Nut Anti-Rotation Fluid End Assemblies

This application claims priority to and benefit of U.S. Provisional Patent Application No. 63/649,548, entitled “NUT ANTI-ROTATION FLUID END ASSEMBLIES,” filed May 20, 2024, the contents of which are incorporated in their entirety for all purposes.

The present disclosure relates generally to reciprocating pumps; and more particularly, but not by way of limitation, to fluid end assemblies.

Reciprocating pumps, also known as positive displacement pumps, are used in many applications and industries to convert mechanical energy into hydraulic energy. Reciprocating pumps generally include two sections: a power end and a fluid end. The power end is configured to move one or more plungers toward, and away from, the fluid end. The fluid end is where the pumping takes place-fluid is drawn in and forcibly pushed out at a high pressure by the plungers.

The present disclosure provides a fluid end assembly for a reciprocating pump that addresses face cracks occurring around a preload-applying nut as a result of pressure pulse-induced vibrations. The fluid end assembly includes a nut in threaded engagement with a body of a fluid end of a reciprocating pump. The nut applies compressive preload to a cover and tensile preload to at least one thread of the body. The fluid end assembly further includes a retainer capable of restricting rotation of the nut relative to the body. Stated differently, the retainer restricts the nut from backing out from the at least one thread of the body such that the tensile preload is maintained between at least one thread of the nut and the at least one thread of the body, and the compressive preload is maintained on the cover. In this way, the fluid end assembly reduces the likelihood of face cracks occurring in the body around the nut.

In an example, the retainer includes an internal retaining ring that can be inserted into a groove of the body of the fluid end, subsequent to preload being applied to the cover, such that the internal retaining ring restricts rotation of the nut to maintain the preload. In another example, the retainer includes a plurality of tabs that can be inserted into the groove and coupled to the nut, subsequent to preload being applied to the cover, such that the plurality of tabs restrict rotation of the nut. In another example, the retainer includes a plurality of spring-loaded detents that may be coupled to the nut prior to preload being applied to the cover. The spring-loaded detents are biased into indents of the body of the fluid end to restrict rotation of the nut. While the different examples of the retainer are described herein in the context of a fluid end assembly, the retainer embodiments may be used in other systems.

In some embodiments, the cover of the fluid end assembly includes a conical portion and the nut includes a split end resembling a split lock nut. The split endis disposed around the conical portion such that conical portion forces threaded tabs of the split end into at least one thread of the body of the fluid end assembly, thereby discouraging rotating of the nut. While the cover including the conical portion and the nut including the split end are described herein in the context of a fluid end assembly, these embodiments of the cover and nut may be used in other systems.

In some embodiments, the fluid end assembly may include a component for determining a value of the preload applied to the cover. For example, the fluid end assembly may include a piston (e.g., a hydraulic piston) used for determining a value for the preload applied. In another example, the fluid end assembly may include a custom load cell capable of measuring a value of the compressive load between the nut and the cover.

Any implementation of any of the apparatuses, systems, and methods can consist of or consist essentially of—rather than comprise/include/have—any of the described steps, elements, and/or features. Thus, in any of the claims, the term “consisting of” or “consisting essentially of” can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb. Additionally, it will be understood that the term “wherein” may be used interchangeably with “where.”

Further, a device or system that is configured in a certain way is configured in at least that way, but it can also be configured in other ways than those specifically described. Aspects of one example may be applied to other examples, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of a particular example. Some details associated with the aspects described above and others are described below.

Some details associated with the aspects are described above, and others are described below. Other implementations, advantages, and features of the present disclosure will become apparent after review of the entire application, including the following sections: Brief Description of the Drawings, Detailed Description, and the Claims.

Referring to, a reciprocating pumpis shown. Reciprocating pumphas two sections: a power endand a fluid end. Power endis configured to move one or more plungers toward, and away from, fluid end. Fluid endis where the pumping takes place-fluid is drawn in and forcibly pushed out at a high pressure by the plungers.

