Patent ID: 8356518

Claim:
An apparatus for inspecting a pipe comprising a body configured and operable for passage through a bore of a pipe to be inspected, a main transducer array comprising a plurality of circumferentially spaced transducers for transmitting ultrasound energy, the transducers being mounted on the body for movement of the transducers between a retracted position, wherein the body can freely move through the bore of the pipe, and an extended position wherein the plurality of transducers are pressed into operative contact with an inner wall of the pipe, an actuator for selectively urging the plurality of transducers to the extended position, a controller for transmitting ultrasound energy into said pipe to propagate a guided wave within pipe walls of the pipe in at least one longitudinal direction along the pipe when the transducers are in the extended positions and for receiving the propagated wave and analyzing said wave to determine the presence or absence of defects in the pipe wall, wherein said transducers comprise shear polarized piezoelectric transducers capable of both emitting ultrasonic energy and detecting reflected ultrasonic waves, wherein each transducer has a contact head for contact with the inner wall of the pipe to be inspected, an outer surface of said contact head defining an intersection of a rectangular parallelepiped and an outer edge of a toroid, wherein the major and minor radii of the toroid are at least 10% smaller than the smallest radius of the pipe to be inspected in order to obtain an approximate point contact of the contact head with the inner wall of the pipe.