Risk analysis in plant commissioning: the Multilevel Hazop

The paper deals with risk analysis and management in the realisation of process plants by engineering and contracting companies. Specifically, a new analytical methodology is developed to manage the typical risks of plant commissioning. Following a detailed study of the commissioning process and its criticalities, Hazop is selected as the most suitable approach in forecasting particular risks of this project stage. Starting from the limitations of both Hazop and Human Hazop (the extension of the technique to the field of procedures performed by humans), a new technique (Multilevel Hazop) is suggested which identifies in advance all the criticalities of each commissioning activity and defines actions to reduce risk and optimise dedicated resources. After implementation of Multilevel Hazop in a real commissioning process, a new version of the technique (Two Stage Multilevel Hazop) is proposed. This allows a significant reduction in implementation costs, justifying use of the technique both in innovative or critical cases, where the expected saving from risk reduction is high, and in general contexts.