Reliability assessments and remaining life of pipelines subject to combined loadings using imprecise probabilities

Imprecise probability approach for the reliability analysis of above ground pipelines with surface corrosion defects, subject to combined loadings is presented. The construction of the permissible region in the load space for above ground corroded pipeline subject to combined loadings is proposed. The dead load of the pipeline (i.e. summation of weights of the pipe, insulation and fluid), transported fluid operating pressure, and extra stresses due to development of defects are considered as variables. While the wind loads which depends on climate change is considered as very uncertain with imprecise values. A non-linear, power law corrosion model is used to represent the loss of pipe wall thickness with time. The permissible region is constructed according to the limit state which is reached when the equivalent stresses in pipe wall reach the yield stress of pipe material. Results obtained for typical pipelines are presented.