US3078004A

US3078004A - Insulated container

Info

Publication number: US3078004A
Application number: US776987A
Authority: US
Inventors: Donald S Randolph
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1958-11-28
Filing date: 1958-11-28
Publication date: 1963-02-19
Anticipated expiration: 1980-02-19
Also published as: GB877741A; DE1195337B; FR1243586A; BE585106A

Description

Feb. 19, 1963 D. s. RANDOLPH INSULATED CONTAINER 7 Sheets-Shae 1 Filed Nov.. 28, 1958 Donald S. Rondo! p h INVENTOR.

ATTORNEY Feb. 19, 1963 D. s. RANDOLPH INSULATED CONTAINER 7 Sheets-Sheet 2 Filed Nov. 28, 1958 Donald S. Randolph 45 INVENTOR.

ATTORNEY Feb. 19, 1963 D. s. RANDOLPH INSULATED CONTAINER '7 Sheets-Sheet 3 Filed Nov. 28, 1958 F I G 4 Donald SLRqndolph INVENTOR.

ATTOR N E? Feb. 19, 1963 D. s. RANDOLPH INSULATED CONTAINER Filed Nov. .28, 1958 7 Sheets-Sheet 4 Donald S. Randolph INVENTOR.

ATTORNEY Feb. 19, 1963 D. s. RANDOLPH INSULATED CONTAINER 7 Sheets-Sheet 5 Filed Nov. 28, 1958 INVENTOR.

ATTORNEY Feb. 19, 1963 D. s. RANDOLPH 3,078,004

INSULATED CONTAINER Filed Nov. 28, 1958 '7 Sheets-Sheet 6 i Donald S. Randolph (A; 2 INVENTOR.

ATTORNEY Feb. 19, 1963 D. s. RANDOLPH 3, 0

INSULATED CONTAINER Filed Nov. 28, 1958 7 Sheets-Sheet 7 Donald S.Rundolph INVENTOR.

ATTORNEY United States Patent 0 3,078,004 WSULATED CONTAINER Donald S. Randolph, Muncy, Pa., assignor to ACE Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Nov. 28, 1958, Ser. No. 776,987 6 Claims. (Cl. 220-14) The present invention relates generally to large insulated containers for the transportation or storage of liquefied gases at sub-zero temperatures. It relates particularly to such a container having an inner tank which is suspended in vacuo within an outer shell, the evacuated space between the tank and the shell being filled with fiberized or powdered insulation, the tank being provided with stable anchorage, flexible suspension and direct access to its inside from outside the shell and with insulation filtering in the evacuating system located outside the shell, whereby the normal maintenance and operation of the container is accomplished without the necessity of breaking the vacuum between the shell and the tank. More particularly, the invention relates to such a. container wherein an anchorage and suspension system cooperate to maintain relative tank and shell stability and are adapted to direct and accommodate wide range temperature change movements of the tank. Although the invention is applicable for many large insulated container purposes, it is particularly adaptable for railroad tank cars and for the storage and transportation of liquefied oxygen, argon and nitrogen.

The maintenance and operation of a railroad tank car having a fiber or powder-in-vacuum insulated tank used for the transportation and storage of liquefied gases present two basic problems. The first relates to the efficiency and commercial feasibility of the car in maintaining the temperature of the contained liquid gases to insure as little evaporation and resultant loss of the contained gas as possible. The second relates to the elimination of the necessity of breaking the vacuum between the shell and the tank once a vacuum has been created. To pull the vacuum required in such a car is a lengthy and expensive operation and its frequent necessity also afiects the commercial feasibility of transporting and storing liquefied gases at very low temperatures.

These two problems are intimately connected. The provision of stabilizing and strengthening structure and accesses for cutting down maintenance and for simplifying operations which eliminate the frequent necessity of breaking the vaccum, also provides heat conductive elements which lower the efiiciency of the car. Furthermore, when inner tank stabilization is accomplished by anchorage to an outer shell, contraction and expansion movements of the tank because of wide range temperature changes are greater at portions of the tank farthest away from the anchorage point resulting in excessive tensions upon the tank, the shell and the anchorage and suspension systems.

