Cargo tank assemblies with ground level access

A cargo tank assembly can include a cargo tank, and a plurality of access ports for the cargo tank, including a manway. A cabinet can be arranged to provide ground-level access to the plurality of access ports. In some embodiments, the cabinet can provide a sole breakable seal for a set of equipment, or for the cargo tank.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to storage containers. In particular, the present disclosure relates to mobile cargo tanks, including cargo tanks for transportation trailers.

BACKGROUND

Mobile cargo tanks can be used in different contexts to transport liquids, solids, sludges, slurries, mixed and pure liquids, and other materials. For example, storage tank vehicles such as chemical trucks can include a cargo tank trailer, configured to be hauled by a semi-trailer truck. Other arrangements can include cargo tanks configured for use with train carriages, with tanker trucks, or otherwise. In some configurations, cargo tanks can be designed to hold pressurized contents. In some configurations, contents can be non-pressurized.

In conventional mobile cargo tank designs, a manway and other equipment, such as inlet ports or couplings, can be disposed on, and extend through, a top or roof of the relevant tank. This can be useful, for example, in order to allow access into an interior storage area of the tank or to vent vapor or otherwise relieve excess pressure from the storage area. In some cases, a ladder can be provided for access to the tank roof, and the manway and other equipment can be surrounded by a balcony. Accordingly, during inspection and other operations (e.g., cleaning of the tank), an operator may be required to climb a ladder and clear a balcony (or other features) in order to access the manway and other tank inlets.

In different installations, conventional cargo tanks can also include a number of seals between the interior storage area of the tanks and the external environment. For example, seals can be provided on manway covers, at tank inlets (or outlets), at hose fittings (or other fittings), and so on. This can be useful, for example, to help to ensure appropriate material containment and handling of materials carried by the cargo tank. However, because operational procedures may require regular inspection of all relevant seals, the inclusion of multiple seals can require an operator to devote substantial time to seal inspection over the course of loading, transport, unloading, and other operations.

SUMMARY

In order to improve accessibility for manways, inlet couplings, and other equipment for cargo tanks, as well as other benefits, it may be useful to locate the manways, couplings, and other equipment relatively low on a body of a cargo tank. In this way, for example, a user may not need to climb a ladder, reach or climb over a balcony, or undertake other similar endeavors to conduct necessary inspections, cleaning, and maintenance.

As an additional benefit, because the need for user access to a tank roof may be reduced (e.g., eliminated), it may be possible to improve the aerodynamic profile of a cargo tank at or near various ports, fittings, or other equipment. For example, in some configurations, a jacket (e.g., as part of a housing) can be disposed around a liquid (or other) tank, with an appropriately aerodynamic profile. Because a user may not need to regularly access various ports, valves, fittings, hoses, and other equipment at the top of the tank, the jacket can be configured to fully enclose the ports, valves, fittings, hoses, and so on at the top of the tank. Accordingly, the various ports, valves, fittings, hoses, and so on can be shielded from drag forces, enabling a more streamlined and efficient profile for the tank to be maintained.

In some cases, it may be further useful to arrange a cabinet to surround a manway, one or more couplings, and other equipment for a cargo tank. This can, for example, allow an operator to access all of the contained manway, couplings, and other equipment via a single access point (e.g., as accessible from ground level). Further, where the cabinet is formed with an appropriate seal, it may be possible not only for the cabinet to appropriately contain materials, but also may provide a greatly reduced number of seals (e.g., a single seal) that requires inspection. As such, an operator may be able to satisfy requirements for seal inspections in significantly reduced time.

Embodiments of the invention can improve on conventional cargo tank designs by incorporating one or more of the features generally noted above, or other features.

According to some aspects of the invention, a cargo tank assembly can include a cargo tank configured for transport of pressurized materials, a plurality of access ports for the cargo tank, a vapor recovery system, and a cabinet. The plurality of access ports can include a manway and one or more of an inlet port to fill the cargo tank, an outlet port to empty the cargo tank, a cleaning port, and an inspection port. The vapor recovery system can include a vapor-recovery fitting configured to attach to an external conduit to discharge vapor from the cargo tank. The cabinet can be arranged to enclose the plurality of access ports and the vapor-recovery fitting, the cabinet thereby providing ground-level access to the plurality of access ports and the vapor-recovery fitting.

