26.6. Inherently Safe Design

Although safety controls can be added to existing processes, a more effective and efficient strategy is called inherently safe design [12]. The idea is to streamline the process to eliminate hazards, even if there is a major process upset. This strategy is based on a hierarchy of six approaches to process plant safety:

1. Substitution: One avoids using or producing hazardous materials on the plant site. If the hazardous material is an intermediate product, for example, alternative chemical reaction pathways might be used. In other words, the most inherently safe strategy is to avoid the use of hazardous materials.

2. Intensification: One attempts to use less of the hazardous materials. In terms of a hazardous intermediate, the two processes could be more closely coupled, reducing or eliminating the inventory of the intermediate. The inventories of hazardous feeds or products can be reduced by enhanced scheduling techniques such as just-in-time (JIT) manufacturing [13].