Tube testing by inside eddy-current probe

The principles of eddy current testing, methods and equipment are reviewed. Use of the inside eddy current probe for detecting corrosion and erosion defects inside heat exchanger tubes is described. The defective areas are easy to locate in the longitudinal direction of the tubes. By indication analysis, defects inside and outside the tubes can usually be separated and also the defect depths can be estimated with sufficient accuracy. Results of typical inspections are shown.