Integrated Cost Index for Inherently Safer Design Alternatives

Inherently Safer Design (ISD) is an approach in process industry to prevent any loss and injuries especially in the design and operation of facilities that use hazardous chemical. The sole purpose is to minimize the frequency and potential impact of chemical plant incident such as fires, explosion and acute toxic exposure. There are four strategies for designing inherently safer process which is substitute, minimize, moderate and simplify. These strategies can either be to choose only one strategy or to apply all of the strategies best at the preliminary stage in designing a plant. Considering the lifetime cost of a process and its operation, an inherent safety approach can lead to a cost optimal option. However, it is still a big question to chemical industry whether the cost is affordable when applying ISD. Therefore, in this this report, safety and economic evaluation have been made for three alternatives chosen from the MMA process routes. Index used in evaluating safety is Prototype Index for Inherent Safety (PIIS). A framework to evaluate modification cost which comprises material and equipment purchasing cost has been developed for the economic evaluation purpose. These two cost evaluations are made to determine the impact of cost towards the inherent safety implementation. This works has shown that inherently safer design does affect the economic feasibility of a process where the safest design does not necessarily be the cheapest design alternative.