The projection scan, a new method for recording and visualizing data from ultrasonic weld inspection

Abstract

A new scanning and flaw-location method — the P-scan or Projection scan — is described. A lightweight ruler carrying either an array of light-emitting diodes or an array of electrodes is mounted on the front of an angle probe parallel to the projection of the ultrasound path in the material. When an echo from a defect is received, the diode directly above the defect is lighted. In this way the A-presentation of an oscilloscope is virtually displayed on the diode or electrode array and the flaw position and depth can be read directly from the diode array or recorded on electro-sensitive paper beneath the electrodes. The method offers the possibility of recording weld defects as projection images on a plane parallel to the surface of the inspected part and/or on planes perpendicular to this surface. The records give to a certain extent a direct visual presentation of the shape, orientation, position and size of defects and can be considered as an ultrasonic equivalent to radiography. The image quality which can be expected has been analysed and is illustrated by examples.