| 摘要 |
This invention relates to the ball plug valves comprising a ball plug of a cylindrical geometry with a hemispherical end rotatably engaging a matching cylindrical cavity with a closed hemispherical end formed within the valve body in a close tolerance wherein a hole bored through said ball plug in an oblique angle with respect to the central axis of said ball plug lines up with the fluid passage hole included in said valve body when said ball plug is rotated to the "open" position, while said hole through said ball plug takes a position substantially perpendicular to said fluid passage hole included in said valve body when said ball plug is rotated to the "closed" position, at which position said ball plug blocking the fluid passage hole shuts off the fluid flow. Various sealing means of annular geometry are disposed intermediate two mating hemispherical surfaces respectively belonging to said ball plug and said matching cavity in the valve body as the illustrative embodiments teaching how to improve the shut-off characteristics of the ball plug valves wherein the annular seals of variable seating pressure controlled by an internal or external means are included. The annular seals of variable seating pressure are also used in the construction of the ball valves applicable to the high pressure or high temperature process. The ball plug valves employing the combination of the "plug in the ball plug" for the throttling purpose under extreme pressure are also disclosed.
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