| 摘要 |
A plug and its attaching hole for use in removably securing an accessory to a pressure container. This plug includes a head portion and a reduced diameter or shank portion continuous with the undersurface of the former. Build-up portions are formed on the outer peripheral surface of the shank portion, while cut-away portions are provided in the peripheral edge of the plug-attaching hole defined in the wall of the pressure container. Upon insertion of the shank portion of the plug into the plug-attaching hole, the build-up portions formed on the outer peripheral surface of the shank portion of the plug are mated with the cut-away portions, and then the plug is turned through a given angle so that the build-up portions may engage the inner peripheral edge surface of the plug-attaching hole provided in the wall of the pressure container. This prevents the plug from being blown away from the pressure container, even if a weld formed around the head portion of the plug on an outer surface of the wall of the container is failed or broken due to deterioration. |
