This lecture covers risk analysis as a global iterative process, the integration of risk analysis at the project design stage for economic reasons, the importance of risk analysis, and the application of Preliminary Hazard Analysis (PHA) to identify major hazards in a system. It also explains the method and steps of PHA, provides an example of a partial PHA for a storage tank of flammable gas, and discusses the advantages and limitations of PHA. Additionally, it delves into the principles and examples of using checklists for hazard identification and action planning, as well as the process and conclusions of Failure Mode, Effects, and Criticality Analysis (FMECA).