Hydraulic fluid pump and retainer assembly for same

1. A method of assembling and preloading a removable valve cover within a fluid end assembly of a hydraulic fracturing fluid pump, the method comprising:

inserting the removable valve cover into a first bore of a monolithic housing of the fluid end assembly, the monolithic housing defining a plurality of pairs of intersecting bores, wherein each pair of intersecting bores defines an internal volume, so that the monolithic housing includes a plurality of laterally spaced internal volumes configured to receive fluid from an inlet manifold of the hydraulic fracturing fluid pump;

threading a set screw into a set screw bore via a first side of a retainer, the set screw bore extending from the first side of the retainer to a second side of the retainer, opposite the first side, and the set screw bore including a threaded portion extending from the first side and a non-threaded portion extending from the second side;

inserting the retainer into the first bore of the monolithic housing such that the first side of the retainer is adjacent to the removable valve cover; and

adjusting an axial position of the set screw within the set screw bore to extend through a plane defined by the first side and to concurrently apply a preload to the removable valve cover by inserting an adjustment tool through the non-threaded portion of the set screw bore and into the threaded portion of the set screw bore.

2. The method of claim 1 , wherein inserting the retainer into the first bore of the monolithic housing includes threading the retainer into the first bore of the monolithic housing.

3. The method of claim 1 , wherein inserting the retainer into the first bore of the monolithic housing includes axially inserting the retainer into the first bore of the monolithic housing and then rotating the retainer relative to the first bore of the monolithic housing to position one or more peripheral lobes of the retainer into a recessed channel of the first bore of the monolithic housing.

4. The method of claim 1 , wherein the set screw is threaded into the set screw bore prior to inserting the retainer into the first bore of the monolithic housing.

5. The method of claim 1 , wherein inserting the removable valve cover includes placing the removable valve cover in a sealing position, and wherein applying the preload holds the removable valve cover in the sealing position.

6. The method of claim 1 , wherein the retainer defines a backstop such that the adjusting of the axial position in a direction away from the removable valve cover over a predetermined distances moves the set screw into abutment with the backstop.

7. The method of claim 1 , wherein the fluid end assembly comprises a reciprocating piston operable to pressurize fluid at the removable valve cover.

8. The method of claim 1 , wherein the first bore of the monolithic housing is one of an outlet valve bore or a service bore.

9. A fluid end assembly of a hydraulic fracturing fluid pump comprising:

a monolithic housing defining a plurality of pairs of intersecting bores, wherein each pair of intersecting bores defines an internal volume, so that the monolithic housing includes a plurality of laterally spaced internal volumes configured to receive fluid from an inlet manifold of the hydraulic fracturing fluid pump;

a removable valve cover closing a first bore of the plurality of pairs of intersecting bores defined by the monolithic housing, the removable valve cover being positioned within the first bore of the monolithic housing;

a retainer positioned within the first bore of the monolithic housing and engaging the first bore of the monolithic housing, the retainer comprising a set screw bore that extends from a first side of the retainer to a second side of the retainer, opposite the first side; and

a set screw threaded into the set screw bore from the first side of the retainer, wherein the set screw is not removable from the second side of the retainer, and wherein the first side of the retainer is positioned adjacent to the removable valve cover.

10. The fluid end assembly of claim 9 , wherein the first bore of the monolithic housing is a threaded bore, and wherein the retainer includes external threads that engage threads of the first bore of the monolithic housing.

11. The fluid end assembly of claim 9 , wherein the first bore of the monolithic housing includes a recessed channel, and wherein the retainer includes a plurality of peripheral lobes that engage the recessed channel.

12. The fluid end assembly of claim 9 , wherein the first side of the retainer is in facing relation with the removable valve cover.

13. The fluid end assembly of claim 9 , wherein the first side defines a plane, and wherein the set screw is positioned within the plane to abut the removable valve cover.

14. The fluid end assembly of claim 9 , wherein the set screw includes a tool interface, wherein the set screw is drivable via the tool interface in a first direction into abutment with the removable valve cover and in a second direction into abutment with a backstop integral with the retainer.

15. The fluid end assembly of claim 9 , wherein the set screw is operable to preload the removable valve cover.

16. The fluid end assembly of claim 9 , wherein the first bore of the monolithic housing is one of an outlet valve bore or a service bore.

17. The fluid end assembly of claim 9 , further comprising a reciprocating piston operable to pressurize fluid at the removable valve cover.

18. The fluid end assembly of claim 9 , wherein the set screw bore includes a threaded portion extending from the first side and a non-threaded portion extending from the second side.

19. The fluid end assembly of claim 9 , wherein the set screw is threaded into the set screw bore prior to positioning the retainer within the first bore of the monolithic housing.