The provision of a suspension system for the inner tank which is comparatively adjustment and maintenance free would eliminate costs incidental to repair and parts replacement and would also eliminate the necessity of breaking the vacuum to examine and repair the system. Such a suspension system should eliminate as nearly as possible longitudinal as well as lateral and vertical tank movements occasioned by the normally rough operations of railroad cars and at the same time provide flexibility to take care of tank movements resulting from temperature changes. Temperature change movements, in the absence of tank-shell anchorage, also result in a shifting of the tanks position within the shell. To achieve stabilization of the inner tank relative to the outer shell, direct rigid anchorage to the outer shell must be accomplished. However, the overall length of the various anchorage and suspension connections. between the shell and the tank must not be so shortened, or so numerous that heat conduction through them to the inner tank is facilitated to the lessening of the efficiency of the .car. Nor can the suspension system be so rigid as not toallow for the expansion and contractionof the inner tank due to wide range temperature changes.

Because of the expense involved in polishing the surfaces of the large tank and outer. shell of railroad tank cars the most practical method of minimizing heat radiation through the evacuated space is to loosely pack fi-berized or powdered insulation between the tank and the shell. The use of this type of insulation also. minimizes heat transfer because of conduction or convection through any remaining gases in the evacuated space. In-tank cars having this type of insulation the use of insulation filters in the evacuating system is a necessity and so is their cleaning andreplacement due to insulation clogging. Because of the necessity of frequent complete and partial or maintenance evacuation operations it is more economical to usecomparatively small, inexpensive filters than larger, more efficient ones. Small filters have been placed at the end of the evacuating pipe line within the evacuation space between the tank and the shell usually at the top of the car in a nozzle arrangement above the level of the insulation material. Since the vacuum had to be broken frequently to provide access to the inner tank and its suspension system for inspection and maintenance, this positioning served as an easy access to the-filter for replacing it and also as a means of keeping the evacuating pipe line clear of insulation material.

Once a direct anchorage between the shell and the tank is provided, access through the anchorage structure to inside the inner tank for inspection, maintenance and cleaning can be facilitated without breaking .the vacuum between the tank and the shell. The provision of such an anchorage and of a comparatively adjustment and maintenance free suspension system for the tank eliminates frequent inspection and adjustment procedures in the evacuation space. Having eliminated the prime necessities for breaking the vacuum, the use of larger more efficient filters becomes practical and economical. Now large filters can be placed outside the .shell and the evacuation process once completed may be dispensed with except for major repairs. Only maintenance of the vacuum which may depreciate over a period of months because of small leaks is necessary. The problem of evacuating pipeline clogging can be handled by allowing a short period of suction through the pipe line back into the evacuation space during the initial evacuating operation. A further advantage of being able to place large filters outside of the evacuating space is that the filters can be changed when necessary without breaking the vacuum and in fact need no longer be a required piece of equipment for tank cars as they need only be utilized at any one of many evacuation maintenance stations which can be supplied with attachable filters for servicing such tank cars.

The positioning of a rigid anchorage between 'thefitank and the shell should be such that movement of the tank due to temperature change or otherwise does not appreciably shift the weight of the tank to cause excessive strain upon the anchorage and consequently on the tank and the shell. In an. elongated tank car the anchorage should direct longitudinal temperature change movements and be compatible with radial temperature change move ments. In this way radial contraction and expansion would occur without setting the tank off center, causing a shift of the tank weight and consequent tension strains upon the anchorage and the suspension system. The

positioning of the anchorage centered at one end of the tank, would so direct and be compatible with these temperature change movements. But, when the tank is in use, the anchorage will be below the liquid line of the lading. If the anchorage is alsoto be used as an access ormanway into the inner tank, a seal against liquefied gas leakage must be provided within the manway. A further result of this type of anchorage is the problem of suspending the other end of the tank to take care of substantially the full distance of longitudinal tank movement occasioned by temperature change. 'Further, there is the possibility that non uniform radial temperature change movement of the tank may occur. It is also possible that comparatively fast or excessive longitudinal movement may be occasioned under abnormal conditions. The end suspension must be adaptable to ride with longitudinal temperature change movement or remain static with relation to the shell during the tanks longitudinal movement when non uniform radial temperature change movement or abnormal longitudinal movement would ordinarily cause tortuous strains within the suspension system.

