Mechanism of Corrosion in Porcelain Insulators and Its Effect on the Lifetime

Abstract

Porcelain insulators should be exchanged periodically, but their lifetime is not clearly defined. One factor that affects service life is corrosion occurring at the pin and cap—each of which is made of iron with a zinc coating. A number of porcelain insulators used for different lengths of time in different locations are gathered, and the corrosion mechanisms of the cap and pin are investigated. The corrosion mechanism of the cap is mainly galvanic corrosion while that of the pin is primarily electrolytic and crevice corrosion as well as galvanic corrosion. Although time is an important factor in corrosion, it is found that corrosion is more influenced by geographical factors. Since the amount of acid rain and sea salt—each of which causes rapid rusting—is dependent on geographical factors, the location of where porcelain insulators are installed should be considered when predicting their lifetime. Theoretically, if there is only galvanic corrosion occurring, the expected lifetime is 56 years in an industrial area when the zinc coating has a thickness of 75 µm. Previous articles dealing with aging have predicted the maximum lifetime of porcelain insulators used in Korea to be approximately 30 years. To prolong the lifetime of porcelain insulators, further study is required in which the use of zinc alternatives, or waterproof coatings (in addition to the zinc coating), could be examined.

Superhydrophobic Surface on Insulators by Using Perfluoropolyether-Functionalized Silica Nanostructures for Preventing Stress Corrosion Cracking at the Pin–Cement Junction

“…The corrosive aqueous species (aqueous chloride/hydrogen sulfide) would be adsorbed on the surface of the pores/crevices at the pin–cement interface, lowering the local threshold fracture stress of pores/crevices. − Simultaneously, the corrosive ions rupture the local passive film within crevice/pores, resulting in local active–passive cell networks across the pin (galvanized steel)–cement interface. The combined and synergistic interaction of mechanical (tensile stress) and chemical forces (corrosion reaction) applied by adsorbed corrosive species in a higher temperature environment (25–45 °C) results in the growth of the local deformation (pores/crevices) at the pin–cement interface, which results in crack propagation throughout the insulator as seen in S1 . Thus, localized deformations (micropore/crevice) at the pin (galvanized steel)–cement contact are considered epicenters of stress corrosion crack propagation. , …”

“…The combined and synergistic interaction of mechanical (tensile stress) and chemical forces (corrosion reaction) applied by adsorbed corrosive species in a higher temperature environment (25−45 °C) results in the growth of the local deformation (pores/crevices) at the pin−cement interface, which results in crack propagation throughout the insulator as seen in S1. 8 Thus, localized deformations (micropore/crevice) at the pin (galvanized steel)−cement contact are considered epicenters of stress corrosion crack propagation. 9 Another reason reported elsewhere for stress corrosion cracking is hydrogen penetration into metal.…”

Application of noble cerium-based anti-corrosion sealing coating approach applied on electrical insulators installed in industrial regions

“…High-voltage insulators provide mechanical support and electrical isolation to conductors from the ground structure. Globally, 72% of overhead transmission lines use porcelain-on insulator pins installed at low-pH (3)(4) and highly corrosive (8-12 µm yr −1 ) industrial sites. In this study, the Ce-based noble sealing coatings were deposited on insulator pins using an economical dip-coating process.…”

“…Insulator assemblies and fittings mostly use galvanized metal parts owing to their successful history of corrosion resistance in low to medium polluted sites. In industrial and marine sites, a contaminated environment exacerbates the risk of corrosive attack for insulators [ 3 , 4 ]. The corrosion rate increases dramatically for contaminated, low-pH industrial and marine sites with frequent rainfall.…”

The Effect of Zn and Zn–WO3 Composites Nano-Coatings Deposition on Hardness and Corrosion Resistance in Steel Substrate

“…Steels used in functional parts of many industrial applications (power plants, automotive, construction) eventually undergo corrosion due to their low thermodynamic stability [ 1 , 4 , 5 , 6 , 7 , 8 , 9 ]. The materials undergo corrosion, which inhibits the proper functioning of parts, which fails parts during their service life [ 10 , 11 , 12 ]. In the United States, it was estimated that the cost of corrosion destruction is 6.2% of the gross domestic product (GDP) and accounts for more than 3% of the world GDP [ 13 , 14 ].…”