AUTOMATIC CALIBRATION IN ULTRASONIC FLAW DETECTION APPARATUS OF PIPE TO BE INSPECTED

摘要

PURPOSE:To enable automatic calibration, by automatically performing gate setting under an optimum condition corresponding to the shape of an actual pipe. CONSTITUTION:A beam distance Wth making the outer or inner surface flaw echo S12 of a welded part max. is calculated by a predetermined formula corresponding to the number of skips of a probe of which the position is set. Around the point on the CRT time axis of a flaw detection apparatus corresponding to said distance Wth, a flaw gate FG1 with predetermined widths a, b is set. A flaw gate start point pulse FGS1 is used in forming the gate FG1 and S11 is a surface echo. The comparison test piece collected from an actual pipe or each probe head is relatively moved to perform the calibration of sensitivity. In this case, a beam distance Wact, when the position of the probe is adjusted so as to make the flaw echo S12 max. in the comparison test piece, is different from the distance Wth of the predetermined formula. Therefore, a flaw peak position SP is detected and the width of the flaw gate starting point pulse FGS2 is widened by the shift amount delta with the distance Wth in the comparison test piece to move FG1 and a flaw gate FG2 is set to take out a flaw signal.