Abstract
Nowadays, it is widely and very well accepted that one single parameter cannot provide sufficient information to predict or estimate the so-called “corrosivity classification” of a soil. For instance, one of the most common soil characteristic factors measured to evaluate the corrosivity classification at various locations is the value of the resistivity of the soil; however, it is a value that changes regularly with many other extrinsic factors as climate, annual rainfall, soil composition, drainage, topography, etc. While there has been numerous efforts on combining and interrelating various factors (such as: resistivity, pH, salt concentration, soil classification, redox potential) to indicate the corrosivity of the soil, the current approaches are still very limited. The focus of this paper is to address the current challenges found when assessing external corrosion of buried onshore oil and gas carbon steel pipelines externally coated and cathodically protected. A review of the time-dependent and time-independent pipeline and soil related properties factors that contribute to the evolution of corrosion in buried pipelines is presented, emphasizing on their spatial and temporal variability. A preliminary mathematical model that combines those factors in one framework is suggested as a promising approach to identify pipeline sections with the highest relative corrosion risk and determining the rate of external corrosion from a set of parameters using Bayesian Networks was conducted.
