Mahdi Hosseini - SIRRI Island Gas Gathering and NGL Recovery Plant, SIRRI Island, I.R.IRAN
Mohammad Shahriari

Tools such as Layer of Protection Analysis (LOPA) can be used to improve the understanding and managing of risks related to process safety. LOPA is a relatively new semi-quantitative method used to ensure that process risk is successfully reduced to an acceptable level. This article presents and discusses the applicability of the LOPA method in determining appropriate Safety Integrity Levels (SIL) for the process industry. The global importance of SIL has grown considerably over the last decade. The various methods available for determining acceptable SIL have a tendency to yield different answers. Up till today, limited guidance on which method to use and for what case has been given. This article briefly describes LOPA as a simplified method for SIL determination. LOPA is considered an effective tool for SIL assignment and allocates risk reduction resources efficiently

Layer of Protection Analysis (LOPA), protection layers, Safety Integrity Level(SIL), Safety Instrumented Systems (SIS), Safety Function Systems (SIF