In addition, in embodiments, a packing nut may not be used to seal the first end of the cylinder bore along the rear side of the housing of the fluid end.

In other embodiments, a piston can be received within the cylinder bore. The piston can include one or more seals, such as O-ring seals or similar types of seals configured to create a fluid seal about a first or proximal end and a second or distal end of the piston. As each piston is reciprocated along its cylinder bore, the fluid is drawn into the fluid passage through the fluid intake and is discharged through the fluid outlet.

In embodiments, the power end can include an engine or other driver that can be coupled to each of the plungers or pistons of the fluid end for driving the reciprocation of the plungers of pistons along their respective cylinder bores of the fluid end for pumping the fluid therethrough.

In embodiments, a series of valves, generally including a suction valve and a discharge valve will be positioned along each cylinder bore of the fluid end for controlling passage of the fluid through the fluid end. In embodiment, each of the suction valves and discharge valves will include a valve seat, a plunger moveable through the valve seat, and a biasing element (e.g., a spring). In embodiments, the valve seat and plunger of each of the suction and/or discharge valves can be coupled together (e.g., connected together by a fastening system, such as a bolt, nut, pin or combination thereof, and/or the biasing element) to form a cartridge valve assembly that can be positioned within and removed from its cylinder bore as a substantially one-piece assembly of cartridge valve unit.

In addition, in embodiments, the valve seat of each suction and discharge valve can be configured with its outer peripheral wall having a stepped wall geometry configured to engage and be held against an inner side wall of the at least one cylinder bore by a differential pressure created within the at least one cylinder bore during pumping operations. Such a construction enabling the valve seat of each of the suction and discharge valves to be maintained in its position along its cylinder bore by a differential pressure can avoid the need to fix each valve seat within its cylinder bore by an interference fitting, enabling removal of the valve seat and entire valve without requiring use of substantial force.

Further, in embodiments, the plungers and/or valve seats of the suction and discharge valves can be formed from lower cost materials, such as carbon steels; and in some embodiments, can include inserts, wear coatings, or other protective materials, that can act as a protective wear and/or corrosion resistant layer or surface. In some embodiments, such inserts or coatings can act as sacrificial layers the can be replaced or reapplied.

According to an aspect of the present disclosure, a fluid end for a pump is provided, the fluid end comprising: a housing having back side and a front side and including at least one cylinder bore extending through the housing from the back side of the housing to the front side of the housing; wherein the at least one cylinder bore includes a pumping chamber and at least partially defines a fluid passage along which a fluid is moved through the housing; a plunger at least partially received within the at least one cylinder bore and configured to reciprocate along a horizontal axis extending through the at least one cylinder bore to pump the fluid along the fluid passage from a fluid intake to a fluid outlet; a discharge valve received within the at least one cylinder bore, the discharge valve being positioned along the fluid passage between the pumping chamber and the fluid outlet and substantially in alignment with the horizontal axis of the plunger; and a suction valve located upstream from the discharge valve, the suction valve in communication with the pumping chamber and the fluid intake; and wherein the at least one cylinder bore is configured to enable insertion and removal of the plunger, the discharge valve, and the suction valve from the front side of the housing.

In embodiments, the fluid end further comprises a packing seal positioned along the at least one cylinder bore and configured to create a fluid seal between the plunger and a surface of the at least one cylinder bore; and wherein the at least one cylinder bore is further configured to enable removal of the packing seal from the front side of the housing.

In embodiments, the fluid end does not include a packing nut along the back side of the housing to retain the packing seal within the at least one cylinder bore.

In embodiments, at least one of the discharge valve and the suction valve comprises a valve seat, plunger, and a biasing element coupled together to form a cartridge valve assembly.

In embodiments, each of the suction valve and the discharge valve comprises: a valve seat having a first end, a second end including at least one seating surface, an outer peripheral wall configured to engage an inner side wall of the at least one cylinder bore, and a valve passage extending therethrough; a plunger including a first portion received through the valve passage of the valve seat and a second portion configured to engage against the at least one seating surface of the valve seat so as to substantially deter passage of the fluid through the fluid passage; and a spring coupled to the valve seat and to the plunger and configured to bias the plunger toward a closed position in engagement with the at least one seating surface of the valve seat.

In embodiments, at least one of the suction valve and the discharge valve further comprises at least one insert positioned along the plunger; and wherein the plunger comprises a first material and the at least one insert comprises a second material having a higher wear resistance, a higher coefficient of friction, or a combination thereof, than the first material.

In embodiments, the valve seat further includes one or more seals positioned along the outer peripheral wall; and wherein the outer peripheral wall of the valve seat includes a stepped wall geometry configured to engage and be held against the inner side wall of the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

In embodiments, the valve seat, the plunger, and the spring of each of the suction valve and the discharge valve are coupled together to form a cartridge valve assembly configured to enable removal of the suction and discharge valves from the at least one cylinder bore as a unit.

In embodiments, the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat is configured to seat along an inner side wall of the at least one cylinder bore in a non-interference fitting engagement so as to be maintained within the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

In embodiments, the fluid end further comprises one or more seals positioned along an outer peripheral wall of the valve seat.

In embodiments, the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the plunger includes at least one wear resistant insert, layer, coating, or a combination thereof.

In embodiments, the fluid end further comprises a cover assembly configured to be received within a front access port formed in the housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the cylinder bore.

According to another aspect, a fluid end for a pump is provided, the fluid end comprising: a housing having a front side, a rear side, and at least one cylinder bore defined therein; wherein the at least one cylinder bore includes a pumping chamber and at least partially defines a fluid passage along which a fluid is moved through the housing; at least one plunger or piston received within the at least one cylinder bore, the at least one plunger being reciprocated along the at least one cylinder bore for pumping a fluid through the fluid end along the fluid passage from a fluid intake to a fluid outlet; a suction valve positioned between the pumping chamber and the fluid intake and configured to control intake of the fluid from the fluid intake into the pumping chamber; a discharge valve received within the at least one cylinder bore, the discharge valve located along the fluid passage between the pumping chamber and the fluid outlet and configured to control release of the fluid from the pumping chamber to the fluid outlet; wherein the discharge valve is positioned horizontally in-line with the plunger along the at least one cylinder bore; and wherein at least one of the discharge valve and the suction valve comprises a cartridge valve configured to enable removal thereof as a unit; and wherein the at least one cylinder bore is configured to enable insertion and removal of the discharge valve and the at least one plunger or piston through the front side of the housing.

In embodiments, the fluid end further comprises a packing seal received within the at least one cylinder bore between an outer surface of the at least one plunger and a surface of the at least one cylinder bore; and wherein the at least one cylinder bore is further configured to enable removal of the packing seal and the plunger from the front side of the housing.

In embodiments, the fluid end does not include a packing nut.

In embodiments, the fluid end further comprises a suction bore extending perpendicular to the cylinder bore between the fluid intake and the pumping chamber; wherein the suction valve is positioned along the suction bore.

In embodiments, the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat is configured to seat along an inner side wall of the at least one cylinder bore in a non-interference fitting engagement so as to be maintained within the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

In embodiments, the fluid end further comprises one or more seals positioned along an outer peripheral wall of the valve seat.

In embodiments, the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the plunger includes at least one wear resistant insert, layer, coating, or a combination thereof.

In embodiments, the fluid end further comprises a cover assembly configured to be received within a front access port formed in the housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the at least one cylinder bore.

In embodiments, the fluid end comprises a plurality of cylinder bores.

According to other aspects, a pump is provided, comprising: a power end including a driver; and a fluid end coupled to the power end, the fluid end comprising: a housing including: a plurality of cylinder bores extending through the housing from a rear side of the housing to a front side of the housing, a plurality of fluid intakes, a plurality of fluid outlets, and a pumping chamber positioned along each cylinder bore between each of the fluid intakes and fluid outlets; wherein a plurality of fluid passages are defined between the fluid intakes and fluid outlets; a plunger positioned within each cylinder bore, the plungers being configured to reciprocate in a horizontal direction along the cylinder bores for pumping a fluid along the fluid passages through the housing and to a discharge; a discharge valve received within each cylinder bore, the discharge valve being positioned along the fluid passage between the pumping chamber and the fluid outlet; wherein the discharge valve is positioned in-line with the plunger of its cylinder bore; and a suction valve located upstream from the discharge valve, the suction valve in communication with the pumping chamber and the fluid intake; wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat of each suction valve and discharge valve comprises an outer side wall having a geometry configured to seat against a portion of an inner side wall of the cylinder bore in a non-interference fitting engagement so as to enable the valve seat to be maintained within the cylinder bore by a differential pressure within the cylinder bore.

