Security device and method to prevent unauthorized discharge of contents from a tank

Security devices are provided to prevent or block unauthorized access through portholes formed in a protective housing assembly when the protective housing assembly is in its first, closed position and to allow access through the portholes when the protective housing assembly is in its second, open position. The protective housing assembly may be mounted on an upper portion of a railway tank car to protect valves, fittings and other components associated with loading and unloading of lading from the tank car. The portholes are typically formed in the protective housing assembly to allow access to an adjacent valve or other component. Each porthole cover may be engaged with a normal access cover of the protective housing assembly to block or restrict access through the respective porthole.

TECHNICAL FIELD

The present invention is related to railway tank cars and more particularly to security devices to prevent unauthorized access to valves, fittings and other components associated with such tank cars.

BACKGROUND OF THE INVENTION

Tank cars have been used for many years to transport a wide variety of commodities including liquids, gasses and other fluids. The contents of a tank car may sometimes be potentially hazardous if appropriate safety precautions are not taken. Also, the contents of a tank car may be valuable and subject to theft or misappropriation.

Most tank cars are designed with an access opening or manway located in the upper portion of the associated tank, proximate a midpoint between opposite ends of the tank car. A manway cover is typically bolted or otherwise secured to the opening to allow only limited access by personnel to the interior of the tank. Various pipes, valves, fittings and other components are also often located in the vicinity of the manway to control adding and discharging lading from the tank car. The valves, fittings and other components are typically selected based on characteristics and properties of the commodity or lading being transported.

Valves, fittings and other components are often mounted on the manway cover of modern pressurized tank cars. Pressure car fittings typically include two “liquid or fluid” valves for loading and unloading of an associated commodity. Respective check valves and induction piping are also provided with respective loading and unloading valves. One or more vapor valves, gauging devices and safety relief valves may also be mounted on the manway cover. Some tank cars may have smaller valves for drawing samples of lading and thermal wells for measuring the temperature of the lading. Non-pressurized tank cars may also have similar valves and fittings mounted on a manway cover similar to a pressurized tank car.

Various types of protective housing assemblies or dome structures are often disposed on the upper portion of a tank car adjacent to the manway to protect associated piping, valves, fittings and other components. All pressurized tank cars are required to have such protective housing assemblies or dome structures covering any pipes, valves, fittings and other components located on an upper portion of the pressurized tank car. A relatively thick, steel ring or cylindrical portion is often provided to protect the valves, fittings, and other components in the event the tank car is derailed and overturns.

Protective housing assemblies and/or dome covers on a typical railway tank car will often include one or more openings which provide access through a sidewall or cylindrical portion of the protective housing to facilitate loading and/or unloading of products carried by the tank car. Multiple ports or openings (sometimes referred to as “portholes”) formed in a protective housing assembly allow access to operate respective valves and fittings disposed within the protective housing assembly. Most portholes have a hinged, flap type cover that may be easily opened and closed as required to provide access through the porthole to an adjacent valve or fitting. Other portholes or openings may remain open without any cover. Unauthorized access may often be obtained to valves and/or fittings used to load or unload tank cars by simply moving these unsecured covers and reaching into the protective housing assembly to manipulate the associated valves and fittings.

SUMMARY OF THE INVENTION

In accordance with teachings of the present invention, security devices and methods are provided to prevent unauthorized access to, and unauthorized operation of valves, fittings or other components associated with discharging fluids from a railway tank car. The security devices may include respective porthole covers that restrict or block access to such components when an associated protective housing assembly has been properly closed and secured. The security devices and associated porthole covers are designed to prevent and/or minimize any damage to the porthole covers, protective housing assembly, fittings and/or valves during an attempt to gain unauthorized access to the valves and fittings.

In accordance with a particular embodiment of the present invention a protective housing assembly includes a cylindrical sidewall configured to be coupled with a tank to generally surround at least one valve of the tank. An access cover is configured to be removably disposed over the cylindrical sidewall. A diameter of the access cover is slightly larger than a diameter of the cylindrical sidewall, such that an outer portion of the access cover overhangs the cylindrical sidewall, when the access cover is in a first, closed position. A hinge assembly is coupled to the cylindrical sidewall and the access cover, and is configured to allow the access cover to be moved to a second, open position wherein an interior portion of the cylindrical sidewall is exposed to a user. The cylindrical sidewall may have at least one porthole disposed therein. The protective housing assembly also includes a porthole cover having a first position in which the porthole cover covers the porthole, and a second position in which the porthole is exposed. In accordance with a particular embodiment, the access cover prevents the porthole cover from being moved from the first position to the second position, when the access cover is in the closed position.

