Using the HAZOP Study and LOPA to Generate Ideas for Inherently Safer Designs

Fundamental changes in a chemical process are most cost-effective at early stages of a design, and specific Inherently Safer Design evaluations are frequently performed at these early stages to identify fundamental improvements that can signicantly decrease the magnitude of the consequences associated with plant accidents. As the detailed design comes into focus, thoughts of Inherently Safer Designs are rarely revisited because the designer's paradigm has shifted. Although fundamental changes are more difficult, there may still be opportunities during the detailed design phase to entertain new ideas of Inherently Safer Design, especially due to the rapidly changing environment of process plant technologies. Thus, it is the duty of the process designers to look for new mechanisms for improving plant safety, and throughout the design process, as teams assemble for various activities, good opportunities for revisiting Inherently Safer Design concepts do materialize. The focus of this paper is to present these opportunities to the reader, provide examples of Inherently Safer Design concepts that provide a useful benefit-cost ratio (even at later stages of the design), and provide tips on how to efficiently infuse focused discussions and ranking criteria into the HAZOP Study and LOPA processes that occur for most major process plant designs.