Mark Hendry, Technical Director at Hydro Group Plc, discusses the rapidly-changing subsea cable market.
In today’s subsea environment, systems being deployed require reliable power and communication connections in more demanding and dynamic environments. We are innovative in our designs and this driven by our international clients’ increased need for cables with multifunctional performance.
The team at Hydro Group are being asked more and more for increasingly complex composite and physically demanding cable designs. Today, most subsea cables designed and manufactured at Hydro Group’s Aberdeen, Scotland facility incorporate numerous specialist elements such as fibre optics, twisted pairs, triples or quads, coaxial, VHF and high-frequency RF components.
As subsea equipment is becoming more complex with data management and collection systems transferring significantly higher volumes of information at faster rates, the Transmission Characteristics, Low Loss and Shielding requirements need to be addressed in the design and composition of the cables.
To ensure the performance of the designs, increasing use of complex software modelling and analysis tools are employed. Hydro Group engineers routinely utilise packages such as Comsol multiphysics software to model designs and provide virtual realisation of the cable characteristics under a variety of simulated conditions. Transmission characteristics and performance are also simulated with the use of Optem software tools.
Hydro Group regularly incorporates stainless steel tubes, rather than PBT tubes, for all of our subsea cable designs incorporating fibre optics. The benefits of utilising optical fibres contained within stainless steel tubes are primarily twofold:
Both of these advantages over PBT Tubed fibre optics are deemed crucial in the demanding conditions seen by subsea optical cables.
Mechanical factors are extremely significant in the overall performance of subsea cable designs. Often these present a much higher risk in the reliability and durability of the design than all other constraints. The application of FEA design and modelling tools such as Comsol and Orcaflex allow simulation and analysis of the design to ensure construction and incorporation of components that will meet the dynamic application requirements. Understanding the static and dynamic forces that will be applied allow the incorporation of features and components such as Vectran braids and cords for tensile strength in light weight and more flexible applications and Contra Helical steel wire armouring packages where significantly higher mechanical forces will be experienced
Hydro Group services a global client base, with ocean environments varying significantly in different regions and therefore different risks to consider such as salinity, water temperatures and seabed conditions. As industry explores deeper sea depths, this affects the design and material selection of cables, with challenges such as UV stability, marine growth, microbial attack and even the burrowing Teredo Navalis Shipworm to be addressed.
With a full appreciation of all electrical, optical, mechanical and environmental requirements imposed on the application of the cable, a robust and reliable cabling solution can be realised.
The combination of the above design factors and the fact that equipment demands are increasing rapidly are driving more customised solutions. In addition to the design approach employed, Hydro Group has invested heavily in new machinery, significantly increasing and improving in-house cable manufacturing capabilities, to compliment this rapidly-evolving market.
With regards to future innovations, as part of Hydro Group’s research and development program, the R&D team is working on a number of cable design projects for specialised applications in energy, defence and renewables. Amongst these we are currently trialling various low-smoke flame retardant materials to address single cable designs capable of operating between separate boundaries from topside to subsea.
Hydro Group Plc, an energy-service firm made up of Hydro Bond Engineering and Hydrocable Systems. It is a major global supplier of harsh environment engineered products to the offshore oil and gas, defence, oceanographic, renewable energies, diving and ROV/AUV markets.