Radially-Inserted Anti-Rotation Key for Pipe Connectors
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Solution Overview
Problem
Existing tubular connections for large diameter offshore oil well pipes face issues with rotation prevention due to inadequate friction, requiring complex anti-rotation mechanisms that can loosen under load, are difficult to install, and may cause metal shavings to fall into the pipe.
Innovation Solution
A pipe connection design featuring a box and pin with mating threads, including slots with specific dimensions for a locking key that aligns and embeds teeth into the slots, reducing installation force and preventing rotation through a jacking bolt and set screw mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional anti-rotation keys are used with interference fit and hammer installation, then rotation prevention is achieved, but installation force is excessive and key can loosen under load
Solution Approach 1:
The anti-rotation key is divided into two distinct sections: a pin section that fits into the pin connector pocket and a box section that fits into the box connector tab. This segmentation allows each section to be optimized independently - the pin section can be driven into place with reduced force while the box section provides the primary locking function, eliminating the need for excessive hammer force required by traditional single-piece interference fit keys.
Solution Approach 2:
The key design features asymmetric tooth placement where teeth are located only on the pin section and not on the box section. This asymmetric configuration reduces installation force by approximately one-half while maintaining effective rotation prevention, as the teeth on the pin section engage the pocket walls to prevent loosening without requiring the box section to withstand equivalent insertion forces.
2Reliability
If specialty tools or explosive powered guns are used to install locking mechanism, then rotation prevention is achieved, but device complexity increases
Solution Approach 1:
The locking key is designed to be self-installing using simple conventional tools. The pin section is driven into the pin connector pocket using a hammer and drift, while the box section is inserted into the box connector tab. This eliminates the need for specialty installation tools or explosive powered guns, significantly reducing device complexity while maintaining reliable rotation prevention through the keyed mechanical interference between the key sections and their respective connector features.
3Reliability
If drilling is used to create hole for locking member, then rotation prevention is achieved, but metal shavings fall into pipe string causing issues
Solution Approach 1:
The slots in the pin connector and box connector are pre-formed during manufacturing before assembly, eliminating the need to drill holes after the pipe connection is made up. The locking key is then inserted into these pre-formed slots, preventing metal shavings from falling into the pipe string while still achieving effective rotation prevention through the keyed mechanical interference of the key with the slot walls.
4Reliability
If complex drill is used to drill made up pipe connection, then rotation prevention is achieved, but device complexity increases and overlapping holes limit locking capacity
Solution Approach 1:
The slots are pre-formed in the pin connector and box connector during manufacturing, eliminating the need for post-assembly drilling operations. This approach avoids the complexity of specialized drilling equipment and prevents the problem of overlapping holes that would limit locking capacity if multiple connections were made. The pre-formed slots ensure consistent geometry and reliable key engagement for every connection.
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 solution effectively prevents rotation of the pipe connections with reduced installation force and eliminates the need for complex tools, minimizing the risk of metal shavings and enhancing the locking mechanism's reliability.
Implementation Method 1
One of the sections has at least one tooth that bites into the slot having the greater circumferential dimension
Implementation Method 2
The workers will then drive a key through the box connector tab and into the pin connector pocket. The key has a slightly greater thickness than the distance from the box connector tab to the innermost wall of the pin connector pocket, resulting in an interference fit.
Data Source
AI summary
A pipe connection includes a box that mates with a pin. A box slot extends through a side wall of the box at a point adjacent the rim for alignment with a pin slot formed on the pin. Each of the slots has a circumferential dimension and an axial dimension that is less than the circumferential dimension. The pin slot has a greater circumferential dimension than the box slot. A locking key has a pin section and a box section located within the pin slot and the box slot, respectively, when the key is installed. The pin section has teeth that bite into the pin slot. The key has a width substantially the same as the circumferential dimension of the box slot.