Top-of-the-Line Corrosion Under Low-Temperature and High-Condensation Rate Conditions

   Condensation of water from warm, humid gas to cold pipeline walls in transporting wet gas is regarded to play a significant role in TOL corrosion. The CO₂ TOL corrosion behavior of carbon steel under low temperature range and high condensation rate conditions was investigated with autoclaves which had the function of condensation forming on samples simulating the subsea wet gas pipeline environment. One side of the carbon steel sample was exposed to water-saturated CO₂ in the temperature range of 20 to 60°C at 0.8MPa, the other side was cooled to as lowest as 5°C which caused a relatively high condensation rate. The corrosion rate of samples was determined by weight loss measurements. The surface morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (SEM and EDS). In addition, considerations regarding the impact of the condensation process on the corrosion products were discussed.