QUANTITATIVE METHOD TO DERIVE DESIGN CASUALTY SCENARIOS FOR MARINE METHANOL TANK PRESSURE RELIEF SYSTEMS

Kurzfassung

This study proposes a quantitative risk assessment approach for pressure relief systems in marine methanol fuel tanks. The approach utilizes a hazard and operability study to identify and qualitatively assess system-related risks. The output is then considered together with available empirical data on the probability or frequency of occurrence. Unavailable data is retrieved from analytical methods or estimated based on expert judgment. The study focuses on key components of the pressure relief system, including the tank, inertization system, venting pipes, valves and the venting mast. Inputs include results of thermodynamic simulations for the evaporation behavior of the tank and analytical methods for the estimation of gas dispersion at the vent outlet. The applied methods account for factors such as fuel flows, thermal induced evaporation, tank geometry, and ship operational states. The tangible results are (i) a compilation of relevant data publicly available for the application of quantitative risk assessment, (ii) the derived values for parameters with limited or no available data on probability or frequency of occurrence, and (iii) the resulting design casualty scenario to be considered in alternative design development processes for a methanol tank pressure relief outlet. Their application supports the development of alternative arrangements for tank venting masts on methanol-powered ships, following a goal-based regulation approach.