Power endincludes a plurality of plunger assemblies, a plurality of crankshaft assemblies, and a power end frame assembly having a plurality of bearing plates. Becauseis a cross-section view of reciprocating pump, only one plunger assembly, crankshaft assembly, and bearing plateis shown. Each plunger assemblyincludes a plunger, a crosshead, and a connecting rod. Plungeris coupled to crossheadvia a ponyrod. Connecting rodcouples crossheadto crankshaft assemblyvia rod cap.

Each crankshaft assemblyhas at least a portion partially positioned within an openingon bearing plateand includes a crankshaftand a crankshaft bearingaround crankshaft. Crankshaft bearingis supported by openingand couples crankshaftto bearing platewhile allowing crankshaftto rotate within opening. Adjacent bearing platesof the power end frame assembly form receptaclesthat accommodate crossheadand configure crossheadto displace linearly as crankshaftrotates.

Fluid endincludes a fluid end assemblyhaving a plurality of bodies, each bodyhaving a chamber, an inlet port, a discharge port, and an access port. Becauseis a cross-section view of reciprocating pump, only one bodyis shown. Chamberis configured to receive a plunger portion of plungerand allow the plunger portion to reciprocate within chamber. Inlet portincludes an inlet valveand is configured to receive a fluid and direct the fluid to enter chamber. Discharge portincludes a discharge valveand is configured to receive the fluid from chamberand direct the fluid to exit body. Access portincludes a coverthat is removable to allow access to components of bodyand/or fluid end assembly. Access portfurther includes a nutthat may be threaded into the bodyof the access port.

Reciprocating pumpincreases pressure of the fluid in chamberby reciprocating plungerlongitudinally within chamber. As a result, low-pressure fluid enters chambervia inlet portand high-pressure fluid exits chamberand is discharged via discharge port. During operation of the reciprocating pump, the nutapplies compressive force to the coverthat counteracts the force of the pressure in chamberthat acts upon the cover.

Fluid ends of conventional reciprocating pumps can suffer from face cracks occurring around nutas a result of pressure pulse-induced vibrations. For instance, the pressure pulse-induced vibrations may cause nutto back out (e.g., rotate counterclockwise) from the at least one thread of bodyof access port, which reduces the tensile preload between the at least one thread of nutand the at least one thread of body. The loss of tensile preload accelerates fatigue of the at least one thread of body, thereby eventually resulting in face cracks in bodyaround nut.

Fluid end assemblyof reciprocating pumpaddresses this problem by including a retainerconfigured to restrict rotation of nutrelative to body. Stated differently, retainerrestricts nutfrom backing out from the at least one thread of bodysuch that the tensile preload is maintained between the at least one thread of nutand the at least one thread of body. In this way, fluid end assemblyreduces the likelihood of face cracks occurring in bodyaround nut. The retaineris depicted as a retaining ring in, though may have other suitable configurations as will be described below.

is a box diagram of fluid end assembly. As described, fluid end assemblyincludes body. Bodyincludes a borethat defines access port. Bodyfurther includes at least one thread(e.g., at least one interior thread). In various examples, the at least one threadmay be a buttress thread, though can be other suitable thread forms in other examples. Fluid end assemblyalso includes coverand nutthat are each configured to be disposed within bore. Nutincludes at least one thread(e.g., at least one exterior thread) capable of engaging with the at least one thread. In various examples, the at least one threadmay be a buttress thread, though can be other suitable thread forms in other examples. Fluid end assemblyfurther includes retainerthat is also configured to be disposed within bore. In some embodiments, retainermay be omitted.

illustrate a portion of a first embodiment of fluid end assemblyincluding a first embodiment of retainer. In this first embodiment of retainer, retainerincludes a retaining ringA (e.g., an internal retaining ring). Cover, nut, and retaining ringA are each shown disposed within boreof bodyin. The at least one threadof nutis engaged with the at least one threadof bodysuch that nutcompresses coveragainst body. In this way, nutapplies a compressive preload on the cover. For instance, with the aid of a tool, nutmay be tightened relative to bodyby rotating nutclockwise to apply the compressive preload. Tightening nutalso applies tensile preload on the at least one threadof bodyvia the at least one threadof nut.

