Patent ID: 6843267

Claim:
A system for sealing an opening of a plastic tank with a multilayer structure comprising at least one layer of high-density polyethylene and at least one internal barrier layer, constituted by a plastic plate welded to the wall of the tank in the location of the periphery of the opening, the plate itself is constituted by a multilayer structure also comprising at least one layer of high-density polyethylene and at least one internal barrier layer and whose external layer welded to the tank has a composition compatible with that of the layer constituting the external wall of the tank, wherein in the location where the external layer of said plate is welded to the layer constituting the external wall of the tank, said plate and said wall of the tank are superposed so that the number of superposed layers in this location equals the sum of the number of layers in said plate and the number of layers in the wall of the tank, and so that the barrier layer of said plate is not in continuity with the barrier layer of said tank.