According to some aspects of the invention, a cargo tank assembly can include a cargo tank configured for transport of pressurized materials, a plurality of access ports for the cargo tank, and a cabinet with a breakable seal. The plurality of access ports can include a manway and one or more of an inlet port to fill the cargo tank, an outlet port to empty the cargo tank, a cleaning port, and an inspection port, and none of the plurality of access ports may include a breakable seal. The cabinet can be arranged to enclose the plurality of access ports to provide ground-level access to the plurality of access ports, and can include a breakable seal for access to the interior of the cargo tank via the plurality of access ports.

According to some aspects of the invention, a method of manufacture for a cargo tank can include forming a cargo tank with an internal area, forming a plurality of access ports for the cargo tank, and disposing a cabinet to enclose the plurality of access ports so that the cabinet provides ground-level access to the plurality of access ports. The access ports can include a manway and one or more of an inlet port to fill the cargo tank, an outlet port to empty the cargo tank, a cleaning port, and an inspection port.

According to some aspects of the invention, a cargo tank trailer can include a tank supported above ground underlying the cargo tank trailer. The tank can include a vessel formed to define an internal storage area arranged to store products therein and a manway coupled to the vessel to allow access into the internal storage area of the vessel by a user standing on the ground.

In some embodiments, the cargo tank trailer can further include a frame configured to be supported on the ground underlying the cargo tank trailer. The tank can be coupled to the frame for movement therewith.

In some embodiments, the tank can further includes piping systems including a vapor recovery system. The vapor recovery system can include a first end that is in fluid communication with the internal storage area of the vessel and a second end that is accessible by the user standing on the ground.

In some embodiments, the tank can further include a housing arranged around the vessel. A vapor recovery system can be located between the vessel and the housing to block access to the vapor recovery system.

In some embodiments, the vessel can include a top end, and a bottom end spaced apart from the top end to locate the bottom end of the vessel between the top end of the vessel and the ground. A venting system can include a pressure-relief vent coupled to the top of the vessel and located between the vessel and the housing, with the pressure-relief vent in fluid communication with the internal storage area of the tank.

In some embodiments, the venting system can further include a vent hose located between the vessel and the housing. The vent hose can have a first end in fluid communication with the pressure-relief vent and a second end that opens to atmosphere toward the bottom end of the vessel.

In some embodiments, the vessel can include a shell, a front tank head, and a rear tank head that cooperate to define the internal storage area. The shell can extend between a front and rear end of the vessel. The front tank head can coupled to the shell at the front end of the vessel and the rear tank head is coupled to the shell at the rear end of the vessel. The manway can be coupled to the rear tank head, or to the shell.

In some embodiments, the housing can include a cabinet coupled to an outer jacket of the housing, with the cabinet is arranged around the manway. The cabinet can be movable between a closed arrangement in which access to the manway is blocked, and an opened arrangement in which access to the manway is allowed.

In some embodiments, the cabinet can include a frame coupled to the tank, a door coupled to the frame, and a seal coupled to the door. The seal can be configured to seal the cabinet when the cabinet is in the closed arrangement.

In some embodiments, the cabinet can be coupled to the housing toward the rear tank head.

In some embodiments, the housing can further include an outer jacket arranged around the vessel. The outer jacket can be arranged around the piping systems to locate the piping systems between the outer jacket and the vessel to block access to the piping systems.

In some embodiments, the vessel can extend along a longitudinal axis of the cargo tank trailer and a cross-section of the outer jacket taken generally perpendicular to the longitudinal axis can be non-circular.

In some embodiments, the housing can further include a plurality of ribs located between the vessel and the outer jacket. The ribs can include a first arcuate portion having a first radius of curvature and a second arcuate portion having a second radius of curvature greater than the first radius of curvature.

In some embodiments, the first arcuate portion can extend circumferentially around the longitudinal axis by a first distance, the second arcuate portion can extend circumferentially around the longitudinal axis by a second distance, with the first distance being greater than the second distance.

