Thermal Protection for Tank Car

Abstract

According to particular embodiments, a railway tank car comprises a tank for transporting a commodity and an opening between an interior of the tank and an external environment. The opening comprises a first mating surface for mating with a cover. A cover covers the opening and comprises a second mating surface for mating with the first mating surface. A first gasket is positioned between the first mating surface and the second mating surface providing a seal between the interior of the tank and the external environment under normal operating conditions. A second gasket is positioned between the first mating surface and the second mating surface and comprises an intumescent material. The second gasket is positioned between the first gasket and the external environment. When the tank is exposed to a fire condition, the second gasket expands to provide a seal between the interior of the tank and the external environment.

Description

RELATED APPLICATION

[0001] This application claims priority to United States Provisional Application Serial No. 63 / 740,481, entitled “THERMAL PROTECTION FOR TANK CAR,” filed December 31, 2024.TECHNICAL FIELD OF THE INVENTION

[0002] This disclosure generally relates to a railroad tank car, and more particularly to improved thermal protection for a tank car. BACKGROUND

[0003] Railroad tank cars transport liquid commodities, such as oil, ethanol, liquid natural gas, etc. Department of Transportation (DOT), Association of American Railroads (AAR), and Transport Canada (TC) specifications require thermal protection for tank cars that transport particular commodities, such as flammable commodities.

[0004] For example, a DOT 117 compliant tank car blankets the tank shell with an insulating and thermal protection layer, such as a ceramic fiber blanket, which is covered and protected by an outer steel jacket. Existing tank cars may be retrofitted to meet the DOT 117 standard. For example, insulating material and a jacket may be applied to the tank of an existing tank car, such as a DOT 111 or CPC-1232 tank car, to bring the existing tank car in compliance with DOT 117 requirements.

[0005] Regulations also require that most railroad tank cars operating in North America be equipped with pressure relief devices. Pressure relief devices protect the tank from events such as product surges, over fills, and commodity reactions, but the primary purpose is preventing catastrophic tank failure by regulating pressure within the tank during a fire condition. The contents of the tank exist in a two-phase state—the liquid phase tank lading (commodity for transport) and the vapor phase above the lading. In a fire situation, heat input to the tank drastically increases the vapor pressure until it exceeds the pressure relief device safety setting and vapor is expelled.

[0006] In addition to pressure relief valves, tank cars may be equipped with various fittings for loading, unloading, monitoring, etc. Conventional top fittings include: fill holes; eduction pipes; safety vents; valves; gauges; and the like. Bottom fittings may include a bottom outlet valve, as one example. SUMMARY OF THE INVENTION

[0007] The embodiments described herein include an improved thermal protection system for a tank car. Particular embodiments place an intumescent material in series between one or more existing gaskets on a railroad tank car and the external environment. When exposed to a fire, the intumescent material expands and fills the gap between the two surfaces normally sealed with the gasket. Thus, even if the gasket melts or otherwise loses some or all of its sealing ability, the intumescent material creates a secondary seal that prevents or minimizes commodity loss.

[0008] According to particular embodiments, a railway tank car comprises a tank for transporting a commodity and an opening between an interior of the tank and an external environment. The opening comprises a first mating surface for mating with a cover. A cover covers the opening and comprises a second mating surface for mating with the first mating surface. A first gasket is positioned between the first mating surface and the second mating surface providing a seal between the interior of the tank and the external environment under normal operating conditions. A second gasket is positioned between the first mating surface and the second mating surface and comprises an intumescent material. The second gasket is positioned between the first gasket and the external environment. When the tank is exposed to a fire condition, the second gasket expands to provide a seal between the interior of the tank and the external environment.

