1. The speed of flying ash. The wearing capacity is in direct proportion to the third power of the flying ash speed, If the flue gas velocity increases by 1 times, the wearing capacity shall be increased by 7 times. 

2.Concentration of Flying Ash If the concentration of flying ash is increased and the impacting times of flying ash is more, the wear will be aggravated. 

3. Characteristics of Ash Particles: The thicker and harder the ash particles are, the more severe the wear is. If the carbon content in flying ash increases, the wear will be also aggravated, because the hardness of coke in ash is higher than that of ash particles. 

4. Impact rate of flying ash. If the flying ash particle is big, the flying ash specific gravity is big, the flue gas velocity is fast and the flue gas viscosity is small, then the opportunities of impacting by the fly ash will be more, the wear will be severe.