Using Layer of Protection Analysis (LOPA) to Determine Safety Integrity Level (SIL) for Hazardous Installation

The purpose of this project is to determine the Safety Integrity Levels (SIL) for hazardous installation by using the risk assessment techniques. Various methods can be used in determining this SIL. The selected method is based on the certain criteria. The method will be used for the whole project as the based techniques to defined SIL. In this case, Layer of Protection Analysis (LOPA) has been chosen as the risk-based approach to evaluate potential consequences and likelihood. Many factors could be considered in order to complete this project. The selection of SIL is very important since in many cases the Safety Instrumented System (SIS) is the last layer of protection for the prevention of hazardous events.
The safety integrity of the safety functions to be implemented in the SIS is to be identified in terms of Safety Integrity levels (SILs). Each SIL is assigned with a specific range of Probability to Fail on Demand (PFD). In this project, current industry practices for the selection of SILs are evaluated to illustrate how each method provides an estimation risk of risk reduction that the SIS will provide for a given process. The level of effort, required expertise, and accuracy of the methods are also compared to assist reader in choosing the appropriate SIL selection methodology. LOPA method will be applied as some related data and tools should be collected in ensuring the successfulness of the project.