During recent shutdown of one of our FCC unit, it is noted that the vibrocat refractory lining in the area of feed injection (1-2 m) got thinned and cracks were also observed. Thinning took place over a period of 4 years since its installation. Erosion is not seen any of other parts of riser. Could anyone has this type of experience. Is it due the high velocity of feed jet?
