Closed-head drum with liner, and method for producing the same

A method for producing a closed-head drum having a liner including a cylindrical internal wall, a disk-shaped lower base, and a disk-shaped upper base in which two liner connectors are disposed, wherein one liner connector has a larger diameter than the other liner connector and serves as a filling and retrieval connector, and the other liner connector serves for ventilation and aerating when filling or emptying, respectively, the liner and the closed-head drum with liquid filling material, wherein an upper end of a bung connector having a smaller diameter is fixedly welded to an adapter ring which has a radially projecting flange ring, a circumferential sealing ring being disposed on, or fastened to, respectively an underside of said flange ring,

• the method for producing a closed-head drum characterized by following method steps:
• providing a commercially available standard closed-head drum having two 2″ bung connectors having 70×6 closures, and a commercially available 2″ bung plug for a 70×6 closure, and a commercially available ¾″ bung plug for a 70×6 closure, wherein one 2″ bung connector having the 2″ bung plug serves as a filling and retrieving bung for the liquid filling material, and another 2″ bung connector serves as a ventilation and aeration bung for filling volume in an interior of the liner and for an intermediate air space between an external surface of the liner and a drum internal wall;
• providing a liner having two dissimilarly sized liner bung connectors, wherein the larger bung connector is provided for the 2″ bung connector having the 70×6 closure and is configured so as to be longer and so as to have a free end that is welded shut, while a hollow sleeve-type adapter ring having a lower sealing ring is welded to an end of a shorter, smaller bung connector;
• rolling up the liner so as to form a slim roll, wherein the welded adapter ring is disposed on a top of the roll;
• inserting the slim roll through the ventilation and aeration bung and fixing the adapter ring by means of a ring nut which encircles the adapter ring and which has a centric passage opening and which has an external thread for the 70×6 closure in the 2″ bung connector of the ventilation and aeration bung, wherein the adapter ring with the lower sealing ring seals the intermediate air space between the external surface of the liner and the drum internal wall in the 2″ bung connector;
• blowing compressed air into the ventilation and aeration bung until the liner is fully inflated and the welded-shut larger liner bung connector pokes out of an opposite filling and retrieving bung;
• cutting off the welded-shut free end of the larger liner bung connector, and inverting the liner bung connector toward an outside, over the 2″ bung connector of the closed-head drum;
• radially welding the liner connector below an internal thread in the 2″ bung connector, and cutting off a surplus and/or projecting liner connector to an exact fit above an annular welding surface below an internal thread,
• placing a vacuum bell jar onto the ventilation and aeration bung and, with a released ring nut and a lifted adapter ring, by means of a vacuum pump that is connected to the vacuum bell jar suction all of the air from the intermediate air space between the external surface of the liner and the drum internal wall, and extracting a vacuum until the external surface of the liner bears in a fully planar manner on the drum internal wall;
• tightening the ring nut and compressing the adapter ring with the lower sealing ring in the 2″ bung connector, for permanently maintaining the vacuum between the liner and the drum internal wall;
• screw-fitting the 2″ bung plug into the 2″ bung connector of the filling and retrieving bung, and screw-fitting the ¾″ bung plug into the adapter ring provided with the internal thread.