Subsea Riser Bending Relief Joint with Ball Joint Detent
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Solution Overview
Problem
Existing subsea riser systems lack effective protection against excessive bending moments, which can occur due to extreme angular displacement of surface vessels, leading to potential damage to the riser or wellhead, especially in varying environmental conditions such as tides and water depth.
Innovation Solution
A connector with a ball joint and adjustable detent mechanisms that maintains alignment until a predetermined bending moment is reached, allowing the ball joint to move and relieve stress, thereby preventing damage to the riser or wellhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid riser connection is used to maintain alignment, then structural integrity is preserved, but the system cannot relieve excessive bending moments caused by extreme angular displacement
Solution Approach 1:
The ball joint connector transitions from a static rigid connection to a dynamic system that can change its mechanical properties. Under normal conditions, the detent mechanisms maintain a locked state providing rigid support. When bending moments exceed the predetermined threshold, the ball joint unlocks and allows angular displacement, transforming the connection from rigid to flexible to relieve excessive stress while maintaining structural integrity.
Solution Approach 2:
The system changes the mechanical parameter of connection rigidity based on loading conditions. The detent mechanisms are designed with specific spring rates and engagement forces that allow the connector to maintain a fixed angular position (zero degrees) under normal bending moments, but unlock and allow angular displacement when the bending moment exceeds the predetermined threshold, thus adapting the structural parameter to the environmental conditions.
2Stability of the object's composition
If detent mechanisms with high engagement force are used to maintain alignment, then alignment stability is improved, but the bending moment threshold for triggering ball joint movement increases
Solution Approach 1:
The detent mechanisms are designed with localized spring elements and engagement features that provide high stability during normal operation. The springs are positioned and dimensioned to engage the locating features on the ball joint with sufficient force to maintain alignment stability, while the overall mechanism is calibrated so that the engagement force corresponds to a specific bending moment threshold that can be adjusted by selecting different spring rates or engagement geometries.
3Adaptability or versatility
If the ball joint is designed to allow free movement to relieve bending stress, then stress relief capability is improved, but alignment maintenance deteriorates
Solution Approach 1:
The ball joint is designed as a dynamic element that transitions between two states: locked and unlocked. When locked by the detent mechanisms, it maintains precise alignment stability. When the bending moment exceeds the predetermined threshold, the detent mechanisms release and the ball joint is free to move, providing stress relief capability. This dynamic behavior allows the system to maintain alignment when needed and relieve stress when necessary.
Data Source
AI summary
A connector for use with a subsea riser installation is provided. The connector comprises a body, wherein the body comprises a first connecting face comprising a through-passageway and adapted for connection to a first external conduit element and a ball joint within the body, wherein the ball joint comprises a through-passageway which is substantially aligned with the through-passageway in the first face, and a second connecting face on an opposite side of the connector to the first connecting face and adapted for connection to a second external conduit element. The connector further comprises at least one detent mechanism adapted to engage a corresponding locating feature on the ball joint, wherein the through-passageway are maintained in alignment and wherein the ball joint is prevented from moving relative to the body until a predetermined bending moment is applied to the ball joint across the axis of the through-passageway in the ball joint.