In this paper we present a framework that addresses the three main parts of a process hazards analysis (PHA) study - hazard identification, hazard evaluation, and hazard mitigation. The framework utilizes a hybrid methodology that effectively combines a qualitative digraph model-based technique for performing hazard identification and a quantitative optimization-based technique for performing hazard evaluation and hazard mitigation. The systems that are used to implement the framework are BatchHAZOPExpert, gPROMS and gOPT. BatchHAZOPExpert is used for hazard identification while gPROMS and gOPT are used for hazard evaluation and hazard mitigation. The application of the integrated framework is illustrated by implementing it on an industrial case study.