Crack ultrasonic monitoring

The method was based on an ultrasonic monitoring of the growing crack, schematically shown in Fig. 10.9 with a WOL compact specimen. The procedure was used to permit either semi-automatic or completely automatic monitoring of the crack growth behavior and had a sensitivity of about 0.25 mm. Today, direct visual measurements of the crack size have been substituted by indirect readings based on the specimen compliance. This is measured by a clip gauge mounted on... 

Clark, W.G. Jr., Ceschini, L.J. An Ultrasonic Crack Growth Monitor. Westinghouse Scientific Paper 68-7D7-BFPWR-P1 (1968)... 

This header has undergone repair after through-thickness cracking of an assembly weld after 108.000 hours of service, it is presently in operation and periodically submitted to ultrasonic inspection during planned maintenance shutdown. Continuous on-line AE monitoring of the integrity of critical welds is expected to contribute supporting continued and safe operation of the header until its replacement, platmed to take place in 1999. 

Ultrasonic techniques. Wall thickness can be measured to monitor the progress of general corrosion, cracks can be detected and hydrogen blisters identified. Certain construction materials such as cast iron cannot be examined by ultrasound. Skilled operators and specialist equipment is required. Plant can be examined in situ except when it is above 80°C. 

Some applications of ultrasonics are inspection for flaws in forgings, flat-rolled products such as strips, sheets and plates, castings, extrusion billets, rolling blooms or slabs, bar stock, pipes, welded joints, bonded joints, monitoring cracks, measurement of thickness, measurement of fluid levels, microstructural features and monitoring corrosion. 

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