While helium leak testing is the most common leak detection method in the industry, it has many disadvantages, such as having operator-dependent results and the frequent need to calibrate equipment. CTRL Systems is heavily involved with the implementation of acoustic ultrasound technology for leak detection and condition-based monitoring in the power generation and transmission industry.
Acoustic ultrasound detection has become a strong alternative approach for vacuum leak detection. As tested and used by NASA on the International SpaceStation2, acoustic ultrasound leak detection technology is now capable of detecting all turbulent flow gas and vacuum leaks and is used by many power plants for condenser leak detection.
Ultrasonic technology’s leak detection capabilities are not found in vibration analysis or infrared, yet its use in conjunction with these more widely used predictive maintenance technology is complementary. In many power plants, technicians use ultrasound when they first suspect a problem — for example with bearings — then verify what they have heard with portable vibration analysis. Likewise, ultrasonic technology can help to confirm if a bearing or gear problem exists where there is an early change in vibration analysis readings, or when thermography picks up a hot spot in a circuit breaker or switchgear. According to plant operators surveyed, ultrasonic devices are often able to better pinpoint the location of the problem in electrical equipment.
Ultrasonic technology is flexible and allows the technician to gather information rapidly. In power plants, ultrasound technology is unique in its ability to detect and pinpoint leaks in air and steam systems, condensers, boiler tubes, and water walls — something infrared and vibration analysis cannot do. This translates directly into improved system efficiency, as it allows the technician to take corrective action to prevent reduced pressure, to avoid adverse impact on the effectiveness of all systems that rely on maintaining proper pressure for efficient operation.
A specific example of ultrasound’s ability is in pinpointing condenser tube leaks. Differences in the tubes are easy to discern if air is escaping. Leaks are easily pinpointed, so the problem can be resolved (tubes cut and capped to stop the leak). When talking about how much faster condenser tube leaks can be found and repaired, one user remarked, “the time savings have been incredible with
CTRL lead a successful energy savings pilot program in China for 3 years with participation from 25% of the power plants in China. The successful pilot resulted in a permanent program being established for the benefit of all power plants to reduce energy waste during production through condenser tube leak detection. The CTRL technology proved to be much faster and more accurate than traditional leak detection methods.
In the case of bearings, vibration analysis is often inadequate. At the point when vibration analysis is just beginning to show signs of something happening, ultrasound can only not “tell” the operator if the bearings are over or under-lubricated or out of round, ultrasound can pinpoint which bearings need immediate attention. In fact, ultrasound can often detect a bearing problem long before the problem is identified through vibration analysis or infrared — before costly damage or catastrophic failure occurs.
Determining inadequate or improper lubrication is one of ultrasonic technology’s strengths. A two-year study of ultrasound at one nuclear facility focused on its use in monitoring the condition of bearings on cooling tower fan motor bearings, which are grease lubricated. Each time a bearing was identified as bad by ultrasonic analysis, maintenance work proved that the bearing was indeed bad.