Patent ID: 6866297

Claim:
A welded structure, comprising: a fuel filling container having a section defining an opening; and a welded part including a pipe-shaped section which has a first end portion disposed in the opening of the fuel filling container, and an annular welding section fixedly disposed around the outer periphery of the pipe-shaped section, the welding section being welded through an annular welding surface to an outer surface of the fuel filling container at a section surrounding the opening of the fuel filling container, wherein the welding section of the welded part includes an annular welding strength providing layer and an annular fuel permeation resistance layer which are coaxial with the pipe-shaped section of the welded part and radially laminated to define the annular welding surface, wherein at least an inner peripheral surface portion of the pipe-shaped section and an outer peripheral surface portion of a second end portion of the pipe-shaped section are formed of a fuel permeation resisting material, such that a joined part may be connected to the second end portion of the pipe-shaped section, wherein the welding strength providing layer of the welding section of the welded part is formed of polyethylene, and the fuel permeation resistance layer of the welding section and the fuel permeation resisting material of the pipe-shaped section of the welded part are formed of a blend resin made of a polyethylene containing 20 to 80% by volume of at least one selected from the group consisting of polyamide, ethylene-vinyl alcohol copolymer, polyacetal and polyester.