Evaluation of statistics of metal-loss corrosion defect profile to facilitate reliability analysis of corroded pipelines

As the model uncertainty of the burst pressure capacity model has substantial effects on the evaluated probability of burst of corroded pipelines, the use of the CSA and RSTRENG burst pressure capacity models is desirable in the reliability analysis of corroded pipelines because they incorporate detailed defect geometric information and have relatively small model uncertainties. Since the detailed defect geometric information is not always available from in-line inspections of corroded pipelines, the present study facilitates the use of CSA and RSTRENG models in the reliability analysis by deriving probabilistic characteristics of parameters that relate the detailed defect geometry to its simplified characterizing parameters based on the high-resolution geometric data for a large set of external metal-loss corrosion defects identified on an in-service pipeline in Alberta, Canada. The implications of the developed statistical parameters for the reliability analysis of corroded pipelines are investigated by evaluating the probabilities of failure of corroded pipelines with representative pipe attributes and corrosion defects based on the B31G Modified, CSA and RSTRENG models.