Tubular Thread Connection Geometry for Galling-Resistant Break-In
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Solution Overview
Problem
Existing tubular connections in downhole drilling operations, such as drill pipes and drill collars, face challenges in withstanding high loads and preventing damage like galling due to inadequate strain hardening of thread flanks.
Innovation Solution
The implementation of a tubular connection design featuring a load flank reduction zone, which includes a limiting flank inset and specific radii configurations, to enhance radial bearing strength and induce compressive stress in thread flanks, thereby improving galling resistance and maintaining compatibility with existing designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If standard thread design is used, then manufacturing simplicity is maintained, but galling resistance and mechanical performance deteriorate under high loads
Solution Approach 1:
The patent applies local quality by introducing a load flank reduction zone specifically in the region where threads engage, while maintaining standard thread geometry elsewhere. This localized modification creates varying root radii (smaller in the load flank reduction zone, larger elsewhere) to concentrate strain hardening exactly where galling occurs, without complicating the overall thread structure or manufacturing process
Solution Approach 2:
The patent changes the geometric parameter of thread root radius locally within the load flank reduction zone. By reducing the root radius in this specific zone, the design concentrates plastic deformation and strain hardening where it is most needed to prevent galling, while maintaining larger radii in other zones to preserve overall connection strength and manufacturability
2Strength
If strain hardening is enhanced, then galling resistance improves, but excessive plastic deformation may occur
Solution Approach 1:
The patent applies local quality by concentrating strain hardening effects specifically in the load flank reduction zone where galling is most likely to occur. The smaller root radii in this zone promote controlled plastic deformation and strain hardening precisely where needed, while larger radii in other zones prevent excessive deformation elsewhere, maintaining overall structural integrity
Solution Approach 2:
The patent provides beforehand cushioning by designing the load flank reduction zone with specific geometric features that control and limit plastic deformation. The varying root radii create a structure that promotes beneficial strain hardening in advance, preparing the thread flanks to resist galling while the overall geometry prevents excessive deformation that would compromise structural integrity
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
This design effectively enhances the galling resistance and mechanical performance of tubular connections by ensuring the radial bearing strength is equal to or greater than the cross-sectional connection strength, preventing excessive plastic deformation and maintaining the shear strength of the connection.
Implementation Method 1
The connection has a radial bearing strength Srb for the plurality of threads representing the amount of force required to induce plastic deformation into the load flanks
Data Source
AI summary
A tubular member having a first connector provided on a first end thereof, this first connector being adapted to receive a corresponding connector provided on another tubular member, forming a tubular connection comprising: a pin connector, a box connector, an outer diameter, an inner diameter, and a longitudinal axis. The pin connector threads or box connector threads feature a threadform having at least one load flank reduction zone such that when the pin connector is threadably engaged with the box connector, the resulting tubular connection radial bearing strength is desirably reduced. More specifically in the preferred embodiment, the at least one load flank reduction zone is preferably configured such that the tubular connection radial bearing strength is between 100% to 110% of the cross sectional connection strength when the box connector is threadably engaged with a pin connector. A method for forming connectors on a tubular member comprising threads which have at least one load flank reduction zone described herein is also provided.