Abstract: A device for safely attaching sections of a rocket motor is disclosed. The device is constructed such that if the temperature of the rocket motor is elevated to the point where ignition of the propellant within the rocket motor becomes a significant danger, the device allows the sections of the motor to disengage. The device comprises a bimetallic retaining ring which either contracts or expands in diameter upon heating. The retaining ring is positioned in such a manner as to lockingly engage two sections of the rocket motor at normal temperatures. At elevated temperatures, however, the expansion or contraction of the bimetallic retaining ring causes the sections of the motor to unlock from one another, such that if the propellant ignites the sections will disengage and the rocket will be rendered non-propulsive.