Retaining ringA maintains the compressive preload and the tensile preload by restricting nutfrom backing out of the at least one thread. For instance, bodyincludes a groovein which retaining ringA may be disposed. Retaining ringA disposed in the groovethereby restricts nutfrom rotating counterclockwise by blocking nutfrom advancing towards the mouth of bore. Retaining ringA may be inserted into groovesubsequent to the compressive and tensile preloads being applied. For instance, retaining ringA may be deformed so that retaining ringA can be inserted into bore, and then released such that retaining ringA snaps back to a pre-deformed state into groove.

In some instances, the end of nutdoes not contact retaining ringA after the preload is applied. In such instances, nutmay marginally rotate counterclockwise and back out from bore, thereby marginally reducing the applied preload, until nutcontacts retaining ringA and is thereafter restricted from rotating.

illustrate a portion of the first embodiment of fluid end assemblyincluding a second embodiment of retainer. Only the differences between the first and second embodiments of retainerwill be described. In this second embodiment, retainerincludes a plurality of tabsB coupled to nut. For example, the plurality of tabsB may include tabsA,B, andC. TabsA,B, andC are coupled to nutvia a plurality of boltsinserted into openingsof nut. In other embodiments, tabsA,B, andC may be coupled to nutin other suitable manners. Similar to the first embodiment, tabsA,B, andC may be inserted into grooveof bodysuch that nutis blocked from advancing towards the mouth of bore. TabsA,B, andC may be inserted into groove, and coupled to nut, subsequent to the compressive and tensile preloads being applied.

illustrate a portion of the first embodiment of fluid end assemblyincluding a third embodiment of retainer. Only the differences between the third embodiment and the first and second embodiments of retainerwill be described. In this third embodiment, retainerincludes a plurality of spring-loaded detentsC. For example, the plurality of spring-loaded detentsC may include spring-loaded detentsA,B,C, andD. Each of spring-loaded detentsA,B,C, andD are coupled to nut. For example, as shown in, spring-loaded detentA (as a representative example of the plurality of spring-loaded detentsC) includes a body having at least one thread, and a detentbiased by a spring (not shown) to be partially exterior to the body. The plurality of spring-loaded detentsC may each be coupled to nutvia respective at least one threadsin this example. In other examples, each of the plurality of spring-loaded detentsC may be coupled to the nutin another suitable manner. In other embodiments, each of the plurality of spring-loaded detentsC may be integral with the nut.

Bodyis shown into include a plurality of indentsdisposed near the mouth of bore. While nutis advanced into bore, each of the respective detentsis forced by bodyto retract against the biasing force of the respective springs until each of the respective detentsis aligned with a respective indent of the plurality of indents. At that point, the respective springs force the plurality of spring-loaded detentsC into the plurality of indents. When each of the plurality of spring-loaded detentsC are disposed in each of the plurality of indents, the nutis restricted from rotating relative to body. The compressive and tensile preloads are thereby maintained.

In some instances, the plurality of spring-loaded detentsC are not perfectly aligned with the plurality of indentsafter the preload is applied. In such instances, nutmay marginally rotate counterclockwise and back out from bore, thereby marginally reducing the applied preload, until the respective springs force the plurality of spring-loaded detentsC into the plurality of indents.

In some embodiments, the retaining ringA and the groove, or the plurality of tabsB and the groove, may be included with fluid end assemblyin addition to the plurality of spring-loaded detentsC.

illustrate a portion of a second embodiment of fluid end assembly. In this second embodiment, coverincludes a conical portion. Additionally, nutresembles a split lock nut. For example, nutincludes a split endthat includes a plurality of tabsA,B such that a gapexists between adjacent tabsA,B.

