Review of the risk assessment of buoyancy loss (RABL) project
This report presents a review of the Norwegian 'Risk Assessment of Buoyancy Loss' (RABL) project, completed in 1988. RABL was undertaken in the aftermath of the Alexander L. Kielland and Ocean Ranger accidents. RABL's stated purpose was to investigate causes of loss of buoyancy of semisubmersible drilling platforms, with the overall objective of developing an analytical procedure for consideration of buoyancy loss. This procedure was intended to be analogous to guidelines applied to fixed platforms in Norwegian waters. RABL demonstrated that it is practical to carry out a risk assessment of buoyancy loss for semisubmersibles. The RABL methodology and procedure were considered to be robust and sensitive to differences between concepts, and RABL recommended that the new analysis methodology should be used to assess safety levels for new platform designs, or for existing platforms subject to changes in operational premises. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. ISBN 0 7176 2729 2 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. iv v EXECUTIVE SUMMARY This report presents a review of the Norwegian 'Risk Assessment of Buoyancy Loss' (RABL) project, completed in 1988. RABL was undertaken in the aftermath of the Alexander L. Kielland and Ocean Ranger accidents. RABL's stated purpose was to investigate causes of loss of buoyancy of semi-submersible drilling platforms, with the overall objective of developing an analytical procedure for consideration of buoyancy loss. This procedure was intended to be analogous to guidelines applied to fixed platforms in Norwegian waters. RABL demonstrated that it is practical to carry out a risk assessment of buoyancy loss for semi-submersibles. The RABL methodology and procedure were considered to be robust and sensitive to differences between concepts, and RABL recommended that the new analysis methodology should be used to assess safety levels for new platform designs, or for existing platforms subject to changes in operational premises. RABL found that the main hazards were ship collisions, ballast system failures and blowouts. Technical recommendations were made on each of these aspects. RABL concluded that upper-deck reserve buoyancy (as required by NMD) provides …
Risk modelling of collsions between supply ships and oil-and gas installations A risk influence modelling framework
Risk modelling of collsions between supply ships and oil-and gas installations Preface This master thesis was written as the final part of the Master of Science programme in Reliability , Availability, Maintainability and Safety (RAMS) at the Norwegian University of Science and Technology (NTNU), Norway. It was written in collaboration with SINTEF Safety Reseach, and was carried out during the autumn semester of 2013. The thesis is a development of a risk analysis framework for ship-platform collision risk. It is a continuation of the project thesis, that was a review of ship-platform collision models used in quantitative risk analyses. Acknowledgment I would first like to thank my supervisor, Professor Jørn Vatn at the department of Production and Quality Engineering (NTNU), for his help and guidance throughout the process of writing this report. I would also like to thank my co-supervisors at SINTEF Safety Research, Eivind Okstad and Stein Hauge, for their assistance along the way. Last, but not least, I would like to thank my girlfriend Ane Sofie Fremstedal. Her support, belief in me and helpful advices has been crucial to maintain a high spirit during the last few weeks of the thesis. This thesis is a framework for risk influence modelling of supply vessel-platform collisions, with the inclusion of central concepts from the Risk OMT model. The framework is a improvement from existing QRA frameworks in the sense that it has taken recent collisions into consideration , and enabled the opportunity to do risk influence modelling for the calculation of site specific risk. It can also be used as a tool for risk management, when the risk influences have been quantified. This model provides no quantifications, but it makes a good foundation for future work. The thesis incorporates knowledge from recent, representative collisions on the Norwegian Continental Shelf (NCS), and considered the guidelines and official safety procedures. This has been used to make three generic collision scenarios are general enough to take all probable collisions into account and at the same time be specific enough to account for the chains of events in previous accidents. These generic collision scenarios has been analysed with event tree analysis (ETA) and fault tree analysis (FTA) to identify and break down the operational barrier functions available to prevent collisions. A large set of risk influencing factors (RIFs) have been identified to be used to express the failure rate probabilities of the basic events …
SOME ASPECTS OF A KNOWLEDGE-BASED EXPERT SYSTEM FOR PRELIMINARY SHIP SUBDIVISION DESIGN FOR SAFETY
Traditional procedural approaches to computer aided ship design usually combine design knowledge and processing information in such a manner that incremental advances in design expertise are rather cumbersome to incorporate without extensive re-programming but his difficulty is more helpfully addressed in the knowledge based approach by an effective separation of logical processing elements from the knowledge elements. This is particularly helpful in the area of design of ships for safety because design knowledge in this domain is rather scarce and often becomes available experimentally. This paper deals with some aspects of the knowledge based design of passenger ferries with particular reference to subdivision using the alternative probabilistic regulations, and arrives at some guidelines on the basis of a critical examination of the premises of the regulations. These rules are then applied to show how designs can be improved from the subdivision point of view.