Turbine Bearing Failure Analysis – Root Cause Investigation and Design Improvements

Overview

This project involved a failure analysis of a turbine bearing system, focusing on identifying the root cause of premature wear and developing design improvements to enhance reliability and service life.

The investigation included review of bearing condition, ambient operating temperatures, oil condition, and original design calculations.

Issue & Engineering Approach

The bearing suffered a complete failure under normal operating conditions. The analysis combined field inspection data with system-level review of operating and design parameters.

Key areas of investigation included:

Bearing condition and wear patterns
Ambient and operating temperature effects on lubrication
Oil viscosity and lubrication performance at start-up and steady state
Review of original bearing clearance and system design assumptions
Influence of oil supply and return piping forces on housing alignment

Root Cause Findings

The likely contributing factors were identified as a combination of interacting effects:

Insufficient bearing clearance, limiting tolerance for thermal and load variation
High oil viscosity during cold conditions, reducing effective lubrication at start-up
Thermal expansion and contraction of oil piping, introducing additional loads and misalignment forces on the bearing housing

These factors combined to create unfavorable operating conditions, particularly during cold starts and transient temperature states.

Design Improvements

To address the identified issues, several system-level improvements were recommended:

Optimization of bearing clearance to better accommodate thermal and operational variation
Addition of an oil heating system to reduce viscosity during start-up conditions
Implementation of a filtration system to maintain oil cleanliness and reduce abrasive wear
Improvements aimed at reducing start-up wear and improving long-term lubrication stability

Outcome

The proposed modifications were intended to improve bearing operating conditions across the full temperature range, reduce start-up wear, and improve overall system reliability.

By addressing both mechanical clearances and lubrication system behavior, the design changes target the underlying causes rather than just the observed wear symptoms. and aim to eliminate catastrophic failure.

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FACTOR ENGINEERING

Southern California

908-319-5692

drews@factoreng.net