A computer program has been developed with which we can assess and manage risk for city gas pipeline in Korea. Risk factor of a facility was expressed in terms of consequence and frequency, and then the risk was correlated to cost. The consequence of incidents was analyzed in the case of small-scale leak, large-scale release and rupture of gas pipeline, and then correlated to cost. The consequences were evaluated in terms of fatalities, burning, damage to building and gas release. In each case, frequency was estimated in terms of major causes of consequences: excavating by third-party work, corrosion, welding defects and ground movement.