Are optical cables susceptible to corrosion

Optical cables are susceptible to corrosion primarily in their metallic armor or protective layers, with environmental factors and electrical stress being key contributors.

Corrosion Mechanisms

Armored optical cables use steel or metal tapes to protect the fiber core. Corrosion occurs when the protective coating is damaged, exposing the metal to moisture, soil chemicals, or saline environments. Copolymer-coated steel armor has been shown to resist corrosion effectively, with damage typically localized to areas where the coating is removed, such as cuts or rodent damage, without significant migration under the cable jacket.

ADS

S (All-Dielectric Self-Supporting) cables, which lack metallic elements, are vulnerable to electrical corrosion. High-voltage electric fields near power lines can cause ionization of air molecules, leading to partial discharges that degrade the cable sheath. Pollutants and moisture can create conductive paths, causing localized heating and material breakdown.

Improper grounding or stray currents can also accelerate corrosion even in dielectric materials. Submarine cables face corrosion from seawater and deep-sea sediments. Spirally wound armored steel wires protecting the fiber core can degrade due to multi-factor corrosion mechanisms, including chemical reactions with ions in sediments and mechanical stress.

The physical properties of sediments, such as particle size and composition, influence the rate of corrosion and the durability of the polyethylene sheathing.

Environmental Factors

Soil and sediment chemistry: Acidic or saline soils accelerate corrosion in buried cables. Moisture and water ingress: Water penetration through damaged jackets promotes oxidation of metallic components.

U

V exposure and temperature extremes: Can degrade polymer coatings, indirectly increasing corrosion risk. Electrical stress: High-voltage proximity or stray currents can induce electrical tracking and partial discharges in dielectric cables.

Protective Measures

Coatings and armor: Copolymer-coated low-carbon steel tape provides excellent corrosion and rodent resistance for armored cables. Track-resistant jackets: ADSS cables can use specialized outer jackets to minimize electrical tracking. Double-armored designs: For areas with high rodent activity or harsh chemical exposure, double-armored cables improve durability.

Environmental testing: Standards like IEC 60794-1-220 define salt mist and corrosion tests to evaluate cable resilience in saline or chemically aggressive environments.

Summary

Corrosion in optical cables is influenced by material composition, environmental exposure, and electrical stress. Armored cables are primarily affected by mechanical damage and chemical exposure, ADSS cables by electrical phenomena, and submarine cables by seawater and sediment interactions. Proper material selection, protective coatings, and adherence to environmental testing standards are essential to ensure long-term cable performance and reliability.