Natural gas pipeline reliability analysis based on utility theory

China's natural gas pipelines construction began in the 1960s, As the service time increases, the corrosion cause the operation reliability decreases most of the current in-service pipelines are in the aging corrosion phase, safe and reliable operations of these pipelines are related to economic development and social stability. It is of great importance and practical significance to study when the corrosion pipelines will retire and how to guarantee these pipelines operating under safe and reliable condition. Firstly, combined with theory of the remaining strength and remaining life we analyze the corrosion leakage probability of pipeline remaining life using the exponential distribution; and then we calculate the internal economic loss value when the in-service pipelines are replaced ahead of scheduled time; Finally, e evaluate the economic loss, loss of life and damage to the environment in terms of the utility function to get the corresponding external loss value; and make sure the most optimal date to exchange the aging corrosion pipelines.