As shown in, split endis configured to be disposed around conical portionsuch that conical portionforces the plurality of tabsA,B in the direction of arrows, away from a central axisextending through nut. For example, an exterior diameter (e.g., distance between outer exterior surfaces) of conical portionis larger than an interior diameter (e.g., distance between opposing interior surfaces of tabsA,B) of split endsuch that when split endis torqued onto conical portion, conical portionforces tabsA,B into the at least one threadof body. As a result, there is greater force engagement between the at least one threadof bodyand the at least one threadof nut, which increases the resistance against nutrotating counterclockwise relative to body, and thereby improves the consistency of the preload applied to cover.

In some embodiments, retaining ringA and the groove, or the plurality of tabsB and the groove, or the plurality of spring-loaded detentsC and the plurality of indentationsmay be included with the second embodiment of fluid end assembly. In some embodiments, a combination of retaining ringA and the plurality of spring-loaded detentsC, or a combination of the plurality of tabsB and the plurality of spring-loaded detentsC, may be included with the second embodiment.

The above-described embodiments of fluid end assemblyand retainerallow for improving the consistency of preloaded applied to coverduring an instance of operation of reciprocating pump. In some embodiments, fluid end assemblymay include a component for determining a value of the applied preload. For example, preload is typically applied manually by an operator, such as by using a hammer and a torque wrench. The various operators that apply the preload can have different strengths, thereby leading to inconsistently applied preloads. It may be beneficial in certain applications, however, to apply a consistent preload across different instances of operation of the reciprocating pump. Additionally or alternatively, it may be beneficial in certain applications to ensure that a predetermined value of preload is applied to cover.

illustrate a portion of a third embodiment of fluid end assemblythat includes a piston(e.g., a hydraulic piston) used for determining a value for the preload applied. As shown in, pistonmay be disposed between coverand nut. Oil is disposed in a gapbetween pistonand nut. Fluid end assemblyfurther includes a hydraulic fittingdisposed within a channel of the nut.

In this third embodiment of fluid end assembly, when assembling fluid end assembly, nutis advanced all the way into bore, but torque need not be applied to build preload. Rather, with nutadvanced into bore, pistonis pressurized in order to apply the compressive preload and the tensile preload. Because a diameter of pistonand a pressure of the oil in gapare known, the compressive and tensile preloads applied can be determined as a product of the oil pressure multiplied by a surface area of a faceof piston.

It should be appreciated that the third embodiment of fluid end assemblyis not limited to including retaining ringA as retainer, as shown in. For example, in other embodiments, retaining ringA may be replaced by the plurality of tabsB, or by the plurality of spring-loaded detentsC. In other embodiments, a combination of retaining ringA and the plurality of spring-loaded detentsC may be utilized. In other embodiments, a combination of the plurality of tabsB and the plurality of spring-loaded detentsC may be utilized.

illustrate a portion of a fourth embodiment of fluid end assemblythat includes a load cellused for determining a value for the preload applied. As shown in, load cellmay be the disposed between coverand nut. Load cellis a custom load cell configured to measure a value of the compressive load between nutand cover. In an example, when load cellis under load and is deformed, the electrical properties (e.g., resistance) of load cellare changed. The electrical properties can be measured and serve as a proxy for measuring the preload applied.

It should be appreciated that the fourth embodiment of fluid end assemblyis not limited to including the plurality of spring-loaded detentsC as retainer, as shown in. For example, in other embodiments, the plurality of spring-loaded detentsC may be replaced by retaining ringA or the plurality of tabsB. In other embodiments, a combination of retaining ringA and the plurality of spring-loaded detentsC may be utilized. In other embodiments, a combination of the plurality of tabsB and the plurality of spring-loaded detentsC may be utilized. In other embodiments, retainermay be omitted.

Referring to, a methodof assembling a fluid end assembly (e.g., fluid end assembly) of a fluid end (e.g., fluid end) of a reciprocating pump (e.g., reciprocating pump) is provided. Methodincludes, at block, providing a cover (e.g., cover) in a bore (e.g., bore) of a body (e.g., body) of the fluid end. At block, a nut (e.g., nut) is advanced into the borevia engagement between at least one first thread (e.g., at least one first thread) of the bodyand at least one second thread (e.g., at least one second thread) of the nutso that the nutcontacts the cover. In some aspects, advancing the nutinto the boreincludes advancing a split end (e.g., split end) of the nutonto the cover. In such aspects, the covermay include a conical portiononto which the split endis advanced.

