the invention concerns a fuel container of plastic material such as a motor vehicle fuel tank , having one or more welded seams as seam locations for the body of the container and / or as connecting or sealing seams between the container wall in the region of openings and closure elements or covers welded thereto . at least some of the welded seams are at least partially penetrated by a duct which extends in the longitudinal direction in the seam and which can be filled with air and vented .