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 …
SHIP DESIGN USING PROBABILISTIC DAMAGE STABILITY RULES-A SENSITIVITY STUDY
Publisher Summary This chapter addresses the calculation of the Attained Index A. The first part considers the variation of A with the degree of details in the modeling of the compartmentation. The exemplified vessel is a recently built Danish ferry and both the SOLAS Part B-1 and the SLF 43/3/2 proposals are applied. The contributions from single and multiple compartment damages are identified. The reason for the different predictions from the two calculation procedures is discussed. The conclusions contain guidelines for the level of details needed in the geometrical definition of the vessel to predict the Attained Index A with acceptable accuracy. The current IMO resolutions contain two different probabilistic damage stability regulations: A.265 for passenger vessels and SOLAS Part B-1 for dry cargo vessels. However, ongoing harmonization studies as those presented in the IMO documents SLF 42/5 and SLF 43/3/2 aim at one single damage stability rule applicable to all kinds of ships. Such a harmonization requires due consideration of both the calculation of the attained index describing the probability of survival, and specification of a suitable minimum level, taking into account the consequences of loss of the vessel. The second part of the chapter considers the variation of the Attained Index A with change in main parameters in the preliminary design phase. The main conclusions are that the height of the main deck may influence the attained index by up to 60 per cent, whereas the length of the machinery room can change A by up to 20 per cent.
Volatile hydrocarbons in the atmosphere of the Kiel Bight (Western Baltic)
Abstract Volatile hydrocarbons (VHCs) in the Kiel Bight atmosphere were collected by adsorption on silanized porous glass (PG). This material proved to have a good capacity to concentrate VHCs, and it is easy to clean and to maintain free of contaminants. VHC concentrations in the atmosphere of the Bight vary strongly, depending on the wind direction and the amount of precipitation. Southerly, southwesterly and westerly winds are responsible for the transportation of VHCs from the land to the Kiel Bight.