Resumen del autor, extraído del trabajo. The decision-making process for the selection of the optimum plant system alternative should by backed up by in-depth analyses which assess the specific problems of the plant under examination and take into account the implications on the area where it is located, thus enabling to obtain a global and unified vision of all the HSE problems. The possibility of managing the HSE aspects of a plant presupposes the setting up of a "safe" plant, whose reliability is maintained in the course of time by means of management and technical processes. To ensure this, however, the first thing we have to do is decide to what extent we want it to be safe, that is, we have to decide on a reference point for the level of safety required for persons, the environment and property. It is only if we can demonstrate that the technical selections we have made guarantee this safety level that we can conclude that the plant has been well designed. The paper aims at highlighting the activities as well as the HSE Management System, to be implemented in the design phase and to be carried out independently of the specific actions of the designers, necessary to have sufficient warranties that the industrial plant is "well designed".