Tubular Threaded Connection Geometry to Prevent Seal Lip Bending
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Solution Overview
Problem
Existing threaded connections for tubular components in hydrocarbon wells face challenges with maintaining a seal under varying compressive and tensile loads, high internal and external pressures, and bending loads, leading to potential separation and degradation over multiple make-ups and break-outs, especially due to the 'jump-out' phenomenon and galling issues.
Innovation Solution
A threaded connection design featuring a male and female element with specific geometric configurations, including radial clearances and interference zones, optimized ratios of Epi/Li and Epe/Le, and angled load and stabbing flanks, which enhance the stability and rigidity of sealing surfaces to prevent separation and maintain a tight seal under load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the distal surface of the male end and/or female end is brought into axial abutting contact against a corresponding abutment surface to improve tensile strength, then the tensile strength is improved, but the structural performance in resisting high external and internal pressures results in a great deal of bending of the sealing lips
Solution Approach 1:
The connection structure is segmented into distinct functional zones: the male and female abutment surfaces handle tensile loads through axial contact, while the sealing lips are positioned separately to handle pressure containment. This segmentation allows each component to optimize its function without compromising the other.
Solution Approach 2:
The threaded zone acts as an intermediary structure that transfers and distributes loads between the abutment surfaces and the sealing lips. The thread geometry and engagement design mediate the stress distribution, reducing direct bending moments on the sealing lips while maintaining tensile strength through the abutment contact.
2Stress or pressure
If the connection is designed to resist high external and internal pressures, then pressure resistance is improved, but the sealing lips experience significant bending under load variations
Solution Approach 1:
The sealing lips are designed with specific local geometric properties including optimized thickness, curvature radius, and material distribution in the sealing zone. These local quality adjustments enhance the sealing lips' ability to resist pressure-induced bending while maintaining effective sealing contact under varying pressure conditions.
Solution Approach 2:
The connection design incorporates pre-compression and geometric constraints that cushion the sealing lips against pressure variations. The abutment surfaces and threaded zone are configured to pre-load the sealing lips in a controlled manner, creating a cushioning effect that prevents excessive bending under subsequent pressure fluctuations.
3Strength
If the threaded zones comprise threads with an increasing width from their respective distal surface, then the connection strength is improved, but the complexity of the threading geometry increases
Solution Approach 1:
The thread geometry employs systematic parameter changes including progressive width increase, optimized pitch variations, and controlled flank angle modifications along the thread length. These parameter changes enhance load distribution and connection strength while maintaining manufacturability through standardized machining approaches.
Data Source
AI summary
A threaded connection includes a first and a second tubular component made up one with the other. A male element of the first component includes, on its external peripheral surface, a male inner lip including an inner mg with a minimum thickness Epi and a male threaded zone. One inner end of the male threaded zone is at a non-zero axial distance (Li) from a male distal end. A female element of the second component includes, in succession over its internal peripheral surface, a female inner recess disposed facing the male inner lip and a female threaded zone, such that in the made up position of the connection, a radial clearance subsists between the male inner ring and the female inner recess and an internal seal is formed locally between the male inner lip and the female inner recess. The connection is such that 10%≤Epi/Li.