Riser Connector External Locking Ring Tension
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Solution Overview
Problem
Deep-sea drilling risers face challenges with excessive weight and high traction forces in auxiliary lines, leading to increased mass and cost, particularly at great water depths, due to the need for larger internal diameters to manage pressure losses and longitudinal forces.
Innovation Solution
A compact connector design using a single external locking ring with a sliding pivot connection for auxiliary lines, allowing relative movement and adjustable clearance, reduces the thickness and mass of auxiliary lines, thereby minimizing the overall weight and cost of the riser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If auxiliary lines are rigidly attached to the main tube to resist longitudinal forces, then the riser can support greater tension loads, but the thickness and mass of auxiliary lines increase significantly
Solution Approach 1:
The patent applies a dynamic connection approach by allowing auxiliary lines to slide within the connector housing rather than being rigidly fixed. The clearance adjustment means (threaded rod) enables controlled movement of auxiliary lines relative to the main tube, allowing them to dynamically adapt to tension forces without requiring excessive thickness. This dynamic arrangement reduces auxiliary line mass while maintaining load-bearing capacity through the collective action of multiple lines.
2Reliability
If auxiliary lines are made thicker to resist high traction forces in deep water, then the riser can operate at greater depths, but the overall mass and float size increase
Solution Approach 1:
The patent segments the load-bearing function by distributing tension forces across multiple auxiliary lines (typically 4-6 lines arranged radially) rather than relying on a single thick line. Each auxiliary line carries a portion of the total load, allowing the use of thinner, lighter individual lines while maintaining overall system reliability for deep water operations. The locking ring and clearance adjustment means coordinate these segmented load paths.
Solution Approach 2:
The patent employs composite construction in the connector assembly, combining the main tube (steel), auxiliary lines (steel or polymer), locking ring (metal), and clearance adjustment means (threaded rod). This composite approach optimizes the mass-strength ratio by selecting appropriate materials for each component, enabling deep water operation without excessive overall mass. The auxiliary lines may use high-strength steel or polymer composites to reduce thickness.
3Device complexity
If a single external locking ring is used to assemble flanges, then the connector design becomes more compact, but the locking mechanism must handle all assembly forces
Solution Approach 1:
The locking ring is segmented with multiple radial arms (typically 4-6 arms) spaced around the circumference, each arm containing a locking element (such as a cam or wedge). This segmentation allows the locking ring to distribute assembly and operating forces across multiple contact points with the flanges, preventing any single point from being overloaded. The segmented design maintains compactness while handling high locking forces through distributed load paths.
Solution Approach 2:
The locking elements on the locking ring arms are asymmetrically designed, with cam profiles or wedge geometries that provide mechanical advantage in the locking direction. This asymmetric geometry allows the locking mechanism to generate high clamping forces on the flanges while requiring relatively small actuating forces, enabling the compact single-ring design to handle all assembly and operating forces effectively.
4Ease of operation
If clearance adjustment means are added to limit relative movement, then auxiliary line positioning is optimized, but the connector assembly complexity increases
Solution Approach 1:
The clearance adjustment means (threaded rod) serves multiple functions: it limits the axial movement of auxiliary lines relative to the main tube, positions auxiliary lines at optimal clearances for load distribution, and can be adjusted during assembly to accommodate manufacturing tolerances. This multi-functional component optimizes auxiliary line positioning without requiring separate adjustment mechanisms for each function, thereby limiting the increase in overall connector complexity.
Data Source
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AI summary
The present invention relates to a riser connector (5) equipped with an external locking ring (11). The locking ring (11) cooperates with a male flange (24) of a male connector element (9) and a female flange (23) of a female connector element (8) by means of a series of tenons. The invention also relates to a riser consisting of several sections (4) assembled by a connector (5).