Variable Length Offshore Cable Installation
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Solution Overview
Problem
Current methods for installing offshore cables, such as inter-array cables in offshore energy parks, are labor-intensive and costly due to difficulties in accurately estimating cable length, leading to issues with cables being too short or too long, which results in costly re-cutting and re-termination operations.
Innovation Solution
A pre-terminated, flexible conduit made of fibre-reinforced polymer, pre-cut to a target length with extension segments and hang-off collars, allowing for adjustable length during installation to accommodate variations in seabed conditions, ensuring efficient cable routing and termination without on-site cutting or re-termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cable is pre-cut to a predetermined length on shore, then the costly labour of cutting and terminating the cable on site offshore is avoided, but it becomes very difficult to correctly estimate the correct length, resulting in the cable being either too long or too short
Solution Approach 1:
The cable system is divided into a main cable body and multiple detachable extension segments. The main cable is pre-cut to a base length on shore, while extension segments are attached to the end. During installation, these extension segments can be selectively added or removed to achieve the precise required length, combining the benefits of pre-cut preparation with on-site length adjustment capability.
Solution Approach 2:
The cable length is made dynamically adjustable through the attachment and detachment of extension segments. The system transitions from a fixed pre-cut length to a variable length configuration, allowing the cable to adapt to different installation scenarios and seabed conditions while maintaining the efficiency of pre-cut preparation.
2Adaptability or versatility
If the cable is connected to the first installation and spooled out to the second installation where it is cut to appropriate length and terminated on site, then the cable length can be adjusted to fit, but this is a very labour intensive and costly operation
Solution Approach 1:
The extension segments are pre-attached to the main cable body on shore before installation. This preliminary preparation eliminates the need for time-consuming on-site cutting and termination operations, as the cable arrives at the installation site already configured with adjustable length capabilities, significantly improving installation efficiency.
Solution Approach 2:
By segmenting the cable into a main body and detachable extension segments, the system enables quick length adjustments through simple attachment/detachment operations rather than labor-intensive cutting and termination, maintaining adaptability while dramatically improving productivity.
3Loss of substance
If the cable is too long, it may have to be cut and re-terminated at the site, thereby destroying the cost-savings of having pre-cut the cable on shore, or laid in different routing which requires other measures in post-lay burial operations and adds unnecessary material costs
Solution Approach 1:
The cable is constructed with a main body and modular extension segments that can be selectively attached or detached. This segmentation allows precise length adjustment without cutting the main cable, eliminating material waste while preserving the cost savings of onshore preparation. The extensions provide the necessary length flexibility to match actual installation requirements.
Solution Approach 2:
If the cable is too long, the excess extension segments can be detached and removed without damaging the main cable or requiring re-termination. This allows the system to discard only the unnecessary extension portions while recovering and preserving the main cable for proper installation, minimizing material waste.
4Reliability
If the cable is too short, it is not fit for purpose and may simply be discarded on the seabed and a new cable must be prepared, which is obviously an extremely inconvenient and costly necessity
Solution Approach 1:
The cable system includes a main body and multiple extension segments that can be attached to extend the total length. If the initial configuration is too short, additional extension segments can be added during installation to achieve the required length, ensuring the cable becomes fit for purpose without discarding it or requiring complex re-preparation.
Solution Approach 2:
The cable length is made dynamically adjustable through the attachment of extension segments, allowing the system to adapt from an initially too-short configuration to the required length during installation, ensuring fitness for purpose while avoiding the need to discard and reprepare the cable.
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
The present invention provides an elongated, flexible conduit precut to an intended target length. Within the flexible conduit is arranged a cable. The elongated flexible conduit according to one aspect is a fibre-reinforced polymer conduit, and the conduit and cable are arranged to be hung-off and terminated at a first end to a first structure. The flexible conduit and internally-arranged cable are pre- cut and pre-terminated to a predetermined target length, whereby, under expected cable-laying conditions, a first or primary hang-off collar at a second end of the conduit will optimally reach the hang-off interface at a second installation such as, for example a hang-off interface arranged in a corresponding deck at a second Monopile foundation. The second end of the flexible conduit comprises a primary, or a main, hang-off interface collar arranged at an intended forecast length. However, to provide for a margin of error, the second end also comprises one or more preinstalled extension segments, each having its own hang-off collar.