The fragments generated from exploded process equipments would cause domino effect after impacting with the other neighboring equipments.An impact probability model based on the Monte Carlo method is derived to analyze the randomicity of the projection distance and direction of the fragments.The difference from the previous models is that the size of bursting vessel is not ignored

that means the initial projection height and the projection horizontal displacement of the fragments are not considered as zero.The comparison of results show that the impact probabilities would be larger if the size of bursting vessel is considered.The influence on the impact probability is higher than 10% when the distance of target is lower than 7 times of the diameter of bursting spherical tank.So the influence of size of bursting spherical tank on impact probability cannot be ignored.