Wall Surface Drag Reduction Application of High-Temperature Resistant Internal Anti-Corrosion Coated Steel Pipes

Literature Overview

Ma Jiaojiao, Liu Yun, Bi Zongyue, Huang Xiaohui, Wei Feng, and Xi Minmin from the National Petroleum and Natural Gas Pipe Engineering Technology Research Center and Baoji Petroleum Steel Pipe Co., Ltd. published this paper in Hot Working Technology in 2023. Funded by the National Key R&D Program (2017YFB0304903), the study analyzes the energy-saving drag reduction effects of internally coated steel pipes, with particular focus on high-temperature resistant anti-corrosion coatings.

Core Technical Content

Drag Reduction Mechanism

The energy-saving drag reduction effect of internally coated steel pipes operates through the reduction of wall surface roughness. When a smooth coating is applied to the internal surface of a steel pipe, the effective roughness height decreases, which in turn reduces the friction factor and pressure drop along the pipeline length.

Key Performance Indicators

Influencing Factors on Drag Reduction

The study identifies several factors that influence the energy-saving drag reduction performance:

1. Coating thickness: Optimal thickness provides maximum smoothness without excessive material usage
2. Coating surface quality: Microscopic roughness of the coating itself affects overall pipe roughness
3. Operating temperature: High-temperature resistant coatings must maintain their surface properties under thermal cycling
4. Flow velocity: Drag reduction effectiveness varies with flow regime (laminar, transitional, turbulent)
5. Pipe diameter: Larger diameters may exhibit different roughness sensitivity

Practical Application Case

The paper presents actual application data demonstrating that high-temperature resistant internally coated steel pipes achieve significant energy savings through reduced frictional pressure losses. The coating effectively reduces the internal surface roughness to a level that produces measurable drag reduction in pipeline flow applications.

Engineering Practice Implications

For pipeline engineering projects:

• Internal anti-corrosion coatings serve a dual purpose: corrosion protection and hydraulic efficiency improvement.
• High-temperature resistant coatings are essential for applications involving hot oil, steam, or geothermal fluids where standard coatings would degrade.
• The drag reduction benefit should be quantified during project economic evaluation, as reduced pumping costs can significantly improve project economics over the pipeline lifetime.

Engineers should consider the following when specifying internally coated pipes:

• Coating adhesion strength must be verified under expected operating temperature ranges
• Thermal expansion mismatch between steel and coating must be accounted for in design
• Coating inspection and maintenance schedules should include roughness measurement to verify continued drag reduction performance

Key Reflections

This study highlights an often-overlooked benefit of internal pipe coatings: hydraulic efficiency improvement beyond the primary corrosion protection function. For long-distance pipeline systems, even small reductions in friction factor can translate to substantial energy savings over the operational lifetime. The high-temperature resistant coating technology developed under this research program represents a significant advancement for applications in oil and gas processing, where internal pipe temperatures can exceed the limits of conventional coatings. Engineers should advocate for the inclusion of drag reduction performance in coating specification requirements, as this provides measurable economic benefits that complement the corrosion protection function. The synergy between corrosion protection and hydraulic efficiency makes internally coated steel pipes a technically and economically attractive solution for modern pipeline infrastructure.