[0009] One advantage of particular embodiments is prevention of tank car commodity loss when a tank car is exposed to fire. Thus, particular embodiments include an enhanced commodity containment system for railroad tank cars exposed to fire.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete and thorough understanding of the particular embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

[0011] FIG. 1 is a schematic drawing illustrating a side view of a railway tank car;

[0012] FIG. 2 is a schematic cross-section of an example tank car top fitting arrangement;

[0013] FIG. 3 is a schematic cross-section of an example tank car top fitting with gaskets;

[0014] FIG. 4 is a schematic cross-section of an example tank car top fitting with intumescent gaskets, according to particular embodiments;

[0015] FIG. 5 is a schematic cross-section of an example tank car top fitting with expanded intumescent gaskets, according to some embodiments;

[0016] FIG. 6 is a schematic cross-section of an example tank car top fitting with intumescent gaskets and an intumescent gasket groove, according to some embodiments;

[0017] FIG. 7 is a schematic cross-section of an example tank car top fitting with intumescent gaskets and double intumescent gasket grooves, according to some embodiments; and

[0018] FIG. 8 is a schematic cross-section of an example tank car manway with an intumescent gasket, according to some embodiments.DETAILED DESCRIPTION

[0019] Railroad tank cars that carry flammable liquids and compressed gases are required to be equipped with thermal protection systems that prevent the loss of commodity, except through the pressure relief valve, when exposed to a fire situation. Current thermal protection systems typically consist of a pressure relief valve and a thermal insulation system that is covered by a metal jacket. The insulation system is designed to withstand the high temperatures associated with fire exposure and maintain the insulation capability for a specified time duration, such as at least 100 minutes in a pool fire.

[0020] The current systems have proven to be effective at protecting the integrity of the tank. There have been, however, instances where sealing systems of the fittings and manway covers and the fittings themselves have deteriorated in the fire and allowed considerable commodity to escape from the tank. This results in potential environmental contamination and, depending on the commodity, may also further fuel the fire.

[0021] Particular embodiments disclosed herein enhance the commodity containment system for railroad tank cars exposed to fires.

[0022] An intumescent material is a material that swells when exposed to heat. For example, when exposed to fire, the intumescent material swells and may seal a gap that exists between two surfaces under normal conditions. Particular embodiments place an intumescent material in series between one or more existing gaskets on a railroad tank car and the external environment. When exposed to a fire, the intumescent material expands and fills the gap between the two surfaces normally sealed with the gasket. Thus, even if the gasket melts or otherwise loses some or all of its sealing ability, the intumescent material creates a secondary seal that prevents or minimizes commodity loss.

[0023] FIG. 1 is a schematic drawing illustrating a side view of a railway tank car. A customary railway tank car 10 includes a tank 12. Tank 12 includes a generally elongated hollow cylinder 18 enclosed at a first end 20 of tank car 10 and a second end 22 of tank car 10.

[0024] A head 42 is coupled to cylinder 18 at first end 20. Similarly, a head 44 is coupled to cylinder 18 at second end 22. Cylinder 18 and heads 42 and 44 at least partially define tank 12. Tank 12 may include jacket 24 that provides protection for cylinder 18 and heads 42 and 44. Jacket 24 may comprise a metal covering surrounding the tank designed to protect and / or secure insulation and / or thermal protections systems.

[0025] Tank car 10 may be used to transport a variety of hazardous and non-hazardous liquid or semi-liquid bulk commodities. Fluid commodities may be loaded into tank 12 through a variety of tank fittings attached to fittings plate 40 (typically within a protective housing 46).

[0026] Fittings plate 40 (located inside protective housing 46) joins the fittings to tank 12 via nozzle 48. Fittings plate 40 is typically a circular shaped plate bolted to tank 12 via nozzle 48.

[0027] FIG. 2 is a schematic cross-section of an example tank car top fitting arrangement. Nozzle 48 is typically a walled cylinder of circular or oval cross-section attached to tank 12. The connection between nozzle 48 and tank 12 may be strengthened via reinforcing pad 61.

[0028] Nozzle 48 projects away from tank 12 and is used for the application of a manway cover, pressure or fittings plate, valves, pressure relief devices, and other fittings. In the illustrated example, fittings 66 are coupled to nozzle 48 via fittings plate 40.