In embodiments, the pump further comprises a packing seal positioned adjacent a first end of each cylinder bore and configured to create a fluid seal about the plunger of each cylinder bore; and wherein each cylinder bore includes a front access port and is configured to enable insertion and removal of the discharge valve, plunger, and the packing seal received within each cylinder bore from the front side of the housing through the front access port.

In embodiments, the pump further comprises a cover assembly configured to be received within a front access port of each cylinder bore formed in the front side of housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the cylinder bore.

In embodiments, each cover assembly comprises a cap having a body having a first end and a second end and a plurality of threads adjacent the second end and configured to engage with corresponding threads formed along the cylinder bore, and a plug having a geometry configured to engage a surface of the inner side wall of the cylinder bore as the cap is tightened thereagainst, and at least one seal; wherein the plug is configured to be held in place within the cylinder bore by pressure acting on the at least one seal.

In embodiments, each cover assembly comprises a cap having a body having a first end and a second end, and at least one groove formed between the first and second ends; a plug configured to fit within the cylinder bore; and one or more pins received through a vertical locking bore formed in the housing and into engagement with the at least one groove to hold the cap and plug within the housing.

In embodiments, each cover assembly comprises a plug configured to be received within the cylinder bore, a cap adapted to fit within the front access port and retain the plug within the cylinder bore; and further comprising a cover positioned along the front side of the housing and configured to slide along the housing from a first position covering the caps of the cover assemblies and a second position enabling access to the cover assemblies.

In embodiments, one or more of the valve seats, plunger, and the housing comprise a first material, and further include one or more inserts of a second material having a wear resistance that is greater than a wear resistance of the first material.

In embodiments, the housing of the fluid end comprises a cast metal material.

According to other aspects, a method for servicing the operative components of a pump from the front side of a fluid end of the pump is provided.

In embodiments, the method comprises removing a cover assembly from a front access port formed in the front side of the fluid end; removing a discharge valve from the cylinder bore through the front access opening; removing a suction valve from the cylinder bore through the front access opening; and removing a plunger or piston from the cylinder bore through the front access opening; wherein the discharge valve is positioned substantially horizontally in-line with the plunger or piston.

In embodiments, the method further comprises removing a packing seal from the cylinder bore through the front access opening. In some embodiments, a packing nut positioned at a first or upstream end of the cylinder bore and along a rear side of the fluid end does not have to be removed to remove the packing seal; while in other embodiments, the fluid end does not include a packing nut for sealing the first or upstream end of the cylinder bore.

In embodiments, the suction and discharge valves can comprise cartridge valve assemblies each including a plunger, a valve seat, and a spring coupled together; and wherein the discharge valve and the suction valve are removed as a unit.

In embodiments, the method further can comprise replacing the suction and discharge valves within the cylinder bore and engage the inner side wall thereof without an interference fit; wherein the valve seats of each of the suction and discharge valves each include one or more seals, and an outer wall having a stepped geometry configured to abut against a portion of an inner side wall of the cylinder bore such that the valve seats are held in place within the cylinder bore by a differential pressure generated within the cylinder bore.

In embodiments, the method further comprises replacing the cover assembly within the front access port.

In some embodiments, replacing the cover assembly incudes positioning a plug within the cylinder bore and engaging the plug with a cap; wherein the plug includes at least one seal and is configured such that as the cap is moved along the cylinder bore in engagement with the plug, the at least one seal and/or a portion of the plug are expanded into a locked condition within the cylinder bore.

In other embodiments, replacing the cover comprises inserting a plug and cap into the cylinder bore through the front access port and inserting one or more locking pins through the fluid end and into engagement with a grove formed about the cap or the pug. In addition, in embodiment, the method can further include moving a front access cover from a first, open position, to a second, closed position covering the front access ports.

Various other aspects, features, and advantages of a packing seal locking assembly and methods of use thereof according to exemplary embodiments thereof are discussed herein. Moreover, it is to be understood that both the foregoing information and the following detailed description provide merely illustrative examples of various aspects and embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. Accordingly, these and other aspects, along with advantages and features of the present disclosure, will become apparent through reference to the following description and the accompanying drawings. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the embodiments of the present disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure, and together with the detailed description, serve to explain principles of the embodiments discussed herein. No attempt is made to show structural details of this disclosure in more detail than may be necessary for a fundamental understanding of the embodiments discussed herein and the various ways in which they may be practiced. According to common practice, the various features of the drawings discussed below are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate embodiments of the disclosure.

FIG. 1A is a perspective view showing a front side of an example embodiment of a fluid end of a hydraulic pump, in accordance with the principles of the present disclosure.

FIG. 1B is a perspective view showing a rear side of an example embodiment of a fluid end of a hydraulic pump, in accordance with the principles of the present disclosure

FIG. 1C is a cross-section view schematically illustrating the fluid end of for hydraulic pump such as shown in FIGS. 1A-1B, including an example embodiment of a semi-linear valve and plunger assembly, in accordance with the principles of the present disclosure.

FIG. 2A is a cross-sectional view of one example embodiment of a semi-linear valve and plunger assembly of a fluid end of a hydraulic pump such as illustrated in FIGS. 1A-1C, in accordance with the principles of the present disclosure.

FIGS. 2B-2C are cross-sectional perspective views of the embodiment of the semi-linear valve and plunger assembly illustrated in FIG. 2A.

FIGS. 3A-3C are cross-sectional views of additional example embodiments of a semi-linear valve and plunger assembly of a fluid end of a hydraulic pump such as illustrated in FIGS. 1A-1C, in accordance with the principles of the present disclosure.

FIG. 4 is a perspective view of another example embodiment of a fluid end for a pump, including a fluid discharge manifold positioned along a front side of the fluid end, in accordance with the principles of the present disclosure.

FIG. 5A is a cross-sectional perspective view of an example embodiment of a cover assembly for a front access port of a fluid end of a hydraulic pump such as illustrated in FIGS. 1A-1C, in accordance with the principles of the present disclosure.

FIGS. 5B-5C are cross-sectional views illustrating another example embodiment of a cover assembly for a front access port of a fluid end of a hydraulic pump such as illustrated in FIGS. 1A-1C, in accordance with the principles of the present disclosure.

FIG. 6A is a perspective view of another example of a fluid end for a hydraulic pump in accordance with the principles of the present disclosure.

FIG. 6B is a cross-section view schematically illustrating the fluid end for the hydraulic pump shown in FIG. 6A, and illustrating a further example embodiment of a cover assembly for a front access port of the fluid end, in accordance with the principles of the present disclosure.

FIGS. 7A-7B are perspective views of another example embodiment of a fluid end for a pump, showing a sliding front access cover assembly for covering the front access ports of the fluid end, in accordance with the principles of the present disclosure.

FIG. 8 is a cross-sectional view of one example embodiment of a semi-linear valve and piston assembly of a fluid end of a hydraulic pump such as illustrated in FIGS. 1A-1C, in accordance with the principles of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to reciprocating pumps and components thereof, including fluid ends that, in embodiments, can include a semi-linear valve construction and front access to the operative components of each cylinder of the fluid end, and will be described in more detail with reference to the attached drawing figures. It will be understood that the following description in combination with the Figures is provided to assist in understanding the embodiments and principles disclosed herein, and should not be interpreted as a limitation on the scope or applicability thereof.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof, and are intended to cover assembly a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or.

Dimensional information in the following description should be understood as nominal dimensions that are intended to encompass variations in dimensions that normally occur in the pumping systems and components thereof such as described herein. Terms such as “approximately,” “about,” and “substantially” may be used to qualify dimensional information in the following description but such qualifications are intended merely to reinforce that the dimensions are nominal dimensions and not to differentiate qualified dimensions from unqualified dimensions.

The terminology used herein is for the purpose of description only and is not intended to be limiting of the present disclosure. Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising” specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

Embodiments of the present disclosure are directed to pumps; including, in various embodiments, semi-linear pumps with at least one valve arranged substantially in-line with a plunger or piston of a pump along a horizontal axis of movement (e.g., reciprocation) of the plunger or piston, and which can include cartridge valve assemblies and improved retention of valves along the cylinder bore s of the fluid ends of the pumps without requiring an interference fitting, and which enable improvements in servicing of the operating components of the pumps and use of lower cost materials therefor.

The term “pump” can include a variety of pumps such as such as a positive displacement reciprocating pump, including hydraulic fracturing pumps, mud pumps, and other, similar plunger or piston pumps adapted to pump a fluid (e.g., including, but not limited to fluids, slurries, and other fluid media).

