Developing a Predictive Model of Near-Neutral pH Stress Corrosion Cracking of Underground Pipelines

Abstract

Near neutral pH Stress Corrosion Cracking (NNpHSCC) on underground oil and gas pipelines is an issue facing industry today. Determining where NNpHSCC is likely to occur and grow is an important aspect to developing an Integrity Management Program. This work focused on developing a predictive model to capture the mechanisms involved with NNpHSCC growth utilizing actual field data. In order to better fit the field findings with the limited laboratory runs, different Hydrogen Enhancement Factors (HEF) were applied depending on the conditions of a given loading cycle. The predictive model generated results which demonstrated to distinct portions of NNpHSCC growth: a dissolution controlled phase and a mechanically activated phase. The output of the model was then compared to the field findings, with varied success. Further improvement and calibrations are required along with the gathering of additional field and laboratory data to fine-tune the field validation of the predictive model.