Capstan Reel Endless Chain Guide for Deepwater Pipe Tension
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Solution Overview
Problem
Deepwater installation of elongate articles like flexible pipes and flowlines poses challenges due to increased weight and tension, requiring complex and costly systems with high maintenance needs, and lacks efficient end termination support for smooth laying operations without manual intervention.
Innovation Solution
A capstan reel system utilizing a rotatable cylindrical body with an endless chain wrapped in a helical direction, featuring radial pressure beams and an end termination support mechanism to manage tension and guide the elongated article, leveraging the capstan effect to reduce the number of tensioners needed and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional VLS with multiple tensioners is used to handle high loads from deep water flow lines, then the load handling capability is improved, but the system becomes large, cumbersome, costly and requires high continuous maintenance
Solution Approach 1:
The patent introduces a guiding means as an intermediary component situated underneath the cylindrical body. This guiding means facilitates the radial direction movement of elongated articles during winding, acting as a mediator between the capstan mechanism and the articles. By adding this intermediate guiding structure, the system achieves better control over multiple parallel articles while maintaining the space-saving benefits of the capstan design, thus resolving the contradiction between load handling and system complexity.
Solution Approach 2:
The patent utilizes the radial dimension by positioning the guiding means underneath the cylindrical body in the radial direction. This allows the system to handle multiple elongated articles arranged parallel to each other in the radial direction, effectively using the third dimension (radial space) to increase capacity without proportionally increasing the overall system footprint or complexity.
2Force
If the number of turns around the cylindrical body is increased to reduce tensioner requirements, then the capstan effect is enhanced, but the need for dedicated guiding means underneath the cylindrical body increases system complexity
Solution Approach 1:
The guiding means underneath the cylindrical body is designed to serve multiple functions: it guides elongated articles in the radial direction during winding, supports the weight of multiple parallel articles, and maintains proper alignment throughout the winding process. By making this single component multi-functional, the patent reduces the need for additional specialized guiding devices, thereby enhancing the capstan effect through multiple turns without proportionally increasing system complexity.
3Ease of operation
If dedicated guiding means is added underneath the cylindrical body for guiding parallel arranged elongated articles, then the guiding capability is improved, but the system becomes more complex, maintenance demanding and costly
Solution Approach 1:
The patent merges the guiding function with the existing structural framework by integrating the guiding means into the cylindrical body assembly. Rather than adding completely separate guiding mechanisms, the design combines the guiding functionality with the structural support elements, allowing the system to guide multiple parallel articles effectively while avoiding the complexity of entirely independent guiding systems.
4Force
If conventional VLS with high number of tensioners is used, then the load handling is improved, but the cost and maintenance requirements increase significantly
Solution Approach 1:
The patent extracts the radial guiding function from the traditional tensioner system and implements it as a separate, dedicated guiding means underneath the cylindrical body. This extraction allows the capstan mechanism to focus on its primary function of handling axial loads through friction, while the guiding means handles radial positioning. As a result, fewer tensioners are needed overall, reducing both manufacturing cost and maintenance requirements while maintaining adequate load handling capability.
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 capstan reel system significantly reduces the number of tensioners required, simplifies maintenance, and enables smooth laying operations by distributing tension efficiently, while the end termination support ensures stable handling of elongated articles during installation and retrieval.
Implementation Method 1
The present applicant has devised and embodied this invention to overcome the shortcomings of the prior art and to obtain further advantages. The invention makes use of the well-known capstan effect which relates to the hold-force required to counter a load-force when a flexible line is wound around a cylinder (a bollard, a winch or a capstan). Because of the interaction of frictional forces and tension, the tension on a line wrapped around a capstan may be different on either side of the capstan.
Data Source
Figure 1~3
Figure 4a
Figure 4b
AI summary
The invention concerns a capstan reel (10) and a method for transporting an elongated article (6, 6a, 6b, 39, 42, 43, 45a, 47) between a floating vessel (2)and a body of water situated below the vessel, and a vessel applying such a capstan reel. The capstan reel comprises a rotatable cylindrical body (100) for spooling the elongated article around the body's axial axis (11), said body comprising a cylindrical contacting surface (35) for indirectly supporting at least a portion of the elongated article. Furthermore, the capstan reel comprises an endless chain (18) spooled at least partly around the cylindrical body in a helical direction relative to the axial axis of the body, acting as an intermediate layer between the cylindrical contacting surface and the intended elongated article, and a chain transfer guide (17) extending across the axial length of the cylindrical body for guiding the endless chain between a chain exit region (T) in a first axial end region (7a) of the cylindrical body and a chain entry region (E) in a second axial end region (7b), the second axial end region being situated at the opposite axial end of the cylindrical body.