Self-Locking Plug Assembly for Leak-Resistant Fluid Ends
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Solution Overview
Problem
Existing plug configurations in pumping systems, particularly in hydraulic fracturing, rely on threaded interfaces that fail under pressure and load cycling, leading to leaks and operational issues due to inadequate loading and torque dependency.
Innovation Solution
A self-locking plug assembly that utilizes the natural outward pressure of the fluid end to drive a lock ring radially outward into a groove, eliminating the need for direct threading and relying on axial forces to maintain the plug's position, using a lock ring and retaining plate mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded interfaces are used to secure the plug, then the plug can be installed and retained in the bore, but the threaded connections fail under pressure and load cycling causing leaks
Solution Approach 1:
The patent removes the threaded interface component entirely from the plug assembly. Instead of using threads to secure the plug, the design extracts the fastening function and replaces it with a self-locking mechanism where the plug body itself engages with the bore through radial expansion, eliminating the weak threaded connection point that fails under pressure cycling.
Solution Approach 2:
The plug assembly performs its own locking function without external fasteners. The plug body is designed to expand radially under axial loading, causing the outer surface to engage directly with the bore wall. This self-service mechanism eliminates dependency on separate fastening components and creates a unified locking system that responds directly to operating pressures.
2Reliability
If axial forces are applied to secure the plug, then the plug position is maintained under pressure, but the design becomes more complex requiring additional components
Solution Approach 1:
The patent combines the plug body and locking mechanism into a single integrated component. The plug body includes both the sealing function and the self-locking function through its geometric design. This merging eliminates the need for separate locking rings, retainers, or fasteners, reducing component count while maintaining position stability under axial loading and pressure differentials.
Solution Approach 2:
The plug assembly transitions from a static fastened state to a dynamic self-adjusting state. Under axial loading and pressure differentials, the plug body automatically expands radially to engage the bore wall, creating a dynamic locking action that adapts to operating conditions. This dynamic behavior replaces complex static fastening systems with a simpler pressure-responsive mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The self-locking plug assembly effectively reduces the likelihood of leakage by maintaining the plug's position under increased pressure without relying on threaded connections, enhancing the durability and reliability of pumping systems.
Implementation Method 1
The lock ring is positioned to be driven radially outward responsive to a longitudinal force applied to the plug body
Data Source
AI summary
A fluid end, includes a plunger reciprocating within a first bore, the plunger increasing a pressure of a fluid within a pressure chamber. The fluid end also includes a second bore. The fluid end further includes a plug assembly associated with the second bore. The plug assembly includes a plug body positioned within the second bore. The plug assembly also includes a lock ring positioned, at least in part, within the second bore, the lock ring positioned to be driven radially outward responsive to a longitudinal force applied to the plug body.