Subsea Heating Cable Helical Protection System
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Solution Overview
Problem
Existing subsea piggyback cables struggle to effectively manage both axial and radial loads without increasing the outer diameter, which limits their transportation efficiency and installation flexibility.
Innovation Solution
A subsea pipeline direct electric heating (DEH) cable design featuring a copper conductor with a standard triple extruded insulation system, an inner and outer semi-conductive polyethylene sheath, and a space filled with helically wound thermoplastic and reinforced semi-conductive thermoplastic elements, providing a compact protection system that absorbs both axial and radial loads without enlarging the cable diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional protective systems are added to piggyback cables to handle axial and radial loads, then the cable's load resistance improves, but the outer diameter increases
Solution Approach 1:
The patent combines protective elements for axial and radial load resistance into a single integrated layer structure. The thermoplastic elements and reinforced semi-conductive thermoplastic elements are arranged together in the same layer, eliminating the need for separate protective layers and preventing diameter increase while providing comprehensive mechanical protection.
Solution Approach 2:
The protection layer is designed to perform multiple functions simultaneously: it resists axial loads, resists radial loads, and provides electrical testing capability through the semi-conductive elements. This multi-functionality eliminates the need for additional specialized components that would increase the cable diameter.
2Strength
If more protective elements are added to increase load resistance, then the cable's mechanical strength improves, but the cable complexity increases
Solution Approach 1:
The patent merges the functions of multiple protective elements into a single integrated layer. Instead of adding separate layers for axial protection, radial protection, and electrical testing, all these functions are combined into one protection layer containing both thermoplastic and reinforced semi-conductive thermoplastic elements arranged together.
3Volume of moving object
If the cable outer diameter is reduced for better transportation efficiency, then transportation costs decrease, but the load resistance capability is compromised
Solution Approach 1:
The patent applies local quality by concentrating protective elements only in the specific region between the inner and outer sheaths where mechanical protection is needed. The thermoplastic and reinforced semi-conductive thermoplastic elements are arranged in this annular space, providing maximum protection with minimum diameter increase. The semi-conductive elements are strategically positioned to provide both mechanical reinforcement and electrical testing capability.
Data Source
Figure 1~2
AI summary
The present invention relates to a piggyback cable (10) comprising a copper conductor (2) with a standard triple extruded insulation system including a conductor screen (13), an insulation layer (14), and an insulation screen (15), an inner sheath (16) surrounding this insulation system, and an outer sheath (18), the space between the inner (16) and outer (18) sheaths being filled with protective elements. The main technical feature of a piggyback cable according to the invention is that the protective elements comprise thermoplastic (21) elements arranged together to form at least one layer helically wound around the said cable (10).