Top of the Line Corrosion (TLC): Causes and Mechanisms

This chapter provides an exhaustive examination of Top of the Line Corrosion (TLC), a critical phenomenon frequently occurring in multiphase and wet gas pipelines undergoing stratified flow. TLC poses a significant threat to the safety and integrity of pipelines utilized for crude oil and gas transport by triggering expedited corrosion, degradation of mechanical integrity, and, at times, leading to disastrous system failures. TLC eventuates as a result of water vapor condensation on the interior upper walls of the pipeline originating from the gas phase. This condensation can transform into a corrosive substance upon the dissolution of carbon dioxide (CO₂), hydrogen sulfide (H 2 S), volatile organic acids, and occasionally, oxygen. TLC is a complex process influenced by an array of factors, such as the rate of water condensation, the temperature of the gas, the partial pressure of CO2, gas velocity, and the presence of organic acids.