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

A liner for inserting into a closed-head drum comprising:

• a cylindrical internal wall,
• a disk-shaped lower base, and
• a disk-shaped upper base in which two liner connectors are disposed,
• wherein the 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,
• wherein the upper end of said 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, the underside of said flange ring.

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 the 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 said 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 the underside of said flange ring,

• the method for producing a closed-head drum characterized by the following method steps:
• providing a closed-head drum having bung connectors, and a first bung plug configured to plug a first bung connector of the bung connectors, and a second bung plug configured to plug a second bung connector of the bung connectors and being smaller than the first bung plug, wherein the first bung connector having the first bung plug serves as a filling and retrieving bung connector for the liquid filling material, and the second bung connector serves as a ventilation and aeration bung connector for the filling volume in the interior of the liner and for the intermediate air space between the external surface of the liner and the drum internal wall;
• providing a liner having two dissimilarly sized liner bung connectors, wherein a larger liner bung connector of the two dissimilarly sized liner bung connectors is provided for the first bung connector and has a free end that is welded shut, wherein a hollow sleeve-type adapter ring having a lower sealing ring is welded to the end of a smaller liner bung connector of the two dissimilarly sized liner bung connectors;
• rolling up the liner to form a slim roll, wherein the welded adapter ring is disposed on the top of the roll;
• inserting the slim roll through the ventilation and aeration bung connector and fixing the adapter ring by a ring nut which encircles the adapter ring and which has a centric passage opening and which has an external thread for the second bung connector of the ventilation and aeration bung connector, wherein the adapter ring with the lower sealing ring is configured to seal the intermediate air space between the external surface of the liner and the drum internal wall in the second bung connector;
• blowing compressed air into the ventilation and aeration bung connector until the liner is fully inflated and the welded-shut larger liner bung connector pokes out of the opposite filling and retrieving bung connector;
• cutting off the welded-shut free end of the larger liner bung connector, and inverting the larger liner bung connector toward the outside, over the first bung connector;
• radially welding the liner connector below the internal thread in the first bung connector, and cutting off the surplus and/or projecting liner connector to an exact fit above the annular welding surface below the internal thread,
• placing a vacuum bell jar onto the ventilation and aeration bung connector and, with a released ring nut and a lifted adapter ring, via a vacuum pump that is connected to the vacuum bell jar, suctioning 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 second bung connector, for permanently maintaining the vacuum between the liner and the drum internal wall;
• and
• screw-fitting the first bung plug into the first bung connector of the filling and retrieving bung connector, and screw-fitting the second bung plug into the sleeve-type adapter ring provided with an internal thread.