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External pressure gasketExternal pressure gasket description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20090102132, External pressure gasket. Brief Patent Description - Full Patent Description - Patent Application Claims
In order to find and produce new oil and gas reserves, exploration continues to lead to greater depths within the ocean. As a result, Christmas tree and wellhead equipment must operate at greater depths and therefore must be capable of withstanding greater external hydrostatic head pressures. For oil wells, the increased external hydrostatic head pressure is not particularly problematic, as the internal pressure of the well typically balances the external hydrostatic head pressure. In gas wells, on the other hand, the external hydrostatic head pressure is much more likely to create problems. This is particularly true when a valve closes in the subsea Christmas tree and pressure is bled from the flow line. When this occurs, equipment downstream of a closed valve can have atmospheric or near-atmospheric pressure on the inside, and full subsea head pressure on the outside. With maximum water depths currently around 10,000 feet, the pressure differential between the inside and the outside can be substantial at around 4470 psi. Most components of the subsea wellhead equipment and Christmas trees are sized based on designs originally intended for surface use. The surface designed components are sized for higher internal pressures and can thus withstand the external subsea pressure. However, gaskets are typically designed for internal pressure only, and therefore may not be suitable for substantial external pressure. One example of this type of gasket is a bonnet gasket found on a valve. To overcome external pressure on the bonnet gasket, some manufacturers have added o-rings or made the gasket with a second, external seal to keep the external pressure off the primary bonnet gasket seal surface. This approach has the disadvantage in that, during factory acceptance testing with internal pressure, a slight leak may occur at the gasket\'s primary seal, which may be masked by the external seal. Another disadvantage is that there is no way to test the external seal with external pressure during the factory acceptance test. Thus, when the equipment is installed, if external pressure were to leak past the external seal, the primary seal may also leak because it is not stiff enough to withstand the external pressure. Another approach to overcoming the pressure differential involves a specialized gasket with a cross-section that is substantially thicker for subsea applications than for surface applications. The use of this type of gasket may result in a bonnet and body with a special gasket seat profile and therefore not desirable. The present invention relates generally to gaskets. More specifically, the present invention relates to gaskets designed to withstand pressure differentials in subsea environments, such as those where the greater pressure may be acting either on the inside or on the outside of the gasket. In one embodiment of the present invention a gasket has an upper surface, a substantially cylindrical inner surface abutting the upper surface, a lower surface abutting the inner surface, and generally opposite the upper surface, and an outer surface abutting the upper surface and the lower surface, and generally opposite the inner surface. The outer surface has a sealing surface between the upper surface and the lower surface, a first depression between the sealing surface and the upper surface, and a second depression between the sealing surface and the lower surface. Continue reading about External pressure gasket... Full patent description for External pressure gasket Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this External pressure gasket patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like External pressure gasket or other areas of interest. ### Previous Patent Application: Heat-assisted hermetic spring seal Next Patent Application: Downhole tubular sealing system Industry Class: Seal for a joint or juncture ### FreshPatents.com Support Thank you for viewing the External pressure gasket patent info. IP-related news and info Results in 3.27318 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , paws |
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