| 摘要 |
A closure assembly for a shipping and storage drum where the drum includes an internally threaded plastic outlet for receipt of the closure assembly includes a plastic closure having a generally cylindrical main body portion which is externally threaded and which constitutes the leading edge of threaded engagement into the outlet. Disposed at the upper end of the main body portion and integral therewith is an annular, peripheral flange the underside of which is shaped with an annular groove which is designed to receive an elastomeric gasket. The annular groove has an outwardly inclined outer wall and a generally cylindrical inner wall. The gasket is held in position as part of the closure by an interference fit between the inside surface of the gasket and the inner cylindrical wall of the groove. The plastic outlet of the shipping and storage drum includes a generally cylindrical raised rib and outward thereto and concentric therewith a generally cylindrical raised wall. Upon full threaded engagement of the closure into the outlet, the raised rib presses into the central area of the elastomeric gasket and the upper surface of the closure is seated within the raised wall and is below the top surface of the wall. The external threads of the closure arranged with two threaded portions, one portion being a straight thread and the lower or leading edge portion being a tapered thread. The thread pitch is the same and the threads are continuous with each other.
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