In some embodiments, the rear tank head can be formed to include a first aperture sized to receive a telescoping cleaning system. The rear tank head can be formed to include a second aperture sized to receive an inspection device.

According to some aspects of the invention, a method of manufacturing a cargo tank trailer can include a number of operations. The method can include coupling a first tank head to a first end of a tank shell, and coupling a second tank head to a second end of a tank shell to form a vessel having an internal storage area. The formed vessel can include a top end, a bottom end spaced apart from the top end, and a longitudinal axis that extends between the first and second tank heads and is located about midway between the top end and the bottom end. The method can further include coupling a manway to one of the first tank head, the second tank head, and the tank shell to cause a portion of the manway to be located between the longitudinal axis and the bottom end of the vessel.

In some embodiments, the method can further includes coupling a vapor recovery system with the vessel. The vapor recovery system can include a first end opening into the internal storage area and a second end located between the longitudinal axis and the bottom end of the vessel.

In some embodiments, the method can further include coupling a venting system with the vessel. The venting system can include a vent opening into the internal storage area and a hose. The hose can have a first end in fluid communication with the vent, and a second end located between the longitudinal axis and the bottom end of the vessel.

In some embodiments, the method can further include coupling a plurality of ribs to the shell and arranging an outer jacket around the ribs. The outer jacket can block access to the first end of the vapor recovery system and to the vent included in the venting system.

In some embodiments, the method can further include coupling a cabinet to one of the vessel and the outer jacket, with the cabinet arranged around the manway.

These and other features of the present disclosure will become more apparent from the following figures and description of example embodiments.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to example embodiments shown in the attached drawings and specific language will be used to describe the same. However, before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. For example, while some concepts of this disclosure are described below in relation to a cargo tank trailer, it will be understood that these and other concepts may also be applied in the context of other mobile storage containers or various stationary storage containers.

Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. For example, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items, as appropriate.

Unless otherwise specified or limited, the phrases “at least one of A, B, and C,” “one or more of A, B, and C,” and the like, are meant to indicate A, or B, or C, or any combination of A, B, and/or C, including combinations with single or multiple instances of A, B, and/or C. Likewise, unless otherwise specified or limited, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, unless otherwise specified or limited, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

As used herein, unless otherwise specified or limited, “ground-level” and similar terms are meant to describe a device, feature, or system that can be generally accessed by operators without the need for the operators to scale ladders or other similar devices.

As used herein in the context of seals, unless otherwise specified or limited, “permanent” is meant to describe a seal that is not configured to be broken during normal operation and maintenance. For example, a weld can provide a permanent seal, as can a line or other formation of caulk or other sealant between two components that are not generally configured to move relative to each other so as to break caulk or sealant. In contrast, unless otherwise specified or limited, “breakable” is meant to describe a seal that is configured to be broken during normal operation and maintenance. For example, a gasket or other seal that surrounds an access door or other equipment can provide a breakable seal, where the access door or other equipment is configured to be opened and closed (thereby temporarily “breaking” the seal) during normal operation and maintenance. Generally, for the purposes of this disclosure, mere contact between two structural members (e.g., a manway and a hatch for the manway) is not considered a “seal,” unless a separate sealing material (e.g., rubber or silicone) is disposed between the members.

As noted above, it may be useful to provide a cargo tank that includes ground level access to components such as a manway for interior access, inlet or outlet ports and fittings, valves, ducts, controls, and other equipment. Further, it may be useful to provide a cargo tank with an enclosed top profile despite the presence of equipment at the exterior of the top of a containment vessel of the cargo tank. It may also be useful to provide a unified access point for a variety of equipment, including manways, inlet or outlet ports, and so on, with limited numbers of seals relating to the access point and the relevant equipment. Embodiments of the invention, including those expressly discussed below, can provide one or more of these (or other) benefits.

FIGS. 1 through 6illustrate aspects of an example cargo tank in accordance with one embodiment of the invention, configured as part of a cargo tank trailer10. As illustrated, the cargo tank trailer10is configured as a DOT 407 stainless steel chemical trailer, although other configurations (including non-trailer configurations) are possible.

