METHOD FOR EDDY CURRENT CONTROL OF WALL THICKNESS OF METAL NON-MAGNETIC PIPES Russian patent published in 2022 - IPC G01N27/90 

FIELD: current control.

SUBSTANCE: invention is intended for eddy current control of the wall thickness of metal non-magnetic pipes. The substance of the invention lies in the fact that excitation is carried out using an attached eddy current transducer in the object of control of eddy currents of three frequencies, the first of which is selected from the condition of a negligibly small value of the penetration depth of the magnetic field compared to the wall thickness, the second frequency is selected from the condition of approximate equality of the penetration depth of the magnetic field to half the wall thickness, the third frequency is selected from the condition of exceeding the penetration depth of the magnetic field of the wall thickness, the introduced voltages of three frequencies are measured, the value of the gap between the eddy current transducer and the test object is determined from the value of the amplitude of the introduced voltage of the first frequency, the wall thickness is determined on the basis of the experimental functional dependence phase of the introduced voltage of the third frequency on the value of the gap and wall thickness for a fixed value of the specific electrical conductivity of the metal of the pipe wall, corresponding to those used when and functional dependence of pipe samples, and for detuning from changes in the specific electrical conductivity of the metal of the pipe wall, the measured value of the phase of the introduced voltage of the third frequency is corrected by a correction value equal to the product of the difference between the measured value of the phase of the introduced voltage of the second frequency and its value for those used in finding the conversion function of pipe samples and the correction factor, while the value of the correction factor is determined by the obtained values of the pipe wall thickness and gap using the linear dependence of the correction factor on these values.

EFFECT: increasing the reliability of monitoring the wall thickness of metal non-magnetic pipes.

1 cl, 6 dwg