Reliability assessment of oil cooling system of turbine in gas compressor station by fault tree analysis

Natural gas is currently the most important source of energy and income for our country. Increasing the length of gas pipeline and gas pressure drop, required to create gas stations with special and critical facilities and its main is reliability. The aim of this study was to evaluate the reliability of the turbines cooling system as one of the sensitive part of these facilities. This cross-sectional study was done in 2012 on oil cooling system in a pressure boosting station. Data was gathered from the documents, Observation and interview. Fault tree analysis used to identify stop function causes of cooling system and qualitative and quantitative safety analysis and reliability calculation. The final event of electromotor failure with probability of 0.07, oil tank leaks and detection failure with probability of 0.03 and failure in each connection with probability of 0.01 are likely to occur. Likely event that lead to system failure is the failure of the oil tank. Oil tank Leakage, oil tank crack, and failure in connections with the sequence probabilities of 0.03, 0.01, 0.002 are the most likely reasons to stop function of cooling system. System Reliability was equal to 0.9953. Due to the sensitivity of the studied system and the obtained results, it is necessary to improve the system reliability. Therefore special attention to the oil tank maintenance, regular review of connections, pumps and sensors maintenance, are important measures.