Corrosion-fatigue damage identification in submerged mooring chain links using remote acoustic emission monitoring

Abstract

This paper investigates the feasibility of detection, localisation, and monitoring of corrosion-fatigue damage in mooring chain links using remote Acoustic Emission (AE) technique in submerged conditions. A large-scale experiment was conducted on a studless R4 chain retrieved after about two decades of operation offshore. Ultrasound signals were continuously measured using fixed and movable arrays of AE transducers placed on perpendicular planes in the water tank enclosing the chain. The AE parameters extracted from the measured signals have been analysed. AE sources were successfully localised on the 3D geometry of the chain links. The results suggest that damage growth can be detected and localised using non-contact underwater AE transducers. • Corrosion-fatigue damage was identified using remote AE during a large-scale experiment on submerged mooring chain links. • An approach for remote AE source localisation on the 3D geometry of the underwater structure has been implemented. • AE source localization identified three damage zones in the mooring chain specimen, all confirmed by post-failure MP testing.