Generally, the cargo tank trailer10includes a frame12supported on ground underlying the cargo tank trailer10, and a cargo tank14supported on the frame12. The frame12of the illustrated cargo tank trailer10is configured to be propelled by a semi-trailer truck (not shown), and accordingly includes a carriage70configured to couple to a fifth wheel of the semi-trailer truck and a plurality of wheels72coupled with the carriage70. In other embodiments, the frame12can instead be configured to be propelled by a locomotive or other motive equipment.

As illustrated inFIGS. 1 and 6, in particular, the top of the cargo tank trailer10does not include external equipment, such as manways, vents or other access ports, related fittings, and so on. As such, as also discussed below, routine work and maintenance may be performed at ground level and it may not be necessary for an operator to regularly access a top of the cargo tank trailer10. Correspondingly, the cargo tank trailer10does not include a ladder, top walkway, top balcony, or other similar features.

As illustrated inFIG. 2in particular, the cargo tank14is formed to include a vessel16that defines an internal storage area24configured to store and transport materials (e.g., pressurized fluids). Generally, a vessel for a cargo tank can be insulated or non-insulated, pressurized or non-pressurized, and configured for single or multiple loads. Likewise, a vessel for a cargo tank can include structures formed from aluminum, carbon steel, stainless steel, fiberglass reinforced plastic, or any of a variety of other materials. In the embodiment illustrated, the vessel16is configured as a non-insulated, pressurized tank (e.g., as rated for pressurization to 25 psi), with a shell26, a front tank head28, and a rear tank head30(see, e.g.,FIGS. 2 and 6). The shell26generally extends along a longitudinal axis36of the cargo tank14between a front end32and a rear end34of the cargo tank14. The front tank head28is coupled to the shell26at the front end32and the rear tank head30is coupled to the shell26at the rear end34. As such, the shell26, the front tank head28, and the rear tank head30generally cooperate to define the internal storage area24.

The cargo tank14further includes a top end76, and a bottom end78spaced apart from the top end76to locate the bottom end78between the top end76and ground. In the embodiment illustrated, the longitudinal axis36is positioned about midway between the top end76and the bottom end78of the vessel16.

The cargo tank14also includes a piping system20, as also discussed below, as well as a plurality of ports, which can be coupled to the vessel16to allow access into the internal storage area24by a user standing at ground level (e.g., on the ground). For example, as illustrated inFIGS. 1, 2, and 5in particular, the cargo tank14includes a manway18, hose apertures68, inlet and outlet ports90aand90bfor filling and emptying the vessel16, respectively, a cleaning port64, and an inspection port66(seeFIG. 5), all of which can provide access to the internal storage area24in various ways and for various operations.

As also noted above, in some embodiments, it may be useful to dispose a manway on a cargo tank in order to allow ground-level access to the interior of the cargo tank, via the manway. To this end, for example, it may be useful to couple the manway18to the vessel16so that a portion of the manway18is located below the longitudinal axis36. Indeed, in the embodiment illustrated, the entire manway18is located below the longitudinal axis36(seeFIG. 1).

Generally, one or more manways configured for ground-level access can be coupled to a tank at one or more locations. In the embodiment illustrated, the manway18is coupled to the rear tank head30. This may be useful, for example, in order to dispose the manway18near other ports and equipment. In other embodiments, however, the manway18can be disposed at other locations, including at locations on the shell26or on the front tank head28.

As also noted above, the vessel16is configured to include various ports and equipment other than the manway18. For example, as illustrated inFIG. 5, the rear tank head30also includes the cleaning port64, which is generally sized to receive a relevant cleaning system. This arrangement may be useful, for example, in order for the vessel16to be used to store and transport materials that may prohibit the installation of a permanent cleaning system within the vessel16. For example, a cleaning system can be carried with the cargo tank14, but not permanently installed in the cleaning port64, and can be selectively received by the cleaning port64only when cleaning operations are to be undertaken.

