Optimizing the design of storage facilities through the application of ISD and QRA

Abstract

Four strategies can be used to achieve safety in chemical processes: inherent, passive, active and procedural; however, the one that offers better results is the inherent safety approach, especially if applied at the initial stages of a project. Inherently Safer Design (ISD) permanently eliminates or reduces hazards to avoid or reduce the consequences of incidents, and can be applied using four strategies: substitution, minimization, moderation and simplification. In this paper, a methodology which allows combining ISD strategies with Quantitative Risk Assessment (QRA) in order to optimize the design of storage installations is proposed; taking into account that 17% of the major accidents in the chemical industry occur during the storage process, causing significant losses, it becomes important to improve safety in these installations. The proposed method applies QRA to estimate the risk associated to a specific design, which can later be compared to others in order to decide which one is inherently safer, incorporating complex phenomena like the domino effect and possible affectation to material and human vulnerable elements. The methodology is applied to two case studies, one based on the San Juanico tragedy occurred in Mexico, 1984, and another one focused on a chlorine storage installation; in this way the method is evaluated on two types of plant, one related to flammable materials and another to toxic substances.