Submarine Cable Joint Bend Restriction for Deepwater Fatigue Protection
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Solution Overview
Problem
Dynamic submarine power cables deployed at greater depths face issues with corrugated metallic water barriers collapsing due to high hydrostatic pressure and increased bending forces, which can lead to fatigue damage at joints in deeper waters.
Innovation Solution
A submarine power cable system with a dynamic submarine power cable comprising joined axial sections and a bend restriction device around the joint location, which can be made of materials like stainless steel or polymers, to restrict bending and mitigate fatigue damage, featuring a transition from corrugated to smooth metallic water blocking layers and potentially including a conductor joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a dynamic submarine power cable is deployed at greater depth, then the cable can reach deeper water levels, but the corrugated metallic water barrier may collapse due to high hydrostatic pressure
Solution Approach 1:
The metallic water barrier is divided into multiple sections (first axial section and second axial section) that are joined at a joint location. This segmentation allows the cable to be constructed with different structural characteristics suitable for different depth zones, enabling deployment at greater depths while maintaining barrier integrity.
Solution Approach 2:
Different sections of the metallic water barrier are designed with different properties - the first axial section has one configuration while the second axial section has another configuration. This local differentiation allows optimization for specific pressure conditions at different depths, with the joint location protected by the bend restriction device.
2Strength
If the metallic water barrier is made with joints to transition from corrugated to smooth sections, then the cable can withstand high hydrostatic pressure at greater depths, but the joint location becomes vulnerable to fatigue damage from bending forces
Solution Approach 1:
A bend restriction device is introduced as an intermediary component that surrounds the joint location. This device acts as a mediator between the bending forces and the joint, restricting excessive bending movements and protecting the joint from fatigue damage while allowing the cable to maintain its pressure resistance capabilities.
Solution Approach 2:
The bend restriction device is installed beforehand at the joint location to prevent fatigue damage before it occurs. By restricting bending movements in advance, the device cushions the joint against the cumulative effects of repeated bending cycles that would otherwise lead to fatigue failure.
3Reliability
If a bend restriction device is provided at the joint location, then fatigue damage at the joint is protected, but the device complexity increases
Solution Approach 1:
The bend restriction device may be constructed using flexible materials such as corrugated metallic layers or polymer sheaths that can accommodate cable movements while still providing bending restriction. This approach protects the joint without requiring complex rigid structures, thereby limiting the increase in device complexity.
Data Source
AI summary
A submarine power cable system including: a dynamic submarine power cable having an element with a first axial section and a second axial section which are joined at a joint location; and a bend restriction device arranged around the dynamic submarine power cable, wherein the bend restriction device extends axially over the joint location, and wherein the bend restriction device is arranged to restrict bending of the dynamic submarine power cable at the joint location.