| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and apparatus for inspecting defects in the weld zone of an electric resistance welded tube in on-line by which even minute weld defects termed as a penetrator and generated in the weld zone of the electric resistance welded tube can accurately be detected. SOLUTION: In the sizing stage of a manufacturing process of an electric resistance welded pipe in which a steel plate is made into an electric resistance welded pipe having a circular cross section through a roll forming stage, an electric resistance welding stage and the sizing stage, a deforming work is applied to the electric resistance welded tube having the circular cross section in a direction in which minute defects in the weld zone are enlarged with deforming sizing rolls. Next, after the deformed tube is restored into the tube having the circular cross section, the ultrasonic flaw detecting inspection of the weld zone is performed. Any of the sizing rolls composed of a plurality of stages is made into a deforming sizing roll for deforming the tube having the circular cross section into a tube having an non-circular cross section. In this inspection device, the ultrasonic flaw detecting device is installed on the side of the poststage of the deforming sizing roll. COPYRIGHT: (C)2009,JPO&INPIT
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