Turret Buoy Conical Coupling Load Distribution
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Solution Overview
Problem
Existing disconnectable turret and buoy assemblies in offshore oil production face challenges in maintaining a secure interface under external loads, requiring excessive machining and potentially leading to premature failure of locking means due to high cyclic load variations.
Innovation Solution
The assembly features an annular projection and recess with specific machining tolerances, allowing for axial compression and radial deformation to create a form-fit, reducing the likelihood of separation and distributing loads effectively, with an optional sealing member for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conical interface is used to ease fit-up of the turret and buoy, then the assembly of the two structures is simplified, but the conical recess must be fabricated extremely heavy and sturdy to resist radial loads
Solution Approach 1:
The conical interface is segmented into two distinct components: a conical projection on the buoy and a conical recess in the turret. This segmentation allows the fit-up ease to be provided by the conical geometry while the load-bearing function is provided by the tapered surfaces that engage under compression, eliminating the need for an excessively heavy recess structure.
Solution Approach 2:
The interface geometry is designed with specific taper angles and dimensional parameters that optimize both fit-up ease and load resistance. The conical surfaces are designed with tolerances that allow for self-aligning during assembly while maintaining sufficient contact area to resist radial loads without requiring excessive material.
2Stability of the object's composition
If high preload is applied to prevent separation of buoy and turret under external loads, then the interface stability is improved, but the locking means are subject to high cyclic load variations and may fail prematurely
Solution Approach 1:
The conical projection and recess are designed to automatically generate the necessary preload through their geometric engagement. When the buoy is lowered onto the turret, the conical surfaces self-align and create compressive preloading that stabilizes the interface without requiring additional locking mechanisms to maintain the preload, thereby reducing cyclic load variations on locking means.
Solution Approach 2:
The conical interface acts as an intermediary mechanism that transforms the vertical compression force into radial clamping pressure. This intermediary action distributes the loads more evenly across the interface and reduces the cyclic variations transmitted to the locking means, improving their reliability.
3Manufacturing precision
If tight machining tolerances are used to achieve a good fit between turret and buoy interface, then the fit quality is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The conical interface design concentrates the precision requirements to specific critical areas of the conical surfaces where contact occurs under load. Non-critical areas can be manufactured with looser tolerances, reducing overall manufacturing cost while maintaining adequate fit quality through the self-aligning conical geometry.
Solution Approach 2:
The interface design incorporates optimized taper angles and dimensional parameters that provide a good fit with relaxed tolerances. The conical geometry naturally compensates for minor manufacturing variations through self-aligning during assembly, achieving acceptable fit quality without requiring tight machining tolerances.
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 ensures a stiff load path and high internal contact stress, preventing separation and allowing the turret and buoy to act as a single structure, while minimizing cyclic loads on locking devices and providing effective sealing against seawater.
Implementation Method 1
under an axial compression force, one of these parts deforms more than the other in a radial direction such as to become compliant with the other part in a form-fit
Data Source
AI summary
Assembly of turret and disconnectable buoy, in which the turret at its lower end and the buoy at its upper end are provided with mating coupling provisions. The coupling provisions comprise an annular projection protruding from one of the turret and buoy towards the other of the turret and buoy and a correspondingly shaped annular recess on the other of the turret and buoy for receiving the annular projection. The annular projection has a base which is wider than a top thereof, whereas the annular recess has a top which is wider than a base thereof.