Determination of Safety Integrity Level (SIL) using LOPA method in the Emergency Shutdown System (ESD) of Hydrogen unit

Petrochemical plants are high risk, high parameter, and high-energy units, with the potential risks of fire, explosion and poisoning. The severe accidents at Bhopal, Mexico City, Samton, Brazil, Panipat, Mumbai and many others have increased the public awareness of the health, property and environmental risks posed by chemical installations. The recent years have seen a convergence of scenario-based Hazard and Operability (HAZOP) studies, Layer of Protection Analyses (LOPAs), and Safety Integrity Level (SIL) determinations. The aim of the research was to study the hazardous scenario identified in the hydrogen unit of petrochemical plant and to determine the SIL for ESD system. 20 hazardous scenarios identified by HAZOP study and determined by SIL by applying the LOPA method for ESD system, were used to control the hazardous scenarios. KS-1, KS-2 and KS-3are three ESD systems applied in the hydrogen unit. The maximum SIL determined for ESD system was SIL3. Since the rise in SIL can be quite costly for the industry, adding other layers of protection can reduce the level of SIL for ESD (SIS).