Conductivity Estimation of Metallic Tubes Using Ferrite Core Horizontal Probe with Eddy Current Method

Abstract

Conductivity evaluation is crucial for monitoring the condition of metallic tubes during inspections and for assessing their service life. Eddy current testing (ECT) is a precise, non-contact method used for this purpose. Industries such as aerospace, power generation, and petrochemicals rely on precise condition monitoring, which requires a deep understanding of the relationship between conductivity variations and probe impedance of metallic tubes. However, experimental analysis of conductivity changes using coil impedance has limitations in terms of cost and complexity. Encircling coil methods provide overall information about the average conductivity of specimens but have limited ability to capture local variations such as hot spots. To address these issues, we propose using a finite element method (FEM) based approach to predict a ferrite core horizontal probe signal near non-ferromagnetic tubes. The probe data can be used to estimate conductivity through regression methods, and the impact of lift-off on ECT results is also investigated.