Overview
Focus: Investigation and Resolution of High Vibration Issues

This case study details the investigation into significant vibration increases in a gearbox output shaft, leading to an operational shutdown. The analysis identifies the flexible coupling as the primary cause and provides actionable solutions to prevent recurrence.

Problem Description

• High Vibration Detected:
  Elevated vibration levels were recorded on the gearbox output shaft, resulting in an immediate operational halt.
• Simultaneous Vibrations:
  Both the compressor and gearbox experienced increased vibration levels simultaneously, suggesting a mechanical link between the two components.

Key Findings

1. Flexible Coupling Damage:

• The simultaneous vibrations indicate possible damage or failure of the flexible coupling.
• Initial assessments pointed to misalignment or wear in the coupling as a potential root cause.

2. Evidence of Mechanical Failure:

• The shutdown analysis revealed that the flexible coupling likely suffered from wear or mechanical failure, leading to excessive vibrations.

Root Cause Analysis

1. Primary Cause:

• Insufficient clearance or damage in the flexible coupling post-maintenance.

2. Contributing Factors:

• Misalignment between the gearbox and compressor.
• Possible material fatigue due to operational stresses.
• Installation issues not aligned with OEM specifications.

Recommended Actions

Short-Term Solutions

1. Install Vibration Phase Monitoring Alarms:

• Set up monitoring alarms on remaining units to detect potential issues early, allowing for up to 14 days of lead time before a shutdown.

Long-Term Solutions

1. Thorough Inspection of Flexible Coupling:

• Inspect for signs of wear, fatigue, or misalignment. Document any anomalies and address them accordingly.

2. Collaborate with OEM:

• Work with the Original Equipment Manufacturer to validate findings and obtain recommendations for repair or replacement.

3. Conduct Detailed Root Cause Analysis:

• Assess factors such as:some text
  • Material Fatigue: Determine if the coupling material has degraded due to operational stresses.
  • Misalignment: Check for any misalignment between the gearbox and compressor shafts.
  • Improper Installation: Verify that the coupling installation followed manufacturer specifications.
  • Operational Stresses: Analyze operating conditions that may exceed design parameters.

Technical Insights

• This case study highlights the importance of maintaining proper clearance and alignment in flexible couplings for optimal performance in high-speed rotating equipment.
• Early detection systems and detailed post-maintenance inspections are crucial in preventing unexpected failures and operational downtime.

Conclusion

The high vibration levels were primarily due to damage or failure of the flexible coupling. Implementing the recommended actions will help mitigate future risks, enhance equipment reliability, and minimize unplanned downtime.

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