Utilizing Layer of Protection Analysis (LOPA) in Verification of Safety Integrity Level (SIL) of Instrumented System

The project is aimed to utilize layer of protection analysis (LOPA) to verify safety integrity level (SIL) of safety instrumented system. Safety instrumented system (SIS) is the last resort in case of emergency happened in plant. Determining the specific safety requirement of safety systems is a vital part to ensure accidents are prevented. Previous study is carried out till classification of Safety Integrity Levels (SIL) for hazardous installation by using the risk assessment techniques. In this study, the focus will be on SIL classification and verification in safety instrumented system (SIS).
The program is developed using Microsoft Excel based on established methodology found in the literatures. Thorough literature surveys are expected in order to gather appropriate SIL verification information which will further integrate in existing spreadsheet. The program is tested using two case studies related to process plant industries. The results obtained show the sufficiency of the protection system and provide risk control strategy including number of SIL required in case of the protection is insufficient. If the protection system is sufficient, it will ensure the design is the optimum. Reliability and accurateness of the result are vital due to main function of the program is to assess and validate the SIS.
The application is used either in designing the SIS or in auditing the effectiveness of the installed SIS. The verification of assigned SIL to a particular Safety Instrumented Function (SIF) is still new compared to SIL classification. Based on industrial perspective, there is no established method on verification of an installed SIS. Most scenarios can be catered by enhancing the existing design rather than adding safety protection layer.
Future study shall be continued to improve the relevancy and reliability of the tool by integrating more parameters in assessing a case.