Risk assessment for ship-to-ship LNG bunkering

In this paper risk assessment for ship to ship LNG bunkering is carried out by exploiting the results of the projects “Risk management system for design and operation of installations for LNG refuelling” (TRiTON) financed by the Greek government, and the “SUstainability PERformance of LNG-based maritime mobility – Plus” (SUPER-LNG PLUS) financed by Interreg-Adrion. Ship to ship bunkering constitutes a simple method when it is difficult to install new storage tanks in the port areas. In brief, risk assessment is conducted including five basic steps: a) hazard identification, b) accident sequence modeling and quantification, c) damage states identification, d) consequence assessment, and e) risk evaluation. First, the Master Logic Diagram (MLD) technique is used to identify the initial events that create a disturbance in the installation and may lead to an LNG release. Corrosion in tanks, pipelines and other parts, and excess external heat owing to a nearby external fire are some of the identified initial events. Moreover, safety functions and systems for preventing LNG release, such as emergency shut-down and pressure safety valves, are identified. Event trees are developed to describe the accident sequence from the initial event occurrence until the LNG release and define the final damage states. By exploiting available failure rate data, the frequency of each damage state is estimated. In parallel, the consequences of LNG release are assessed on the basis of the heat radiation or overpressure dose an individual receives. Finally, risk is calculated by combining the frequencies of the various damage states with the corresponding consequences. A case study for a Greek port is, herein, presented.