Mooring chains for permanently moored structures – including FPSOs - have shown rapid corrosion of the chain in warm waters. Cathodic protection of mooring lines is normally not provided due to the discontinuous nature of chain links and installation constraints. In recent years, corrosion allowance and pre-emptive replacements of mooring systems are the most common solutions against this corrosion phenomenon.

This study addressed CP of mooring lines with ROV installable clamp anode design. The study is divided into three different sections to examine possible issues and constraints. Including, 1) Mechanical & Electrical properties testing to examine function and continuity between clamp and chain links and between chain links. 2) Development of a computer-based CP model of the mooring chain to simulate CP attenuation with realistic contact resistances between chain links. 3) Sea trials using a section of mooring chain to measure actual contact resistances between chain links and the polarization level of mooring chain links with a single Al anode.

The test results indicate that the subject technology could support new and retrofit CP designs via ROV installable CP System, enhance the operational lifetime of the mooring chains and be beneficial for all other marine and offshore assets.

Subject
Test methods, Anodic protection, Cathodic protection, Free corrosion potential, Seawater, Electrical continuity, Cables, Anode resistance, Force, Corrosion modeling, Polarization, Electrode potential, Anodes
Keywords:
Corrosion, Cathodic Protection, Sacrificial Anode Cathodic Protection, SACP Anode, ROV Installable Anode, Mooring Chain, FPSO, Attenuation, Subsea, Remotely Operated Vehicle (ROV)
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2022
Association for Materials Protection and Performance (AMPP)
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