Explosion risk analysis on Town Border Stations (TBS) of natural gas using Failure Mode & Effect Analysis (FMEA (and Fault Tree Analyses (FTA (methods

Attention to safety of process plants adjacent residential area, especially in the big cities is extremely importance from the perspective of the safety engineering and risk management. This study was carried out whit the aims of identification of hazard points of explosion in Town Border Station (TBS) and qualitative and quantitative analysis of their occurrence causes and estimation of leak probability in this station. Hazard points of the explosion and qualitative analysis of the failures conducted by means of Failure Mode and Effect Analysis (FMEA) method. Occurrence probability of related accidents was estimated by means of Fault Tree Analysis (FTA) method. To determine of the basic event occurrence probability of the fault tree used form the expert opinions and the related data banks. Hazard points identified of the explosion in the TBS stations were ten. A total of 67 failures in gas leak of the Sensing that had highest the Risk Priority Number (RPN=24) were identified. Also Earth System of the Station had the lowest the Risk Priority Number (RPN=4). The results show that the leak probability of the Sensing was equal to 0.52 per year. Process failure (FP =0.334) and Mechanical failure had the highest and the lowest failure probability of the Sensing gas leakage. Prevention and control of the Sensing gas leak and the prevention both of the occurrence process failures and unsafe behavioral had considerable importance in the explosion risk reduction of TBS.