There are currently over 50# CO2 pipelines that cover a distance of ~5,000 miles (8000 km). The lack of CO2 transport infrastructure is definitely a limiting factor for CCS scale-up.
Existing oil and gas pipelines can be converted to CO2 transport pipelines for short-distance, low-volume transport. For these distances, CO2 may be transported in the gas phase.
For long-distance, large-volume transport, the pressures need to be above the critical pressure of CO2 (74 bar). In general new pipelines would need to be constructed. For longer distances CO2 is transported in the liquid phase.
CO2 should be dehydrated to very low dew points to ensure no water can condense in the CO2 stream. Otherwise it would form carbonic acid which corrodes steel pipelines. Dry CO2 is not corrosive, even if it contains contaminants.
The ISO has developed a standard for CO2 specification for pipeline transport – ISO 27913:2016. Among other things, it sets specifications for CO2 purity (>95 mol%), water dew point limits to prevent corrosion and hydrate formation, and concentrations of other trace impurities.
CO2 pipelines and ships pose no higher risk, because the infrastructure is already safely managed for transporting hydrocarbons. International standards are being developed to increase CO2 infrastructure safety.