Investigation of Severe Corrosion of Mooring Chain in West African Waters

摘要

Recent detailed observations of the performance of mooring chains fora floating production unit in tropical West African waters have shownsevere localized corrosion (pitting) of the steel chain after only sevenyears of use. This paper describes the investigation of this phenomenonas part of the Joint Industry Project (JIP) research program SCORCH(Seawater Corrosion of Rope and Chain) funded by the major oilcompanies, most Classification Societies and various offshore operatorsand manufacturers. It is shown that there is a high likelihood that thechain has been subject to microbiologically influenced corrosion (MIC)as a result of the elevated levels of water pollution in the operationalarea. However, despite the large localized loss of steel in corrosion pits,the breaking load shows only a relatively small reduction compared tothe Minimum Breaking Load specified in design guidelines.