FIGS. 1A-1C, 4 and 6A-7B illustrate examples of pumps 10 according to some of the embodiments disclosed herein. For purposes of discussion herein, embodiments of the pump 10 are shown and described herein as a “hydraulic fracturing pump” for pumping hydraulic fracturing fluid. However, it will be understood that the pump 10 may comprise any other type of pump, such as, for example, any type of high-power pump, high-pressure pump, reciprocating pump, and/or high-flow rate pump suitable for pumping solids, semi-solids, slurries, liquids, fluids, or combinations thereof. In some embodiments, the pump 10 may be, for example, a hydraulic fracturing pump for pumping solids, semi-solids, slurries, liquids, fluids, or combinations thereof, such as hydraulic fracturing fluid.

For example, in embodiment, the pump 10 can comprise a reciprocating plunger or piston pump used to pump a fracturing fluid at high flow rates and high pressures sufficient to fracture a reservoir formation to allow hydrocarbons to more easily flow from the formation toward a wellbore for production. In various applications, a hydraulic fracturing operation may include as many as six or more hydraulic fracturing units, and each of the hydraulic fracturing units may include a prime mover, such as an electric motor or internal combustion engine, either directly connected, or connected via a transmission, to the reciprocating plunger pump to supply power to drive the reciprocating plunger pump to pump the fracturing fluid into the formation to stimulate production of the well. For example, typical flow rates for a hydraulic fracturing operation may range from about 1,500 to about 4,000 gallons per minute, and typical pressures may range from about 7,500 to about 15,000 pounds per square inch. In addition, as noted, although many examples discussed in this disclosure are explained in relation to hydraulic fracturing pumps, such as reciprocating plunger pumps for pumping fracturing fluid and related methods, other flow control-related and/or pumping-related operations, components, and methods, which can operate at various pressures and pumping cycle rates, are contemplated.

During operation of the pump, the plungers or pistons of the pump 10 are driven in a reciprocating motion along a cylinder bore to pump a fluid along a flow passage from a suction or intake/intake where a low pressure fluid is drawn into the flow passage, to a fluid outlet where pressurized fluid will be discharged, such as through a discharge manifold. As will be understood, the fluids pumped through the pump 10 can comprise any fluid media, including fracturing fluids, slurries, fluids containing proppants such as sand and other particulates, etc. Over time, the areas of intersection between the cylinder bore and the suction or fluid intake and discharge or fluid outlet bores are subject to high wear rates and corrosion due to the high cyclic pumping rates and the fluids being pumped therethough. To protect against increased wear and corrosion, such pumps generally use forged stainless steel to form the fluid end blocks rather than carbon steel, leading to increased manufacturing costs and inefficiencies.

In addition, Applicant has also recognized that servicing of such pumps also is subject to substantial issues and inefficiencies. For example, servicing the valves of such pumps may generally require accessing vertical valve bores, while servicing packing assemblies of such pumps may generally require accessing horizontal cylinder bores. Servicing of packing assemblies also typically is performed from a side of the fluid end adjacent the associated power end of the pump, which may require that service personnel lean over the fluid end to remove large packing nuts that retain a packing assembly, which may be ergonomically challenging given the limited space and other elements such as stay rods between the fluid and power ends restricting access to the packing nuts. Moreover, the valve seats of the suction and discharge valves often have a tapered construction and are press-fitted into corresponding tapered portions of the respective vertical bores in an interference fitted engagement, and thus, in order to install and remove the respective suction and discharge valve seats from the respective bores, hydraulic tools are often required to exert sufficient installation and extraction forces, which can be upwards of twenty tons or more, on the respective valve seats to dislodge them from such interference fitted engagement.

In some embodiments, the fluid ends and valve assemblies presented herein may have a relatively enhanced reliability, resulting in less frequent service of the pumps and replacement of operating components such as valves thereof. For example, in some embodiments, a pump is provided that can include a fluid end may comprise a housing or block having one or more cylinder bores positioned horizontally and can receive a packing assembly and a reciprocating plunger or piston therealong. In addition, at least one valve bore, such as a valve bore for a discharge valve further can be axially aligned with the cylinder bore and thus substantially in-line with the plunger or piston received within the cylinder bore. Further, the cylinder bore can have open rear and front or first and second ends, and will be configured with an increased size so as to facilitate access to and removal of the valves, plunger or piston, and in embodiments, the packing assembly as well, from the cylinder bore via the front side of the fluid end, such that access to the packing assembly from the rear or drive side of the fluid end is not needed, nor is removal of a packing nut thereby improving efficiencies associated with assembly and service of the fluid end. Still further, in some embodiments, the fluid ends and valve assemblies will be configured to substantially reduce wear, corrosion, and fatigue failures thereof, which may thereby mitigate the need to use stainless steel construction, allowing the use of relatively more efficient carbon steel, as well as facilitating removal and replacement of components such as valve seats, packing assemblies, etc. in the field. Various embodiments of the present disclosure directed to addressing the foregoing and other problems existing in the art are described hereinafter.

As illustrated in FIGS. 1A-1C, in an example embodiment, the pump 10 may include a fluid end 12 and a power end 14 coupled to the fluid end 12 for supplying power thereto. The power end 14 (schematically depicted in FIGS. 1A-1B) may include a driver 15 that is configured to actuate one or more movable components such as plungers 26 (FIGS. 2A-3C) or pistons 126 (FIG. 8). In embodiments, the pump 10 may comprise a reciprocating plunger pump, with the fluid end 12 having a manifold body, housing or block 13 with a plurality of cylinders (FIGS. 1C-3C), each including a cylinder bore 22 extending through the housing and receiving a reciprocating plunger or piston therein. It will be understood by those skilled in the art that the pump 10 can include pumps having reciprocating plungers or pistons, without limitation, and references below to embodiments including plungers are applicable to pumps having reciprocating pistons as well.

In some embodiments, the power end may include, for example, a housing with mechanical power transmission components, such as a crankshaft, bearings supporting the crankshaft in the housing, crossheads, reduction gears, and/or connecting rods and plungers connected to the connecting rods. In some embodiments, the power end assembly may be configured to convert power into reciprocating motion. For example, the power end may be configured to convert rotational power into reciprocating motion, or the power end assembly may be configured to convert electric or hydraulic power into reciprocating motion. The power end further will be coupled to the fluid end with the driving components of the power end (e.g., connecting rods, drive rods, etc.) in communication with corresponding ones of the plungers or pistons of the fluid end for driving a reciprocating motion thereof.

In addition, as illustrated in FIGS. 2A-4, in embodiments, the power end 14 can be coupled to the fluid end 12 by a plurality of stay rods 16. In embodiments, the stay rods 16 can be extended through the housing 13 from the first or rear side 13A to the second or front side 13B of the housing. In embodiments, the distal ends 17 of the stay rods can project through the front side 13B of the housing 13 of the fluid end and can be secured with fasteners 18 to secure the power end and fluid end together.

In embodiments, the housing 13 of the fluid end 12 generally is illustrated in FIGS. 1A-1C, 4, and 6A-7B as a single, unitary piece, but also may be formed of multiple sections, for example, including a block with a suction manifold or fluid intake manifold and/or a discharge manifold coupled thereto. In addition, in the illustrated embodiment, the fluid end 12 can include multiple cylinders 20 received within the housing. For example, FIG. 1A show an embodiment of a pump 10 with a fluid end 12 having five cylinders 20 spaced therealong. However, it will be understood that the fluid end can have greater or lesser numbers of cylinders 20.

In embodiments, a series of fluid passages 11 will be formed through the housing 13, each extending through each cylinder from a fluid intake 27 in communication with a cylinder bore 22 (FIG. 1C) of the cylinder 20, through an internal pumping chamber 28 of the cylinder 20, and to a fluid outlet 29 at an opposite or downstream end of the pumping chamber. During pumping, a low pressure fluid F is drawn through a suction bore and into the pumping chamber 28 and in which the Fluid is pressurized, after which a high pressure fluid F′ is released from the cylinder through a discharge bore to a discharge manifold.

As shown in FIGS. 1C-3C, each of the cylinders 20 of the fluid end 12 will include a cylinder bore 22 that can extend through the housing 13 of the fluid end along a substantially horizontally extending axis CA. A plunger or a piston can be received within each of the cylinder bores, with the plunger or piston being reciprocated along the axis CA of the cylinder bore 22 in the direction of arrows 25A/25B. In embodiments, each cylinder bore 22 can include a first or proximal end 23A located adjacent a rear side 13A of the housing and which can be accessible through a rear access port 24A, and a second or distal end 23B located adjacent a second or front side 13B of the housing, and which can be accessible through a front access port 24B. In embodiments, a pumping chamber 28 is defined between the first and second ends 23A/23B of each cylinder bore 22. In addition, in embodiments, as indicated in FIGS. 2A-3C, the cylinder bore 22 of each cylinder will have an expanded size/diameter, and will further be configured to enable access to and insertion, servicing and removal of the operative components within each cylinder from the front side of the housing of the fluid end.

