Inverted Tail Plug Assembly for Gas Lift Valve Leak Sealing
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Solution Overview
Problem
Gas lift valves in oil and gas wells suffer from leaks at the interface between the tail plug and the gas injection valve core, leading to inefficiencies and operational challenges, including costly delays and equipment failures.
Innovation Solution
The design incorporates an NPT thread for connecting a brass tail plug to a stainless-steel bore, with the crush washer positioned closer to the top and an O-ring seal groove, enhancing the leak-proof barrier by ensuring a tighter seal, even under extreme pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional tail plug design is used with basic sealing components, then the device complexity is low, but gas/pressure leaks occur at the interface between the tail plug and gas injection valve core
Solution Approach 1:
The sealing system is divided into multiple independent components: an O-ring seal positioned in a first groove, a crush washer positioned in a second groove, and an inverted tail plug design. This segmentation allows each component to address specific sealing challenges at different locations, preventing gas leaks through multiple potential failure points without creating a single complex integrated solution
Solution Approach 2:
The crush washer acts as an intermediary element between the inverted tail plug and the gas injection valve core interface. This intermediate component provides additional sealing capability and distributes clamping forces, preventing direct contact issues between the tail plug and valve core while enhancing the overall seal integrity without requiring complete redesign of either component
2Reliability
If the tail plug is tightened to ensure sealing, then the seal improves, but the gas injection valve core threads may strip under excessive torque
Solution Approach 1:
The crush washer is positioned to provide cushioning protection before the full tightening force is applied to the threads. This intermediate compliant layer absorbs excess torque and distributes clamping forces, preventing thread stripping while still achieving the necessary seal compression. The cushioning effect occurs before thread failure can happen, protecting the vulnerable threaded interface
Solution Approach 2:
The inverted tail plug design changes the geometric parameters of the sealing interface, positioning the sealing surface and thread interface at different locations. This parameter change allows the sealing force to be applied optimally without concentrating excessive stress on the threads, separating the sealing function from the threading function to prevent thread stripping
3Strength
If the tail plug is loosened to protect threads, then thread stripping is prevented, but gas/pressure leaks increase
Solution Approach 1:
The sealing function is segmented from the fastening function by using multiple components: the O-ring provides primary sealing, the crush washer provides secondary sealing and torque distribution, and the inverted tail plug provides mechanical fastening. This segmentation allows the tail plug to be loosened slightly to protect threads while the dedicated sealing components maintain effective sealing without requiring excessive clamp force
Solution Approach 2:
The crush washer serves as a mediator that maintains seal effectiveness even when the tail plug is not fully tightened. This intermediate component compensates for reduced clamping force by providing its own sealing mechanism and distributing the available force more evenly, preventing leaks without requiring high tightening torque that would risk thread stripping
Data Source
AI summary
Embodiments of the present invention relate to an improved tail plug and assembly for a gas lift valve for use in oil and gas wells. The tail plug assists in preventing a pressurized component of the gas lift valve from depressurizing through leaks in the valve to the ambient. At least portion of the tail plug may be maintained in the gas lift valve via a treaded connection. The tail plug may further prevent leaks via an O-ring and/or a crush washer, where the O-ring and/or the crush washer are located on the tail plug below its threaded connection.