In some embodiments, the cleaning port64can be configured to receive a telescoping cleaning system, such as a cleaning system92with a telescoping wand94and a cleaning head96, as illustrated inFIG. 7. In some embodiments, the cleaning port64can be configured to facilitate tank cleaning with a pipe that can be anchored at a front bulkhead of the vessel16(not shown).

As also illustrated inFIG. 5, the rear tank head30further includes an inspection port66for an inspection device (not shown). For example, an optical or other inspection device (not shown) can be inserted through the aperture66, as appropriate, in order to inspect various internal features of the vessel16. In some embodiments, an inspection device (e.g., like a cleaning system) can be configured to be received in the aperture66only temporarily, and can be stored elsewhere when not in use.

In the embodiment illustrated, the cleaning and inspection apertures64and66are generally between two and three inches in diameter. Likewise, the apertures64and66are disposed, generally symmetrically, on opposite sides of the manway18. In other embodiments, other configurations are possible, including configurations with differently sized or located apertures, configurations with different numbers of apertures, and so on.

In the embodiment illustrated, the cargo tank trailer10further includes hose apertures68configured to store and transport hoses for use with the cargo tank14. As with the manway18and the cleaning and inspection apertures64and66, the hose apertures68are disposed generally adjacent to the rear tank head30. Accordingly, the cargo tank14can afford an operator ground level access, from a single location (i.e., at the rear of the cargo tank14), to a variety of equipment including the manway18, the apertures64,66, and68, and so on. Further, because an operator may not need to climb to the top of the cargo tank14for routine inspection and maintenance (e.g., access operations via the manway18), external ladders for accessing the top of the cargo tank14, and other similar equipment, can be omitted from the cargo tank14. This can allow for more aerodynamic configuration of the cargo tank14, generally, as also discussed below.

In some embodiments, a cargo tank can include a housing configured to enclose part or all of a containment vessel of the cargo tank, as well as various equipment secured to the vessel. For example, in the embodiment illustrated, the cargo tank14includes a housing22. As illustrated inFIGS. 1 and 2in particular, the housing22is generally arranged around the vessel16to limit access to the vessel16, the piping system20(as also discussed below), and other equipment, and to provide, as appropriate, an aerodynamic profile for the cargo tank14as a whole.

In the embodiment illustrated, the housing22includes an outer jacket54, a plurality of internal ribs56, and a cabinet58. The outer jacket54is disposed to generally surround the shell26, the front tank head28, and the rear tank head30of the vessel16. The ribs56are disposed between the vessel16and the outer jacket54, and are generally configured to support the outer jacket54relative to the vessel16.

In some embodiments, although a vessel may be generally cylindrical, an outer jacket for the vessel may be somewhat non-cylindrical. This may be useful, for example, in order to allow the outer jacket to cover various fittings or other equipment, while still providing a relatively streamlined cross-section during transport. In the embodiment illustrated, for example, although the vessel16is generally cylindrical, a cross-section of the outer jacket54taken generally perpendicular to the longitudinal axis36is non-circular. As illustrated inFIG. 1in particular, the cross-section of the outer jacket54includes a first portion54ahaving a first radius of curvature and a second portion54bhaving a second radius of curvature that is greater than the first radius of curvature. Generally similar third and fourth portions54cand54dof the outer jacket54interconnect the first and second portions54aand54b, in order to provide a fully closed profile for the outer jacket54. This configuration can be useful, for example, in order for the second portion54bof the outer jacket54to provide internal space to accommodate the piping system20(and other equipment) in addition to the vessel16itself.

To support the second portion54bof the outer jacket54, the ribs56generally include a first arcuate portion60having a first radius of curvature and a second arcuate portion62having a second radius of curvature greater than the first radius of curvature, as illustrated inFIG. 2in particular. The first arcuate portion60extends circumferentially around the longitudinal axis36by a first distance, generally extending over the sides and/or bottom of the vessel16, but not necessarily over the top of the vessel16. The second arcuate portion62extends circumferentially around the longitudinal axis36by a second distance that is somewhat smaller than the first distance, generally extending over a top portion of the vessel16, but not substantially over the sides or bottom of the vessel16. Accordingly, the ribs56can generally conform to, and support, the non-cylindrical profile of the outer jacket54. In some embodiments, including as illustrated inFIG. 2, certain of the ribs56may include only an instance of the first arcuate portion60(e.g., as with the rib56a), or only an instance of the second arcuate portion62(e.g., as with the rib56b), rather than both. For the rib56a, that the first arcuate portion60extends over the top portion of the vessel16. As noted above, this may not generally be true for other instances of the first arcuate portion60.

