WELD EXAMINATION FOR STEEL PIPE

摘要

PURPOSE:To obtain an accurate weld examination by a method inwhich ultrasonic wave is projected perpendicularly on the pipe surface and multiple reflected wave forms from the inside surface of the pipe are checked. CONSTITUTION:An ultrasonic probe is scanned along a line crossing the weld line of welded steel pipe. Ultrasonic wave is projected perpendicularly on the surface of the pipe to get multiple waves reflected back from the inside surface of pipe. As the welded part is formed in such a shape as the ultrasonic wave projected perpendicularly on the pipe surface is scattered, there are differences in wave forms reflected from the inside surface of pipe between for the matrix material of pipe and for the welded part of pipe. The integrated value of echoes from the inside surface within a preset duration, grand sum of echo waves or attenuation characters of multireflected waves and so on are recorded and thereby these values are compared with each reference value or the characteristic curve previously designated to discriminate whether they are from the matrix material or from the welded part.