Integrated methodology for safety analysis based on a system-theoretic approach and numerical simulation

The System-Theoretic Process Analysis (STPA) method is a useful approach to analyze system safety, however, it still has inadequate capabilities for quantitative safety analysis. To overcome this limitation, an integrated methodology was investigated for quantitative safety analysis of the complex socio-technical system that combines a system-theoretic approach and numerical simulation. In the proposed methodology, STPA method is utilized to discover potential unsafe control actions (UCAs) and corresponding causes based on the operational principle of the target system from systemic perspective. Moreover, the consequences of identified UCAs can be quantified and certain safety constraints also were improved to prevent UCAs using numerical simulations. The blind shear ram preventers (BSRPs) as complex system, with tightly interacting diverse subsystems or components are, is employed to illustrate the applicability of the methodology. The results verified that the proposed methodology could effectively evaluate potential hazards and quantify the analysis results. These results will be helpful for the design and operations of the BSRP system in deepwater drilling activities. The developed methodology also has a more general application to safety analyses in other process industries.