The E.O.Paton Electric Welding Institute of the NAS of Ukraine has been developing a technology and technical means of long-range LH guided wave UT of extended pipelines. An experimental welded pipeline 48 m long from 6 m pipes was constructed to study the processes of GW propagation. Pipes of 114 mm outer diameter and 6 mm wall thickness from St.3 steel grade were used in the pipeline. The pipeline is mounted on special supports, insulating it from the environment. During research performance different acoustic arrays based on piezoelectric transducers were created and tested for excitation of a guided wave of the longitudinal and torsional mode. The arrays provide the required force of piezoelectric transducer clamping to the pipe surface to establish a reliable dry contact. To optimize the technology of defect detection in pipes by reflected echo-signal parameters, the method of physical simulation of real defects by mechanical introduction of local discontinuity models in pipes was used. The following was accepted as such discontinuity models: pipe wall thinning of (18x10) size at 3.2 m distance from the point of acoustic array mounting; cut by the pipe circumference of 2.5 mm width; 2.5 mm depth; 0.5 L length, where L is the length of pipe circumference, at the distance of 4.48 m from the point of acoustic array mounting; cut of 2.5 mm width, 2.5 mm depth; 0.3 L length at 14.91 m distance from the point of acoustic array mounting. The working frequency of the excited signals was 19.6 kHz. Application of the technology and technique of long-range guided wave UT requires complete understanding of the factors affecting the test results, and practical experience of result interpretation.
Method and technology of diagnostics of pipeline systems by guided low-frequency ultrasonic waves
Methode und Technologie zur Diagnose von Pipelinesystemen durch geführte niederfrequente Ultraschallwellen
2010
7 Seiten, 5 Bilder, 5 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
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