Natural Gas as a cheap, clean, easy to transport & with high heating value is one of the most important sources of energies used all over the world. City Gate Stations (CGS) are one of the main and important parts of natural gas distribution systems. Considering the sensitivity of the pressure reduction stations in the gasification process, it is necessary to identify all the risks and analyze their feasibility in order to prevent potential accidents and damages, and based on that, identify the existing risks and manage them appropriately. The main goal of this research is identifying process hazards and operational difficulties in one of CGSs to develop practical pathways to prevent hazardous conditions or reducing incidents consequences. HAZOP study has done and 4 nodes have defined for the process and 47 process deviations recognized by using process parameters and guide words, 113 consequences and 97 causes have identified. Then risks have calculated and evaluated by Risk Matrix and 27 recommendations including process changes, new safeguards and protective systems have suggested.