The protective housing assembly may also include a pivot pin that is disposed through the porthole cover and coupled to the cylindrical wall. The pivot pin allows rotation of the porthole cover from the first position to the second position. In accordance with one embodiment, the porthole cover is disposed upon an exterior surface of the cylindrical wall. In this embodiment, the upper portion of the access cover may cooperate with an upper edge of the porthole cover to prevent the porthole cover from being rotated from the first position to the second position, when the access cover is in the closed position.

In accordance with another embodiment, the access cover may form at least one slot in the outer portion of the access cover. In this embodiment, an upper portion of the porthole cover may be disposed in the slot, to prevent rotation of the porthole cover from the first position to the second position, when the access cover is in the closed position.

Technical benefits of the present invention include preventing unauthorized access to valves, fittings or components such as loading and unloading valves associated with a tank car. Security devices formed in accordance with teachings of the present invention prevent or block access through portholes or openings which are often formed in protective housing assemblies associated with tank cars. The security devices prevent operation of unloading valves or other components which would allow unauthorized removal of fluids from a tank car or unauthorized release of potentially hazardous fluids to the surrounding environment. Anhydrous ammonia is one example of a commodity that may be stolen from tank cars. Security devices incorporating teachings of the present invention prevent unauthorized access to valves and fittings used to control loading and unloading of lading from a tank car and at the same time allow normal loading and unloading procedures when proper access is obtained by opening the protective housing assembly.

Further technical benefits of the present invention include providing security devices which are relatively light weight and may be manufactured with relatively low cost. Such security devices may be activated or deactivated by normal opening or closing of an associated protective housing assembly or dome structure. The security devices may be formed as integral components of a protective housing assembly or dome structure. Alternatively, security devices formed in accordance with teachings of the present invention may be added on to an existing housing assembly or dome structure. Security devices incorporating teachings of the present invention do not interfere with normal emergency response procedures in the event of damage to an associated tank car or other emergency conditions.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention and its advantages are best understood by reference toFIGS. 1-7B, wherein like numbers refer to same and like parts.

Various aspects of the present invention will be described with respect to a railway tank car satisfactory for carrying pressurized fluids. Such railway cars may sometimes be referred to as “pressure tank cars”. A protective housing assembly or dome assembly formed in accordance with teachings of the present invention may also be satisfactorily used on non-pressure tank cars to prevent unauthorized access to valves, fittings or other components which control loading or unloading of commodities carried by such tank cars. A protective housing assembly with one or more security devices formed in accordance with teachings of the present invention may also be used on other types of railway cars and other types of tanks such as tanks on highway trucks, tanks carried on barges and storage tanks located at either temporary or permanent facilities. The present invention is not limited to use with railway tank cars.

The terms “engage”, “engaged” and “engagement” are used in this application to describe various types of attachments, couplings, connections or mountings between one or more security devices and a protective housing assembly formed in accordance with teachings of the present invention. For example the term “engagement” may be used to describe a slideable connection between a security device and portions of a protective housing assembly. Engagement may be used to describe a rotatable or pivotable attachment between a security device and portions of a protective housing assembly. For some embodiments, the terms “engage”, “engaged” and “engagement” may be used to describe forming a security device as an integral component of a protective housing assembly. For other embodiments, the terms “engage”, “engaged” and “engagement” may be used to describe adding one or more security devices to an existing protective housing assembly.

FIG. 1illustrates portions of a railway tank car20with a conventional protective housing assembly30mounted thereon. Tank car20preferably includes manway or access opening22located in an upper portion thereof, proximate a midpoint between opposite ends21aand21bof tank car20. Protective housing assembly30includes a generally hollow, cylindrical portion32and lid or normal access cover34. Hinge assembly36allows lid34to rotate between a first, closed position, as shown inFIG. 1, and a second, open position (not expressly shown). Cylindrical portion32may sometimes be referred to as a sidewall.

A protective housing assembly formed in accordance with teachings of the present invention may have various configurations and dimensions. The present invention is not limited to use with protective housing assemblies which have a generally hollow cylindrical portion or cylindrical sidewalls. A protective housing assembly having sidewalls with a wide variety of geometric configurations such as square, rectangular, triangular, etc. may be formed with security devices in accordance with teachings of the present invention.

