Velocity guidelines for preventing pitting of carbon steel piping when the flowing medium contains CO{sub 2} and sand

Book · Thu Aug 01 04:00:00 EDT 1996

OSTI ID:268166

Shadley, J R; Shirazi, S A; Dayalan, E; Rybicki, E F ^[1]

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1. Univ. of Tulsa, OK (United States)

In carbon steel piping systems handling fluids containing water and dissolved CO{sub 2}, under a range of conditions, an FeCO{sub 3} (iron carbonate) scale can form on the pipe wall and provide a measure of protection against CO{sub 2} corrosion. If the fluid also contains sand, particles of sand impinging the pipe wall can remove the protective scale or prevent it from adhering to the pipe wall. Without the scale to protect the pipe, CO{sub 2} corrosion can progress at an accelerated rate. This process is referred to by many as erosion-corrosion. Whether erosion-corrosion occurs and how severe it will be depend on environmental factors such as pH and temperature, and on how erosive the conditions are, i.e., the erosivity. Factors that determine erosivity include fluid properties, flow parameters, and sand conditions. For other factors held constant, when flow velocities are low, FeCO{sub 3} scale provides protection for all pipe surfaces. In high velocity flows, scale is not able to adhere anywhere on the pipe wall, and CO{sub 2} corrosion proceeds uniformly over the surface of the pipe. But, at intermediate velocities, pitting can occur at sand particle impingement points resulting in extremely high penetration rates. Flow velocities defining the boundaries between these three erosion-corrosion behaviors are called threshold velocities. In previous work, threshold velocities were determined for laboratory and representative oilfield conditions. In this paper, threshold velocities are determined and compared for conditions with and without a commercial imidazoline type inhibitor. Threshold velocities presented are based on experimental results from a flow loop circulating water, oil, inhibitor and sand and on a computer program for predicting sand erosion.

• OSTI ID: 268166
• Report Number(s): CONF-960389--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
36 MATERIALS SCIENCE
CARBON DIOXIDE
CARBON STEELS
CORROSION INHIBITORS
CORROSION PROTECTION
CORROSIVE EFFECTS
EROSION
EXPERIMENTAL DATA
FLOW RATE
IRON CARBONATES
MATHEMATICAL MODELS
MITIGATION
NATURAL GAS INDUSTRY
PETROLEUM INDUSTRY
PIPELINES
PITTING CORROSION
PROTECTIVE COATINGS
RECOMMENDATIONS
TEST FACILITIES