EFFECT OF SOIL CORROSION IN FAILURES OF BURIED PIPELINES

Over the last few years, several failures in transmission and distribution water/gas pipelines have been reported around the world. The failure of buried pipeline is controlled by several factors, such as pipe material, soil corrosion, internal and external loading, etc. Among these, soil corrosion makes a significant contribution towards failure mode and mechanisms in buried pipes, yet few studies have been done. Although a number of corrosion models have been developed over the years, the applicability of the model predominantly depends on the type of soil and its moisture change over time at the pipe depth. By incorporating a corrosion model, the remaining life of the pipe can be estimated on the basis of applied traffic and pressure loads, which determine the stresses in the pipe segment. Depending on the model, the estimation can show significant variability, and consequently affect the pipe renewal and rehabilitation plans that ultimately have economic impacts. Therefore, it is important for the pipeline asset owners to understand the effect of corrosion models in the remaining life calculation. This paper reviews briefly the available corrosion models and the sensitivity of each parameter in pipe corrosion pit properties and in the remaining life estimation. Finally, a comparison among the corrosion models on the basis of the remaining life estimation is provided to improve the renewal plan.