Localized Corrosion of Mooring Chain Steel in Seawater

Corrosion of mooring chains is regarded as one main threats to the offshore systems. Localized corrosion even more dangerous than uniform because it may not show significant mass loss but can cause stress concentration and initiate cracks under force, leading accelerated degradation chains. steel in seawater influenced by many factors such local heterogeneities steel, electrochemical microbiological environments. It difficult predict mechanism fully understood. The aim this work was study localized on chain which helpful search for corresponding monitoring tools mitigation methods. behavior grade R4 studied artificial containing microorganisms collected from a practice field. using different techniques potentiodynamic polarization, linear polarization resistance measurements impedance spectroscopy. microstructures inclusions compositions were SEM: Scanning Electron Microscope EDS: Energy Dispersive Spectroscopy. microbial cells observed epi-fluorescence microscopy. morphology pit geometry investigated photo-microscopy. rate has been found be much higher presence bacteria. In case corrosion, applying measurement formulas considered representative. representative areas have introduced match physical results with measurements. Inclusions, MnS TiVCr critical influence corrosion. discussed.