Ultrasound, Ultrasonic Test, Partial Discharge



Ultrasound is one of the more versatile condition monitoring technologies available today. It is easy to learn to use, easy to implement and inexpensive. It provides a great complement to vibration, infrared and electrical inspection techniques. Ultrasound is commonly used for on-line leak detection, mechanical and electrical inspections.

Ultrasonic detectors include both contact and airborne type sensors which detect sound waves above the range of human hearing in the 20 kHz to 100 kHz range. Using a heterodyne technique, an ultrasonic signal is reduced to frequencies which can be heard by humans via headphones. Most detectors display a decibel measurement which can be used for trending. The signal can also be recorded and analyzed in both the time and frequency domains.

Leak Detection

Leaks are a common cause of wasted energy. Leaks in a system cause assets to operate more than necessary. Air leaks in industrial environments may not be heard over the high background noise. The directional nature of ultrasound allows these air leaks to be quickly located.

The cost of air leaks is high. Energy cost savings in the range of tens of thousands of dollars per year is commonly possible at many plants. And the extra mechanical wear on equipment is expensive. A quarterly ultrasound survey can result in increased efficiency and substantial savings.

In extreme cases, air leaks can be even more expensive. One client had four large 4160 V compressors which operated continuously overloaded to maintain air pressure. The compressors were overheated causing unexpected motor insulation failures and high downtime costs. After identifying and repairing many air leaks, only two compressors operated continuously and the other two cycled on and off as needed resulting in lower energy usage. And even more importantly, the motors operated within specification and the insulation failures ceased.

Mechanical Inspections

Ultrasound is used for condition monitoring of production machines and trending normal operating levels to identify changes indicative of developing problems. All rotating equipment produces frictional forces with high frequency ultrasonic signatures which are often masked by ambient plant noise and low frequency vibrations. Changes in these signatures serve as early indicators of failure.

 Ultrasound provides a fast means to monitor machine condition. It provides overall data that is indicative of friction levels, random impacting, rubbing, and energy produced by the machine at the sensor pickup point. It is a great complement to a vibration testing program.

Ultrasound is also very useful for inspecting steam traps, valves, pumps and other mechanisms. These devices often have a sound signature when properly operating. A change in the signature indicates a failure in the mechanism.

Electrical Inspections

Ultrasound is used for routine scans of switchgear, substations and transmission lines. It is useful whenever there is line of sight access to the cause of electrical discharge. It detects arcing, tracking and partial discharge which cause asset failure and downtime.

Ultrasound is an effective inspection tool for significant arcing and tracking issues indicative of impending failures. It also provides a quick means to survey for partial discharge indicative of longer term insulation concerns and safety issues. Ultrasound provides warning of arc flash danger from a safe distance.

To learn more about how Torq can help you with ultrasound technology, contact us.

  • Compressed gas leaks
  • Heat exchangers
  • Boilers and condensers
  • Tanks and pipes
  • Valves and steam traps
  • Electrical arcing, tracking & partial discharge
  • Switchgear
  • Transformers
  • Circuit breakers
  • Bearing faults
  • Gear problems
  • Coupling defects