Abstract: The tube closure comprises a cap and a nut which work in concert with each other to effectively seal a nipple at the end of a threaded tube or pipe and which facilitate removal of the cap. The cap has a flared end portion, a narrowed neck portion, a head portion, and an inner cylindrical sealing surface which engages the nipple. The cap is removably engaged within the nut with the nut at the neck portion, and is sealingly engaged on a cylindrical surface of the nipple. The cap may be removed from the nut by withdrawing the head through the nut, with an axial separation force. Removal of the cap from the nipple requires an axial cap removal force. The required axial separation force is greater than the cap removal force. The engagement of the cap within the nut allows the unscrewing of the nut to provide an axial force on the cap to disengage the cap from the nipple without separating the nut from the cap.