In this paper, the use of tone-burst eddy current thermography (TBET) is proposed to detect defects in pipes. An optimum frequency of excitation was used to obtain the maximum temperature contrast between the defective and non-defective regions. The simulation studies were carried out using copper pipes with tungsten rings and validated with experiments. It was demonstrated through experiments that it is feasible to detect the disbond between graphite and tungsten tiles and the copper pipe in a divertor block that is used in a prototype fusion reactor.