Industrial ultrasound is one of the most versatile technologies available to maintenance and reliability teams.
Although sometimes associated primarily with compressed-air leak detection, modern ultrasound instruments can be used across mechanical, electrical and process applications.
Typical applications include:
- Bearing condition monitoring
- Precision lubrication
- Compressed-air leak detection
- Gas leak detection
- Valve passing
- Steam-trap inspection
- Electrical inspection
- Mechanical friction detection
- Hydraulic-system inspection
This makes ultrasound particularly useful for industrial plants seeking a fast, non-invasive method of identifying energy losses and developing equipment problems.
How Industrial Ultrasound Works
Many mechanical, electrical and fluid-related problems generate high-frequency acoustic energy. These frequencies are generally above the normal range of human hearing.
Industrial ultrasound instruments convert this ultrasonic energy into information that technicians can hear, measure, trend and analyse. Because ultrasonic signals are relatively directional, technicians can often locate the source of a problem even in noisy industrial environments.
Bearing Condition Monitoring
Rolling-element bearings generate characteristic ultrasonic energy as their operating condition changes. Increased friction can produce measurable changes before a major mechanical defect develops.
Ultrasound can therefore assist in identifying:
- Lubrication deficiency
- Excessive lubrication
- Early bearing deterioration
- Increased friction
- Certain installation problems
When readings are periodically collected and trended, changes in bearing condition can be identified before they become severe.
Ultrasound-Guided Lubrication
One of the most valuable applications of industrial ultrasound is condition-based bearing lubrication. Traditional grease programs often rely on fixed schedules.
For example, a technician may lubricate a bearing every three months regardless of its actual condition. But bearing lubrication requirements vary according to:
- Speed
- Load
- Temperature
- Grease type
- Environment
- Operating hours
- Bearing condition
Adding grease simply because a calendar says it is due can result in over-lubrication. With ultrasound-guided lubrication, technicians monitor the bearing while grease is being applied. The objective is to provide the required lubrication based on actual bearing response. This can help reduce both excessive and insufficient lubrication.
Compressed-Air Leak Detection
Compressed air is one of the most widely used utilities in industrial plants — and frequently one of the most expensive. Even relatively small leaks can waste significant energy when they operate continuously.
Ultrasound allows technicians to detect leaks in:
- Compressed-air piping
- Fittings
- Couplings
- Hoses
- Valves
- Pneumatic systems
- Instrument-air networks
A structured leak-management program can identify, quantify, tag, repair and verify leaks. The result can be lower compressor demand and reduced energy consumption.
Detecting Valve Passing
A closed valve should restrict flow. However, worn seats, damaged sealing surfaces or contamination can allow fluid to pass through a valve that is supposed to be closed. This internal leakage may generate ultrasonic turbulence.
By comparing ultrasound levels upstream, across and downstream of the valve, experienced technicians can assess whether passing is likely. This technique can be applied to many industrial valves without dismantling the equipment.
Steam-Trap Inspection
Steam traps are designed to remove condensate and non-condensable gases while retaining steam.
Failed steam traps can result in:
- Live steam loss
- Poor heating performance
- Water hammer
- Process inefficiency
- Increased energy consumption
Ultrasound, frequently combined with temperature measurement, can help determine whether a steam trap is operating correctly.
Electrical Inspection
Electrical problems can generate ultrasonic emissions even before severe temperature rise occurs.
Ultrasound can assist in detecting phenomena associated with:
- Arcing
- Tracking
- Corona
- Loose electrical connections
Applications may include switchgear, substations and other electrical assets, subject to the appropriate safety procedures and equipment ratings. Ultrasound and infrared thermography can be particularly complementary. Thermography identifies abnormal heat patterns, while ultrasound may detect certain discharge mechanisms.
Ultrasound in Oil & Gas Facilities
Oil and gas plants present demanding maintenance environments where equipment availability and safety are critical.
Ultrasound applications may include:
- Valve inspection
- Compressed-air leak surveys
- Instrument-air systems
- Bearing inspection
- Lubrication optimization
- Steam systems
- Certain gas-leak applications
- Electrical inspections
Where equipment is used in hazardous areas, the selected instrument must have the appropriate hazardous-area certification required by the facility.
Ultrasound Should Be Part of a Multi-Technology Program
Like every condition-monitoring method, ultrasound has strengths and limitations.It becomes significantly more powerful when correlated with other technologies.
For a bearing, for example:
- Ultrasound may identify increased friction.
- Vibration analysis may identify bearing defect frequencies.
- Oil analysis may detect wear particles.
- Thermography may identify increasing temperature.
Together, these technologies allow the reliability engineer to develop a much stronger understanding of machine condition.
From Detection to Reliability Improvement
The objective of an ultrasound program should not simply be to find defects. The greater objective is to eliminate the mechanisms creating those defects.
Examples include:
- Improving lubrication practices
- Repairing compressed-air leakage
- Correcting recurring steam-trap failures
- Investigating repeated valve leakage
- Identifying electrical deterioration earlier
This moves the organization from reactive maintenance toward proactive reliability.
Frequently Asked Questions
Can ultrasound detect bearing problems?
Yes. Ultrasound is particularly effective for identifying frictional changes, lubrication problems and certain early-stage bearing conditions.
Can ultrasound be used for lubrication?
Yes. Ultrasound-guided lubrication allows technicians to observe bearing response while applying grease.
Can ultrasound detect compressed-air leakage in noisy plants?
Yes. Because ultrasonic frequencies are relatively directional, leaks can often be located even in noisy industrial environments.
Can ultrasound detect valve passing?
It can help identify turbulence generated by internal leakage across closed valves.
Is ultrasound a replacement for vibration analysis?
No. The technologies complement each other. Ultrasound is especially useful for early frictional conditions while vibration analysis provides detailed mechanical diagnostics.
Can ultrasound instruments be used in hazardous areas?
Only instruments carrying the appropriate certification for the classified area should be used.
