Self-Locking Threaded Connection for High-Torque Pipe Sealing
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Solution Overview
Problem
Conventional threaded connections for shale gas wells face challenges in providing sufficient torque capacity and seal performance, especially in small pipe diameters, and struggle to withstand combined loads and elevated temperatures, leading to inefficiencies and increased manufacturing costs.
Innovation Solution
A self-locking threaded connection design featuring male and female threaded zones with varying thread root widths, where the thread root width decreases initially and then remains constant, allowing for a locking region that provides enhanced torque capacity and seal performance without the need for additional abutment surfaces, and is optimized for machining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional threaded connections with abutment surfaces are used to achieve torque capacity, then torque transmission is enabled, but the abutment surfaces reach critical plastication threshold rapidly especially in small diameter pipes
Solution Approach 1:
The invention removes the abutment surfaces from the connection design entirely. Instead of relying on abutment surfaces for torque transmission, the connection uses a self-locking threaded zone where the thread geometry itself provides the torque capacity through friction and mechanical interlocking, thereby eliminating the plastication issue of abutment surfaces
Solution Approach 2:
The invention changes the thread geometry parameters by using a self-locking threaded zone with specific lead angles and thread profiles that enable torque transmission without abutment surfaces. The threaded zone is designed with parameters that create a self-locking effect, where the friction angle exceeds the lead angle, preventing loosening under load
2Device complexity
If integral connection type with direct pipe body connection is used, then manufacturing complexity is reduced, but torque capacity and seal performance are insufficient especially in small pipe diameters
Solution Approach 1:
The invention applies local quality by creating a specialized self-locking threaded zone with specific geometric properties at the connection point, while the rest of the pipe bodies remain simple cylindrical structures. The threaded zone has varying root widths and specific lead angles that provide enhanced torque capacity and self-locking capability without complicating the overall integral connection design
3Manufacturing precision
If conventional threaded connections are used to meet API standards for outer diameter, then drift tolerances are maintained, but inner diameter reduction limits torque capacity and seal performance
Solution Approach 1:
The invention changes the thread geometry parameters by using a self-locking threaded zone with varying root widths. The thread root width decreases initially and then remains constant, creating a profile that occupies less radial space than conventional threads. This allows the connection to meet API outer diameter standards while maintaining sufficient inner diameter for torque capacity and seal performance
4Force
If self-locking threaded zone with varying root widths is used, then torque capacity and seal performance are enhanced, but machining complexity increases
Solution Approach 1:
The invention applies partial action by using a threaded zone that is only partially self-locking. The threaded zone has a first portion with varying root widths that provides self-locking capability, and a second portion with constant root width that simplifies machining. This partial self-locking approach achieves sufficient torque capacity while reducing overall machining complexity compared to a fully self-locking threaded zone
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 connection achieves high torque capacity and seal performance, exceeding 85% pipe body efficiency, with reduced manufacturing costs and improved durability under severe testing conditions, including bending and elevated temperatures, while maintaining liquid sealability and withstanding cyclical fatigue.
Implementation Method 1
the connection is not having any abutment surfaces, but rely on two threaded zones with low taper thread and both threaded zones being in a self locking arrangement
Data Source
AI summary
A self-locking threaded connection partially in a non-locking engagement includes a first and a second tubular component provided respectively with male and female threaded zone at their respective ends. First portions of the female threaded zones with varying thread width and root cooperate together along a self-locking tightening arrangement. A locking region within the threaded connection is located in the middle of non-locking, and radially centered to the pipe body API tolerances in order to withstand high torque and seal performances.