Highly gas-tight metal nozzle boss for high-pressure composite containers

Metal nozzle boss for high-pressure composite vessel, the metal nozzle boss combined with a plastic liner (2) of the high-pressure composite container, comprising: a cylindrical nozzle head part (6), having both a vertical through hole (7) and an internal thread (8) , at an upper portion of an inner circumferential surface of the vertical through-hole (7) is formed, has a disk-like nozzle collar portion (9) projecting to an outer edge of a lower end of the nozzle head part (6) to the outside, and an upper inclined surface (18 ) and a lower inclined surface (19) which are provided on an upper surface or a lower surface of the nozzle collar portion (9), the metal nozzle boss (1) comprises: a seal ring mounting part (13) in a lower surface of a multi-stepped support socket (16) projecting from an outer peripheral surface of the metal nozzle boss (1) projects at a position below the lower inclined surface (19) upwardly and outwardly is pressed; a sealing device (12) extending from the seal ring mounting portion extends (13) downward and both an outer fastening thread ...