Ohio University

Top-of-the-line Corrosion Mitigation Project (TLC-JIP)

Top of the Line Corrosion (TLC) is a corrosion phenomenon driven by water vapor condensation that is specific to the nine to two o’clock positions on a pipeline circumference. It’s a process exclusively encountered in stratified flow regimes, as standard corrosion inhibitors which are typically present in the bottom of the line brine cannot provide any protection to the top section of the pipe. Corrosion control techniques such as batch treatment with inhibitors or spray pigging are often implemented to mitigate TLC, but these methods are costly and intrusive.

The Institute for Corrosion and Multiphase Technology has developed a solid understanding of sweet corrosion (CO2-dominated) TLC based on more than 10 years of research. However, there are still some unclear aspects, especially regarding sour (H2S-dominated) TLC.

The objective of the TLC Mitigation JIP, which started in 2013, is to confidently ensure that any given transport pipeline will not suffer from TLC. In order to achieve this objective, it’s necessary to understand the mechanisms that lead to TLC and develop mechanistic models (TOPCORP) to predict if TLC is a concern.

Another important objective of the TLC Mitigation JIP is to identify and implement the right mitigation method when TLC is a concern. Different functional groups have been tested as possible volatile corrosion inhibitors. The study of innovative carriers to transport inhibitor to the top of the line and the effect of mono-ethylene glycol in the condensation process are also considered in this project.


  • Guidelines for the selection and use of methods of mitigation for TLC.
  • Field database. Analysis of TLC field experience in both sweet and sour environments.
  • An improved corrosion prediction model, TOPCORP.
  • An improved understanding of the phenomena of top of the line corrosion and its mitigation in sweet and sour environments (with a focus on sour environments).
  • The ability to predict whether or not flow lines will be subject to significant TLC, requiring mitigation measures.

Please contact Fernando Farelas for more information on the TLC-JIP.