Method and Apparatus for Metal Thickness Measurement in Pipes with a Focused Magnetic Field

An apparatus and methods for inspecting pipes which may comprise a body attached to a tether for movement in a pipe. The body may comprises at least a transmitter coil and a receiver coil. The receiver coil may be disposed between at least two transmitter coils. The apparatus may also include a circuit for energizing the transmitter coil with a pulsed electromagnetic source and a circuit for receiving and processing a signal from the receiver coil. Methods include inserting an inspection device into a pipe and energizing transmitter coils. A magnetic flux is emitted from the transmitter coils. The method also includes inducing an eddy current within a pipe wall and measuring the electromagnetic flux induced in a receiver coil by the eddy current within the pipe wall.