This paper proposes a new method, risk-oriented hazard analysis (ROGA), for carrying out the risk-based hazard analysis of chemical plants. The aim of ROGA method is to determine the status of a plant's safety technology by determining the risk that arises as a result of a source of hazard taking effect and by evaluating all measures taken to control this risk. The contribution consists of two parts. In this first part, the deductive hazard analysis and its extension by a semi-quantitative risk assessment associated with sources of hazards is explained with the help of a risk graph.