Nonlinear magnetic method for estimation of wall thinning in carbon steel pipe

Abstract

This paper proposes a nonlinear magnetic method to estimate the thickness of carbon steel pipe used in the secondary steam cycle of nuclear power plants. The principle of the proposed method is based on utilizing the nonlinear property of magnetic saturation in carbon steel. A magnetic sensor system for the nonlinear magnetic method is designed by the magnetic circuit concept, and is modeled and analyzed with the finite element method and an equivalent electric circuit. The sensor system is built to experimentally test its performance in the estimation of wall thinning. To demonstrate the feasibility and validity of the proposed nonlinear magnetic method, the measured data from the sensor system are used to estimate the wall thinning, and are compared with the analysis results.