The Physics & Astronomy Colloquium Series presents Srdjan Nesic , Director of the Institute for Corrosion and Multiphase Technology of Ohio University, discussing "Internal Corrosion of CO2 Transmission Pipelines made from Carbon Steel – Current Understanding and Main Challenges" on Sept. 02.

Abstract : Internal corrosion plays an important role in integrity management of CO2 transmission pipelines, since carbon steel, the most common material of construction, is susceptible to corrosion attack. It is well known that any free liquid water in such pipelines may lead to catastrophic corrosion rates, and must be eliminated. Conversely, the pure dense phase CO2 does not corrode carbon steel. This is still true in the presence of very small amounts of “dissolved” water in dense phase CO2, when negligible corrosion is found. However, serious problems arise when, in addition to dissolved water, other “impurities”, such as O2, H2S, SO2, NO2, etc., are present in dense phase CO2, and severe corrosion rates are seen due to a complicated interplay between these species, which is not understood. Even the basic thermodynamic properties of such “mixtures” are not properly established. Corrosion mechanisms of carbon steel in dense phase CO2 environments remain unknown and we are currently not able to determine proper compositional thresholds for safe operation. The effect of basic operational parameters, such as temperature, pressure and flow is still unclear, all of this stifling any modeling efforts that would enable prediction of corrosion rates.

Building on the long-standing research activity in CO2 corrosion of oil and gas pipelines, the Institute for Corrosion and Multiphase Technology (ICMT) at Ohio University has focused over the past decade on the problem of internal corrosion of pipelines for CO2 transmission. We have established that much of the basic understanding developed for lower CO2 pressure systems does carry over to dense phase CO2 conditions, yet many fundamental question remain unanswered, particularly when it comes to carbon steel corrosion in dense CO2 phase with impurities. The ICMT is now spearheading further research in this field, leveraging the existing knowledge base, advanced modeling and our unique experimental capabilities. In this presentation, the current state of art as well as the main challenges lying ahead will be discussed, focusing on the ubiquitous effect of “impurities” on both thermodynamic properties and corrosion of carbon steel.