Researchof Effect From Pipeline Coating Damage To The Characteristic Of Ultransonic Guided Wave

Pipeline is a safe and economical tool to transport large amount of oil, gas, and otherkinds of energy. As buried under the ground for long period, there would exist falling off,peeling, brittle, and aging in the external coating of long-distance pipeline, which maycause corrosion perforation, even leakage, in long-distance pipeline. At present, there aremany detection methods of buried metal pipeline coating. Most of them are accomplishedby the measurement above the ground or indirect test of the performance of the coating.According to the principle of the test, methods could be divided into AC and DC law.However, there isn’t still a method testing whether pipeline coating peels accurately.Ultrasonic testing is a new and widely used non-destructive testing technology thatincludes some certain characteristics. For example, long-distance measurement could beachieved by excitation of a single point. The change of parameters of ultrasonic signaland the attenuation of ultrasonic energy would appear in the interface between the defectsand the coating. The pipe model can be simplified as a plate model from a local analysis,thus based on the actual project, pipe coating model was simplified in this paper, and theeffect on the ultrasonic transportation from the interface of the steel plate and organicglass, which provides a reliable method of analysis to the measurement of the coating.In this paper, the basic theory, transportation, and measurement methods ofultrasonic wave were researched as well as the transportation characteristics in the steelplate and the results of modal and dispersion equations. The dispersion curves of theultrasonic guided wave in the steel plates and organic glass were draw, and the effect onthe dispersion curves from the single-double layer structure was analyzed. Throughtheoretical studies, as the transportation velocity relates to the transportation medium,when the wave transports in the steel plate without glass layer, the velocity should bedifferent. Using this theory, based on ANSYS simulation surrounding, the steel platemodel and organic glass model were established, and the procedure of transportation of wave in various models was simulated. Force vibrations were engaged in both models.Changes of the wave velocity were compared through data. Experimental platform wasestablished and the simulation results were testified by the experimental results.Through ANSYS simulation, the velocity of ultrasonic guided wave in the doubleplate, which shows that the velocity in the double plate was less than that in single layer.By the conclusion above, in practice, when the pipeline coating peeling occurs, there willexist obvious changes of the amplitude and the wave size of the measured ultrasonicguided wave signal, which is fundamental to the qualitative research of pipeline coatingpeeling.