Seismic damage assessment of a crude oil hydrodesulphurisation unit. Part II: hazard-consistent fragility assessment

This study presents a methodology for developing hazard-consistent component-specific fragility functions for a system of interconnected industrial assets. The approach begins with the seismic hazard assessment of the area of interest carried out for an intensity measure that can be used as a practical yet reasonably accurate statistical predictor of the response of such assets to ground motions of different severity. The response is evaluated via nonlinear time history analyses with an ensemble of ground motions whose spectral content is consistent with the hazard assessed for the site. This methodology is applied to a hydrodesulphurisation unit of a crude oil refinery located in a high-seismicity industrial area of Greece. The exposure model and the unit assets’ models have already been presented in detail in the companion paper. The case study shows that even low-to-moderate intensity ground motions pose a non-negligible probability of damage to assets such as pumps, heat exchangers, high-temperature separators, liquid storage tanks, and piping system. The proposed methodology lays the groundwork for comprehensive system-level seismic risk and resilience assessment studies that evaluate the impact on refinery units or on the entire facility, as will be demonstrated in an upcoming dedicated study.