Abstract: There are two different concepts for safe clearance in tank farm: fire safe clearance, and protective safe clearance. As for the scientific determination of protective safe clearance, the destructive factors of a bomb are analyzed and the destruction degrees of buildings classified. Then the level of allowable destruction of building is obtained according to the building's importance and its resistivity to impact wave, and the safe clearance for impact wave prevention is calculated on the basis of the charge volume in the bomb. The protective safe clearance for a hidden tank shall be determined in accordance with the level of allowable destruction, location of explosion, and the safe clearance between two hidden tanks.