A device for continuous blast treatment of parts is disclosed. The device employs an overhead monorail conveyor for carrying parts to be treated into a blast chamber where the parts are subject to a particulate blast, as for example, abrasive treatment. At least one rotary vestibule is employed to convey the parts on the monorail into and out of the blast chamber while providing dynamic abrasive tight sealing of the entrance and exit openings to the blast chamber.