A disaster in a process plant is sometimes enlarged by its propagation to another part of the plant, and only a properly arranged process plant can prevent such a chain disaster. Therefore, safety must be considered in arranging equipment modules in the early design phase. Previously, only economical factors were focused on, and safety was considered after decided the plant layout. The purpose of this study is to develop a method to arrange the equipment modules with consideration of required safety. To consider chain disasters, not only the positions of the equipment modules, but also their directions become the decision variables, thus the problem is an enormous combinatorial optimization one. In this sturdy, a characteristic of this problem is considered, and an evolutionary searching method is found to be suitable. In the proposed method, the equipment modules are divided into module groups for the first step, and sub-arrangements within each group are generated under the consideration of safety. An initial arrangement is obtained by merging these sub-arrangements, and this arrangement is brushed up by alternating the location and the direction of the equipment modules. Finally, the effectiveness of the proposed method is demonstrated by solving an example problem.