Providing knowledge to avoid the risk of brittle failures in high strength mooring chains.
Challenge
Recent years several incidents related to failures of high-strength mooring chains used in mobile offshore units mooring systems have been reported. The fractures are found to be brittle in a material shown to be ductile through the standard tests. The presence of hydrogen in combination with a material that is susceptible to hydrogen is considered to be part of the cause. A criteria to identify an acceptable susceptibility threshold for mooring chain materials is missing.
Objective
First objective of the JIP is to define an acceptance criteria and an associated test procedure to differentiate between materials with detrimental and acceptable susceptibility to hydrogen degradation. The work will consist of establishing a test program, testing, developing a recommendation and project management.
Benefits
- Leaner mooring systems with high reliability taking advantage of the high capacity of the high strength chain
- Provide knowledge that can be used to avoid this failure mode on new chains on high strength materials in the future
Project details
DNV manages the project. Currently the JIP have 13 participants: Equinor ASA, Aker BP ASA, BP Exploration Operating Company Ltd, Inpex Operations Australia Pty Ltd, Jiangsu Asian Star Anchor Chain Co Ltd, Hamanaka Chain Mfg Co Ltd, Vicinay Marine Innovación Aie, Delmar Systems AS, First Marine Solutions Ltd, IKM Mooring Services AS, Intermoor AS, Odfjell Drilling AS, Transocean and Havtil (observer).
Project Status
The JIP was kicked of in September 2023. First workshop was held in February 2024. Testing and analysis work will commence 2024 Q3 and the JIP will be completed Q1 2025. Leaner mooring systems with high reliability taking advantage of the high capacity of the high strength chain.
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