Achievements of Studies on CO₂ Corrosion in Gas Pipelines

Corrosion, especially corrosion due to CO₂, is one of the most common phenomena in natural gas development, processing and utilization. The paper introduces the latest international achievements made in the studies on pipeline corrosion due to CO₂, with the emphasis on that by IFE. Discussed are the CO₂ corrosion mechanism and characteristics in single- and multi-phase flows, with the mechanism grouped into uniform corrosion, pit corrosion, and ablation. It is pointed out that CO₂ corrosion depends on such factors as PH value, temperature, lateral CO₂ pressure, Fe²⁺ concentration, flow velocity, hydrate, H₂S content, etc. Determination of CO₂ corrosion rate usualy involves weight-loss, radioactive or field electrode method. Such models as Dewaard-Milliams, IFE-CORR and the prediction model for CO₂ corrosion in a non-corrosion-inhibiting medium are given for corrosion rate calculation. The following measures a-gainst CO₂ corrosion are suggested by analizing the different aspects of the CO₂ corrosion; ①corrosion.inhibitor, ②preventing the generation of hydrate, ③promoting pH value, ④decreasing lateral CO₂ pressure, ⑤lowering down temperature, ⑥preventing turbulent flow, and ⑦anti-corrosion materials.