The concomitant presence of CO2 and acetic acid may lead to a particularly violent corrosion type from steels to carbon in piping, transporting humid gases denominated as Top of Line corrosion (TLC). As for its enormous economic and technological impact associated to the occurrence of TLC in some areas in the world, its mechanism action is yet to be determined. The central objective of this study, developed under a collaboration between Grenoble - INP (France), IFE (Norway)and the petroleum companies Total (France) as well as ConocoPhillips (U.S.A) consisted of an experimental and theoretical analysis based on the qualitative behavior frequently found in situ for TLC cases. This style of attack is characterized by an extremely high corrosion speed (enabling leading to leaks and interruptions in very short periods of operation) followed by an abrupt slowing down of operation after a certain time (not predictable). In this conference, a group of results will be presented that allowed a mechanism proposition based on experimental techniques (impedance and electrochemical noise, a null resistance amperometry applied to an artificial cavity) and of numeric simulation of the interior of a cavity.
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