When the gas contains ethylene glycol (MEG) and organic acids these components will also dissolve in the water condensing on the pipe wall and affect the potential corrosion rate and the protective properties of the corrosion product film that forms on the pipe wall. The film formation process has been studied in small scale experiments where carbon steel pipes are exposed to an aqueous phase and where various condensation rates are simulated by varying the replenishment rate of the test liquid.
The experiments show that the organic acid in the condensing water is consumed (converted to the deprotonated salt) in the corrosion process and the corrosion rate will depend on how fast the organic acid is replenished. The replenishment rate has been studied in loop experiments, and the results indicate that the corrosion rate can be directly related to the replenishment rate under certain conditions.
The paper discusses the experimental approaches and the results obtained in the corrosion film formation and organic acid replenishment studies.