Thesis
Fire safety risk model for a main vertical zone of a large passenger ship
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16756
- Person Identifier (Local)
- 201882664
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- The scope of this thesis is to shed light on the everlasting issue of on-board fires, with a particular focus on large passenger ships, by proposing a fire risk model for a Main Vertical Zone (MVZ). Historically, fire had and always has been a pressing accident type, along with flooding. Despite the regulatory effort, the total loss trend of fire incidents attributes to around 10% of those. Moreover, as per the high-level hazard identification conducted as part of this thesis, it was ascertained that cruise ships dominate the frequency of accidents whereas RoPax dominate the fatalities. The latter could be explained by the fact that numerous RoPax ships operate in less developed countries, where regulation enforcement is questionable and also experience higher transportation work in terms of volume. Conversely with RoPax ships, cruise ships are becoming larger by the day, offering novel designs and pertinent entertainment, which is usually translated into complex designs, in addition to the higher transportation volume in terms of passengers and crew. Various statistical analyses were scrutinised towards understanding how shipborne fires break out, including the one from research project SafePASS, being the most recent one, and having particular focus on all ships carrying passengers. Amongst all samples the frequency of fire events remained the same, highlighting the issue. Passenger ships, which accommodate large capacities of people experience higher fatality rates, underlining the urgency of improved safety measures. Therefore, for the purpose of this thesis focus was given on large passenger ships. On the other hand, the maritime industry and its stakeholders have always had a rather reactive stance towards safety, with the exception of cruise operators where safety is paramount with respect to their business longevity. The most prevalent example of the aforementioned being the birth of Safety of Life at Sea (SOLAS) after the sinking of the RMS Titanic. Accordingly with the high-level hazard identification, the engine room appeared to be the most usual culprit for fire and explosion events on board ships, attributing to more than 50% of such events, which is to be expected as ship’s engine room acts as a process and propulsion plant with inherent fire risks. The most frequent ignition scenario is the release of flammable oil (fuel or lubricating) which comes into contact with a hot surface, which are abundant in an engine room. Furthermore, the current status of the engine room fire safety has been characterised as sub-optimal as it investigates events only prior or next to ignition and has a particular focus on mitigation through various active and passive means (smoke detectors, deluge systems and fire boundaries respectively). Nevertheless, fire events continue to take place, highlighting the need for further research. Irrespective of the commendable research initiatives, such as project SAFEDOR and FIREPROOF, aimed at introducing the risk assessment and risk-based design respectively, the industry still has a focus on events proximate to ignition. Additionally, in line with Safety II and resilience engineering, systemic analysis of safety critical equipment and operations is thought to be the way forward towards a fire free system. Safety barriers have been adequately used in other industries, such as aerospace, oil and gas, and navy ships, but their adoption within the maritime industry is lagging behind. Sensory equipment and data analysis have been historically employed towards inferring safety barrier statuses, particularly that of technical elements. Systemic investigation, on the other hand, necessitates the investigation between the technical system and the asset and the operator, therefore, organisational and operational elements must be taken into account in order to provide a systemic coverage. Consequently, this research proposes a holistic simulation-based Main Vertical Zone (MVZ) fire risk model, specifically designed to demonstrate the efficacy of safety barriers. The fire risk model of the MVZ was stipulated in the form of a risk contribution tree (bow-tie) having preventive measures on the left-hand side and mitigating on the right. Since engine room fires are historically more prevalent compared to other areas, particular focus was given towards establishing a framework for the systemic derivation of a the so termed Release Prevention Barrier (RPB), aimed at averting engine room flammable oil leaks. Focus on flammable oil leaks was given as the author believes that treating hot surfaces is counter-intuitive as the lagging (if necessary by the provisions) may deteriorate over time and improper fitting could almost be guaranteed through repeated maintenance. The proposed framework offers a systemic structured way of establishing the said barrier, with focus on the placement of sensory equipment, which, as per the literature review, is not straightforward whatsoever. The framework is rather generic in the sense that it can be applied on any flammable oil line of any ship, highlighting its applicability. On the right-hand side, mitigating measures from SOLAS and the Fire Safety Systems Code (FSS Code) were deemed to be adequate towards that end, mainly due to their historical contribution in mitigating the effects of fire. Moreover, these have been scrutinised adequately within project FIREPROOF. Full-scale 3D Computational Fluid Dynamics (CFD) simulations were utilised towards assessing the risk of fire within the MVZ. Except for the engine room, passenger cabin and large public space decks are also liable to fire events, following the occupancy trends of such ships. Moreover, engine room fires, although statistically prevalent, do not pose as much risk to passengers as the aforementioned decks. To that effect, fire simulations were conducted on all these decks. To realise the fire simulations and to demonstrate the inherent difficulties posed by the lack of ship-borne fire data, first principle engineering was utilised to the full extent to deterministically assess the risk in way of pyrolysis modelling. For the purpose of the CFD simulations the Fire Dynamic Simulator (FDS) and Pyrosim were utilised, being the industry standard. Thermophysical and chemical data were employed to successfully construct design fires, while the pyrolysis methodology was successfully validated and verified against full-scale experiments, deeming the design fire methodology as suitable for use onboard ships and subsequently assessing the risk within the MVZ. Investigation beyond a MVZ was not sought as it violates the mentality of the MVZ itself, and due to difficulties posed by computational power and respective means necessary to do so. In the case of the engine room fire simulation, a hybrid deterministic approach was stipulated using both first principles and statistical means in way of Monte Carlo simulations. This was performed in an effort to showcase the tremendous difficulties posed by such an endeavour and the reason why deterministic engine room fire simulations are not available.
- Advisor / supervisor
- Vassalos, D. (Dracos)
- Boulougouris, Evangelos
- Resource Type
- DOI
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