In some aspects, a piston (e.g., piston) is provided in the boresubsequent to providing the coverin the boreand prior to advancing the nutinto the bore. In some aspects, a load cell (e.g., load cell) is provided in the boresubsequent to providing the coverin the boreand prior to advancing the nutinto the bore.

At block, a preload is applied to the cover. In some aspects, the preload may be applied by torquing the nut. For example, the nutmay be manually torqued, such as by using a torque wrench (e.g., a hydraulic torque wrench). In other aspects, the preload may be applied by pressurizing the piston. In some aspects, a predetermined amount of preload is applied to the cover. For example, the pistonmay be pressurized an amount corresponding to the predetermined amount preload so that the predetermined amount preload is applied. In another example, the amount of preload applied can be determined via load cell, and thus the nutmay be torqued until the predetermined amount of preload is achieved.

At block, a retainer (e.g., retainer) is applied such that the retainerrestricts rotation of the nutrelative to the body. The retaineris applied subsequent to the preload being applied to the cover. For example, the retainermay be a retaining ringA that is applied by being inserted into a groove (e.g., groove) of body. When in the groove, the retaining ringA is disposed relative to the nutsuch that the retaining ringA restricts rotation of the nutrelative to the body. In another example, retainermay be a plurality of tabs (e.g., plurality of tabsB) that are applied by being inserted into the grooveand coupled to the nut. When in the groove, the plurality of tabsB are disposed relative to the nutsuch that the plurality of tabsB restrict rotation of the nutrelative to the body. In another example, the retainermay be a plurality of spring-loaded detents (e.g., plurality of spring-loaded detentsC) that are applied by being inserted into a plurality of indents (e.g., plurality of indents) of body. When in the plurality of indents, the plurality of spring-loaded detentsC are disposed relative to the nutsuch that the plurality of spring-loaded detentsC restrict rotation of the nutrelative to the body.

The above specification and examples describe the structure and use of illustrative implementations. Although certain examples have been described above with some particularity, or with reference to one or more individual examples, those skilled in the art could make numerous alterations to the disclosed implementations without departing from the scope of this invention. So the various illustrative implementations of the methods and systems are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and examples other than the one shown may include some or all of the features of the depicted example. For example, elements may be omitted or combined as a unitary structure, and/or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form more examples having comparable or different properties and/or functions and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several implementations.

In a first aspect, a fluid end assembly includes a body defining a bore and including at least one first thread, a cover configured to be disposed within the bore, a nut including at least one second thread, and a retainer configured to be disposed relative to the nut such that the retainer restricts the nut from rotating relative to the body. The at least one second thread is configured to engage with the at least one first thread such that, when the at least one second thread is engaged with the at least one first thread, the nut applies compressive force to the cover.

In a second aspect, in combination with the first aspect, the at least one first thread and the at least one second thread each include buttress threading.

In a third aspect, in combination with one or more of the first through the second aspects, the nut is disposed between the cover and the retainer.

In a fourth aspect, in combination with one or more of the first through the third aspect, the body defines a groove configured to receive the retainer.

In a fifth aspect, in combination with one or more of the first through the fourth aspect, the retainer includes a retaining ring.

In a sixth aspect, in combination with one or more of the first through the fourth aspect, the retainer includes a plurality of tabs coupled to the nut.

In a seventh aspect, in combination with one or more of the first through the sixth aspect, the retainer includes a plurality of spring-loaded detents.

In an eighth aspect, in combination with the seventh aspect, the body defines a plurality of indents configured to receive the plurality of spring-loaded detents.

In a ninth aspect, in combination with one or more of the first through the eighth aspect, the fluid end assembly further includes a hydraulic piston disposed between the cover and the nut.

In a tenth aspect, in combination with one or more of the first through the ninth aspect, the fluid end assembly further includes a load cell disposed between the cover and the nut and configured to determine a compressive load between the cover and the nut.