Risk-based process plant design considering inherent safety

An inherently safer approach is becoming a key parameter of process and plant design. However, a lack of established guidelines and methods hinders most industries from utilizing inherent safety concepts to a full extent. This paper presents a risk-based design decision-making tool considering inherent safety. The tool is called the Risk-based Inherent Safety Index (RISI). The proposed indexing approach is an extension of the Integrated Inherent Safety Index (I2SI) earlier developed by Khan and Amyotte (2004, 2005). The RISI incorporates both consequence and probability of accident occurrence reduction through application of inherently safer design principles throughout the process design life cycle. Unlike other available dimensionless index-based matrices, risk components of the proposed indexing approach are expressed in terms of SI units. The RISI is applicable at different stages of the process design life cycle. Analytical and subjective equations assess the damage potential of major process accidents: fire, explosion and toxic release. The explosion accident scenario is studied separately in terms of vapor/gas explosion and dust explosion. The decision-making potential based on the quantitative results of the methodology is demonstrated by evaluating alternatives for biodiesel production.