The present invention has for its objects the provision, in a container having an outer shell within which is suspended in vacuo an inner tank for the transportation and storage of liquefied gases at'sub-zero temperatures, of a direct, rigid anchorage between the tank and shell wherebylongitudinal' temperature change movements of the tank are directed toward tank end suspensions and whereby tank stability relative to the outer shell is provided; of a flexible tank suspension system for securing relative tank and shell positioning and adapted to allow for temperature change movements of the tank; of an anchorage whose structure may be utilized as a direct manway access to the inside of the tank from outside the shell; and of such'an anchorage which provides a seal against liquefied gas leakage, utilizing the evaporative and expansion characteristics of the contained lading to assist in sealing itself within the inner tank. This invention provides for the normal maintenance and operation of such a container without the necessity of breaking the vacuum between the tank and the shell and the consequent practicality of using large efficient filters in the evacuating system, placed outside of the shell. It also provides rigid anchorage and flexible yet strong suspension for the inner tank providing relative stability between the tank and the shell and allowance for temperature change movements without excessive heat conduction through the tank and shell anchorage and suspension connections.

These and other objects of the invention will become apparent to those skilled in the art upon a reading of the specification with reference to the following drawings which form a part thereof:

FIGURE 1 is a perspective view, partly broken away of a railroad tank car with its various pipe line systems not shown;

FIG. 2 is a front end elevation of the tank car eliminating the car understructure and showing the front terminal ends of the pipe systems;

' FIG. 3 is a diagrammatic sketch of the tank car pipe line systems;

FIG. 4 is a sectional view partly broken away taken along the lines 4-4 of FIG. 2; FIG. 5 is a sectional, segmented view of the tank car, taken along the line 55 of FIG. 2 except the rear segment shows the rear end of the inner tank partly broken away and the rear end tank suspension when the tank is cold;

FIG. 6 is a detail section partly broken away taken along the line 6-6 of FIG. 5;

FIG. 7 is a sectional view taken along the line 7--7 of FIG. 5;

FIG. 8 is an end elevation taken along the line 8-8 of FIG. 5 showing the front end tank suspension slightly distorted;

FIG. 9 is a sectional view taken along the line 9-9 of PEG. 8;

FIG. 10 is a sectional view partly broken away taken along the line ll1tl of FIGS;

FIG. 11 is a side elevation of the forward suspension taken along the line 11-11 of FIG. 8;

FIG. 12 is an end elevation showing the rear end tank suspension taken along the line 12-12 of FIG. 5;

FIG. 13 is a sectional view taken along the line 13--13 of FIG. 12;

FIG. 14 is a sectional view taken along the line 14-14 of FIG. 12; and, V

FIG. 15 shows the rear segment of FIG. 5 when the tank is at ambient temperature.

There is presented in FIG. 1 a railroad car underframe, indicated generally at 16, mounted on wheels. Tank saddles 17 support an elongated cylindrical outer shell 18 within which is centrally positioned a smaller correspondingly shaped inner tank 19. The tank and the shell ends are ellipsoidal in shape, concaved outwardly. The front end of the tank is reinforced against longitudinal stresses by strengthening ribs 20, shown in FIG. 5. The cylindrical portion of the outer shell is provided with stiffening rings 21 attached to the inside wall of the outer shell and the shell end is also reinforced by ribs 22 shown in FIG. 5. When the tank car is in operation, the space between the shell and the tank, indicated at 23, is evacuated. The stiffening rings and the shell end ribs act to strengthen the shell against the forces of atmospheric pressure. Prior to evacuating, the space is filled with fiberized or powdered insulation material, not shown, packed to a uniform density to insure against settling and the creation of voids in the insulation when the car is in service. a

A safety head nozzle 24 is positioned rearwardly at the top of the shell. It is provided with a bursting disc assembly, not shown, mounted beneath the closure plate and is designed to rupture at a predetermined pressure to relieve against the build up of gas pressure occasioned by damage to the tank or pipeline systems.

Pipe lines are provided for evacuating the space, loading and unloading the tank and venting. Indicating instruments, operating, test and safety valves in the pipe lines are positioned forward of the front of the shell and a Weather housing 25 is provided to cover and provide access to them. The pipe systems are shown in FIGS. 2 through 5.

