Adoption of new advanced computational techniques to hazards ranking in LNG carrier operations

The risks of hazards of liquefied natural gas (LNG) carrier operations and their fundamental causes are investigated in this study. A new framework is developed through the combination of a risk matrix approach and a fuzzy evidential reasoning (FER) method. The risk matrix approach is employed to identify the major hazards associated with the LNG carrier operations. In the risk matrix methodology, linguistic terms are used to estimate how likely hazards may occur in LNG carrier operations at sea, and the consequences of the hazards. The failures of an LNG spill from a transfer arm and an LNG containment system are identified as the hazards of “very high risk”. The fault tree analysis (FTA) diagrams of “very high risk” hazards (top events) are used to identify their causes (basic events) and failure logics. Due to the unavailability of historical failure data, the safety/risk level of each cause is investigated using the FER approach. In the FER approach, the safety levels of the basic events of the top event are assessed using three safety parameters (i.e. occurrence likelihood, consequence severity and failure consequence probability) and combined using evidential reasoning (ER) in fuzzy environment in order to reveal the top events’ safety/risk levels.