Evaluation of corrosion process and monitoring techniques of mooring chain steel in the marine environment
J. Zhang (TU Delft - Mechanical Engineering)
Johannes M C Mol (TU Delft - Team Arjan Mol)
Lotfollah Pahlavan (TU Delft - Ship Hydromechanics and Structures)
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Abstract
Currently, as the utilization of offshore wind energy continues to increase, floating wind turbines are expected to be widely used. As the fixed system of the turbine, the safety of the mooring chain has gradually attracted the attention of researchers. Mooring chains immersed in seawater are mainly subjected to various mechanical loads and corrosion. Therefore, premature failure and frequent replacement are the main problems of mooring chain systems. In order to avoid huge losses of safety caused by structural failure, it is urgent to establish mooring integrity management, accurately identify hazards, and evaluate the service life of the mooring system. Considering the requirements of sufficient mechanical properties and economic benefits, high-strength low-alloy steel has gradually replaced low-carbon steel as the main material for mooring chains. However, there are few studies on the detailed corrosion process of mooring chain steel.
This research aims to explore the corrosion process of mooring chain steel and the influence of marine environmental factors on the corrosion process. Traditional electrochemical techniques, morphology observation and new in-situ non-destructive technique acoustic emission are used to investigate the corrosion process. The experiment includes the exploration of the corrosion process of steel under natural and accelerated conditions. Experiments on the influence of flow velocity and temperature are also included. The corrosion process of mooring chain steel is successfully explored during the monitoring process. Acoustic emission signals related to corrosion are separated. Their sources are reasonably identified. The effects of water flow velocity and temperature of the corrosion process are summarized.