Threaded Tubular Connection with Minimal Outer Diameter Seal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing integral threaded tubular connections for oil and gas well casings face issues with seal efficiency, tensile efficiency, and wear robustness due to sharp annular edges caused by tolerances and deflection during assembly, leading to potential premature failure and reduced performance under high radial loads.
Innovation Solution
A threaded tubular connection design featuring a tubular female end with a minimal outer diameter at the intermediate metal-to-metal seal location, combined with radiused or tapered portions, and a tubular male end with corresponding sealing surfaces, allowing for axial and radial load absorption while maintaining a compact radial profile, thereby reducing friction and enhancing connection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If integral assemblies with expanded and swaged ends are used to minimize outer diameter, then drift operability and installation ease are improved, but sharp annular edges may form due to tolerances and deflection, causing increased friction and premature failure
Solution Approach 1:
The patent applies radiused portions at the critical cross-section of the tubular end, replacing sharp edges with curved surfaces. This curvature eliminates the sharp annular edges that cause friction and premature failure, while maintaining the compact outer diameter necessary for drift operability. The radiused geometry allows smooth contact with surrounding casing during installation.
Solution Approach 2:
The patent introduces a localized radiused portion at the critical cross-section where sharp edges typically form, while maintaining the original geometry elsewhere. This localized modification specifically addresses the friction problem at the critical location without affecting the overall compactness or requiring changes to the entire assembly structure.
2Strength
If couplings with increased outer diameter are used to ensure rigid connection, then connection strength is improved, but bore hole diameter must be increased, reducing installation flexibility
Solution Approach 1:
The patent merges the coupling function directly into the tubular element by providing both male and female threaded ends on the same component. This integral design eliminates the need for separate couplings with increased outer diameter, maintaining connection strength through positive thread interference while preserving the original outer diameter for flexible installation in existing bore holes.
Solution Approach 2:
The patent divides the connection function into two threaded ends (male and female) that can engage with each other, allowing the connection strength to be achieved through thread interference rather than increased outer diameter. This segmentation of the connection function enables maintaining compact dimensions while ensuring rigid connection.
3Ease of manufacture
If tolerances and deflection during assembly are not controlled, then manufacturing and assembly ease are improved, but sharp annular edges form, increasing friction and reducing seal efficiency
Solution Approach 1:
The radiused portions are designed to accommodate the deflection and tolerance variations that occur during assembly. The curved geometry at the critical cross-section provides a tolerance buffer that prevents sharp edge formation even when assembly deflection occurs, maintaining smooth surfaces without requiring extremely tight tolerances on the entire assembly.
Solution Approach 2:
The radiused portions are pre-designed into the critical cross-section to cushion against the harmful effects of tolerance accumulation and assembly deflection. This beforehand geometric preparation prevents the formation of sharp edges before they can cause friction and seal efficiency problems during operation.
Data Source
AI summary
A threaded tubular connection includes a box member having a female external thread, a female internal thread, and a female intermediate sealing surface between the female external thread and the female internal thread, and a pin member having a corresponding male external thread, a male internal thread, and a male intermediate sealing surface, such that male threads interlock by thread engagement with female threads, and intermediate sealing surfaces form an intermediate metal-to-metal seal when the threaded tubular connection is made up. The box member includes a minimal outer diameter at the intermediate metal-to-metal seal location, the minimal outer diameter being smaller than respectively an external and an internal outer diameter respectively being located above the female external thread and the female internal thread.