| 摘要 |
<p>A ball valve (10) having a body (12) with an open valve chamber (16) therein, passage (14) into the valve chamber (16), an opening (19) through the top of the body (12), a boss (20) having an internal recess (28) opposite and aligned with said opening (19), a closure (46) releasably secured to said body (12) and closing valve chamber (16), a ball (22) positioned within said chamber (16) and having a passage (23) therethrough, an upper shaft (24) extending through said opening (19) and a lower shaft (26) positioned in said boss recess (28), rotation of said upper shaft (24) rotating said ball (22) to control flow through said valve (10), and a sealing assembly (54) positioned to seal against said ball (22) and having resilient seals (60, 164) and metal seal signs (56, 160) for sealing against pressure independent of the direction of flow or pressure even after the valve has been exposed to sufficient heat to destroy the resilient seals of the sealing assembly.</p> |
