Patent ID: 7955675

Claim:
A weld joint adapted for being mounted integrally to a resin fuel tank by heat-welding, the weld joint, comprising: a tubular portion for connection to a tube or a connector in piping; and a weld portion at a base end portion of the weld joint for being welded and bonded to a rim portion around an opening of the resin fuel tank, the weld portion having a main body and an extremity portion facing the resin fuel tank, the main body of the weld portion being made of a resin alloy material that is obtained by alloying a barrier resin of fuel-impermeability with a modified high-density polyethylene (HDPE) having affinity for the barrier resin, or by alloying the barrier resin with the modified HDPE and HDPE; wherein the weld portion includes a highly-weldable layer in the extremity portion of the weld portion facing the resin fuel tank, the highly-weldable layer is made of HDPE and/or a modified HDPE having good weldability to the resin fuel tank, and an extremity end surface of the highly-weldable layer serves as a weld surface for welding the weld portion to the resin fuel tank, wherein the extremity portion of the weld portion is formed entirely from the highly-weldable layer throughout an entire circumference of the extremity portion, wherein a radial outer peripheral surface of the highly-weldable layer defines a tapered surface that gradually reduces in diameter in a direction away from the extremity end surface of the extremity portion facing the resin fuel tank toward the tubular portion of the weld joint, the resin alloy material is integrally bonded to the highly-weldable layer over the entire tapered surface and a surface of the highly-weldable layer closer to the tubular portion of the weld joint.