The present disclosure is directed to pressure control devices for storage containers and, more particularly, to a pressure control device with a blind tapped connection base that, when coupled to a storage container, reduces the likelihood of fugitive emissions from that storage container.
Storage containers, such as storage tanks, vessels, conduits, and the like, can be utilized to store various fluids (e.g., oil, gas, etc.). The internal vapor pressure of these storage containers may vary based on various factors, such as, for example, the amount of fluid in the storage container, the temperature of the fluid in the storage container, the volatility of the fluid in the storage tank, the temperature outside the storage container, and the rate of filling or emptying. Pressures above or below certain thresholds may, however, damage the storage container. For example, positive pressures or vacuum over-pressures may cause the storage container to collapse. Pressures above certain thresholds can also lead to excess emissions and product loss, while pressures below certain thresholds can compromise the quality of the fluid stored in the container (as this increases the likelihood that contaminants will be pulled in from the atmosphere).
Pressure control devices, e.g., thief hatches, lock down hatches, pressure vacuum relief valves, and emergency pressure relief valves, can be installed on a storage container to control pressure in the storage container, e.g., relieve undesirably high or undesirably low pressures in the storage container that can occur as a result of any of the above-noted factors. Conventionally, pressure control devices such as thief hatches and lock down hatches are directly attached to the roof of the storage container with fasteners (e.g., studs, bolts, nuts, and the like) by way of holes cut directly into the roof of the storage container and associated through holes formed in the connection flange of the pressure control device. However, attaching pressure control devices in this way tends to create a source of fugitive emissions, i.e., emissions of gases or vapors from pressurized equipment due to leaks or other unintended releases of gases or vapors, as gases or vapors can escape from the storage container to the ambient environment through the holes. This is particularly problematic in oil and gas applications, which tend to generate volatile organic compounds (VOCs) and other dangerous emissions. As a result, oil and gas applications have been the subject of increasing regulatory focus in recent years.
In accordance with a first exemplary aspect of the present invention, a pressure control device is provided for use with a storage container. The pressure control device includes a base defined by a sidewall and a flange extending outwardly from the sidewall. The flange is adapted to be connected to a surface of the storage container. The base includes a port defined by the sidewall and adapted to be in fluid communication with an interior of the storage container. The pressure control device also includes a lid movably coupled to the base to selectively expose the port of the base to an environment surrounding the pressure control device. The pressure control device further includes a plurality of blind holes formed in a bottom side of the flange of the base. The plurality of blind holes are configured to facilitate connection of the pressure control device to the storage container while preventing leakage from the storage container through the connection, thereby reducing fugitive emissions.
In accordance with a second exemplary aspect of the present invention, a pressure control device is provided for use with a storage container. The pressure control device includes a base defined by a sidewall and a flange extending outwardly from the sidewall. The flange is adapted to be connected to a surface of the storage container. The base includes a port defined by the sidewall and adapted to be in fluid communication with an interior of the storage container. The pressure control device also includes a lid movably coupled to the base to selectively expose the port of the base to an environment surrounding the pressure control device. The pressure control device further includes a plurality of holes formed in the flange of the base. The plurality of holes extend only partially between a top side and a bottom side of the flange of the base. The plurality of holes facilitate connection of the pressure control device to the storage container while preventing leakage from the storage container through the connection, thereby reducing fugitive emissions.
In accordance with a third exemplary aspect of the present invention, In accordance with a first exemplary aspect of the present invention, a pressure control device is provided for use with a storage container. The pressure control device includes a base defined by a sidewall and a flange extending outwardly from the sidewall. The flange is adapted to be connected to a surface of the storage container. The base includes a port defined by the sidewall and adapted to be in fluid communication with an interior of the storage container. The pressure control device also includes a lid movably coupled to the base to selectively expose the port of the base to an environment surrounding the pressure control device. The pressure control device further includes a plurality of blind holes formed in a bottom side of the flange of the base. The plurality of blind holes are configured to facilitate connection of the pressure control device to the storage container while preventing leakage from the storage container through the connection, thereby reducing fugitive emissions. The pressure control device further includes a plurality of fasteners sized to be arranged in the plurality of blind holes, respectively, to facilitate the connection of the pressure control device to the storage container.
