Development of a layers of protection incorporated inherent safety index for chemical processes

To date, numerous inherent safety indices, tailored to different process design stages and hazards, have been proposed to assess the inherent safety of chemical processes. However, traditional inherent safety indices mainly focus on identifying and evaluating process hazards, with limited consideration of risk mitigation. This work develops an enhanced inherent safety index (EISI), which integrates risk reduction strategies (RRSs) within layers of protection (LOP) into the various hazard sub‐indices of the pioneering inherent safety index (ISI), thereby enabling a more comprehensive inherent safety assessment. According to the LOP framework, RRSs are identified for each sub‐index, with different scores assigned to reflect the relative effectiveness of each measure. A designed formula is used to calculate the value of EISI. The proposed index was applied to the acetic acid process as a case study. The results indicate that the safety level of the acetic acid process significantly improves when appropriate RRSs are incorporated. Based on a comparison of three distinct risk mitigation schemes, the EISI has been demonstrated to be practical for assessing the safety performance of chemical processes with control measures of varying priorities. The EISI provides stakeholders with a list of RRSs to address various process hazards during the design stage. It expands conventional inherent safety indices by incorporating risk mitigation elements, thereby facilitating industries in developing a comprehensive safer chemical process.