Abstract: Multi-channel automatic on-line ultrasonic inspection system for real time high-speed pulse echo testing is done across the width of a hot moving workpiece, such as steel plates and the like. In addition to a multiplexed transducer array search unit, the system includes an adjustable ultrasound fluid couplant, a main ultrasonic instrument modified with a digital multi-channel R.F. attenuation controller and a digital automatic flaw gate controller combined as on-line calibration means. The calibration means automatically corrects echo pulses for attenuation errors due to effects of variations in workpiece alloy or composition and temperature, and timing errors due to effects of variations in thickness and transducer gap, respectively. System further includes an ultrasonic data buffer/controller (UDBC) for digitizing, encoding and storing corrected or uncorrected flaw area data passed by the flaw gate during workpiece movement.

Abstract: Apparatus and method for acoustically inspecting hot flat plates while on-line by utilizing an array or arrays of transducers continually spaced a set distance from the bottom of the plates by serrated rollers spring mounted with the array of transducers in a container with overflowing liquid wetting the passing plate to acoustically couple the transducers to the plate and a spray of sufficient force to temporarily cool the hot plate and dispel steam and vapor formed, the spray being in a direction opposite the direction of travel of the hot plate; and support of the unit on a track mounted carriage, with the liquid reused through a reservoir connected system. It is critical that the spray be at an angle of 27.degree. or less to the horizontal and that the spray have sufficient force to have an apparent liquid velocity of at least 44 feet per second, adding the speed of the water and the hot plate together.