[0029] Fittings 66 may include fill holes; eduction pipes; safety vents; valves, such as pressure release valves; gauges; and the like.

[0030] Nozzle 48 includes nozzle flange 62. Nozzle flange 62 provides a mating surface for fittings plate 40. Fittings plate 40 is coupled to nozzle 48 via bolting or other fastening mechanism to nozzle flange 62.

[0031] Protective housing 46 is coupled to fittings plate 40 and provides protection for fittings 66. Protective housing 46 comprises hinged housing cover 68 that provides access to fittings 66.

[0032] FIG. 3 is a schematic cross-section of an example tank car top fitting with gaskets. FIG. 3 is a detailed view of Section A circled in FIG. 2.

[0033] Gaskets provide seals between various surfaces of tank car 10. Gaskets are material inserted in the joint between two mating surfaces to prevent leakage through the joint. The gaskets prevent commodity from the interior space 80 of tank 12 from reaching the external environment 82. For example, flange gasket 70 provides a seal between nozzle flange 62 and fittings plate 40. Fitting gasket 72 provides a seal between fittings plate 40 and fitting 66.

[0034] Gaskets are designed to reduce non-accidental release of contents from rail tank cars. Gasket material may comprise various different polymers depending on the application and desired characteristics.

[0035] While some gaskets may be formulated to withstand high environmental temperatures, they are not typically designed to withstand the extreme temperatures from fire exposure. Designing gaskets for such extremes would reduce the effectiveness of the gasket for its main purpose, which is preventing commodity release during normal operating conditions.

[0036] As described above, an intumescent material is a material that swells when exposed to heat. Particular embodiments place an intumescent material in series between one or more existing gaskets on a railroad tank car and the external environment. When exposed to a fire, the intumescent material expands and fills the gap between the two surfaces normally sealed with the gasket. Thus, even if the gasket melts or otherwise loses some or all of its sealing ability, the intumescent material creates a secondary seal that prevents or minimizes commodity loss. Particular embodiments and their advantages are best understood by reference to FIGS. 4 through 8, wherein like reference numbers indicate like features.

[0037] FIG. 4 is a schematic cross-section of an example tank car top fitting with intumescent gaskets. Intumescent fitting gasket 84 is coupled to fittings plate 40 between fittings plate 40 and fitting 66 and is positioned between fitting gasket 72 and external environment 82. Intumescent flange gasket 86 is coupled to nozzle flange 62 between nozzle flange 62 and fittings plate 40 and is positioned between flange gasket 70 and external environment 82.

[0038] During a fire event, intumescent fitting gasket 84 will expand to seal the gap between fittings plate 40 and fitting 66, and intumescent flange gasket 86 will expand to seal the gap between nozzle flange 62 and fittings plate 40. An example is illustrated in FIG. 5.

[0039] FIG. 5 is a schematic cross-section of an example tank car top fitting with expanded intumescent gaskets. In the illustrated example, intumescent fitting gasket 84 is expanded (illustrated by double sided arrow) to seal the gap between fittings plate 40 and fitting 66, preventing commodity from the interior space 80 of tank 12 from leaking to the external environment 82 upon failure of fitting gasket 72. Similarly, intumescent flange gasket 86 is expanded (illustrated by double sided arrow) to seal the gap between nozzle flange 62 and fittings plate 40, preventing commodity from the interior space 80 of tank 12 from leaking to the external environment 82 upon failure of flange gasket 70.

[0040] An advantage of locating intumescent fitting gasket 84 between fitting gasket 72 and external environment 82 and intumescent flange gasket 86 between flange gasket 70 and external environment 82 is that intumescent fitting gasket 84 and intumescent flange gasket 86 are not in contact with the commodity in tank 12 during normal operation. Thus, fitting gasket 72 and flange gasket 70 may be designed to perform optimally for particular commodities and the stresses of normal operating conditions, while intumescent fitting gasket 84 and intumescent flange gasket 86 may be designed to perform optimally during fire conditions.