In embodiments, the fluid end 12 can include one or more fluid inlets or intakes 27 in communication with the cylinder bores 22 of each of the cylinders 20, and which will be in communication with a fluid source for supplying the low pressure fluid F into the pumping chambers 28; and one or more discharge ports or fluid outlets 29 located along the cylinder bores downstream from the pumping chambers thereof and configured for discharging the fluid from the pumping chambers 28 at a higher pressure.

For example, during a pumping operation, the plunger 26 of each cylinder 20 will be moved/reciprocated along its cylinder bore 22 in the direction of arrows 25A/25B via operation of power transmission components of the power end 14; and as the plunger is at least partially retracted along its cylinder bore 22 in the direction of arrow 25A, a suction valve 30 of each fluid intake 27 is caused to open and a flow of low pressure fluid F will be drawn from the fluid source, for example, from a suction or fluid intake manifold, through a suction bore 31, along a fluid passage 11 and into the pumping chamber 28. As the plunger reverses direction and is thereafter moved forwardly toward/into the pumping chamber in the direction of arrow 25B to pressurize the fluid, the suction valve 30 will be closed and a discharge valve 32 opened to enable the pressurized fluid F′ (e.g., the fluid at a higher pressure than as received from the fluid source) to be discharged from the pumping chamber 28 through a discharge bore 33 of the fluid outlet 29.

In some embodiments, the pressurized fluid can be discharged from the fluid end 12 through one or more external ports 34 (FIG. 1A) defined through the housing 13 for downstream use, such as, for example, as part of a hydraulic fracturing operation or other operation. For example, in embodiments such as shown in FIGS. 1A-1B, the fluid end 12 can include an internal manifold within the housing 13 of the fluid end. In embodiments, such an internal manifold can include an internal discharge passage 36 in communication with the fluid outlets of the cylinders and along which the pressurized fluid is directed to the one or more external ports 34, which, in embodiments, can be formed along the sides 13C of the housing 13, or along the front side 13B of the housing.

In other embodiments, such as shown in FIG. 4, the pump 10 may include an external discharge manifold 35 that can be mounted along the housing 13 of the fluid end 12. For example, in embodiments, the discharge manifold 35 can comprise a separate manifold that can be mounted along an upper side 13D or along the front side 13B of the housing. In some embodiments, the manifold 35 can include a fluid discharge passage 37 that will be in communication with the fluid outlet of each cylinder 20 of the fluid end 12 to receive the pressurized fluid therefrom. In embodiments such as shown in FIG. 4, the fluid discharge passage 37 can extend substantially along the length of the discharge manifold 35 and can have one or more external ports or openings 38 at the ends thereof, through which the pressurized fluid F′ is discharged for downstream use, such as, for example, as part of a hydraulic fracturing operation or other operation.

Exemplary embodiment of a cylinder 20 of the fluid end 12 are shown in, for example, FIGS. 2A-2C, and include a plunger 26 received within the cylinder bore 22. The plunger is reciprocal along the cylinder bore in the direction of arrows 25A and 25B during a pumping operation. As the plunger is moved rearward in the direction of arrow 25A, the suction valve 30 is caused to open to draw the low pressure fluid though the suction bore 31 and into the pumping chamber 28. As the plunger is mover forward in the direction of arrow 25B along its return stroke, the fluid within the chamber is compressed, and as the discharge valve 32 is opened, the now pressurized fluid is released to through the discharge bore 33 and to the discharge manifold.

In embodiments, the plunger 26 can include a body 40 with a first end 41 that can project from the first end 23A of the cylinder bore and through the rear side 13A of the fluid end housing, and a second end 42 having a front face 43 configured to compress the fluid within the pumping chamber 28 so as to pressurize the fluid as the plunger is moved forwardly in the direction of arrow 25B. The first end of the plunger 26 further can be coupled to a connecting rod or similar connector of the power end such as by a clamping ring, for driving the reciprocation of the plunger along the cylinder.

In some embodiments, a packing assembly 44 can be received within the cylinder bore 22 for creating a substantially fluid tight seal about the first end 41 of the plunger 26. In embodiments, the packing assembly 44 can include a packing seal 46 positioned adjacent the first end 23A of the cylinder bore, and a sleeve 47 received along the cylinder bore and positioned in front of the packing seal 46. The packing seal and the sleeve of the packing assembly generally will be positioned between the side wall 21 of the cylinder bore 22 and the body 40 of the plunger 26; and, in some embodiments, may comprise a sacrificial wear component between the plunger and the side wall of the cylinder bore to protect against wear of the side wall and of the cylinder bore and the plunger during reciprocation of the plunger through the cylinder bore.

As generally illustrated in FIGS. 2A-2B, in embodiments, the packing seal can include one or more sealing elements 48, including, for example, one or more of a lantern ring 49, which can be positioned at an upstream end of the packing seal, one or more pressure rings 51 stacked in front of the lantern ring, and one or more seals or gaskets 52, such as lube seals or other seals positioned at a front or forward end of the packing seal between the packing seal and the sleeve 47. In addition, in some embodiments, other sealing elements such as an adapter ring, junk ring, header ring, scraper ring, and one or more additional seals also can be used. For example, in some embodiments, an additional seal, such as an O-ring 53, can be received within the lantern ring at the rearmost and thereof as shown in FIG. 2A.

In addition, in embodiments, the packing seal can project outwardly from a rear access port 24A of the fluid end; and in some embodiments, a packing nut 54 can be secured within rear access port 24A, such as by threaded connection, to seal the first end 23A of the cylinder bore 22 and secure the packing seal within the cylinder bore. In embodiments, with the expanded diameter and configuration of the cylinder bore 22, which enables front side access to the packing seal from the front of the fluid end, a packing nut 54 may not be required for sealing the rear access port 24A and securing the packing seal within the cylinder bore; and in some embodiments, may not be used. In some further embodiments, the packing nut can be replaced with a cover configured to fit within and substantially enclose and seal the rear access port and seal the packing seal within the cylinder bore 22.

As further illustrated in FIGS. 2A and 2B, in embodiments, the sleeve 47, can include an elongated tubular body 56 that extends along the cylinder bore 22 from a first end 57 in abutment with the packing seal 46 to second or front end 58 located at a downstream end 28A of the pumping chamber 28. In embodiments, the sleeve 47 can include an opening 59 at least partially formed about the body 56. The opening 59 generally will be aligned with the suction bore 31 of the fluid intake 27 to enable to the low pressure fluid F flow through the opening 59 and into the pumping chamber 28 of the cylinder bore 22. In some embodiments, such as illustrated in FIG. 2A, the second or a of the sleeve 47 can engage or abut against a portion of the discharge valve 32 and/or the side wall 21 of the cylinder bore 22 at the downstream end 28A of the pumping chamber 28.

As shown in FIGS. 2A-3C, in embodiments, a collection chamber 60 can be positioned along the cylinder bore 22, downstream from the pumping chamber 28. The pressurized fluid F′ released from the pumping chamber through the discharge bore 33 by the discharge valve 32 can flow directly into the collection chamber 60 in the horizontal direction. As shown in FIGS. 1A-3C, the collection chamber 60 can include a discharge port 61 formed along a sidewall thereof, and which discharge port 61 can be in communication with the fluid discharge manifold of the fluid end (e.g., an internal discharge manifold such as illustrated in FIG. 1A, or an external discharge manifold such as illustrated in FIG. 4) for transferring the pressurized fluid thereto.

As generally illustrated in FIGS. 1C-3C, in embodiments, the cylinder 20 generally can comprise a semi-linear in-line valve configuration. For example, as shown in FIG. 2A, the discharge bore 33 of the fluid outlet 29, along which the discharge valve 32 is located, generally can be arranged horizontally downstream from and substantially directly in-line with the cylinder bore 22 along the horizontal axis CA of the cylinder 20. The discharge valve 32 can be positioned within the cylinder bore between the discharge bore 33 and the downstream end 28A of the pumping chamber 28 and the collection chamber 60, and further will be oriented substantially in-line with the plunger 26 in a linear direction along the horizontal axis CA. As a result, the use of a vertically oriented fluid outlet in which the discharge valve and discharge bore are arranged perpendicular to the cylinder bore can be eliminated.

