Co2 Corrosion on Natural Gas Compressors: Criteria and Guidelines

Liquid water and CO2 can easily lead to carbon steel corrosion, especially at high pressures. Corrosion can happen either during normal running or during pressurized standstill conditions. The present paper describes three real cases of gas lift compressors operating in offshore platforms that suffered internal damage due to the formation of carbonic acid and unfavorable process conditions. The damages found were slightly different on each machine due to specific design characteristics (such as the presence or not of inlet guiding vanes), different manufacturers and process conditions. Full description of the failure mode and relevant root cause analysis as well as the modifications implemented to solve the issue are provided. Additionally, a review of the monitoring tools used to diagnose internal corrosion will be presented, including typical responses that can be expected in compressors subjected to CO2 corrosion. Finally, detailed criteria to define CO2 corrosion potential are proposed as well as comprehensive guidelines on material selection to avoid similar problems.