The dimensions of cylindrical portion32may be selected to accommodate the outside diameter of manway22and manway cover24, to allow cylindrical portion32to generally surround the valves in manway cover24. Various valves and fittings designated25,26,27,28and29may be mounted on manway cover24to control loading and unloading of commodities from tank car20. Protective housing assembly30prevents damage to valves and fittings25through29in the event tank car20is derailed and turns over. One of these valves will typically be a safety valve that discharges fluid from tank car20when the pressure of fluid contained therein exceeds a predetermined, maximum value.

A vent opening or discharge opening may also be formed in normal access cover34to allow any fluids discharged from the safety valve to exit from protective housing assembly30. The vent opening may also have a respective cover which opens and closes in response to any fluids discharged from the associated safety valve.

A plurality of portholes or openings38may be formed in cylindrical portion32of protective housing assembly30. Respective porthole covers40may be mounted on the exterior of cylindrical portion32adjacent to each porthole30. For the example shown inFIG. 1, portholes38and porthole covers40have generally circular configurations. Pivot pin42may be used to rotatably or pivotally mount each porthole cover40adjacent to respective porthole opening38. Porthole covers40may be rotated from a first closed position as shown inFIG. 1to a second, open position (not expressly shown) which allows access to and/or operation of adjacent valves25through29.

FIGS. 2 and 3Aillustrate protective housing assembly70formed in accordance with teachings of the present invention. Protective housing assembly70may include cylindrical portion72, normal access cover74and hinge assembly76. For the embodiment of the present invention as represented by protective housing assembly70, portholes78have a generally circular configuration. The dimensions associated with cylindrical portion72, normal access cover74and portholes78may correspond approximately with similar dimensions and configuration of cylindrical portion32, normal access cover34and portholes38, of FIG.1.

Protective housing assembly70is shown inFIG. 2in its first, closed position with normal access cover74blocking access to an associated manway, manway cover and any valves or fittings disposed on the manway cover.FIG. 3Ashows protective housing assembly70in its second, open position which allows access to the associated manway cover and any valves or fittings disposed thereon.

For the embodiment of the present invention as shown inFIGS. 2 and 3A, protective housing assembly70preferably includes at least four portholes78and at least four porthole covers80, respectively disposed on portholes78.FIG. 2illustrates porthole covers80in their first, closed position blocking access through the respective porthole80. InFIG. 3A, one of the porthole covers80is shown in its second, open position (dotted lines), which allows access through the respective porthole78.

Respective pivot pins82may be used to rotatably or pivotally mount each porthole cover80adjacent to respective porthole opening78. The length of porthole covers80is selected such that when each porthole cover80is in its first position, the respective porthole cover80will extend from immediately adjacent to normal access cover74and cover the associated porthole78. The width of porthole covers80is preferably selected to be larger than the diameter of the associated porthole78.

For the embodiment of the present invention as shown inFIGS. 2 and 3A, first end81of porthole cover80has an increased width that cooperates with normal access cover74to prevent rotation of each respective porthole cover80from its first position to its second position, when normal access cover74is in its first, closed position. The second end84of each porthole cover80may have a generally curved or accurate surface. The length of porthole covers80may be selected to be slightly less than the height of cylindrical portion or sidewall72.

The dimensions and configuration of porthole covers80are selected to prevent the opening of porthole covers80when normal access cover74is in the closed position. As illustrated inFIG. 2, normal access cover74overhangs cylindrical portion72and an upper edge79of porthole cover80, at first end81. Since porthole cover80is rotatably mounted to cylindrical portion72using pivot pins82, the cooperation of the upper edge of porthole cover80at first end81with the overhanging portion of normal access cover74prevents porthole cover80from rotating in either direction (clockwise or counterclockwise) with respect to pivot pin82. Thus, when normal access cover is locked or latched in the closed position, unauthorized access to the interior of protective housing assembly70is prevented.

In the illustrated embodiment, porthole cover80is formed from a metal plate that may generally conform to the circumference of cylindrical portion72. As long as the edge of normal access cover74overhangs at least a portion of the edge of the plate at first end81, porthole cover80will be prevented from rotating when normal access cover74is in its closed position.

