Fuel tank and method for reducing vapor permeation through a fuel tank

A method of reducing fuel vapor permeation through a polymeric multi-layer fuel tank comprising:

• forming a multi-layer polymeric fuel tank having a wall defining an enclosure in which a hydrocarbon fuel is stored with the wall having a hydrocarbon fuel vapor permeation barrier layer which is discontinuous at a seam and at least one polymeric structural layer outboard of and adhered to the barrier layer;
• providing a separate overlay having a hydrocarbon fuel vapor permeation barrier layer of a polymeric or metal material resistant to hydrocarbon fuel vapor permeation therethrough and at least one polymeric structural layer adhered to the barrier layer throughout the barrier layer of the overlay;
• disposing the overlay over at least a portion of the seam, discontinuous barrier layer and outer structural layer of the wall;
• heating to a temperature of at least about 200° C. the structural layer of the overlay and a confronting portion of the structural layer of the wall;
• and
• applying pressure of at least 5 psi to urge into engagement the heated structural layer of the overlay and the confronting heated portion of the structural layer of the wall to adhere and bond them together throughout the structural layer of the overlay.