A Direct Assessment of Failure Pressure of High-Strength Steel Pipelines with Considerations of the Synergism of Corrosion Defects, Internal Pressure and Soil Strain

摘要

In this work, a new, finite element analysis-based model, the CX model, was developed to investigate the effect of corrosion defect, internal pressure and soil-induced strain on the local stress distribution and corrosion reaction on pipelines. The relevant calculations and analysis were also conducted on three industry models. Results demonstrated the predicted failure pressures of various grades of pipelines by the industry models are conservative when small defects are present, while overestimation of failure pressure occurs with the increase of the steel grade and the corrosion depth. The prediction reliability decreases with the increasing corrosion depth and the steel grade. The geometry of corrosion defect affects remarkably the local stress distribution, and plays a critical role in the failure pressure prediction of pipelines. Furthermore, while elastic deformation affects the steel corrosion slightly, usually at an undetectable level, plastic deformation increases corrosion of the steel significantly. The CX model is capable of simulating the distributions of corrosion potential and corrosion current density at corrosion defect, and thus providing an essential method to predict the defect propagation.