In further accordance with any one or more of the foregoing first, second, and third exemplary aspects, a pressure control device may include any one or more of the following further preferred forms.
In one preferred form, the plurality of blind holes are circumferentially arranged around the central passage of the base.
In another preferred form, the flange has a first depth, and wherein each of the plurality of blind holes has a second depth equal to 25% to 75% of the first depth.
In another preferred form, the pressure control device further includes a plurality of fasteners arranged in the plurality of blind holes for connecting the pressure control device to the storage container.
In another preferred form, each of the plurality of fasteners has a diameter and each of the plurality of blind holes has a depth that is between 2 and 3 times the diameter of a respective fastener of the plurality of fasteners.
In another preferred form, the lid includes a circumferential edge and a sealing element arranged in a channel formed in the circumferential edge. The lid is movable between a closed position, in which the sealing element sealingly engages a top end of the sidewall, thereby sealing the port of the base from the environment, and an open position, in which the sealing element is spaced from the top end of the sidewall, thereby exposing the port to the environment.
In another preferred form, the pressure control device further includes a pressure relief assembly for providing pressure relief to the storage container. The pressure relief assembly includes a center assembly coupled to the lid, and a pressure sealing element coupled to the center assembly. The center assembly is movable between a non-operational position, in which the pressure sealing element engages a top end of the base, thereby preventing fluid communication between the port and the environment, and a pressure relief position, in which the pressure sealing element is spaced from the top end of the base, thereby facilitating fluid communication between the port and the environment.
In another preferred form, a pressure spring is arranged within a space defined by the lid and the center assembly. The pressure spring is configured to bias the center assembly to the non-operational position.
In another preferred form, the pressure control device further includes a vacuum relief assembly for providing vacuum relief to the storage container. The vacuum relief assembly includes a vacuum pallet, and a vacuum sealing element coupled to the vacuum pallet. The vacuum pallet is movable between a non-operational position, in which the vacuum sealing element engages a portion of the pressure control device, thereby preventing fluid communication between the port and the environment, and a vacuum relief position, in which the vacuum sealing element is spaced from the portion of the pressure control device, thereby facilitating fluid communication between the port and the environment.
In another preferred form, the plurality of fasteners are integrally formed into the plurality of blind holes, respectively.
The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the several FIGS., in which:
With reference still to
As best shown in
The lid or cover 108 in the illustrated example has a substantially annular body 128 with a circumferential edge 132. The lid or cover 108 includes a sealing element 136, which in this example takes the form of an annular gasket, disposed or arranged in a channel 140 defined in the circumferential edge 132. When the lid or cover 108 is in the closed position, which is illustrated in
Unlike conventional thief hatches, which utilize through holes to facilitate the connection to the storage container, the thief hatch 100 includes a plurality of blind holes 150 formed (e.g., tapped) in the bottom side 119 of the flange 116 of the base 104. In other words, the holes 150 extend only partially through the flange 116, with each hole 150 extending between the bottom side 119 and an interior portion 158 of the flange 116. The thief hatch 100 in this example includes sixteen (16) blind holes 150 circumferentially arranged around the port 124, though any number of blind holes 150 can be utilized and/or the blind holes 150 can be arranged in a different manner (e.g., spaced at different distances from one another). The depth 162 of each of the holes 150 can vary according to, for example, the size of the storage container 54, the thickness t of the flange 116, and/or the diameter of a fastener to be formed or inserted therein for coupling the thief hatch 100 to the storage container 54. As an example, the depth 162 of each of the holes 150 can be in a range of between two (2) and three (3) times the size of the diameter of the fastener to be formed or inserted therein. It will be also appreciated that the blind holes 150 need not have the same depths 162, i.e., one or more of the blind holes 150 can have a different depth 162 than one or more other blind holes 150. The diameter 166 of each of the holes 150 can also vary according to, for example, the size of the storage container, the thickness t of the flange 116, and/or the diameter of the fastener to be formed or inserted therein. As with the depths 162, it will be appreciated that the blind holes 150 need not have the same diameters 166, i.e., one or more of the blind holes 150 can have a different diameter 166 than one or more other blind holes 150.
