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Description:
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The project is targeted to develop a scheme for non -intrusive detection of flaws in metal pipelines . In the laboratory , experiments were conducted on a steel pipeline section . The generation and detection of the acoustic pulse is non -intrusive and can be performed with just an electrical contact of the pipe . Acoustic pulses are generated by a pulsed magnetic field .
In the investigation , the magnetic pressure in a coil generates the acoustic pulses . The pulses propagate in either direction along the pipe . A detector picks up these acoustic pulses and any reflected pulses . Reflections are caused from the ends of the metal pipeline section as well as any imperfections and /or discontinuities , like thin spots due to corrosion in the pipeline . The pressure pulse causes a temporary local change in the diameter of the pipe , leading to a voltage change of the charged electrode of the detector . The reflections recorded by the detector on the oscilloscope indicate existence and , from the time delay , the location of any defect . Reflected pulses from thin areas , with a longitudinal extension of about one pipe radius and a reduction of the wall thickness of 40 % were detected clearly . The attenuation of the pulses for pipes buried in sand was also studied . Measurements were done with varying sand depths . The length of sections of pipeline that can be checked with this pulse -echo method is about 14 m , or 7 m in both directions , for pipelines buried under 3 feet of sand . Experimental results are presented . |