In some embodiments, as shown in FIG. 2A, the suction bore 66 of the fluid intake can still be located in a substantially perpendicular orientation with respect to the cylinder bore 22, with the suction valve 30 of the fluid intake 27 in communication with the cylinder bore 22, and being positioned adjacent an upper end of the suction bore 31 substantially in alignment with the opening 59 formed through the sleeve 47 such that as the suction valve 30 is opened, the low pressure fluid is passed from the suction bore 31 into the pumping chamber 28.

As generally shown in FIGS. 2A-2C, the semi-linear valve configuration according to the principles of the present disclosure, the discharge port 61 to be relocated, for example, along an upper portion of the collection chamber 60 such that the pressurized fluid flowing into the collection chamber can be directed upwardly and through the discharge port 61 to the discharge manifold of the fluid end. FIG. 3A illustrates another example embodiment in which the discharge port 61 is configured as an elongated slot or opening that is located along at least one side of the collection chamber 60. FIG. 3B illustrates still a further embodiment, showing two discharge ports 61 positioned adjacent the upper and lower portions of the collection chamber 60.

In embodiments, each of the suction valve 30 and the discharge valve 32 can have a substantially similar or the same construction. In some embodiments, the suction valve 30 and the discharge valve 32 may act as one-way valves or check-valves, allowing fluid to flow only in a single direction, either into the pumping chamber 28 of the fluid end cylinder via the suction bore by operation of the suction valve, or from the pumping chamber 28 through the discharge bore and to the discharge port. In this example manner, the fluid end 12 can draw a fluid from the fluid source into the fluid end at a first pressure and discharge the fluid from the fluid end 12 at a higher pressure. As illustrated in, for example, FIG. 1A, in some pump embodiments, the fluid end 12 may include multiple (e.g., two, three, four, or five) sets of suction ports, cylinder bores, packing assemblies, plungers, and/or discharge ports to pump fluid at high pressures and/or high flow rates.

In addition, as shown in FIGS. 2A-3C, in various embodiments, the suction and discharge valves can be configured as cartridge valve assemblies 67, each including a plunger 70 having a first portion or stem 71 and a second portion or disc 72 located in front of the stem; a valve seat 73; and a biasing element 74, which, in embodiments, can comprise a spring 76 (e.g. a compression spring wave spring, etc. though other types of resilient biasing materials also can be used); and a fastener 77 (e.g. a nut). In embodiments, the stem 71 of the plunger will be extended through a valve passage 78 defined through the valve seat 73 and the fastener 77 can be secured to the distal end of the stem 71 with the biasing element 74 (e.g., spring 76) being engaged between the fastener 77 and a section of the valve seat (e.g., a projection or an opening defined along the passage of the valve seat). As a result, each of the suction and discharge valves can be coupled together to provide a substantially unitary structure forming the cartridge valve assembly that generally can be removed from the cylinder 20 as a single assembly or unit. In other embodiments, the plungers and valve seats of the suction valve, the discharge valve, or both, can be positioned within their respective suction and discharge bores independently of each other, and the biasing elements further can be fixed to another feature of the suction and/or discharge ports.

In addition, as shown in FIGS. 2A-2C, in embodiments, the valve seats 73 of each of the suction and discharge valves can include a body 80 having an outer side wall 81 configured with a stepped geometry adapted to engage against corresponding complimentary portions 21A of the side wall 21 of the cylinder bore 22, and one or more radial seals 82 at spaced locations along the outer side wall 81, as shown in FIGS. 2A-3C. The stepped geometry of the valve seats and the radial seals enables the valve seats to be seated and secure along within their respective suction and discharge bores without having to be force or press fit in place so as to be engaged with their respective suction or discharge bores in an interference type fitting as conventionally used. The valve seats further can be kept in place by the compressive engagement of the seals against the inner wall of the cylinder bore and/or the suction or discharge bore, and by differential pressures created within the cylinder bore (e.g., in some embodiments between the chamber and each of the discharge and suction bores) during pumping operations as the fluid is drawn through the suction bore, into the chamber of the cylinder and then discharged through the discharge bore. Once such differential pressures are relieved, the valve seats can be removed without requiring high applications of force to dislodge the valve seats.

Such a construction whereby the valve seats be installed without having to be pressed into position in an interference fitting can enable much easier and more efficient installation and removal of the valve seats from the cylinders. For example, in some embodiments, the geometry of the valve seats can be configured such that the valve seats can be somewhat self-locating along their suction and discharge bores. The removal of the valve seats from their respective discharge and suction bores further can be accomplished without having to exert significant substantially high forces (e.g., several tons) and without requiring the use of hydraulic extraction tools, enabling installation, removal, and replacement of the suction and discharge valves in the field to be much more efficient.

Still further, as generally illustrated in FIGS. 2A-3C, in embodiments, the cylinder bore of each cylinder 20 will can be configured with an expanded or increased diameter of a size and configuration sufficient to enable removal of the operative components of the cylinder, such as the discharge valve 32, suction valve 30, the plunger 26, sleeve 47, and the packing seal 46 through the front side of 13A of the fluid end. For example, as generally illustrated in FIGS. 2A-3C, the cylinder bore can be sized with an expanded diameter sufficient to enable front access to and removal and replacement of the suction and discharge valves, the plunger, sleeve, and the packing seal from the front side of the fluid end, while still providing for a substantially fluid tight seal between the packing assembly and the inner wall of the cylinder bore and the plunger as the plunger is reciprocated therealong. In some embodiments, as indicated in FIG. 2A, the side wall 21 of the cylinder bore 22 rearward of the pumping chamber 28 may not include a packing recess for receiving the packing seal, and further may have a substantially straight configuration with additional seals provided between the sleeve and packing seal and the side wall of the cylinder bore as needed.

By enabling substantially direct access to and removal of the operative components of the cylinder through the front side of the housing of the fluid end, greater efficiencies in the servicing of the pumps is enabled, including removal and replacement of components such as the suction and discharge valves, the plunger, and the packing seal. Such efficiencies can be further enhanced by the cartridge valve assembly construction of the suction and discharge valves in which the plungers, valve seats and biasing elements (e.g., springs) of the suction and discharge valves are coupled together, and which enables each of the suction and discharge valves to be removed from the cylinders and replaced as a unit rather than having to replace individual components thereof.

Additionally, the ability to access and remove/replace the discharge and suction valves, the plunger, and the packing seal, from each cylinder through the front side of the fluid end, can avoid having to remove the packing nut from cylinder bore at to access the packing seal, which is generally made more difficult by the limited space between the power end and the fluid end, which often may require removal of the stay rods enable access to the packing nut. Moreover, since removal of the packing nut is not needed to access the packing seal with the fluid end construction according to the principles of the present disclosure, the packing nut could be eliminated and replaced with another type of cover in some embodiments. Still further, by eliminating at least the vertical bore for the discharge of the fluid from the pumping chamber and providing direct front-side access to the operative components within the cylinders, the stay rods 16 can be extended all the way through the housing of the fluid end and can remain in place secured along the front side of the fluid end by their fasteners 18 during servicing.

As noted above, in addition to enabling front side access for easier and providing more efficient access to and servicing of the operative components within the cylinders, the semi-linear valve construction of the fluid ends of the present disclosure enables the vertical cross-bore geometry of the conventional valve arrangements to be reduced by one of the cross-bores (e.g., by removal of a vertical discharge bore for the discharge of the pressurized fluid). The removal of the vertical discharge bore can provide a reduction in the cyclic stress profile at the intersection of the cylinder bore and the suction and discharge bores, which in turn can mitigate the need for the valve seats and plungers of the valves and the housing of the fluid end to be formed using a stainless steel construction. This can allow for the use of materials other than stainless steel to be used for the fluid end housing and components. For example, in embodiments, the materials of construction for the housing and valve components can be expanded from stainless steels (traditional materials) to include carbon steel alloys, coated steels, and other high strength, high fatigue resistant alloys that are costly or difficult to source in stainless steels.

In some embodiments, the semi-linear cylinder and valve construction of the fluid ends of the present disclosure also may enable the use of castings or forgings for construction of the fluid end housing, which can directly affect the total cost and potentially the weight of the fluid ends. In addition, in other embodiments, lower cost materials such as carbon steels and alloys can be used to form the valve seats and plungers and the housing with an additional optional application of a wear resistant coating, the use of inserts of wear resistant materials, and/or heat treatments applied thereto. For example, in embodiments, the valve seats and plungers of the suction and discharge valves could be constructed from a first material (e.g., a carbon steel, alloy or similar material), and a wear resistant coating or inserts (e.g., a sleeve, plate, etc.) of a different material having a greater wear resistance than the first material can be applied or positioned along surfaces exposed to wearing and/or higher stress during pumping operations. In embodiment, such inserts, sleeves and/or coatings can further act as a sacrificial protective layer that can be replaceable.

