Defensive Armour for Cables
Layers of vital protection
Cables live tough lives, and are constantly menaced by cold, heat, stress, water, chemicals, impact, vibration, etc. Many threats are part of the task, installation or environment and can affect the operation of the cable, and thus endanger production, equipment or people. That is why they need protection in layers around the core of the cable.
Nexans’ R&D is therefore not just about producing better wires and conductors, it is also focused on finding better ways to protect the cores (whether metal or optical fiber) in all sorts of conditions. This requires expert knowledge of both materials and designs.
The bedding, or filling of the cable core assures that the cable is round, but also that any ingress of water due to damage to the cable jacket will not propagate inside the cable.
Well-known solutions exist, but innovative designs such as EASYFIL® have been developed, where the bedding holds the wires together, allows for easy stripping, and makes it easier to install because they are made of a slippery material.
Well-protected submarine cable
Armoring assures the mechanical integrity of the cable by withstanding pulling loads and crushing forces in mining, for example. They can also protect against electromagnetic interference in highly disturbed environments, e.g. along electrified railway lines.
In special cases, high-performance plastics (aramid yarns) are used for this function, either to provide a completely dielectric cable (fiber optics) or for lightweight cables used for remote controlled submarine vehicles (ROVs) in oil and gas submarine exploitation. In this last case, cables have been developed, which have neutral buoyancy in sea water, to avoid exerting a load on surface ships or submarine vehicles.
And finally, external jackets, often incorporating complex designs and special compounds, provide protection against a range of threats such as:
- Hazardous chemicals: To meet the environmental concerns of refineries and the petrochemical industry, Nexans developed HYPRON® lead-free cables. This all-in-one design combines inner aluminum tape for watertightness, High Density Polyethylene (HDPE) for resistance to inorganic chemicals (like Chloride), and Polyamide for resistance to organic chemicals in an incredibly tough, co-extruded, triple-protective layer.
- Smoke, gases and fire: To meet public and material safety concerns in buildings, rolling stock, shipbuilding, etc., Nexans has a host of solutions. Fire-retardant characteristics depend on the performance of the materials used for the jacket, and to some extent the bedding. Improved HFFR (Halogen-Free Flame (or Fire)-Retardant) materials have been developed, based on highly flammable polyethylene, using fillers to obtain a self-extinguishing, low smoke material. These insulations are gradually replacing PVC-based materials or fluoropolymers, which are less combustible than PE, but which generate unacceptable amounts of dangerous fumes in case of fire.
- Rough sea conditions: Among our most complex and protected cables are umbilicals which are used to carry energy, telecommunications, fluids and chemicals for offshore oil and gas installations. To meet threats from currents, ship anchors, and deep-water pressure, they employ an array of armoring and protection, including steel wires, synthetic composites and compressive elastomers to relieve cable stress during laying.
- Animal, insect and human threats: Chemicals, fire and weather are not the only enemies of cables; living creatures can also pose a threat. Outdoor fiber-optic and copper cables – e.g. trackside train control cables or buried LAN cables – can be attacked by rodents (rats, gophers, squirrels, etc.). Metal shielding and special glass yarns fully ensure that they are rodent-resistant. For home wiring, Nexans Australia developed a termite-proof cable without having to use the poisonous chemicals normally used for this purpose. And to protect against human invasion (and electricity theft), Nexans devised concentric, bi-concentric and tri-concentric designs which create a short-circuit when pierced, thus foiling thieves.