Optimal Design of Onshore Natural Gas Pipelines

The optimal design level for onshore natural gas pipelines was explored through a hypothetical example, whereby the pipe wall thickness was assumed to be the sole design parameter. The probability distributions of the life-cycle costs of various candidate designs for the example pipeline were obtained using Monte-Carlo simulation. The life-cycle cost included the cost of failure due to equipment impact and external corrosion, and the cost of periodic maintenance actions for external corrosion. The cost of failure included both the cost of fatality and injury as well as the cost of property damage and value of lost product. The minimum expected life-cycle cost criterion and stochastic dominance rules were employed to determine the optimal design level. The allowable societal risk level was considered as a constraint in the optimal design selection. It was found that the Canadian Standard Association design leads to the minimum expected life-cycle cost and satisfies the allowable societal risk constraint as well. A set of optimal designs for a risk-averse decision maker was identified using the stochastic dominance rules. Both the ASME and CSA designs belong to the optimal design set and meet the allowable societal risk constraint.