As shown in FIGS. 1A-1C, according to some embodiments, the fluid end 12 may include a front access port 24B aligned with the second end 23B of each cylinder bore 22 (FIGS. 2A-2C) for providing front side access to the cylinder bore during assembly and/or maintenance of the fluid end 12. In embodiments, each front access port 24B may be selectively closed via a cover assembly 85 to seal the second end of its cylinder bore 22 during a pumping operation. In some embodiments, each front access port may be defined in the front side 13B of the housing 13 by a circular aperture and passage having an interior wall having a substantially cylindrical configuration, and which can open and extend into or be part of its cylinder bore.

In embodiments, such as shown in FIGS. 2A-2C and 5A, the cover assembly 85 can include a plug 86 having a substantially cylindrical body 87. One or more seals 88 may be applied about the plug body, and the plug body also can be configured with an outer wall geometry having a locking ring and/or load segments 89 configured to engage a section of the side wall of the cylinder bore. As shown in FIG. 5A, the plug 86 may be sized to fit snugly (e.g., in a substantially press-fitting manner) within the passage of front access port with the load segments 89 engaging a portion of the side wall of the access port and with the seals 88 being expanded into engagement with the side wall of the cylinder bore via pressure acting on the plug to secure the cover assembly in place covering the front access port.

In other embodiments, the cover assembly 85 can include a cap 90 and a plug or retainer 91. As illustrated in FIG. 5B, in embodiments, the cap 90 can include a substantially cylindrical body 92 that can include a plurality of threads 93 formed thereabout. In some embodiments, the threads 93 of the cap 90 can gauge corresponding threads of the front access port 24B to secure the cap 90 and retainer within the front access port. In embodiments, the retainer 91 can have a generally T-shaped cross section, including a first or forward portion 96 configured to be received within a slot 97 formed in the body 92 of the cap 90 and second portion 98. In embodiments, slot 97 can define a drop in feature that enables the first portion of retainer to fit together with and be substantially locked with the cap, such as illustrated in FIGS. 5B and 5C, such that as the cap is threaded thought the front access bore, the retainer is urged along the front access bore into tighter sealing engagement therewith.

In addition, as illustrated in FIG. 5C, the cap can include a series of grooves 99 extending therethrough, which can be configured to receive corresponding ridges of the first portion of the retainer to also provide a drop in feature that enables the cap and the retainer to fit together. In addition or alternatively, the grooves 99 formed in the cap 90 can provide engagement surfaces for a tool that is needed to facilitate removal of the cap and retainer from the front access port.

As illustrated in FIG. 5B, the second portion 98 of the retainer 91 can include one or more seals 101 received about the outer side wall 102 thereof, and its outer side wall 102 further can be configured with an expanding outer diameter. As the cap 90 is rotated into threaded engagement with the front access port, the retainer 91 generally will be urged along the passage of front access bore and the cylinder bore, causing the seal(s) 101 to be compressed as the outer side wall 102 of the second portion of the retainer bears against the inner side wall of the cylinder bore so as to secure the cover assembly 85 in place to enclose the front access port.

FIG. 3 illustrates another embodiment of cover assembly 85. In this embodiment, the cover assembly can include a cap 105 and a retainer 106. In embodiments, the cap can include a substantially U-shaped construction with a pair of outwardly expanded side portions 107, which, in embodiments, can be configured to exert a biasing force against the side wall of the front access bore as the cap is driven into the front access bore to provide a substantially tight, sealed engagement with the side wall of the cylinder bore. The retainer 106 can have a corresponding configuration (e.g., a substantially A-shaped configuration) that is adapted to be received between the side portions 107 of the cap 105 and a seated engagement. In addition, a fastener 108, such a screw or bolt, can be received through the cap and into a corresponding fastener bore 109 within the retainer 106. As the fastener is threaded through the cap and into the retainer, the cap and retainer can be forced into tighter contact, causing the side portions of the cap and side portions 111 of the retainer to expand into contact with the inner side wall of the front access bore. The side portions 111 of the retainer 106 further can include a seal ring received thereabout and which will be compressed against the side wall of the front access port to provide a sealing engagement with the front access port.

FIGS. 6A and 6B illustrate still a further embodiment of a cover assembly 85 for closing and sealing a front access port of the fluid end 12 in accordance with the principles of the present disclosure. In this embodiment, the cover assembly 85 can include a cap or plug 113 configured to be received with the front access port 24B. In embodiments, the cap or plug 113 can have a cylindrical body with a first end 114, which can include one or more seals (e.g., O-rings) 116 positioned thereabout, and a second end 117. As shown in FIG. 6B, the cap or plug 113 further can include a groove or notch 118 formed along its body adjacent the second end thereof.

As further illustrated in FIG. 6B, the cap or plug 113 can be inserted through the passage of the front access port 24B and at least partially into the cylinder bore, with the one or more seals 116 engaging against the inner wall of the cylinder bore. One or more locking pins 120 can be inserted through vertical locking passages 121 extending through the housing 13 of the fluid end and positioned adjacent each side of the passage of the front access port. In embodiments, the locking pins 120 can engage and substantially fit within the groove or notch 118 formed about the body of the cap or plug so as to lock the plug in a secured position enclosing and sealing the fluid access bore. In some embodiments, the locking pins can comprise shear pins, and in other embodiments, the locking pins can include threaded pins or bolts. Other pin connectors also can be used. In addition, in embodiments, the seals provided about the about the first end of the cap or plug further can expand as pressure is applied thereto during the operation of the pump to complete sealing of the front access port.

FIGS. 7A-7B illustrates still a further embodiment of a cover assembly 85 for enclosing and sealing access to the front access ports 24B of the fluid end 12 in accordance with the principles of the present disclosure. In the embodiment of FIGS. 7A and 7B, the cover assembly 85 includes a sliding cover plate 123—positioned along the front side 13B of the housing 13 of the fluid end 12. The sliding cover plate 123 can include a series of openings 124 formed at spaced locations therealong, and will be movable between a first position in which the openings 124 can be aligned with the front access ports 24B of the fluid end, and a second position in which the sliding cover plate 123 is shifted laterally such that the openings 124 of the cover plate 123 are misaligned with the front access ports 24B.

In embodiments, a plug or cap, such as discussed above, can be inserted into each of the front access ports, with one or more seals thereof engaging the side wall of the front access port and/or the second end or the cylinder bore, and with the with or without a threaded, pinned or other mechanical connection to further lock the plug or cap in place, and the sliding cover plate can be moved to its second position, covering and preventing access to and substantially securing each plug or cap within its front access port. In embodiments, the sliding cover plate can include a single sliding cover plate, while in other embodiments, can include multiple sliding cover plates each configured to cover one or more of the front access ports. In some embodiments, the sliding cover plate or plates can be manually moved between the first and second positions, or in other embodiments, can be moved mechanically, hydraulically, or pneumatically using, for example, a motor, hydraulic or pneumatic cylinder, or other actuator.

FIG. 8 discloses a further embodiment of a cylinder 20 of the fluid end 12. The construction of the cylinder 20 illustrated in FIG. 8 is substantially similar to discussed above with respect that FIGS. 2A-3C, and in the embodiment of FIG. 8, the plunger is shown as having been replaced with a piston 126. As shown in FIG. 8, the piston 126 generally can include an elongated body 127 having a first end 128 and a second end 129. A series of sealing rings, such as O-rings 131, can be positioned about the body of the piston, for example, being positioned adjacent the second or front end thereof, and a cap including a sealing ring can be received within the first end 23A of the cylinder bore and about the first end 128 of the piston, with the piston reciprocating therethrough. As the piston is reciprocated along the cylinder bore, the seals provided about the body of the piston will engage in the side wall of the cylinder bore to provide fluid sealing contact therewith. In this embodiment, a packing seal generally is not required.

