AE06.pdf

The workstation has access to the plant data that

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The workstation has access to the plant data that provides the operating status of the various equipment in the plant. If no changes in the plant status are detected, then a leak is declared and the software validates the leak, begins to locate the leak in the piping system and quantifies the leak based on previous leak test data. A workstation display provides an overview of all of the sensor locations in the plant. The operator can navigate from this screen to a more detailed view of sensor locations. The workstation also has access to data from other plant monitoring systems, which include the main coolant pumps vibration data, loose parts monitoring data, pipe temperatures and displacements and humidity monitoring systems. These data also provide valuable information for 223 Acoustic Leak Testing
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correlation with the changes in the root mean square levels and leak validation. Continuous Leak Monitoring of Chemical Feed Supply Line A continuous leak monitoring system has been developed for a chemical feed supply line. Sensors are mounted on a stainless steel pipeline at locations near potential leak sites such as elbows and valves. The sensors are adhesively bonded to a special shoe that conforms to the diameter of the pipe while providing a flat surface for sensor attachment. The shoe is also bonded to the pipe’s outer surface. Next to each sensor, a pulser is mounted within 1 m (3 ft) as shown in Fig. 23. Periodically, the pulser is driven with a high voltage spike so that it launches a sound wave that travels along the pipe wall. The sound is detected by the sensor and is used to verify system operation and the connection of sensor to pulser. No leaks have been detected during normal operation when the pipe is full of a liquid chemical. However, during a nitrogen purge, at 60 percent of the normal operating pressure, a valve was cracked to simulate a very small leak. The leakage was detected by a sensor located 5 m (15 ft) away and produced an energy level reading greater than 100 times that of normal operation. Another sensor located 30 m (100 ft) away detected the same leakage with a reading twice as high as for normal operations. Leak Monitoring of Heat Exchanger in Chemical Industry When hazardous or corrosive chemicals are used in chemical plants, acoustic emission leak monitoring can be integrated into plant controls to provide continuous feedback of pipeline or vessel integrity. Advance detection of very small leaks can prevent environmental incidents as well as the catastrophic loss of equipment and human life. To develop an application of continuous leak monitoring, it is imperative to understand not only the physics of why a leak makes noise but also the variables associated with the process being monitored and the potential for false calls. One example involves the development of a continuous leak monitoring system for a sulfuric acid plant. 11 This application focuses on a heat recovery system that extracts heat from concentrated acid in a stainless steel heat exchanger. If an internal leak occurs, water or steam will mix with the acid, forming a highly corrosive dilute acid.
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  • Fall '19
  • Acoustic Emission

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