In the embodiment illustrated, the multiple instances of the first arcuate portion60generally exhibit the same curvature, and generally extend to similar degrees around the vessel16. Likewise, the multiple instances of the second arcuate portion62generally exhibit the same curvature, and generally extend to similar degrees around the vessel16. As noted above, however, there are exceptions to this general rule, including with regard to the rib56a. Further, in other embodiments, other arrangements are possible. For example, different ribs to support an outer jacket can be configured to exhibit any variety of different configurations, including as may result in a profile of the relevant outer jacket that substantially varies along the longitudinal length of the relevant cargo tank.

The ribs56can be formed in various ways. In some embodiments, the ribs56can be formed from foam, can be formed from a rigid (e.g., metallic) material, or can include a combination of foam structures and rigid (e.g., metallic) structures. Accordingly, for example, a set of ribs (e.g., the ribs56) can generally be designed to provide an appropriate balance between structural stability and overall weight, while also potentially serving as thermal insulators for the relevant cargo tank (e.g., to insulate against heat flow between the outer jacket54and the vessel16).

Usefully, the outer jacket54(and the housing22, generally) can be used to enclose a variety of different equipment for the cargo tank14. For example, in the embodiment illustrated, the outer jacket54substantially surrounds the piping system20. In the embodiment illustrated, the piping system20is generally configured for use to vent the internal storage area24of the vessel16, and to recover vapors from the internal storage area24. Accordingly, as illustrated inFIGS. 3 and 4in particular, the piping system20includes a vapor recovery system38and a venting system40as shown inFIGS. 3 and 4. In other embodiments, other configurations are possible.

Generally, it may be useful to arrange the outer jacket54to enclose as substantial a portion of the piping system20as is possible, in order to generally protect components of the piping system20, as well as to shield the components from drag and thereby provide a generally more streamlined profile for the relevant cargo tank. In the cargo tank trailer10, for example, the outer jacket54of the housing22generally encloses almost all of the piping system20, except at select locations (e.g., at the cabinet58).

Generally, a piping system or other equipment to be enclosed by a housing of a cargo tank can be disposed at any number of locations on the cargo tank. As illustrated inFIG. 3in particular, a number of parts of the piping system20, including ports into the vessel16for the vapor recovery system38and for the venting system40, are located within a front-most compartment54ethat is defined by the outer jacket54, by the internal ribs56of the housing22, and a floor portion84(e.g., a foam floor plate). However, other components of the piping system20extend to other parts of the cargo tank trailer10, as also discussed below.

As illustrated inFIGS. 3 through 5in particular, the vapor recovery system38generally extends from a port and a corresponding tank vapor-recovery fitting42within the compartment54e, along piping38a, to an external-attachment vapor-recovery fitting44(seeFIG. 5) at the rear tank head30of the vessel16. Generally, the tank fitting42can be configured to allow vapor to flow out of (or into) the top of the internal storage area24of vessel16at the compartment54e. Similarly, the external-attachment fitting44can be configured to be coupled to an external system (e.g., an offloading tank and/or pump system) in order to allow vapor to flow out of (or into) the vapor recovery system38generally. Accordingly, as appropriate, vapor can be drawn from (or discharged into) the vessel16via the tank fitting42and can be discharged from (or drawn into) the vapor recovery system38at the external-attachment fitting44.

