This paper is concerned with a quantitative nondestructive evaluation of pipe wall thinning using an Electro-Magnetic Acoustic Transducer (EMAT). First, two methods for sizing wall thickness, pulse-echo method (PEC) and electromagnetic resonance measurement technique (EMAR) are examined using calibration specimen of SS400. It was shown that EMAR is superior to PEC for its sizing accuracy. Secondly, we discuss a feasible measurement strategy based on EMAR technique. Finally, the feasibility studies of the method are summarized for evaluating mock Flow-Accelerated Corrosion (FAC) test samples.