@inproceedings{631f4d556afb49d18a048c654b52b125,
title = "IMPROVED RELIABILITY ASSESSMENT METHODS FOR SUBSEA CABLES ON ROCKY SEABED USING NPV CALCULATION",
abstract = "To date, the offshore renewables industry has drawn substantially on prior design guidance and recommended practices from the oil and gas industry. This includes the extension of the existing DNV-RP-F109 to cover on-bottom stability of subsea power cables for offshore wind. However the overwhelming focus of oil and gas design practice is to avoid loss of containment events which represent potentially catastrophic safety, health and environmental consequences. In contrast, the mechanical failure of subsea power cables in an offshore wind farm represents in practice a purely economic consequence. The inherited factors of safety are therefore entirely inappropriate. A more relevant approach to provide the most reliably cost-effective product is to quantitatively consider the lifetime design risk through an assessment of the relative net present value (NPV) of different options. This allows comparison between increased upfront costs to reduce the probability of component failure versus the future cost of additional maintenance and repair. NPV reliability methods are recommended in ISO 2394 and the new BS10009 Bottom stability of cables on rocky seabeds. In this paper the NPV of two on-bottom stability risk management strategies are quantitatively compared for subsea cables on rocky seabeds that are being designed to BS10009. Drawing on recent research findings from The University of Western Australia together with published field data, an example cable is analysed to determine that the probability of cable mechanical failure across the design life is around 3.54 x 10-3. This is roughly half an magnitude lower than the limit detailed in IEC 61400-1. This scenario is compared to the same cable with the addition of filter units (rock bags), which reduces the overall and annual probabilities of failure. The increased upfront cost is compared against the reduced risk of replacing a segment of cable after failure. Based on the low cable probability of failure it is found that, for this worked example, there is no positive NPV benefit to place filter units on the cable from an on-bottom stability perspective.",
keywords = "NPV, Offshore wind, reliability-based design, subsea power cable",
author = "Nicholas McGrath and Terry Griffiths and Jack Jorgensen and Fabrizio Pistani and Scott Draper and Liang Cheng",
note = "Funding Information: The authors acknowledge the large body of research which underpins this paper, of which the contributions from The University of Western Australia{\textquoteright}s Coastal and Ocean Engineering Lab (COEL) and Oceans Graduate School (OGS) form a substantial part. The authors also acknowledge with thanks the efforts of the British Standards Institute and the steering group members for their contributions to the drafting of the new BS 10009. Publisher Copyright: Copyright {\textcopyright} 2023 by ASME.; ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2023 ; Conference date: 11-06-2023 Through 16-06-2023",
year = "2023",
doi = "10.1115/OMAE2023-102341",
language = "English",
series = "Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE",
publisher = "ASME International",
booktitle = "Ocean Renewable Energy",
address = "United States",
}
