Marine Load Raising System Tension Equalizing Mechanism
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Solution Overview
Problem
Conventional marine load raising and lowering systems for offshore pipeline laying face issues with cable entanglement and wear in deep water operations, leading to reduced cable lifetime and potential breakage due to the rotation of the load connector and relative movement of cable portions.
Innovation Solution
A marine load raising and lowering system utilizing two winches with synchronized driving means and a tension equalizing mechanism, where both cables are connected to a load connector with terminal ends, and a first tension equalizing mechanism with movable cable-engaging members to equalize tension and minimize relative movement, reducing wear and entanglement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single winch and cable system is used for deep water operations, then the system structure is simple, but cable wear increases and cable lifetime is reduced due to entanglement and rotation
Solution Approach 1:
The single cable system is segmented into two separate cable portions, each handled by its own winch. This segmentation prevents the cables from entangling with each other while maintaining the functional capability of the abandonment and recovery system.
Solution Approach 2:
Two winch systems are merged into a coordinated operation through a synchronization mechanism. The operating means connect both driving means to perform synchronous raising and lowering, combining the advantages of multiple cables while maintaining controlled operation.
2Strength
If a rotatable equalizing sheave is used to prevent overload, then load distribution is improved, but cable entanglement and wear increase due to load connector rotation
Solution Approach 1:
The rotatable equalizing sheave is extracted from the system and replaced with a fixed equalizing mechanism. The tension equalizing function is maintained through a different mechanism that does not involve rotation of the load connector, thereby eliminating cable entanglement and wear caused by rotation.
Solution Approach 2:
A fixed equalizing mechanism acts as an intermediary between the two cable portions, distributing load evenly without requiring rotation. This intermediary mechanism transfers tension equalizing function from a rotating component to a fixed structure.
3Strength
If cable portions are allowed to move relative to each other for tension equalization, then load balance is improved, but cable wear increases due to grazing and friction
Solution Approach 1:
The system maintains equipotential tension distribution through a fixed equalizing mechanism that ensures both cable portions experience equal tension forces. This eliminates the need for relative movement between cable portions while maintaining load balance.
Data Source
AI summary
The invention relates to a marine load raising and lowering system for use on a vessel, comprising: i. a first winch comprising first driving means for raising or lowering a first cable from the first winch; ii. a second winch comprising second driving means for raising or lowering a second cable from the second winch; iii. operating means connected to the first and second driving means of respectively the first and second winch for synchronising the driving means so as to perform synchronous raising or lowering of the first and second cable; iv. a load connector; wherein the first and second cable are both connected to the load connector with a respective terminal end of the first and second cable, wherein the system further comprises a first tension equalizing mechanism adapted to equalize the tension in the first and second cables, said first tension equalizing mechanism having interconnected first cable-engaging members to engage with the first and second cable, wherein said first cable-engaging members are movable relative to a first reference structure to be mounted on the vessel, and wherein said first tension equalizing mechanism is configured to move the first cable-engaging members under the effect of a difference in tension in the first and second cable so as to equalize said tensions.