A shell nozzle 26 located atop the shell near the front end, houses the inner open end of the evacuating pipe line 27. To avoid the entry of insulation into the line it is bent upwards into the housing nozzle above the level of the material. Screening may be provided around the pipe between the level of the insulation material and the open end of the pipe. The pipe extends forward and through a tight opening in the upper center of the front end of the shell. An insulation filter 29 is positioned in the pipe line outside the shell between two shut off valves St). This placement of the filter allows cut-off of both the vacuum pump and the evacuation space to allow changing of the filter at any time. The evacuating pipe line is provided with a connection to a vacuum gauge 31 shown in FIG. 3 only. The outer or front end of the line forms a hose connection to a vacuum pump line.

To load the tank, liquefied gas is directed into the rom end of the fill pipe 35 located below and forward of the front end of the shell. The entry end of the pipe is provided with a valve 36 for blowing off trapped pressure before disconnecting the line from the hose connection to the source of supply. A shut off valve 37 is positioned in the pipe line between the entry end and the shell. The pipe enters the vacuum space at an upper side location in the front of the shell through an opening provided with a heat barrier sleeve 38 to prevent cold embrittlement of the shell at the point of contact with the sleeve. It extends rearwardly in the vacuum space not touching but along an upper side of the tank, is bent upwardly toward the center of the top of the tank, then forwardly along the top of the tank but off center, then downwardly to end in an opening provided in the tank at that point. This lengthy route between the shell and the tank provides impedance to heat conductivity.

Although both loading and unloading could be accomplished through one line, the discharge line now to be described, the fill line is provided both as ancillary equipment, for instance as a second vent line, and for alternate or simultaneous use as a fill line.

In the tank car shown the liquid is unloaded by a discharge pipe line 39 receiving the lading at its inner end through an opening in the tank located rearward of the front end and centrally at the bottom of the tank. The

pipe line is extended downward then bent to the side and upwardly, not touching but along the lower side of the tank, then bent to the front to extend to the end of the tank, bent again around the front end of the tank to a lower, side of center point in the vacuum space, then bent forward to extend through an opening in the front end of the shell at a lower side location. The opening is provided with a heat barrier sleeve 40. The route for the pipe, is arranged to provide, in this instance, a vapor trap to prevent liquid contact with the closed valve 41.

The length of the pipe is therefore effective to impede heat conductivity. The discharge pipe line terminates in an open end providing a connection for delivery of the lading. A shut-oif valve 41 is placed in the pipe line between the opening and the shell. A valve 42 at the outer terminal of the line is used to blow off trapped pressure before disconnecting the discharge line and hose con nection to the lading receptacle. Relief valves 54 are positioned in the fill and discharge line as a safety measure designed to function where blow-

01f valves

36 and 42 are not opened quickly enough.

Normally liquid gases such as oxygen, nitrogen and argon cannot be stored or transported without evaporation taking place. To relieve the pressure set up by gas in its vapor phase, a vent pipe line 43 is provided. It travels, within the vacuum space, a long heat-resistant route corresponding to that of the fill pipe line 35 except that it is placed on the other side of the top center line of the tank. Its tank terminal is protected from the accidental entry of liquified gas by the provision of a splash .cover 44 at the tank vent opening. The vent line extends through an opening in the front end of the shell and this opening is also provided with a heat barrier sleeve 45. The opening is positioned on the upper side location of the shell end opposite to the location of the fill line shell opening. It extends downward to its discharge end near the bottom of the shell and includes a gate valve 46 bet-ween the discharge end and the shell. This gate valve is kept in open position when the liquid lading is being loaded or stored or transported in the tank. A check valve, not shown, may be placed in the vent line near its discharge end for single directional flow. The gate valve is closed when unloading to provide pressure to assist the unloading. A vent line safety extension 47 enters the vent line between the gate valve and the shell. A safety relief valve 48 spring loaded to discharge at a predetermined pressure is placed in the extension line. The extension line also provides a bursting disc assembly 49, shown only in FIG. 2, having a frangible disc designed to rupture at a pressure above the discharge pressure of the safety relief valve. The discharge end of the extension line is positioned near the bottom of the shell close to the discharge end of the main vent line.

