Editing CO2 Pipelines (section)

== Physical Properties and Phases ==

''Main article [[Properties of Carbon Dioxide]]''

CO<sub>2</sub> is generally transported in dense phase (compressed fluid) or supercritical conditions to increase density and reduce volumetric flow, improving transport economics. CO<sub>2</sub> becomes supercritical above its critical point (critical pressure ~7.38 MPa and critical temperature ~31.1 °C).<ref name="NISTcritical">CITE NIST + a PT diagram</ref>

>>INSERT P-T Phase Diagram

Commercial CO<sub>2</sub> pipelines operate across a broad pressure range; one 2025 technical summary reports typical operating pressures of ~83–152 bar, with peak pressures up to ~172–193 bar in some systems (site- and design-dependent).<ref> Find the VITO reference</ref> Maintaining pressure above minimum operating limits helps avoid two-phase flow and associated operability and integrity issues.

Gas phase CO<sub>2</sub> is also completed in certain circumstances, however due to the higher pressure loss as a result of the different density and viscosity, these pipelines are limited to large diameter and short distances to be cost effective <ref>CITE</ref>

===Two Phase Flow===