Corrosion behavior of pipeline steel welds in simulated produced water with different CO2 partial pressures under high temperature

In this work, the CO2 corrosion behavior of pipeline steel welds was systematically investigated. This was done by weight loss experiments in which welded samples were immersed in simulated produced water with different CO2 partial pressures. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) were used to effectively characterize the morphology, composition and phase of the corrosion products. The results showed that the corrosion rate of welded joints decreased as the immersion time increased. The corrosion rate of welded joints and the type of corrosion products formed also depend on the CO2 partial pressure. The layers of corrosion products had inhomogeneous distributions of iron, carbon, oxygen and calcium, with a higher concentration of iron in the internal corrosion film than that in the external corrosion film.