[0041] Although flange gasket 70 and fitting gasket 72 are still illustrated in FIG. 5, the integrity of flange gasket 70 and fitting gasket 72 may be compromised by the fire event. In other situations, flange gasket 70 and fitting gasket 72 may be completely or partially destroyed by the fire event.

[0042] FIG. 6 is a schematic cross-section of an example tank car top fitting with intumescent gaskets and an intumescent gasket groove. FIG. 6 is similar to FIG. 4, except intumescent fitting gasket 84 and intumescent flange gasket 86 are each seated in an intumescent gasket groove 88. For example, intumescent fitting gasket 84 is seated in intumescent gasket groove 88 recessed into fittings plate 40, and intumescent flange gasket 86 is seated in intumescent gasket groove 88 recessed into nozzle flange 62.

[0043] Intumescent gasket groove 88 aids in positioning the intumescent gaskets when in their unexpanded states and provides additional sealing surface for the intumescent gaskets in their expanded states.

[0044] FIG. 7 is a schematic cross-section of an example tank car top fitting with intumescent gaskets and double intumescent gasket grooves. FIG. 7 is similar to FIG. 6, except for additional intumescent gasket grooves 88. Intumescent fitting gasket 84 and intumescent flange gasket 86 are each seated in an intumescent gasket groove 88 and each are opposite an additional intumescent gasket groove 88.

[0045] For example, intumescent fitting gasket 84 is seated in intumescent gasket groove 88 recessed into fittings plate 40 and positioned below intumescent gasket groove 88 recessed into fitting 66. When exposed to heat, intumescent fitting gasket 84 may expand into intumescent gasket groove 88 recessed into fitting 66.

[0046] Intumescent flange gasket 86 is seated in intumescent gasket groove 88 recessed into nozzle flange 62 and positioned below intumescent gasket groove 88 recessed into fittings plate 40. When exposed to heat, intumescent flange gasket 86 may expand into intumescent gasket groove 88 recessed into fittings plate 40.

[0047] The additional intumescent gasket groove 88 provides additional sealing surface for the intumescent gaskets to expand into in their expanded states.

[0048] Although FIGS. 4-7 illustrate examples of a tank car top fitting, other tank car components may also benefit from intumescent gaskets. An example is illustrated in FIG. 8.

[0049] FIG. 8 is a schematic cross-section of an example tank car manway with an intumescent gasket. Manway 90 comprises manway nozzle 92 that provides access to tank 12 and manway cover 94 that controls access to manway nozzle 92. Manway cover 94 is sealed to manway nozzle 92 via manway gasket 96. Intumescent manway gasket 98 is coupled to manway nozzle 92 between manway nozzle 92 and manway cover 94 and is positioned between manway gasket 96 and external environment 82. During a fire event, intumescent manway gasket 98 will expand to seal the gap between manway nozzle 92 and manway cover 94.

[0050] Although the illustrated examples show intumescent gaskets in particular expanded and non-expanded configurations, some embodiments include other configurations. For example, the examples illustrated in FIGS. 4-7 illustrate intumescent gaskets coupled to a bottom surface that expand upward in the vertical direction to seal a gap between the bottom surface and a top surface. In other embodiments, the intumescent gasket may be coupled to the top surface and may expand downward in the vertical direction to seal a gap between the top surface and a bottom surface. Similarly, in the example illustrated in FIG. 8, the intumescent gasket expands horizontally. In some embodiments the intumescent gasket may be coupled to either vertical surface and may expand horizontally or radially in either direction. In some embodiments, the unexpanded gasket may extend the entire gap between a first surface and a second surface and when exposed to heat may expand it a lateral direction to more fully seal the gap between the first surface and the second surface.

