TESTING DEVICE FOR WELDED PORTION OF RECTANGULAR STEEL PIPE

摘要

PURPOSE: To enable probing the bead-equipped inner surface of a steel pipe by providing an inner surface probe of a specific angle of refraction in a position which is on the outer surface of the steel pipe and distant from an incidence point by a specific distance in a direction perpendicular to a welding line. ;CONSTITUTION: In order to enhance distinction between a defect echo and an inner-surface bead echo, the testing distance Y₁ between a welding line L and an incidence point P is deviated outward from a 0.5.N skip point by α so that Y₁=0.5.S.N+α (S: skip, N: 1, 3 or 5). α= (1/ 6-5/6)ω (ω: bead width). When N=1, a beam is directly applied to an inner surface bead 4; when N=3, the beam is reflected once by either the outer or inner surface of a rectangular steel pipe 1; when N=5, the beam is reflected twice. When the thickness of the steel pipe 1 is great, N is 3 or 5 to match the thickness. The angle of refraction of an inner surface probe 11 is about 65° to 80° to prevent decrease in the distinction between the bead 4 and a defect 6 and to prevent a surface-wave echo and a defect echo from being mixed. Thus the defect echo can be easily distinguished from the bead echo.;COPYRIGHT: (C)1996,JPO