Impact of Prolonged Exposure to Sour Service on the Mechanical Properties and Corrosion Mechanism of NACE Carbon Steel Material Used in Wet Sour Gas Multiphase Pipeline

The oil and gas industry is involved with severe corrosive/sour environmental conditions due to H2S, CO2, moisture content. National Association of Corrosion Engineers (NACE) has developed standards enable users select suitable materials for given sour which utilize laboratory testing. A failed piping sample (API-5L-X65) was removed from a pipeline after 15 years service. Optical microscopy used compare the microstructure corroded near exposed surface both service environment, further away it. Moreover, pitted samples were analyzed using scanning electron microscope coupled energy dispersive X-ray (SEM/EDS) understand deposits’ morphology. Furthermore, XPS analysis proves presence significant content sulfur compound. Additionally, mechanical properties non-corroded evaluated compared. Micro-hardness carried out on cross-section any evident hardness variation inner diameter (ID) outer (OD) piping. All results suggest that prolonged exposure resulted in development micro defects, resulting reduction strength impact toughness, at Understanding corrosion mechanism pipelines media long-term helps repair/replacement planning extending usable design life material, paving way develop additional ways monitor changes critical materials’ when