[0051] Although particular gaskets are illustrated herein, gaskets may be used in rail tank cars for a variety of sealing applications, such as manway lids, end caps, inlets and outlets, hatches, vents, valves, nozzles and flanges. Particular embodiments disclosed herein may function in conjunction with any such gaskets to provide enhanced thermal protection when located in series with any of the existing gaskets.

[0052] The term “opening” is used herein generally to refer to any opening between an interior of the tank and an external environment, such as nozzle opening, manway opening, fittings plate opening, or any other similar opening. The term “cover” is used herein generally to refer to any cover for an opening, such as a fittings plate cover, manway cover, etc., or other items that may cover an opening, such as a gauge that couples to a gauge opening, etc.

[0053] Tanks may also be transported by truck, marine vessel, aircraft, etc., and the intumescent gaskets disclosed herein may be used with any such tanks.

[0054] Modifications, additions, or omissions may be made to the systems and apparatuses disclosed herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components.

[0055] Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following example embodiments.

Claims

1. A railway tank car comprising:a tank for transporting a commodity;an opening between an interior of the tank and an external environment, the opening comprising a first mating surface for mating with a cover;a cover that covers the opening, the cover comprising a second mating surface for mating with the first mating surface;a first gasket positioned between the first mating surface and the second mating surface, the first gasket providing a seal between the interior of the tank and the external environment under normal operating conditions, anda second gasket positioned between the first mating surface and the second mating surface, the second gasket comprising an intumescent material and positioned between the first gasket and the external environment; wherein:when the tank is exposed to a fire condition, the second gasket expands to provide a seal between the interior of the tank and the external environment.

2. The railway tank car of claim 1, wherein the opening is formed by a nozzle and the cover comprises a fittings plate.

3. The railway tank car of claim 1, wherein the opening is formed by a manway nozzle and the cover comprises a manway cover.

4. The railway tank car of claim 1, wherein the opening is formed by an opening in a fittings plate and the cover comprises a fitting.

5. The railway tank car of claim 1, wherein the second gasket is positioned within a groove in the first mating surface.

6. The railway tank car of claim 5, wherein the second mating surface comprises a groove opposite the groove in the first mating surface, and when the tank is exposed to a fire condition, the second gasket expands into the groove in the second mating surface.

7. The railway tank car of claim 1, wherein the second gasket is positioned within a groove in the second mating surface.

8. The railway tank car of claim 7, wherein the first mating surface comprises a groove opposite the groove in the second mating surface, and when the tank is exposed to a fire condition, the second gasket expands into the groove in the first mating surface.

9. A tank for transporting a commodity, the tank comprising:an opening between an interior of the tank and an external environment, the opening comprising a first mating surface for mating with a cover;a cover that covers the opening, the cover comprising a second mating surface for mating with the first mating surface;a first gasket positioned between the first mating surface and the second mating surface, the first gasket providing a seal between the interior of the tank and the external environment, anda second gasket positioned between the first mating surface and the second mating surface, the second gasket comprising an intumescent material and positioned between the first gasket and the external environment; wherein:when the tank is exposed to a fire condition, the second gasket expands to provide a seal between the interior of the tank and the external environment.

10. The tank of claim 9, wherein the opening is formed by a nozzle and the cover comprises a fittings plate.

11. The tank of claim 9, wherein the opening is formed by a manway nozzle and the cover comprises a manway cover.

12. The tank car claim 9, wherein the opening is formed by an opening in a fittings plate and the cover comprises a fitting.

13. The tank of claim 9, wherein the second gasket is positioned within a groove in the first mating surface.

14. The tank of claim 13, wherein the second mating surface comprises a groove opposite the groove in the first mating surface, and when the tank is exposed to a fire condition, the second gasket expands into the groove in the second mating surface.

15. The tank of claim 9, wherein the second gasket is positioned within a groove in the second mating surface.

16. The tank of claim 15, wherein the first mating surface comprises a groove opposite the groove in the second mating surface, and when the tank is exposed to a fire condition, the second gasket expands into the groove in the first mating surface.

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