Notably, because the external-attachment fitting44is disposed for ground-level access, an operator can execute vapor recovery operations without necessarily having to climb to the top of the cargo tank14in order to directly access the fitting44(e.g., to attach an external conduit and thereby close a flow loop for a larger vapor recovery arrangement). Correspondingly, routine access to the tank fitting42within the compartment54e, as well as routine access to the piping38a(outside of the cabinet58), is generally blocked by the continuous configuration of the outer jacket54. This arrangement, for example, can discourage un-necessary climbing of the cargo tank14by operators, while also providing an improved aerodynamic profile for the cargo tank14, despite the equipment (e.g., the tank fitting42) extending from the top of the vessel16.

In the embodiment illustrated, the external-attachment fitting44is disposed for ground level access within a compartment that is fully enclosed by the cabinet58. Accordingly, in order to access the external-attachment fitting44(e.g., to attach an external conduit to close a vapor-recovery loop), an operator can simply open the cabinet58. Similarly to the discussion above, therefore, the illustrated arrangement (and others) can provide an operator the benefits of single-location, ground level access to the external-attachment fitting44, as well as other frequently used equipment (e.g., the manway18, the apertures64,66, and68, and so on).

In some embodiments, still other systems and equipment can be enclosed and accessed in a similar fashion as the vapor recovery system38. As illustrated inFIGS. 3 and 4, for example, the venting system40includes a pressure-relief vent46(or other valve) that is coupled to the top end of the vessel16to be in fluid communication with the internal storage area24. The pressure-relief vent46is generally configured to allow gases from inside the vessel16to escape to atmosphere when the vessel16is being filled, and to allow gases from the atmosphere to enter the internal storage area24of the vessel16when the product stored in the vessel16is being discharged.

Similarly to the tank fitting42of the vapor recovery system38, the pressure-relief vent46is fully enclosed by the outer jacket54. Accordingly, the pressure-relief vent and other equipment of the venting system40can be shielded from drag forces during travel. In the embodiment illustrated, the pressure-relief vent46is disposed within the compartment54e, along with the tank fitting42. In some embodiments, the tank fitting42, the pressure-relief vent46, or other fittings (or equipment) can instead be disposed within different compartments of the housing22.

In the embodiment illustrated, the pressure-relief vent46vents directly to (and from) the compartment54e, which is at least partially sealed relative to other compartments of the housing22. In order to route gases to and from the compartment54e, the cargo tank14further includes a vent hose48(or other conduit) that is disposed between the vessel16and the housing22. Generally, the vent hose48has a first end50in fluid communication with the compartment54e(and, thereby, the pressure-relief vent46). Correspondingly, a second end52of the vent hose48opens to atmosphere toward the bottom end of the vessel16.

As with the external-attachment fitting44of the vapor recovery system38, routine access to the pressure-relief vent46and the first end50of the vent hose48is generally blocked by the outer jacket54. Further, as also discussed above, the second end52of the vent hose48is generally disposed for ground-level access. Accordingly, an operator can execute various operations relating to pressure relief without necessarily having to climb to the top of the cargo tank14to directly access the pressure-relief vent46or the compartment54e. In the embodiment illustrated, the second end52of the vent hose is disposed outside of the cabinet58. In other embodiments, other configurations are possible.

In view of the discussion above, it will be recognized that the top of the cargo tank14, in contrast to conventional designs, does not include certain ports or other equipment that are configured to be accessed for regular operations and maintenance. This may be generally useful, for example, in order to reduce (e.g., eliminate) the need for an operator to climb to the top of the cargo tank14in order to perform routine operations (e.g., routine inspection and maintenance). Further, ports and other equipment that are disposed to the exterior (e.g., at the top) of the cargo tank14are substantially enclosed by the outer jacket54, as may protect the equipment and improve the aerodynamic characteristics of the cargo tank14as a whole. In other embodiments, similar arrangements can be made for any number of ports, fittings, or other equipment.

As also discussed above, it may sometimes be useful to provide single-location, ground-level access for routinely used systems. In some embodiments, it may also be useful for the single-location, ground-level access to be selectively enclosed (e.g., closable by a user). To this end, for example, as illustrated inFIG. 5in particular, the cabinet58is disposed adjacent to the rear tank head30, and generally encloses the manway18, the apertures64,66, and68, the inlet and outlet ports90aand90b, and the external-attachment fitting44of the vapor recovery system38, as well as various other equipment (e.g., onboard pumps for the cargo tank trailer10).

