29 - Top-of-the-line corrosion

Abstract

The fundamentals of top of the line corrosion (TLC or TOL) have been presented in detail in Chapter 16. This chapter focuses on how these mechanisms can be modeled. Several modeling approaches have been proposed over the last 25years, increasing in complexity and accuracy as new knowledge emerges. As pertains to TLC, the modeling approach is usually divided into two main aspects: modeling of water condensation and modeling of corrosion in dewing conditions. Although much progress has been made, the modeling of localized corrosion, sour TLC, and stabilization remain considerable challenges. As for any model, the validation of the predictions with field data is an essential but difficult step, and a comprehensive methodology has been proposed. Nevertheless, TLC prediction models are now considered a useful tool for failure analysis and pipeline design.