Hinged Subsea Termination Head for Catenary Cable Management
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Solution Overview
Problem
The installation of subsea cables or umbilicals with fixed termination heads results in high tension loads and bending moments during lowering, complicating the connection and handling process, as the cables hang in a catenary configuration, which is inefficient and can lead to deformation and operational challenges.
Innovation Solution
A hinged subsea termination head assembly that pivots about a pivot axis, allowing the cable or umbilical to adopt a natural catenary curvature, reducing tension loads and bending moments by extending in a pigtail loop, which can perform a rolling motion during pivotal movement, thereby aligning the resultant force with the global center of gravity of the subsea structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a fixed termination head is used during lowering, then the cable provides large tension loads, but the handling and installation becomes complicated and bending moments increase
Solution Approach 1:
The termination head is made movable through a hinge connection that allows it to pivot between horizontal and vertical positions. This dynamic adjustment enables the termination head to adapt its orientation during lowering operations, reducing bending moments and improving handling characteristics while managing tension loads effectively
2Device complexity
If the termination head is fixed, then the structure is simpler, but the bending moment on the structure increases significantly
Solution Approach 1:
The hinge connection introduces a controlled degree of freedom that allows the termination head to pivot, dynamically adjusting the load distribution. This reduces the bending moment transmitted to the subsea structure by allowing the termination head to orient itself favorably during lowering operations
3Shape
If the cable hangs in catenary configuration, then the cable naturally forms loops, but the cable may deform or kink during installation
Solution Approach 1:
The pigtail loop configuration combined with the hinged termination head allows the cable to dynamically adjust its shape during lowering. The loop can perform rolling motion that accommodates the catenary configuration while preventing kinks and deformation through controlled movement rather than rigid positioning
Data Source
AI summary
A subsea termination head assembly adapted for both communicating and controlled load earning connection via a termination head to a subsea structure to be installed on the seabed, is described. The termination head allows a subsea cable, a power cable, a power umbilical or an umbilical, to be connected to the subsea structure before lowering them as a unit from a vessel and into the sea. The termination head assembly and subsea structure are to be lowered together while concurrently paying out the cable all the way to the seabed. The termination head is arranged to be hingedly connected relative to the subsea structure, which allows the termination head to pivot about a pivot axis in order to let the subsea cable adopt a natural catenary curvature in the sea during lowering thereof. The cable extends in a pigtail loop from the termination head and into the subsea structure. The pigtail loop is able to perform a “rolling motion” during such pivotal movement of the termination head.