Flow-Related Corrosion in Large-Diameter Multiphase Flowlines

A strong relationship between field measurements of flow regime and corrosion rate has been found. In multi flow, the slug flow regime produces high liquid velocities and high inherent turbulence levels for significant periods. The exact mechanism for removing a corrosion-inhibitor film from a pipe wall or preventing the film from forming remains unclear, but high turbulence and wall shear stresses always are present when flow-related corrosion occurs. The levels of wall shear stress may be estimated for a variety of pipeline features when subject to a passing slug. This provides a basis for realistic corrosion-inhibitor trials in the laboratory and a means of relating this information to field conditions. The onset of slug flow may be predicted to identify those times when a flowline may be especially at risk.