| 摘要 |
<p>A subsurface safety valve for wells has a ball valve supported for rotation between open and closed positions in response to control fluid pressure supplied from the top of the well and a spring which overcomes the hydrostatic pressure of the control fluid. The ball is split and has a pressure equalizing flow passage through a ball cap initially opened before the ball is rotated, the ball valve base including a screen to preclude entry of large particles. An adjustable connection in the valve support and housing structure enables adjustment to compensate for tolerances and effect snug engagement of the ball cap with its seat. Control fluid pressure enters the pressure responsive region through a balanced sleeve. An internal spring guide has a seat adjustable relative to the valve housing to provide a smooth continuous bore when the valve is open. The valve closing spring is disposed about the spring guide and engages an adjustable seat, the spring being exposed at its outer diameter to enable use of springs of large selected sizes and strengths for different depths of valve installation.</p> |
