Causes

The most common causes of abnormal noise detectable by visual inspection are:

• Vibration.
• Looseness of mechanical components.
• Fluid leaks.
• Friction.
• Bad lubrication.
• Mismatch of mechanical elements.
• Bad electrical connection.
• Loss of soundproofing material.
• Mechanical resonance.
• Beating.

Cases

Through visual inspections the most common cases of abnormal noise that are diagnosed are:

• Advanced stage bearing failures.
• Bad connections in power electrical connections.
• Steam leaks.
• Compressed air leaks.
• Gearboxes with wear or broken teeth.
• Beating between two nearby rotating machines operating at close frequencies.

Diagnosis

Detection of abnormal noise in visual inspections is by auditory detection.

Points to consider:

• In case of steam leaks it is recommended to find the place of the leak and take a photograph.
• If you can detect the source of the abnormal noise, include it in the report.
• Detection of abnormal noise may lead to ultrasound analysis to detect the source of the noise or specify the diagnosis.
• The measurement of noise levels with portable instrumentation could be part of the visual inspections although it is not usual.