Characterization of the Corrosion Layer on Pipeline Steel in Sweet Environment

摘要

CO2 corrosion, or 'sweet corrosion,' is the most prevalent form of attack encountered in oil and gas pipelines. Corrosion of carbon steel in CO2-containing environment is very complex and requires extensive attention. Various mechanisms have been proposed to explain the phenomenon. However, these mechanisms either apply to very specific conditions or have not received widespread recognition or acceptance. To establish a fundamental understanding of CO2 attacks on steel, it is essential to conduct further studies to investigate the formation, composition, microstructure, and characteristics of the surface film induced by carbon dioxide corrosion. In this study, corrosion behavior of API pipeline steel has been assessed in 2 g/l NaCl solution purged with CO2 as the corrosive media. Specimens were immersed in the corrosive solution (open system) for 15, 45, 100, and 185 h. In this study, scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy were employed systematically to characterize the composition, microstructure, and formation of the surface film on API X42 steel.