| 摘要 |
<p>1457838 Well &c DEL NORTE TECHNOLOGY INC 3 Dec 1974 [11 April 1974] 52284/74 Heading E1F A safety valve comprises a housing 60-64 having an internal cavity with a ball valve 26 mounted therein for axial and rotational movement, actuators 41, 42 for urging the ball valve respectively into a closed position with the bore 32 of the bell valve transverse to the housing bore and an open position with the bore 32 aligned with the housing bore, an annular substantially non-compressible gasket seal 86 for engaging the ball valve in the closed position and a metallic surface seal 85 surrounding both the inside and outside periphery of the gasket seal 86. Under normal working conditions the ball valve is held in the open position by adjusting the hydraulic pressure in chamber 55 so that the force applied to the ball valve by the actuator 42 is greater than the force applied to the ball valve by the spring-biassed actuator 41 and the well pressure. If, however, the well pressure increases to a dangerous level, the ball valve is forced into the closed position since the increased well pressure overcomes the difference in the forces applied by the actuator 41, 42.</p> |
