Abstract: Tank closure with a self-locking closure apparatus arranged at the orifice rim of a pour-in socket-piece. The closure apparatus consists of a closure part and a pour-in opening which is closable by means of the closure part. Between the rim of the opening and a refueling nozzle to be introduced a gas outlet gap remains for the gases which escape when refueling the tank. A guide is provided for reception of the refueling nozzle. In order to free the exiting gases from fluid droplets, it is provided that the guide exhibits a reduced-scale segment closely surrounding the refueling nozzle. Exit openings are provided at the side of the reduced-scale segment which is placed toward the pour-in socket-piece, through which the gases pass out of the guide to the outside. Inlet openings are arranged at the side of the reduced-scale segment which faces away from the tank, through which the gases in the interior of the guide enter.