Ultrasonic Guided Wave Inspection of Defects in Oil and Gas Butt-Welded Bend Based on B-scan Imaging

In order to inspect the defect in the oil and gas butt-welded bend by ultrasonic guided wave, the influence of elbow and girth weld on the propagation of L(0,2) mode and T(0,1) mode was firstly analyzed. It is found that the girth weld causes the reflection of ultrasonic guided wave, meanwhile, the elbow and girth weld cause the attenuation and mode conversion of ultrasonic guided wave. The above phenomenon makes it difficult to inspect the defect in the oil and gas butt-welded bend. Then, the method of ultrasonic guided wave inspection based on B-scan imaging is proposed, which was used to assist the identification of the defect signal by the B-scan image. Finally, two oil and gas butt-welded bends with defects were processed, and the above method was used for the test. The experimental results show that the method of ultrasonic guided wave inspection based on B-scan imaging can effectively inspect and locate the defects in elbow and in the straight pipe after the elbow.