Submarine Cable Joint Bend Restriction for Deepwater Fatigue Control
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Solution Overview
Problem
Dynamic submarine power cables deployed at greater depths face corrugated metallic water barrier collapse due to high hydrostatic pressure and increased bending forces, posing risks from component 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 restricts bending and mitigates fatigue damage, using materials like stainless steel or polymeric materials to protect the cable from bending-induced stress.
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 sections optimized for different depth conditions, with the joint location protected by a bend restriction device to maintain integrity at greater depths.
Solution Approach 2:
Different sections of the metallic water barrier can have different properties - for example, the first axial section may be corrugated while the second axial section is smooth. This local differentiation allows optimization for specific depth conditions and pressure requirements at different locations along the cable.
2Length of moving object
If component joints are introduced in the dynamic submarine power cable for deeper water installations, then the cable can be deployed at greater depths, but the joint location becomes vulnerable to bending forces and fatigue damage
Solution Approach 1:
A bend restriction device is introduced as an intermediary component that surrounds the joint location. This device acts as a protective intermediary that restricts bending at the vulnerable joint location while allowing the cable to maintain its dynamic properties elsewhere, thereby protecting the joint from fatigue damage during deep water deployment.
Solution Approach 2:
The bend restriction device is pre-installed at the joint location before cable deployment. This preliminary protective measure ensures that the joint location is already protected against bending forces before the cable is subjected to dynamic movements and fatigue loading during operation at greater depths.
3Reliability
If a bend restriction device is added to protect the joint location, then fatigue damage at the joint is reduced, but the device complexity of the cable system increases
Solution Approach 1:
The bend restriction device can be implemented as a flexible bellmouth or shell structure that surrounds the joint location. This flexible shell provides bending protection while maintaining the dynamic properties of the cable and avoiding excessive complexity in the overall system structure.
Data Source
Figure 1~2
Figure 3~4
AI summary
A submarine power cable system comprising: a dynamic submarine power cable (5) comprising an element having a first axial section and a second axial section which are joined at a joint location; and a bend restriction device (19) arranged around the dynamic submarine power cable (5), wherein the bend restriction device (19) extends axially over the joint location, and wherein the bend restriction device (19) is arranged to restrict bending of the dynamic submarine power cable (5) at the joint location.