A plurality of fasteners 198 can be used to couple (e.g., mount, attach) the thief hatch 100 to the storage container 54. More specifically, the plurality of fasteners 198 can be used to connect the base 104 of the thief hatch 100 to the surface 58 (e.g., the roof) of the storage container 54. The fasteners 198 can take the form of studs, bolts, nuts, and/or the like. In some cases, the plurality of fasteners 198 can be integrally disposed or formed into the plurality of blind holes 150, while in other cases, the plurality of fasteners 198 can be separately manufactured and then disposed or inserted into the plurality of blind holes 150 by a user (e.g., an end user at the facility in which the storage container 54 resides) or a machine. In any event, the plurality of fasteners 198, once inserted into the blind holes 150, will extend outwardly (downwardly in
As discussed above, the connection between conventional pressure control devices and a storage container tends to create a source of fugitive emissions, with gases or vapors escaping from the storage container to the ambient environment through the through holes. However, the thief hatch 100, by utilizing the blind holes 150 instead of through holes to connect to the storage container 54, eliminates this source of fugitive emissions, as gases or vapors no longer have a leakage path from the storage container 54 to the ambient environment via the connection, thereby reducing the potential for fugitive emissions.
To this end, the lid assembly 306 includes a lid or cover 308, a center assembly 310, a vacuum pallet assembly 314, a pressure spring 322, and a vacuum spring 326, as illustrated in
The center assembly 310 is generally movable in a vertical direction based on a set pressure achieved by the pressure spring 322. The movement of the center assembly 310 is, however, limited or guided by the lid or cover 308. When the thief hatch 300 is in its initial or non-operational position (i.e., it is not providing vacuum or pressure relief), the pressure sealing element 342 sealingly engages the open top end 317 of the sidewall 312 of the base 304, and the vacuum sealing element 346 sealingly engages a bottom portion of the center assembly 310. When, however, the pressure within the storage container 54 exceeds a maximum pressure threshold (i.e., pressure relief is needed), such that the pressure from the storage container 54 acting on the center assembly 310 exceeds the counteracting force provided by the pressure spring 322, the center assembly 310 moves vertically upward. This movement decouples the pressure sealing element 342 from the sidewall 312 of the base 304, thereby providing pressure relief to the storage container 54. When, however, the pressure from the storage container 54 falls below a minimum or vacuum pressure threshold (i.e., vacuum relief is needed), such that the vacuum from the storage container 54 exceeds the counteracting force provided by the vacuum spring 326, the vacuum pallet assembly 314 moves vertically downward. This movement decouples the vacuum sealing element 346 from the center assembly 310 (which cannot move in a downward direction due to the lid or cover 308), thereby providing vacuum relief to the storage container 54.
Notwithstanding the operational differences between the thief hatch 300 and the hatches 100, 200, the thief hatch 300 can be coupled to the storage container 54 in a similar manner as the thief hatch 100 and the lock down hatch 200. In other words, the thief hatch 300 includes a plurality of blind holes 350, similar to the blind holes 150, that can be used to couple the base 304 of the thief hatch 300 to the surface 58 of the storage container 54. As such, the thief hatch 300, like the thief hatch 100 and the lock down hatch 200, eliminates fugitive emissions that may otherwise result as a result of the connection between the thief hatch 300 and the storage container 54, thereby reducing potential for fugitive emissions.
Finally, while pressure control devices 50 in the form of the thief hatch 100, the lock down hatch 200, and the thief hatch 300 have been illustrated herein, the pressure control device 50 can, in other examples, take the form of a different type of thief hatch or lock down hatch, a PVRV, or another type of pressure control device. Additionally, while not illustrated herein, it is conceivable that the principles described herein—blind hole tapping to facilitate a leak proof connection, can be incorporated into an adapter for coupling a pressure control device to the storage container 54.
Number | Date | Country | |
---|---|---|---|
62219455 | Sep 2015 | US |