Rotatable Anti-Rotation Key for Threaded Tubular Connections
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Solution Overview
Problem
Existing locking systems for threaded connections in oil and gas wells face challenges with repeatability due to manufacturing tolerances and space limitations, particularly in subsea applications where large devices cannot be used, leading to issues with maintaining secure azimuthal alignment and preventing decoupling.
Innovation Solution
A system featuring a rotatable, non-circular planar key with a recess on one tubular and a fastener to pin the key in place, which includes a lateral edge and teeth to resist decoupling forces by engaging with the radial surface of an adjacent tubular, ensuring rotational coupling and preventing further decoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If keys are used to insert into grooves for locking, then relative rotation between connectors is limited, but manufacturing tolerances and loading variances cause poor repeatability of azimuthal alignment
Solution Approach 1:
The key is made rotatable within the recess rather than being fixed, allowing it to dynamically adjust its orientation. The key can rotate to different angular positions depending on the relative orientation of the tubulars, ensuring proper engagement with the radial surface regardless of manufacturing tolerances or loading conditions.
Solution Approach 2:
The key's ability to change its angular parameter (rotation angle) allows it to adapt to varying conditions. By changing the key's rotational state between unlocked and locked positions, the system achieves reliable azimuthal alignment despite variations in manufacturing precision or applied loads.
2Length of moving object
If small wall thickness tubulars are used, then space is saved, but the key must be low profile which limits locking effectiveness
Solution Approach 1:
Instead of increasing key height in the radial direction (which would require thicker walls), the solution uses the tangential dimension by allowing the key to rotate. The key engages the radial surface through rotational movement within the recess, achieving effective locking without increasing the radial profile height.
Solution Approach 2:
The key transitions from a static, low-profile component to a dynamic element that rotates to achieve engagement. This rotational capability allows a low-profile key to generate sufficient locking strength by leveraging the rotational motion to bite into the radial surface.
3Strength
If large locking devices are used, then locking capability is improved, but space limitations in subsea applications prevent their use
Solution Approach 1:
The key serves multiple functions: it acts as a locking element, a rotational indicator, and an engagement mechanism all in one compact component. This multi-functionality allows effective locking capability to be achieved without requiring separate large-scale locking devices.
Solution Approach 2:
The key combines the locking function with the rotational coupling function into a single integrated component. By merging these functions, the system achieves strong locking capability without the need for additional separate locking mechanisms that would increase device size.
4Ease of manufacture
If the key is fixed in position, then manufacturing is simplified, but the key cannot adapt to relative rotation between tubulars
Solution Approach 1:
The key is designed with rotational freedom within the recess, transforming it from a fixed static component to a dynamic one. This allows the key to automatically adapt its angular position based on the relative orientation of the connected tubulars, ensuring proper engagement without complex adjustment mechanisms.
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 system effectively maintains threaded connections by generating a resistive force that prevents decoupling, ensuring secure attachment and alignment of tubulars even under varying loads and space-constrained conditions.
Implementation Method 1
a resistive force from the side wall to the lateral edge transfers to the second tubular to rotationally couple the first and second tubulars
Implementation Method 2
The outer edge includes at least one tooth that projects outward from the key and bites into the radial surface of the second tubular and transfers the decoupling force to the second tubular
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4~5
AI summary
An anti-rotation system for use in retaining a threaded connection between a pin and a box. The anti-rotation system includes a key that sets in a recess formed in one of the box or pin. The key is selectively in contact with one of the other of the box or pin, and is activated when the threaded connection begins to decouple. The key is profiled and operates in a cam like fashion to wedge itself between the box and pin when these members begin to decouple and prevents further relative rotation.