These accidents were considered catastrophes due to their consequences. In this sense, reducing the risk of accidents related to chemical plants is of major importance (King, 1990). The conse- quences of such accidents may affect people, assets and the envi- ronment. Human consequences can be physical or psychological, with dramatic effects that can result in multiple fatalities or injuries (Walter, 1998); the consequences on assets are usually destruction of equipment and buildings; the environmental consequences can include the release of a hazardous material into the atmosphere, into the soil or into the water (Casal, 2008; Lees, 1996). Therefore it is necessary to devote time and efforts at researching on process safety. This concept must be now part of our daily life in order to ensure the sustainable development of the planet.