Erosional velocity

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Erosional velocity

The flow of a gas-liquid multiphase system may cause erosion if velocities are high. This is the description of empirical relationships for estimating whether erosion will occur in a system at a certain velocity used at PQplot.

As a rule of thump, pipe erosion begins when velocity exceeds the value of C/SQRT(ρ) in ft/s, where ρ = gas density (in lb/ft3) and C = empirical constant (in lb/s/ft2) (starting erosional velocity). We used C=100 as API RP 14E (1984) suggested C=100 for continuous and 125 for non continuous service.


Erosion is normally expressed as a rate of metal loss, usually mm/year. It usually occurs in turns or protrusions; or with solids content.

One can relate Erosional velocity to a metal loss rate (see RP O501).


  • Mokhatab S, Poe WA, Speight JG (2006) "Handbook of Natural Gas Transmission and Processing", Section 11.6 - Design Considerations on sales gas pipelines, subsection 11.6.1 - Line Sizing Criteria, Elsevier, 2006.