ULTRASONIC EXAMINATION METHOD FOR TRANSVERSAL CRACK OF WELDING BEAD

摘要

PURPOSE:To improve the S/N ratio and detect transversal cracks stably and surely, by moving a probe, which is provided at an inclination to the direction of the welding bead line, along the welding bead to detect flaws. CONSTITUTION:The whole of a flaw detecting device is supported elastically by the internal spring of a ball bearing 6 and is made run along the surface of a steel pipe P while following the surface of a welding bead B. Since the main body of a probe 1 turns around pivots 3 and 3 when the welding bead is not bisymmetrical, the flaw detecting device runs smoothly. A probe holder 9 is positioned as inclined in the direction of the welding bead line for flaw detection. This positioning is properly selected considering the detection capability. As required, a rotary table 5 is turned around the axis for a base 4, and the probe holder 9 is turned around the axis also. During the flaw detection, water is supplied from a water supply hole 13 to form a jet water column from the lower part of a transmission hole 9b toward the bead B.