Ultrasonic device for measuring thickness of a tank bottom flat plate

An ultrasonic measuring device for measuring the thickness of a large flat plate having an upper surface and a lower surface, said ultrasonic measuring device comprising:

• a) a probe drive frame having a chassis and at least two wheels mounted on the chassis for supporting said frame on the upper surface of the flat plate;
• b) means for driving said probe drive frame over the upper surface of the flat plate;
• c) an encoder mounted on one of the wheels, said encoder transmitting an encoder signal corresponding to the movement of the wheel on which said encoder is mounted over the upper surface of the flat plate;
• d) a plurality of ultrasonic probes mounted on the chassis of said probe drive frame, each of said plurality of probes including a transmitter means for generating and emitting a directed beam of ultrasonic waves toward the flat plate upon receipt of an ultrasonic signal, and including a receiver means for receiving a single echo from the upper surface of the flat plate and a plurality of echoes from the lower surface of the flat plate and transforming said single echo from the upper surface and said plurality of echoes from the lower surface into response signals;
• e) a pulser-receiver in electrical communication with said plurality of ultrasonic probes, said pulser receiver transmitting ultrasonic signals to said ultrasonic probes, generating a synchronizing signal, receiving the response signals from the ultrasonic probes, and amplifying the response signals to generate amplified response signals for output transmittal;
• f) a gated peak detector in electrical communication with said pulser-receiver for receiving the amplified response signals and the synchronizing signal from the pulser-receiver, said gated peak detector gating the amplified response signals to extract the upper surface echo and a first lower surface echo to generate gated response signals;
• g) a processing unit in electrical communication with said encoder, said pulser-receiver, and said gated peak detector, said processing unit receiving the encoder signal from said encoder, the synchronizing signal from said pulse-receiver and the gated response signals from said gated peak detector, and said processing unit calculating a thickness of the flat plate according to the gated response signals and a known speed of sound value for the flat plate, and calculating a position of said plurality of ultrasonic probes according to the encoder signal, whereby the thickness of the flat plate is determined along the path of the probes over the upper surface of the flat plate.