Various configurations are available for porthole cover80, within the teachings of the present invention. In the illustrated embodiment, porthole cover80is generally a rectangular configuration proximate first end81. This configuration enhances the cooperation between porthole cover80and normal access cover74to prevent rotation of porthole covers80to expose portholes78, when normal access cover74is in the closed position. The second end84is arcuate and generally conforms to the curvature of porthole78, in order to fully cover porthole78when porthole80is in the closed position. Other sizes, configurations and features of porthole covers, portholes, and normal access covers that help prevent unauthorized access to the interior of the protective housing assembly are described herein.

Lid or normal access cover74may also include vent opening86and vent opening cover or flap88. A plurality of restrictions90and91are formed within vent opening86to prevent unauthorized access through normal access cover74when protective housing assembly70is in its first, closed position. For the embodiment of the present invention as shown inFIG. 3A, restrictions90and91may be bars formed as integral components of normal access cover74. For other applications which will be discussed later in more detail, other types of restrictions, such as heavy metal screens may be engaged with an interior surface of a normal access cover74adjacent to an associated vent opening, to allow any fluids discharged from a safety valve to escape therethrough and at the same time to prevent access through the vent opening to one or more valves disposed within the associated protective housing assembly.

FIG. 3Billustrates an additional feature that may be incorporated into protective housing assembly70, ofFIGS. 2 and 3. An anti-bending lug96is incorporated into protective housing assembly70, to further prevent unauthorized access to the interior of protective housing assembly70. Anti-bending lugs96prevent an unauthorized user from prying porthole cover80away from cylindrical portion72to potentially fracture pin82and/or allow rotation of porthole cover80about pin82when normal access cover74is in the closed position.

Anti-bending lugs96, in the illustrated embodiment, comprise metal angles that are affixed to protective housing assembly70, independent of porthole cover80. Therefore, porthole cover80may slide through a gap between an upper leg97of anti-bending lug96, and cylindrical portion72of protective housing assembly70. Anti-bending lugs96may be welded or otherwise affixed to a lower edge of cylindrical portion72, or welded or otherwise affixed to another portion of protective housing assembly70(other than porthole cover80). In an alternative embodiment, anti-bending lug96may be formed integrally with cylindrical portion72or another component of protective housing assembly70.

FIG. 4illustrates an alternative embodiment of the present invention, as represented by protective housing assembly70a. Protective housing assembly70amay include cylindrical portion72a, lid or normal access cover74aand hinge assembly76ahaving approximately the same overall dimensions and configurations as the corresponding components previously described with respect to protective housing assembly70. InFIG. 4, normal access cover74ais shown in its first, closed position (solid lines). Cylindrical portion72aof protective housing assembly70amay also include portholes78a(shown in dotted lines) having approximately the same dimensions and configurations as previously described with respect to protective housing assembly70.

Respective porthole covers180are pivotally or rotatably mounted on the exterior of cylindrical portion72, adjacent to each porthole78aby pivot pins42a. Each porthole cover80preferably includes first portion191and second portion192. First portion191may be generally described as having an elongated, rectangular configuration. Second portion192has a generally circular configuration. Pivot pins42are disposed through porthole covers180proximate the juncture between first portion191and second portion102. The dimensions and configuration of second portion192are preferably selected to be greater than the associated porthole78asuch that when porthole covers180are in their first position, second portion192will block or restrict access through the respective porthole78.

First portion191is generally rectangular in configuration. The shorter leg of the rectangle is relatively narrow, and approximately equal to one third of the diameter of second portion192. The width (e.g., diameter) of second portion192is selected such that it is slightly larger than porthole78a, and completely covers porthole78awhen porthole cover180is in the closed position. The configuration of porthole cover180reduces the overall size of porthole cover180, for example by including the relatively thin, rectangular first portion191. Accordingly, porthole cover is smaller, lighter, easier to handle and install, and easier to operate. However, it still effectively prevents unauthorized access to the interior portion of the protective housing assembly70a.

Normal access cover74amay have approximately the same configuration and dimensions as previously described with respect to protective housing assembly70. However, normal access cover74amay also be provided with a plurality of slots171which are formed in lid74a. The location of each slot171may be selected to correspond with the location of porthole78ain cylindrical portion72b. The width of each slot171is selected to be slightly greater than the width of first portion191of the associated porthole cover180. When lid or normal access cover74ais in its first, closed position, a portion of porthole cover180will extend through respective slot171. Engagement between first portion191and slot171prevents movement of porthole cover180from its first, closed position to its second, open position, when normal access cover or lid74ais in its first, closed position.

