The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 2000
Filed:
Jun. 21, 1999
David G Holliday, Spring, TX (US);
Dril-Quip, Inc, Houston, TX (US);
Abstract
There are disclosed three embodiments of a gate valve having a fail safe actuator which is especially useful in a subsea environment at considerably depth below water surface. The gate is urged to open position by control pressure and is moved to closed position, upon loss of a controlled condition, by means of a spring acting between the actuator and the stem. In one embodiment, when the body pressure is low, a floating ring sealably shiftable within an annular space between the stem and actuator is urged by body pressure into a position to engage a stop on the stem, and thus provide a force urging it in a direction to close the gate, when body pressure is below ambient, and by ambient pressure to a position to engage a stop on the actuator when body pressure is above ambient. In a second embodiment of the invention, the valve includes a balance stem which is spring-pressed to engage the end of the gate opposite its operating stem, when body pressure is low relative to ambient, but moves out of engagement with gate and into a limited position in engagement with the actuator, when body pressure is high relative to ambient. In the third embodiment of the invention, the valve includes both the floating ring and the spring-pressed balance stem of the first and second embodiments.