| 摘要 |
<p>A subsea barrier valve 20 with a valve clapper 60 adapted for free swinging movement on a clapper shaft 62 between a position which closes the flow passage through the valve and a position proximate the fully open position such that the clapper is held open by a pressurized flow of gas through the valve. In the event of an upstream pipeline failure, the clapper closes in a "fail-safe" manner. The clapper can be pivoted and locked in the full open position by axial rotation of a locking shaft 105 which extends through a cover member 30 for an access opening in the valve body 21. The locking shaft 105 extends perpendicular to the clapper shaft 62 and is interconnected therewith by a gear drive 106 including a clutch gear 126 which allows a limited range of free pivotal movement of the clapper 60. The locking shaft 105 is controlled by actuator means 140,141 mounted on the cover member 30 by a separable fastener 142. The cover member 30 is clamped by a releasable clamp means 35. Projecting mandrels 260 on a clamping ring component 85 of the releasable clamp means 35 can be seized by a grappling tool for release or installation of the clamp means. A similar mandrel 149 on the cover member 30 allows for retrieval of the valve 20 or its intervals when the cover member 30 is released. Mandrels 208 provided on a support plate 144 for the actuator means 140,141 permit the retrieval or replacement of the actuator means.</p> |
