Fluid end access cover locking mechanism

Abstract

A reciprocating fluid end access port plug includes an access plug body, expansion assembly and bolt. The access plug body can be shaped and sized to be received within the fluid end access port to inhibit a flow of fluid therethrough, and can define an inner end surface, an outer end surface defining an axially aligned threaded aperture, and a generally cylindrical wall extending therebetween. The expansion assembly can be configured to securely retain the access plug body in a desired plug position within the fluid end access port, and can include a locking drive member defining an aperture generally aligned with the threaded aperture of the access plug body, and a plurality of radially positioned locking segments. The bolt can have a threaded shaft configured to traverse through the aperture of the expansion assembly for threaded contact with the threaded aperture of the access plug body.

Description

RELATED APPLICATION INFORMATION[0001]This application claims the benefit of U.S. Provisional Application No. 62 / 635,300, filed Feb. 26, 2018, the contents of which are fully incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates generally to positive displacement fluid end plugs, and, in particular, to positive displacement fluid end plugs fixed by threaded rotation.BACKGROUND[0003]Oil and gas is commonly extracted from subsurface rock formations of the earth using a process called hydraulic fracturing, a technique that increases rock permeability by opening channels through which hydrocarbons can flow to recovery wells. In hydraulic fracturing, fluid is pumped into the rock formations at pressures that exceed the critical fracture pressure of the rock formations (sometimes as high as 50,000 PSI), where the high pressure fluid enters a reservoir rock and cracks or fractures it. Large quantities of solids or proppants are carried in suspension by the flui...

AI Technical Summary

Benefits of technology

The present disclosure provides a reciprocating pump fluid end access port plug that can handle excessive pressures and cyclical loading without causing a breakdown of the internal threading of the access port or shortening the serviceable life of the fluid end. The plug includes an access plug body with a threaded aperture, an expansion assembly, and a bolt. The expansion assembly includes a locking drive member and a plurality of radially positioned locking segments with tabs that secure the access plug body in a desired position within the access port. The bolt is used to increase the threaded connection between the access plug body and the expansion assembly, causing the locking segments to expand radially outward and into contact with the inner radius of the access port. This design ensures secure placement of the plug within the access port and provides a reliable connection to the fluid end for continued use in the pump.

Problems solved by technology

As the fluid end is subjected to high pressurization and depressurization, which can occur up to three times per second as the pump reciprocates, the fluid ends are prone to cracking and failure due to metal fatigue.

Friction, temperature, and exposure to corrosive elements can also take a toll on the material components.

To avoid failure while in service, generally the retaining nut 68 must be tightened down to a specific torque limit, which represents an added maintenance burden.

Over time the internal threads of the access ports can become worn (or even stripped) as they are continually subjected to stress during operation; particularly if they are frequently removed for internal inspection or maintenance.

Premature failure of the access port threads and / or seizing between the threads and the access port plug typically marks the end of the serviceable life of the fluid end, as the fluid end cannot function without the access ports properly sealed.

Replacement of the fluid end 52 is costly and results in maintenance down time.

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