The construction of the fluid ends and features thereof as described herein, can facilitate the installation, and servicing of such fluid ends and the operative components thereof to enable greater efficiencies in the servicing of high-power reciprocating pumps such as used for hydraulic fracturing and other applications in the oil and gas industry. For example, in embodiments, the cylinders of the fluid ends each can be constructed with a semi-linear, in-line configuration in which at least one valve of each cylinder (e.g., the discharge valve) is reoriented to position the valve and its corresponding valve bore along a horizontally extending axis of it associated cylinder, in a generally linear alignment with the cylinder bore so as to eliminate at least one cross-bore along the cylinder. Moreover, the cylinder bore of each bore can be accessible through a front access port of the fluid end and can have an increased size/diameter and wall configuration designed to enable access to and removal, servicing and replacement of substantially all of the operative components (including the valves, plunger or piston, and packing seal) contained within the cylinder from the front side of the fluid end of the pump.

In some example embodiments, a method of installation of the operative components of the fluid end can comprise positioning a packing assembly including a sleeve and a packing seal within each cylinder of the fluid end. In embodiments, during an initial construction and/or installation of the fluid end, the sleeve and packing seal can be positioned within each cylinder bore from the front or rear side of the housing of the fluid end. in some embodiments, a packing nut can be inserted into the cylinder bore and engaged therewith to secure the packing seal within the cylinder bore and seal the rear access bore of the fluid end. A plunger or piston further will be received within the cylinder bore, with the sleeve and packing seal being positioned between the plunger and a side wall of the cylinder bore.

The suction valve and discharge valve can then be positioned within their respective suction and discharge bores, before or after the installation of the plunger or piston. In embodiments, the valve seats of the suction and discharge valves can be located along the suction and discharge bores and urged into seated contact with corresponding surfaces of the side walls of their respective suction and discharge bores.

In embodiments, the valve seats will include an outer wall geometry, which can include a stepped profile, configured to fit with corresponding mating surfaces along the side walls of the suction and discharge bores can be urged into position with the seals of the valve seats in compressive engagement with the side walls. The construction of the valve seats does not require the valve seats to be forcibly engaged with the side walls of their bores and/or the cylinder bore using a substantial application of force to create an interference fit between the valve seats and the side walls of the bores. Rather, in embodiments, the seals and the geometry of the outer side walls of the valve seats enables the valve seats to be substantially maintained in their seated positions by the engagement of the seals with the side walls of the bores and by a differential pressure generated within the cylinder bore and the suction and discharge bores during a pumping operation. Thereafter, the cylinder bore can be closed/sealed by application of a cover assembly to or over a front access bore.

In embodiments, a method for servicing the fluid end is provided. In embodiments, to service the fluid end, which can include repairing a cylinder and/or the one or more of the operative components contained therein, the method may generally include removing a cover assembly from a front access port formed in the front side of the fluid end to open and provide direct front side access to the cylinder bore through the front side of the fluid end. Thereafter, in embodiments, the discharge valve can be from the cylinder bore through the front access port; and likewise the suction valve can be removed from the cylinder bore through the front access opening. Since the seals and the geometry of the outer walls of the valve seats of the suction and discharge valves enable the location and maintaining of the valve seats within their bores without being press-fitted in a tight interference fitting, special tools, such as hydraulic extraction tools, and the application of substantial force are not required to dislodge the valve seats for their removal. In addition, in embodiments, the plunger or piston can be removed from the cylinder bore from the front side of the fluid end through the front access port.

In some embodiments, the method further can comprise removing a packing seal from the cylinder bore through the front access port. By enabling front side access to and removal of the packing seal, a packing nut positioned at a first or upstream end of the cylinder bore and along a rear side of the fluid end does not have to be removed to remove the packing seal; and in some embodiments, the fluid end may not need to include a packing nut for sealing the cylinder bore. In some embodiments, the suction and discharge valves can comprise cartridge valve assemblies each including a plunger, a valve seat, and a spring coupled together to form a combined connected together valve structure. In such embodiments, the method of servicing can include removing each of the discharge valve and the suction valve as a unit.

In embodiments, as part of a servicing operation, the method further can comprise replacing the suction and discharge valves within the cylinder bore and engage the inner side wall thereof without an interference fit; wherein the valve seats of each of the suction and discharge valves each include one or more seals, and an outer wall having a stepped geometry configured to abut against a portion of an inner side wall of the cylinder bore such that the valve seats are held in place within the cylinder bore by a differential pressure generated within the cylinder bore. In embodiments, the method further comprises replacing the cover assembly within or over the front access port. In some embodiments, replacing the cover assembly can include positioning a plug within the cylinder bore. In embodiments, the plug can includes at least one seal and is configured such that as the plug is moved along the cylinder bore in engagement, the at least one seal is expanded into a locked condition within the cylinder bore.

In other embodiments, replacing the cover can comprise inserting a retainer into the cylinder bore through the front access port and engaging the retainer with a cap. In embodiments, the cap can be threadedly engaged with the front access bore such that as the cap is tightened into the front access bore, the retainer and one or more seals positioned thereabout can be engaged in compressive contact with the side walls of the cylinder bore. Alternatively, in other embodiments, a plug or cap can be inserted into the front access port and one or more locking pins placed through the fluid end and into engagement with a grove formed about the cap or the plug to secure the cap or plug in place covering the front access port. Still further, in another embodiment, the method can include inserting a plug or cap into each front access port and moving a sliding front access cover from a first, open position exposing the front access ports, to a second, closed position covering the front access ports.

Having now described some illustrative embodiments of the disclosure, it should be apparent to those skilled in the art that the foregoing is merely illustrative and not limiting, having been presented by way of example only. Numerous modifications and other embodiments are within the scope of one of ordinary skill in the art and are contemplated as falling within the scope of the disclosure. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, it should be understood that those acts and those elements may be combined in other ways to accomplish the same objectives. Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and/or configurations will depend on the specific application in which the systems, methods, and/or aspects or techniques of the disclosure are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments of the disclosure. It is, therefore, to be understood that the embodiments described herein are presented by way of example only and that, within the scope of any appended claims and equivalents thereto, the disclosure may be practiced other than as specifically described.

This application claims priority to, and the benefit of U.S. Provisional Application No. 63/758,455, filed Feb. 14, 2025, titled “SEMI-LINEAR FLUID END FOR PUMPS,” the disclosure of which is incorporated herein by reference in its entirety.

Furthermore, the scope of the present disclosure shall be construed to cover assembly various modifications, combinations, additions, alterations, etc., above and to the above-described embodiments, which shall be considered to be within the scope of this disclosure. Accordingly, various features and characteristics as discussed herein may be selectively interchanged and applied to other illustrated and non-illustrated embodiment, and numerous variations, modifications, and additions further may be made thereto without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

Claims

1. A fluid end for a pump, the fluid end comprising:

a housing having back side and a front side and including at least one cylinder bore extending through the housing from the back side of the housing to the front side of the housing;

wherein the at least one cylinder bore includes a pumping chamber and at least partially defines a fluid passage along which a fluid is moved through the housing;

a plunger at least partially received within the at least one cylinder bore and configured to reciprocate along a horizontal axis extending through the at least one cylinder bore to pump the fluid along the fluid passage from a fluid intake to a fluid outlet;

a discharge valve received within the at least one cylinder bore, the discharge valve being positioned along the fluid passage between the pumping chamber and the fluid outlet and substantially in alignment with the horizontal axis of the plunger; and

a suction valve located upstream from the discharge valve, the suction valve in communication with the pumping chamber and the fluid intake; and

wherein the at least one cylinder bore is configured to enable insertion and removal of the plunger, the discharge valve, and the suction valve from the front side of the housing.

2. The fluid end of claim 1, further comprising a packing seal positioned along the at least one cylinder bore and configured to create a fluid seal between the plunger and a surface of the at least one cylinder bore; and wherein the at least one cylinder bore is further configured to enable removal of the packing seal from the front side of the housing.

3. The fluid end of claim 2, wherein the fluid end does not include a packing nut along the back side of the housing to retain the packing seal within the at least one cylinder bore.

4. The fluid end of claim 1, wherein at least one of the discharge valve and the suction valve comprises a valve seat, plunger, and a biasing element coupled together to form a cartridge valve assembly.

5. The fluid end of claim 1, wherein each of the suction valve and the discharge valve comprises:

a valve seat having a first end, a second end including at least one seating surface, an outer peripheral wall configured to engage an inner side wall of the at least one cylinder bore, and a valve passage extending therethrough;

a plunger including a first portion received through the valve passage of the valve seat and a second portion configured to engage against the at least one seating surface of the valve seat so as to substantially deter passage of the fluid through the fluid passage; and

a spring coupled to the valve seat and to the plunger and configured to bias the plunger toward a closed position in engagement with the at least one seating surface of the valve seat.

6. The fluid end of claim 5, wherein at least one of the suction valve and the discharge valve further comprises at least one insert positioned along the plunger; and wherein the plunger comprises a first material and the at least one insert comprises a second material having a higher wear resistance, a higher coefficient of friction, or a combination thereof, than the first material.

