I am operating high pressure natural gas pipelines with 3% CO2. The gas is typically dehydrated and the lines are piggable. We have issues with loosing our dehydration for periods of several days at a time. The gas is water saturated upstream of the dehydrator and cools 20 or 30 degrees F as it flows through the pipeline. How big of a concern do I have with carbonic acid corrosion? The area is very hilly. Is gas velocity a major issue? Is there a velocity above which I would not have an issue with this corrosion mechanism?