This paper presents a risk-based method to analyze the failure scenarios and associated consequences that may happen during the cargo handling operation of a LNG carrier. The paper determines the possible leakage causes and classifies their consequences. Those causes are related to failures of the components involved in these operations such as valves, piping system and control system. The risk involved in loading and unloading operations is described considering the probability of occurrence of each failure mode and the consequences of the leakage based on a risk matrix method. Recommendations to avoid the occurrence of LNG leakage are discussed.

INTRODUCTION

The production of Liquefied Natural Gas (LNG) has increased due to the increasing worldwide demand for that fuel. That demand implies in the necessity of transportation of large amount of the product between the production areas and the consumer countries, implying in the increase in the operations with LNG carriers. Although the safety standards for design, construction and operation of this kind of ship are very stringent, there are registers about minor accidents with those ships. The probability of accidents is greater during cargo loading and unloading operations due to the great number of systems and pieces of equipment involved in those operations. This paper presents a methodology for risk analysis of LNG carriers operations aiming at defining the most critical pieces of equipment as for avoiding LNG leakage during loading and unloading operations. The methodology is based on Probabilistic Risk Assessment concepts. The method of risk analysis allows building a risk profile for the ship operation and possible mitigation actions can be developed to avoid any catastrophic consequences associated with LNG leakage. The method is applied in the analysis of a LNG carrier operation in a seaside terminal. The pieces of equipment considered critical for loading and unloading operations are identified and the Cause- Consequence diagram is built.

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