ULTRASONIC FLAW DETECTING METHOD FOR WELDED ZONE OF SEAM WELDED STEEL PIPE

摘要

PURPOSE:To detect a defect of a welded zone with high accuracy by welding an internal surface by advanced pressing, and performing ultrasonic flaw detection principally as to an outside welded zone by a jet water method by using a surface wave. CONSTITUTION:The probe 1 is held by a holder 2 and the probe 1 and a steel pipe P are coupled together by a water jet flow; and water Wa run through a conduit and flows out of the lower end of a guide cylinder 4 for water column formation to detect a defect. If there are drops of water and oil or foreign matter, etc., on the external surface of the steel pipe P, an ultrasonic wave is reflected by the foreign matter, etc., to become a noise, so a dewatering member 6 and an air blowing nozzle 7 are provided to prevent the water from moving and also to blow away the foreign matter. Consequently, misdetection is eliminated securely and the accuracy of defect detection is improved.