Offshore Cable Hang-Off Pivot Structure for Fatigue Relief
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Solution Overview
Problem
Dynamic cables suspended from offshore structures experience repeated bending due to environmental loads and movement, leading to fatigue failure of cable components. Current solutions, such as bend stiffeners, may not adequately distribute strain variations and require water barriers.
Innovation Solution
A transfer system with a hang-off device comprising a base and pivotably connected first and second elements, allowing the transfer device to pivot around these axes and bend above the hang-off device, thereby reducing strain variations and eliminating the need for a water barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bend stiffener is introduced to distribute cable curvature, then local strains are kept below critical value, but device complexity increases and water barrier is required
Solution Approach 1:
The patent applies dynamics by making the hang-off device itself movable through pivotable connections. The first element pivots relative to the base at a first pivoting axis, and the second element pivots relative to the first element at a second pivoting axis. This dynamic configuration allows the cable to bend above the hang-off device rather than at the structure interface, eliminating the need for bend stiffeners and water barriers while maintaining strain control.
2Reliability
If cable bending point is kept at structure interface, then connection is secure, but water barrier is required and strain variations increase
Solution Approach 1:
The patent moves the cable bending point from the horizontal plane at the structure interface to a vertical position above the hang-off device. By repositioning the bending location in the vertical dimension, the cable can flex freely above water level while the hang-off device remains securely connected to the structure, eliminating the need for water barriers.
3Ease of operation
If traditional hang-off device is used, then cable is supported, but strain variations in cable components increase
Solution Approach 1:
The patent transforms the static hang-off device into a dynamic system with multiple pivotable elements. The first element pivots relative to the base at a first pivoting axis, and the second element pivots relative to the first element at a second pivoting axis. This dynamic configuration allows the cable to bend above the hang-off device rather than at the structure interface, eliminating the need for bend stiffeners and water barriers while maintaining strain control.
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 configuration reduces strain variations in cable components, minimizes fatigue, and allows for a more flexible design that avoids the need for traditional bend stiffeners or water barriers, enhancing the durability and efficiency of cable systems.
Implementation Method 1
a first element pivotably connected to the base at a first pivoting axis; a second element pivotably connected to the first element at a second pivoting axis
Data Source
AI summary
A transfer system connectable to an offshore structure. The transfer system has a transfer device connectable to a connector box on the offshore structure. The transfer device has a tensile element. The transfer device is defined with a lower section and an upper section, where the tensile element is removed from at least parts of the upper section. The transfer system further has a hang-off device with a base mechanically connectable to the offshore structure. The hang-off device has a first element pivotably connected to the base at a first pivoting axis. The lower section is suspended from the first element into a wet zone of the offshore structure while the upper section is extending above the first element into a dry zone of the offshore structure.