Kabel Shanghais Shenghua (Gruppe) Co., Ltd.
How Does the Marine Environment "Attack" Cables? A Detailed Look at the "Multi-Layer Defense" of Specialized Jacket Materials
Ordinary cables that perform excellently in land-based applications may see their lifespan plummet from decades to just a few short years once deployed in the marine environment. The ocean is not a single challenge, but a "compound battlefield" composed of UV radiation, saltwater, biological organisms, mechanical forces, extreme temperatures, and fire risks. Therefore, the jacket of a marine cable is far from a simple plastic cover; it is an engineered system designed for multi-layered defense.
Here are the primary threats posed by the marine environment and the key counter-strategies implemented in jacket materials:
1. Ultraviolet Radiation: Combating "The Cutting Edge of Sunlight"
Threat: Constant direct sunlight causes the polymer chains in ordinary materials to break, leading to photo-oxidative degradation. This results in the jacket surface becoming chalky, cracked, and losing its elasticity.
Solution: Use UV-stabilized polyolefin materials (such as cross-linked polyethylene) incorporating sufficient carbon black. Carbon black is an excellent UV absorber and screen, converting harmful radiation into harmless heat. This is crucial for cables to serve long-term on offshore platforms, decks, and coastal buoys.
2. Saltwater Immersion and Corrosion: Combating "The Penetration of Salt"
Threat: Seawater, especially chloride ions, is highly penetrative and corrosive. It can cause rust in metallic armor/screens and may lead to water treeing in insulation materials, ultimately causing electrical failure.
Solution:
Chemical Barrier: Use materials like Ethylene Tetrafluoroethylene (ETFE) as an outer or intermediate layer. Their exceptional chemical inertness effectively blocks the penetration of salt and oils.
Physical Barrier: In areas requiring extremely high mechanical protection, use galvanized steel wire or copper-clad steel tape armor. A tightly extruded outer sheath provides a sealed barrier against seawater, offering dual protection.
3. Biofouling: Combating "The Weight of Life"
Threat: Marine organisms like barnacles and algae attaching and growing on the cable surface (biofouling) can significantly increase the weight and hydrodynamic drag of subsea cables. This may lead to free spans, exacerbated vibration, and even structural damage.
Solution: Add silicone or fluoropolymer-based additives to the jacket compound. These additives create a smooth, low-surface-energy "non-stick" layer on the jacket surface, greatly reducing the adhesion strength of organisms so they are more easily washed away by currents.
4. Mechanical Stress: Combating "The Force of the Ocean"
Threat: Subsea cables must withstand complex mechanical stresses including ocean current impact, abrasion on rocks, fishing trawl nets, anchor strikes, and even iceberg scouring.
Solution: A combined mechanical protection system is formed by integrating high-strength aramid yarn reinforcement, metallic armor, and a high-tear, high-abrasion-resistant elastomeric jacket (like polyurethane). This ensures structural integrity under tension, compression, bending, and impact.
5. Extreme Temperatures: Enduring "The Test of Ice and Fire"
Threat: Jacket materials must maintain flexibility from the sub-zero temperatures (tens of degrees below zero) in polar regions to the high temperatures in tropical surface waters, avoiding brittle cracking in the cold or softening deformation in the heat.
Solution: Select cold-resistant/heat-resistant elastomers with a broad operating temperature range (e.g., -40°C to +90°C). This ensures they remain pliable for installation in freezing conditions and stable in high-temperature environments.
6. Fire Safety: Mitigating "Onboard Risks"
Threat: For cables used inside ships or offshore platforms, the smoke and toxic gases emitted during a fire pose a major safety hazard.
Solution: Mandatory use of Halogen-Free, Low-Smoke, Flame-Retardant materials that comply with the IMO FTP (International Maritime Organization Fire Test Procedures) Code. These materials produce low smoke density and do not release toxic halogen acid gases when burning, buying crucial time for personnel evacuation and firefighting.
Conclusion: A Synergistic Defense System
The design philosophy behind marine-grade cable jackets is not about "single-point solutions" but about building a multi-layered, integrated, synergistic defense system. A single jacket might incorporate: a carbon-black-stabilized, halogen-free polyolefin layer to resist UV; an ETFE layer as a chemical barrier; a silicone-modified surface to prevent biofouling; with internal metallic armor and aramid taking the mechanical load—all while the overall compound meets stringent fire safety and environmental standards.
This complex materials engineering is precisely what ensures the stable and reliable operation—for over 25 years—of critical systems like subsea observation networks, offshore wind farms, transoceanic communications, and shipboard power systems in one of Earth's harshest environments: the ocean. Choosing the right cable jacket is, in essence, selecting a custom-tailored "suit of lifelong armor" for your marine assets.
