Correlation between Lube Oil Condition & Bearing Temperatures

Greg Livingstone & Sanya Mathura

Examines how bearing operating conditions—like high load, speed, temperature, and vibration—impact lubricant condition. It helps you understand and explain the relationship between bearing behavior and lube oil performance in rotating equipment.

Examines how bearing operating conditions—like high load, speed, temperature, and vibration—impact lubricant condition. It helps you understand and explain the relationship between bearing behavior and lube oil performance in rotating equipment.

High-speed rotating equipment, such as compressors, rely on fluid film bearings—including tilting pad journal (TPJ) bearings and equalized (Kingsbury style) thrust bearings—for precise rotor support and positioning. Maintaining the rotor position within a 10th of a millimeter of oil is crucial for efficient and reliable operation.

A key monitoring tool for these systems is temperature trending, which involves continuously monitoring bearing temperatures using sensors like thermocouples or resistance temperature detectors (RTDs) mounted on the bearing housing.

By plotting this data over time, significant changes or gradual increases in temperature can be identified, indicating potential issues such as inadequate lubrication, misalignment, overloading, or impending bearing failure.

This paper investigates the correlation between bearing temperature behavior and lubricant condition in fluid film bearing systems. It explores how degradation mechanisms—particularly oxidation and shear-induced stress—alter lubricant chemistry, which in turn affects film thickness, deposit formation, and thermal transfer efficiency.

Drawing on case studies from turbine and compressor applications, as well as tribological modeling and field diagnostics, the study illustrates how localized varnish and shear-stress deposits drive temperature instability and bearing degradation.

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