This configuration allows for a rectangular first portion191having a relatively thin profile, and still protect unauthorized access to the interior of protective housing assembly70a. In accordance with a particular embodiment of the present invention this configuration prevents an unauthorized user from bending the top edge of the porthole cover away from cylindrical portion72beyond the overhang of normal access cover74ofFIGS. 10 and 11, which may provide unauthorized access to protective housing assembly70, if the associated components were not sturdy enough.

FIG. 5illustrates another alternative embodiment of the present invention as represented by protective housing assembly70b. Protective housing assembly70bmay include cylindrical portion72b, normal access cover74band hinge assembly76b, having approximately the same overall dimensions and general configurations as similar components previously described with respect to protective housing assembly70. InFIG. 5, normal access cover74bis shown in its first, closed position (solid lines) and its second, partially open position (dotted lines). Cylindrical portion72bof protective housing assembly70bmay also include portholes78b(shown in dotted lines) having approximately the same dimensions and configuration as previously described with respect to protective housing assembly70.

For the embodiment of the present invention as shown inFIG. 5, respective porthole covers80bmay be formed as integral components of normal access cover74b. For some applications, first ends81bof each porthole cover80bmay be welded or otherwise bonded with the edge of normal access cover74b. For other applications, porthole covers80bmay be formed from the same sheet of material which is used to form normal access cover74b. The length of each porthole cover80bfrom first end81bto second end82bmay be approximately equal to, but less than the height of cylindrical portion72b. The width of porthole covers80bmay vary from first end81bto second end82b. For example, in the illustrated embodiment, porthole cover80bis wider proximate normal access cover74band tapers to a thinner portion at a lower end82b.

When lid or normal access cover74bis in its first, closed position, a portion of each porthole cover80bwill extend over and block access through respective portholes78. When lid or normal access cover74ais in its second, open position (dotted line position inFIG. 9) porthole covers80bwill be in their second position, which allows access through respective portholes78b.

For some applications, protective housing assemblies70aand70bmay have four portholes78formed therein and four porthole covers180and80b. However, a protective housing assembly may be formed in accordance with teachings of the present invention having any number of portholes and porthole covers.

For some applications, a generally cylindrical skirt (not expressly shown) may be attached to and extend from a normal access cover similar to the relationship between porthole covers80band normal access cover74b. Appropriate slots or openings (not expressly shown) may be provided in the cylindrical portion or skirt as required to accommodate hinge assembly76and locking mechanism94. Examples of locking mechanisms satisfactory for use with the present invention are shown inFIGS. 2-6.

Vent opening cover88is illustrated in more detail in FIG.3C. Vent opening cover88provides partial access to vent opening86, without allowing unauthorized access. Vent opening86may be disposed above a safety valve vent similar to vent28of FIG.1. The safety valve vent is used as a safety precaution to allow the release of any tank contents that are vented through a safety valve associated with the tank car.

Traditional safety vent covers allowed for unauthorized access to the interior of protective housing assembly70. Vent opening cover88is configured such that it may only be opened partially, but still allows for safe venting of gas and liquids from the interior of protective housing assembly70.

Vent opening cover88may have a similar configuration to previous vent covers and those described in this specification. However, vent opening cover includes an extension leg100that is disposed at an acute angle α to an adjacent portion of normal access cover74. Thus, when vent opening cover88is lifted, extension leg100cooperates with normal access cover74to prevent vent opening cover88from being opened beyond an amount where the angle between main plate102of vent opening cover88and the surface of normal access cover74exceeds the angle α.

Thus, vent opening cover88prevents access to the interior of the fittings protective housing through the protective housing vent, while the protective housing cover is closed and pinned. Permanent application of this semi-open closure prevents access to the interior of protective housing assembly70(when normal access cover74is locked, latched, or otherwise pinned), while still allowing mandatory venting of the protective housing assembly.

An anti-access device103suitable use in a particular embodiment of the present invention is illustrated inFIGS. 3C and 3D. Anti-access device103can be of solid construction (e.g., cast or sheet metal), or multi-piece such as a ring with wire cross members, or wire cross members attached directly to the bottom side of the vent opening cover88.

As is most evident inFIG. 3D, anti-access device103comprises a ring104having wire cross members106extending thereacross. Another set of wire cross member108extend across ring104and are oriented generally perpendicular with wire cross members106.

