CO2 corrosion and material selection

I wouldn't call myself an "experienced corrosion engineer" but I do have experience of corrosion in aqueous systems. From what you say, the CO2 is dissolved in the crude oil. If your crude oil were exposed to the atmosphere, any dissolved CO2 would be in equilibrium with CO2 gas above the liquid - in other words there would be a CO2 partial pressure over the liquid. As this partial pressure would be greater than that in the atmosphere, the CO2 would eventually be lost to the atmosphere, just as soda water eventually "goes flat." If you now put the crude oil in an enclosed vessel under pressure, such that all the CO2 remains dissolved, the CO2 must still be exerting a partial pressure, but it cannot escape. I believe that the pressure required to keep all the CO2 dissolved is essentially the partial pressure of the CO2. The ppCO2 will, of course, depend on the temperature. The water will also exert its partial presssure, but much less than CO2.

Thank you very much for your response, Energyconversion.

As in my original question, my case is piping, full of mixed liquid and there is no vapor at all and there is no chance CO2 escape, and the pipe works at 110 kpa and temperature

The pipe works at 110 kpa, temperature 50C. And my question is whether carbon steel acceptable for this service.

CO2 will dissolve in water and oil. It will be appreciated very much if you could give me a clue what the difference in solubility of CO2 in water and oil, separately.

Sorry, I would only be able to research that on the internet for you. Better that you do it yourself!

Thanks anyway. Energyconversion