PURPOSE: To prevent the release of a filler neck due to an overheat by forming only the lower end edge of a 1st burring part by spreading it in a polygonal conical shape and spreading the corner part thereof to the outside from the inner peripheral diameter of a 2nd burring part.
CONSTITUTION: Plural corner parts 15 are formed as the lower end edge of the 1st butting part 2 of a filler neck 19. So even when the soldering part of the filler neck 19 and a tank 20 is fused due to an overheat, the risk of releasing of the filler neck 19 can be prevented. Moreover, since the formation of the outer peripheral edge in a polygonal conical shape only on the lower end edge of the 1st burring part 2 is sufficient, the pipe spreading work thereof is easy and yet the deformation of the valve seat face of the filler neck is prevented and the fixing of a pressure valve can be secured. Yet, the gas ventilation at the brazing time is surely performed by the desistance of a gas ventilation part 5 and the reliability in brazing can be improved.
ADACHI ISAO
HAGIWARA ATSUSHI