It should be recognized by those of ordinary skill in the art that anti-access device103is an optional component. Anti-access device103may be particularly suited for applications in which restrictions90and91are not formed in normal access cover74. In this embodiment, vent opening86will form a circular opening, as illustrated by opening86aof FIG.3D. As further evident fromFIGS. 3C and 3D, anti-access device103is an optional component that may be attached to an interior surface of normal access cover74, to prevent unauthorized access to valves.

An alternative configuration for a porthole cover110, pivot pin112, and associated components of porthole cover110, is illustrated inFIGS. 6A and 6B.FIG. 6Aillustrates a mounting flange114that is used to secure protective housing assembly108to a tank car or other type of tank fitting. A cylindrical portion116of protective housing assembly108may be configured similarly to other cylindrical portions, or sidewalls described herein. Such a cylindrical portion includes a porthole at the location designated by the reference number118. A normal access cover120is also provided, that is similar in configuration to other normal access covers described within this specification.

Porthole cover110protects protective housing assembly108from unauthorized access by a user, since the porthole cover110is mounted inside the protective housing assembly, out of reach of the user when normal access cover120is in a closed position. The purpose of porthole cover110is to prevent access to the interior of the fittings' protective housing through the porthole, while the protective housing lid is closed and/or pinned. The design is similar to others described within this specification, except that the porthole cover110is installed on the inside of the housing. Also, protective housing assembly108ofFIG. 6A, includes two retainer lugs122. Retainer lugs122are situated on either side of an anti-pivot tail124that is integral to porthole cover110. As illustrated inFIGS. 6A and 6B, as normal access cover120is closed, retainer lugs122trap anti-pivot tail124in a space between retainer lugs122, preventing the porthole cover from opening. Thus, normal access cover120must be in an open position (at least partially) in order for porthole cover110to be free to rotate away from porthole118, and provide access to any valves within protective housing assembly108.

Protective housing assembly108also includes an anti-bending lug126that prevents porthole cover110from being bent inwardly, with respect to cylindrical portion116. Anti-bending lug126may be sized, configured, and formed from materials similar to anti-bending lug96ofFIG. 3B. Awasher128is provided upon pivot pin112, in order to maintain porthole cover110pivotally mounted upon pivot pin112.

Another alternative configuration for a porthole cover140, and associated components of porthole cover140, are illustrated inFIGS. 7A and 7B.FIG. 7Aillustrates a mounting flange142that is used to secure protective housing assembly144to a tank car or other type of tank fitting. A cylindrical portion146of protective housing assembly144may be configured similarly to other cylindrical portions, or sidewalls described herein. Such a cylindrical portion includes a porthole148(dotted lines in FIG.7B). A normal access cover150is also provided, that is similar in configuration to other normal access covers described within this specification.

Porthole cover140protects protective housing assembly144from unauthorized access by a user, since the porthole cover140is mounted inside the protective housing assembly, out of reach of the user when normal access cover150is in a closed position. The purpose of porthole cover140is to prevent access to the interior of the fittings protective housing through the porthole, while the protective housing lid is closed and/or pinned.

A pair of retainer guides154are coupled with cylindrical portion146, and configured to allow porthole cover140to slide vertically, with respect to cylindrical wall146. The configuration of porthole cover140is such that a lifting stop156protrudes upward toward normal access cover150, to within a distance d of a lower edge of normal access cover150. A lifting tab158protrudes inward from porthole cover140. Lifting tab158provides a surface for a user to engage porthole cover140, and slide porthole cover140upward with respect to cylindrical wall146.

In operation, when normal access cover150is in its closed position, porthole cover140will only be free to slide vertically a distance d, before lifting stop156engages a lower edge of normal access cover150. Thus, as long as normal access cover150is in its closed position, porthole cover140cannot be lifted by an amount sufficient to expose porthole148. Accordingly, an unauthorized user cannot gain access to the interior of protective housing assembly144, through porthole148, while normal access cover150is pinned and/or locked in a closed position.

Various materials may be used to form the various components of the protective housing assemblies described herein. For example, various metals, plastics, composites and/or metal alloys may be used. The particular material selected may be based upon the type of material carried in the associated tank. Furthermore, the specific type of material may be recommended or required by various governing bodies that control the transportation of materials carried in the tank, for example the American Association of Railroads (AAR).