Outcome Analysis of Major Accidents and Determining the Safety Integrity Level of Processes in Sour Water Stripping Unit of Gas Refinery Using LOPA Technique

Development of oil and gas resources involves serious process hazards which put these industries among the most hazardous industries. Therefore, preventive approaches through risk identification and evaluation using new techniques such as Layers of Protection Analysis (LOPA) are receiving vast attention these days.The present study aimed to analyze probable major accidents in sour water reduction unit of gas refineries. It also tried to investigate the adequacy of safeguard layers in the system and provide suggestions to promote the level of safety using dependent and independent (active and reactive) protection layers where recommended safety measures did not seem sufficient. This descriptive study used LOPA to analyze the consequences of unacceptable risks to determine the risk situation after applying layers of control and protection. It also suggested protective layers as corrective actions for high-risk areas. Finally, in necessary cases, a safety integrity code was developed. Based on the determined role of available protective layers in controlling the potential risks, the further protective layers were recommended as a way to reduce risk to acceptable levels. In addition, the safety integrity level required by some equipments was determined in necessary cases. This study revealed that the effectiveness of available protective layers was not adequate in some. Therefore, additional protective layers are required to improve the preventive potential of process safety systems.