A disk-donut stripper is widely equipped in many fluid catalytic cracking (FCC) units in petroleum refineries. However, wear accidents are often reported in these strippers, especially in disk-donut strippers of compact coaxial FCC units. In this study, theoretical analyses based on cold model experimental facts and the geometrical features of these FCC units were conducted on the causes of wear accidents in disk-donut FCC strippers. The gaps in the stripper baffles caused by objects penetrating through baffle or welding defects, which act as short-cut passages for gas streams, are thought to be the root cause of these wears. Three speculations were hence proposed on three categories of wear. Three cases of CPFD model were established to validate these speculations. The simulated locations with the highest wear magnitudes are agreeable with the wear accidents reported in industry. The high solid velocities through the gaps entrained by the high-velocity gas stream explain why these high wear magnitudes appear in these locations. Finally, two suggestions were provided to avoid such wear accidents in disk-donut FCC strippers. (C) 2015 Elsevier B.V. All rights reserved.