Pull-in Head Assembly for Subsea Cable Installation
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Solution Overview
Problem
The installation of cables and cable protection systems is hindered by issues such as snagging, entanglement, and unpredictable tension due to the lack of rotational constraint, leading to potential damage and costly delays, especially in subsea environments.
Innovation Solution
A pull-in head assembly with a flexible pulling line and a retaining member that allows for secure connection and controlled tension application, minimizing the risk of snagging and entanglement by using a divergent bore design and a resilient retaining member that can release when a predetermined force is exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single winching cable is used to pull both the cable and Cable Protection System, then the installation process is simplified, but the pull-in force becomes unpredictable and entanglement risk increases
Solution Approach 1:
The invention divides the pulling operation into two distinct phases using separate winching cables: the first cable pulls the Cable Protection System into the structural interface, and the second cable pulls the cable up to the hang-off. This segmentation eliminates the unpredictability of combined pulling while maintaining procedural simplicity through clear sequential steps.
2Productivity
If winching cables are used to install cable and Cable Protection System, then installation is achieved, but cable rotation and entanglement occur due to lack of rotational constraint
Solution Approach 1:
The invention preliminarily constrains the cable and Cable Protection System against the front surface of the structural interface during the pulling operation. This preliminary constraint prevents rotational movement and entanglement before they can occur, while still allowing the winching cables to perform their installation function effectively.
3Strength
If fasteners are used to secure winching cable to cable, then connection is achieved, but snagging occurs when fasteners contact or lock with external abutments
Solution Approach 1:
The invention extracts the problematic fastening operation from the main installation sequence by using a separate, dedicated fastening step that occurs after the cable and Cable Protection System are pulled into position. This separates the high-strength connection requirement from the snagging-prone pulling operation, allowing each function to be optimized independently.
4Reliability
If Cable Protection System is constrained to support structure, then protection is provided, but installation time increases due to investigation and rectification of snagging issues
Solution Approach 1:
The invention rushes through the critical pulling operation by using a dedicated second winching cable specifically for pulling the cable to the hang-off, rather than using the first cable for both purposes. This skips the time-consuming investigation and rectification of snagging issues by preventing them in the first place through proper cable routing and constraint.
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
The solution effectively reduces the risk of snagging and entanglement during cable installation, ensuring predictable tension and efficient deployment of cable protection systems, even in subsea environments, by allowing the pull-in head to rotate and release from the connector when a specific force is applied, thus preventing damage and reducing installation time and costs.
Implementation Method 1
a resilient retaining member that can release when a predetermined force is exceeded
Data Source
AI summary
A pull-in head assembly (8) for releasably connecting a pulling arrangement (112) to an elongate flexible structure (4, 6). The pull-in head assembly 8 comprises a pull-in head having a body (30) which defines a pulling axis X of the pull-in head. The body (30) has a front end and a rear end and a bore (48) which extends through the body (30) along the pulling axis X. The bore (48) is configured such that a pulling line (28) can be threaded through the body (30).