Patent ID: 9310338
Filing Date: 2016-04-12
CPC Classification: E21B,G01B,G01N,G01V

Claim Text:
1. A method of inspecting a pipe, comprising: lowering a probe into a first pipe, the first pipe being concentrically placed within a second pipe, the probe including a transmitter, a first detector separated from the transmitter by a first distance equal to or greater than twice a diameter of the first pipe, and a second detector separated from the transmitter by a second distance equal to or greater than a diameter of the second pipe; providing a driving signal to the transmitter; receiving a first detector signal from the first detector; receiving a second detector signal from the second detector; determining a first phase shift between the first detector signal and the driving signal; determining a second phase shift between the second detector signal and the driving signal; determining a wall thickness of the first pipe from the first phase shift; determining a total wall thickness from the second phase shift; and subtracting the wall thickness of the first pipe from the total wall thickness to determine a wall thickness of the second pipe.