Generally, the cabinet58includes a frame80coupled to the cargo tank14, a closeable door82coupled to the frame80, and a seal74(e.g., a rubber or silicone gasket) coupled to the door82and configured to seal the cabinet58when the cabinet58is in the closed arrangement. (In other embodiments, the seal74can instead, or additionally, be coupled to the frame80.) Accordingly, the cabinet58is movable between a closed arrangement in which the cabinet58is sealed and access to the manway18and other internal equipment is blocked, and an opened arrangement in which the cabinet58is unsealed and access to the manway18and other internal equipment is allowed. Accordingly, an operator can readily access equipment for inspecting, cleaning, filling, and emptying the vessel16via the single access opening provided by the closeable door82of the cabinet58.

As appropriate, the cabinet58can be coupled to the outer jacket54or to the vessel16. In the embodiment illustrated, for example, the cabinet58is configured to seat closely against the rear tank head30, with a silicone or other permanent seal between the cabinet58and the rear tank head30. Further, the cabinet58is configured to be permanently attached to the out jacket54of the housing22(e.g., via tack or stich welds). In other embodiments, other configurations are possible.

In some embodiments, providing single-location, ground-level access for systems of a cargo tank (e.g., via the cabinet58) can also provide a single breakable seal for the cargo tank, which can generally replace one or more breakable seals that might typically be provided on individual equipment to which the ground-level access is provided. This can, for example, significantly reduce the number of seals that require routine inspection by operators, thereby significantly reducing the amount of inspection time required for the relevant tank.

As noted above, for example, the cabinet door82, when closed, is configured to form a breakable seal with the remainder of the cabinet58via the seal74. Correspondingly, in some embodiments, access ports into the vessel16that are disposed within the cabinet58can be configured not to include seals. For example, the manway18can be configured with a door that directly contacts the vessel16, rather than having a silicone, rubber, or other seal disposed between the door and the vessel16. Accordingly, the seal74for the cabinet58can provide a single breakable seal for the entire tank trailer10, and an operator may need to routinely inspect only the seal74, rather than the seal74and separate seals for each of the manway18, the inlet and outlet ports90aand90b, the apertures64,66, and68, and so on.

Consistent with the discussion above, it may be useful to manufacture, as well as use, cargo tanks according to the invention. For example, according to one method of manufacturing for the cargo tank trailer10, the front tank head28is coupled to the front end32of the shell26and the rear tank head30is coupled to the rear end34of the shell26, in order to form the vessel16and the internal storage area24.

Before, during, or after formation of the vessel16, components of the manway18are coupled to at least one of the front tank head28, the rear tank head30, and the shell26so that at least part of the manway18is located between the longitudinal axis36and the bottom end78of the vessel16. In this way, for example, ground-level access to the vessel16can be provided via the manway.

In some implementations, the cabinet58is also coupled to the vessel16, to surround the manway18, as well as other equipment, and thereby providing single-location, ground-level access to the manway18and the other equipment. In some implementations, the cabinet is configured with a breakable seal (e.g., the seal74), while equipment within the cabinet for accessing the internal storage area24of the vessel are not equipped with breakable seals.

Thus, embodiments of the invention may provide improved cargo tanks relative to conventional designs. For example, by providing single-location, ground-level access for a variety of equipment, embodiments of the invention may decrease the need for operators to climb to the top of a cargo tank, while also generally improving the efficiency of any number of routine (or other) operations. Further, by disposing certain equipment within a housing of a cargo tank, including in combination with providing the noted ground-level access, the general aerodynamic profile of a cargo tank may be improved.

In other embodiments, other benefits are also possible. For example, when a manway or other port is disposed on a lower half of a cargo tank, opening the manway or other port can tend to naturally vent heavier-than-air materials (e.g., pure nitrogen) out of the cargo tank. Accordingly, operators may not be required to rely on more time consuming purging operations to ensure that a cargo tank has been appropriately evaporated (e.g., before undertaking internal maintenance or cleaning).

While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only example embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.