7. The fluid end of claim 5, wherein the valve seat further includes one or more seals positioned along the outer peripheral wall; and wherein the outer peripheral wall of the valve seat includes a stepped wall geometry configured to engage and be held against the inner side wall of the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

8. The fluid end of claim 5, wherein the valve seat, the plunger, and the spring of each of the suction valve and the discharge valve are coupled together to form a cartridge valve assembly configured to be removed from the at least one cylinder bore as a unit.

9. The fluid end of claim 1, wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat is configured to seat along an inner side wall of the at least one cylinder bore in a non-interference fitting engagement so as to be maintained within the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

10. The fluid end of claim 9, further comprising one or more seals positioned along an outer peripheral wall of the valve seat.

11. The fluid end of claim 1, wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the plunger includes at least one wear resistant insert, layer, coating, or a combination thereof.

12. The fluid end of claim 1, further comprising a cover assembly configured to be received within a front access port formed in the housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the cylinder bore.

13. A fluid end for a pump, the fluid end comprising:

a housing having a front side, a rear side, and at least one cylinder bore defined therein;

wherein the at least one cylinder bore includes a pumping chamber and at least partially defines a fluid passage along which a fluid is moved through the housing;

at least one plunger or piston received within the at least one cylinder bore, the at least one plunger being reciprocated along the at least one cylinder bore for pumping a fluid through the fluid end along the fluid passage from a fluid intake to a fluid outlet;

a suction valve positioned between the pumping chamber and the fluid intake and configured to control intake of the fluid from the fluid intake into the pumping chamber;

a discharge valve received within the at least one cylinder bore, the discharge valve located along the fluid passage between the pumping chamber and the fluid outlet and configured to control release of the fluid from the pumping chamber to the fluid outlet;

wherein the discharge valve is positioned horizontally in-line with the plunger along the at least one cylinder bore; and

wherein at least one of the discharge valve and the suction valve comprises a cartridge valve configured to enable removal thereof as a unit; and

wherein the at least one cylinder bore is configured to enable insertion and removal of the discharge valve and the at least one plunger or piston through the front side of the housing.

14. The fluid end of claim 13, further comprising a packing seal received within the at least one cylinder bore between an outer surface of the at least one plunger and a surface of the at least one cylinder bore; and wherein the at least one cylinder bore is further configured to enable removal of the packing seal and the plunger from the front side of the housing.

15. The fluid end of claim 13, wherein the fluid end does not include a packing nut.

16. The fluid end of claim 13, further comprising a suction bore extending perpendicular to the cylinder bore between the fluid intake and the pumping chamber; wherein the suction valve is positioned along the suction bore.

17. The fluid end of claim 13, wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat is configured to seat along an inner side wall of the at least one cylinder bore in a non-interference fitting engagement so as to be maintained within the at least one cylinder bore by a differential pressure within the at least one cylinder bore.

18. The fluid end of claim 17, further comprising one or more seals positioned along an outer peripheral wall of the valve seat.

19. The fluid end of claim 13, wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the plunger includes at least one wear resistant insert, layer, coating, or a combination thereof.

20. The fluid end of claim 1, further comprising a cover assembly configured to be received within a front access port formed in the housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the at least one cylinder bore.

21. The fluid end of claim 1, wherein the fluid end comprises a plurality of cylinder bores.

22. A pump comprising:

a power end including a driver; and

a fluid end coupled to the power end, the fluid end comprising: a housing including: a plurality of cylinder bores extending through the housing from a rear side of the housing to a front side of the housing, a plurality of fluid intakes, a plurality of fluid outlets, and a pumping chamber positioned along each cylinder bore between each of the fluid intakes and fluid outlets; wherein a plurality of fluid passages are defined between the fluid intakes and fluid outlets; a plunger positioned within each cylinder bore, the plungers being configured to reciprocate in a horizontal direction along the cylinder bores for pumping a fluid along the fluid passages through the housing and to a discharge; a discharge valve received within each cylinder bore, the discharge valve being positioned along the fluid passage between the pumping chamber and the fluid outlet; wherein the discharge valve is positioned in-line with the plunger of its cylinder bore; and a suction valve located upstream from the discharge valve, the suction valve in communication with the pumping chamber and the fluid intake; wherein the suction valve and the discharge valve each include a valve seat and a plunger movable through the valve seat; and wherein the valve seat of each suction valve and discharge valve comprises an outer side wall having a geometry configured to seat against a portion of an inner side wall of the cylinder bore in a non-interference fitting engagement so as to enable the valve seat to be maintained within the cylinder bore by a differential pressure within the cylinder bore.

23. The pump of claim 22, further comprising a packing seal positioned adjacent a first end of each cylinder bore and configured to create a fluid seal about the plunger of each cylinder bore; and wherein each cylinder bore includes a front access port and is configured to enable insertion and removal of the discharge valve, plunger, and the packing seal received within each cylinder bore from the front side of the housing through the front access port.

24. The pump of claim 22, further comprising a cover assembly configured to be received within a front access port of each cylinder bore formed in the front side of housing for sealing the front access port; and wherein removal of the cover assembly from the front access port enables access to the cylinder bore.

25. The pump of claim 24, wherein each cover assembly comprises a cap having a body having a first end and a second end and a plurality of threads adjacent the second end and configured to engage with corresponding threads formed along the cylinder bore, and a plug having a geometry configured to engage a surface of the inner side wall of the cylinder bore as the cap is tightened thereagainst, and at least one seal; and wherein the plug is configured to be held in place within the cylinder bore by pressure acting on the at least one seal.

26. The pump of claim 24, wherein each cover assembly comprises a cap having a body having a first end and a second end, and at least one groove formed between the first and second ends; a plug configured to fit within the cylinder bore; and one or more pins received through a vertical locking bore formed in the housing and into engagement with the at least one groove to hold the cap and plug within the housing.

27. The pump of claim 24, wherein each cover assembly comprises a plug configured to be received within the cylinder bore, a cap adapted to fit within the front access port and retain the plug within the cylinder bore; and further comprising a cover positioned along the front side of the housing and configured to slide along the housing from a first position covering the caps of the cover assemblies and a second position enabling access to the cover assemblies.

28. The pump of claim 22, wherein one or more of the valve seats, plunger, and the housing comprise a first material, and further include one or more inserts of a second material having a wear resistance that is greater than a wear resistance of the first material.

29. The pump of claim 21, wherein the housing of the fluid end comprises a cast metal material.

30. A method for servicing a fluid end of a pump, comprising:

removing a cover assembly from a front access port formed in a front side of the fluid end;

accessing and removing a discharge valve from a cylinder bore of the fluid end through the front access port;

removing a suction valve from the cylinder bore through the front access opening; and

removing a plunger or piston from the cylinder bore through the front access opening; and

wherein the cylinder bore is configured with an expanded diameter sufficient to enable the discharge valve, suction valve, and plunger to be removed from the front side of the fluid end.

31. The method of claim 30, further comprising removing a packing seal from the cylinder bore through the front access opening.

32. The method of claim 31, wherein the fluid end comprises a plurality of cylinders, each cylinder including a cylinder bore extending through the fluid end from a first end located at a rear side of the fluid end to a second end located at the front side of the fluid end; and a packing nut received within the first end of the cylinder bore along the rear side of the fluid end for sealing the packing seal within the cylinder bore from the rear side of the fluid end; and wherein removing the packing seal does not include removing the packing nut from the cylinder bore.

33. The method of claim 30, wherein the discharge valve is positioned within a discharge bore that is oriented substantially horizontally in-line with the cylinder bore.

34. The method of claim 30, wherein the suction valve and the discharge valve each comprise a cartridge valve assembly including a plunger, a valve seat, and a spring coupled together; and wherein the discharge valve and the suction valve are removed from the cylinder bore as a unit.

35. The method of claim 30, wherein the suction valve and the discharge valve each comprise a plunger, a valve seat though which the plunger is received, and a spring; and further comprising replacing the valve seat of the suction valve within a suction bore and the discharge valve without an interference fitting; and wherein the valve seats of each of the suction and discharge valves each include one or more seals, and an outer wall having a stepped geometry configured to abut against a portion of an inner side wall of the cylinder bore such that the valve seats are held in place within the cylinder bore by a differential pressure generated within the cylinder bore.

36. The method of claim 30, further comprising inserting a packing seal, plunger, suction valve and a discharge valve within the cylinder bore through the front access port, and replacing the cover assembly within the front access port.