Reliability Analysis of Aged Natural Gas Pipelines Based on Utility Theory

Article history: Received: 27.08.2014. Received in revised form: 08.12.2014. Accepted: 11.12.2014. Pipelines are of major importance for transport of natural gas, but a lot of the current in-service pipelines are in wear-out 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 corroded pipelines will be retired and how to guarantee that these pipelines will be operating under safe and reliable conditions. The paper proposes a model for assessing risk in natural gas pipelines, and for classifying sections of pipeline into risk categories with utility theory. It aims to help transmission and distribution companies when engaged in risk integrated assessment and decision making consider multiple dimensions of risk from pipeline leakage accidents. Firstly, we analyze the corrosion leakage probability of pipeline remaining life using the exponential distribution; secondly, we evaluate the economic loss, loss of life and damage to the environment in terms of the utility function to get the corresponding risk value of external loss. Finally, we calculate the internal economic loss when in-service pipelines are replaced ahead of scheduled time and then schedule a most optimal date to exchange the aging pipelines containing corrosion. To verify the effectiveness of the proposed methods, a numerical application based on a real case study is presented.