The Detection and Imaging for Thick Walled Pipes Using Circumferential Guided Wave

In this paper,circumferential guide wave detection method was presented,which could detect thick walled pipe defects rapidly.Dispersion curves of circumferential Lamb wave in thick walled pipe with 269mm outside diameter and 32mm wall thickness was calculated firstly.Then experimental system was built.Studies were made of the effect of frequency and size of piezoelectricity crystal on the detecting results,and imaging research on defect was carried out.The experimental results indicated that circumferential Lamb wave could detect flaws for a long distance.It is better to select low frequency and larger size of piezoelectricity crystal in practical testing.Axial acoustic beam of circumferential Lamb wave is concentrated in thick walled pipe.And it can evaluate damage through B scan imaging.