To build up pressure for unloading, a vaporizer cirunit, not fully shown, is provided between the discharge and vent line. The discharge line connection 50 of this circuit has agate valve 51 to close the circuit when pressure for unloading the tank is not required. When the valve 51 is opened, the vapor trap in the discharge line is destroyed and liquid is permitted to how into the vaporizer circuit.

An instrument panel may be provided within the housing for mounting vacuum, liquid and pressure gauges. Try-cocks for ancillary testing may also be positioned on the panel and communicate by separate pipes to various levels on the inside of the tank. The openings through the shell to accommodate the instrument and try-cock pipes should be sleeved and the pipes made to run a lengthy course for heat conductivity impedance and flexibility.

Because of the rigid tank stability and direction rearward of longitudinal temperature change movement of the tank provided by the present invention and now to be described, the positioning forward and the lengthy routing of the pipe systems between the shell and the tank present more than sufficient flexibility to accommodate contraction and expansion of the tank due to temperature changes without straining the systems. Maintenance of the pipe systems because of tank movement is therefore eliminated.

To prevent displacement of the tank from its position relative to the shell because of external shock or forces usually attendant with the operation and maintenance of railroad cars, stability against relative tank and shell movement is provided by a tank nozzle, designated generally 55, to rigidly interconnect the front ends of the shell and tank, and by front and rear end tank suspension, designated genera-11y in FIG. 1 at 56 and 57 respectively, to support the tank Within the shell. The suspensions are arranged to bearingly encompass and tangentially frame the tank. The tight encompassment and tangential support of the tank provides axial stability of the tank, that is, holds the tank axis substantially fixed relative to the axis of the shell and assists relative longitudinal stability of the tank and shell. The rigid anchorage provided by the-nozzle interconnecting the front ends of the tank and shell provides relative longitudinal stability, assists axial stability of the tankand restrains tank rotational movement.

The front end suspension consists of three sets offour elongated cables or as in this instance rods 60 secured at their ends to a shell inner surface bearing ring 62, and intermediate their ends to'a tank -bearing-ring66. The rear end suspension consists of three sets of'four elongated bars 61 secured at their ends to a shell inner surface bearing ring 63, and retained intermediate their ends along a tank bearing ring 67. In the rear suspension shown, lock pads '64 are spaced between the inner surface of the shell to which they are secured, and the outer surface of the shell ring 63 which in the instance shown actually bears against the pads rather than the shell. The pads provide stop abutments 65 for restraining forward travel of the shell ring when installed and during contraction of the tank. The pads also act-as reinforcement for the shell ring and may provide additional points of securement of the bar ends to restrain rearward movement of the ring along the shell wall. The rod supports may be secured mediate their ends to the tank ring 66 by welding as indicated in FIG. 9 at 70. The bar supports are retained mediate their ends in their path of curved travel along the outer surface of the ring 67 by means of M-spacers 71 which are secured to the ring mediate the bar ends. Spacers 72 are positioned between the bars at their points of tangency with the ring and each are secured along one of their sides to an adjacent bar. Forward and aligned with the points of tangent spacers, stops 72a are secured to the tank and abut the forward edge of the tank ring 67 and the forward side of the

frontmost bars

61a and 610 to restrain forward shifting of the ring during tank expansion and which, with the spacers, each of which is secured to but one bar, retain the bars in their paths of travel and allow flexure movement of the bars. Rearward movement of the ring along the tank during contraction may be permitted to allow for non uniform or abnormal temperature change movements of the tank and in such a case,

when the tank again expands, slippage of the ring forward to the stops 72a will be permitted under the urging of the tangent bar extensions which are initially installed under flexure tension as will be discussed.

FIGURES 5, 8 and 11 relating to the front end suspension show exaggerated spaces, indicated at 73 of FIG. 8, between the ring 66 and the rods. The rods are installed to cause the spaces when the tank is at ambient temperature. In operation, when the tank is cooled, the rods, being in contact intermediate their ends with the tank bearing ring 66, will also cool and shorten to maintain supporting encirclement of the ring and tank as shown at the rod tangent points 74 in FIG. 8.

FIGURE 8 and the dependent views taken from it show the arrangement of a set of support rods between the shell and tank rings 62 and 66 respectively. The frontmost rods 60a and 66c lie in the same plane and are shown as having their inner surfaces intermediate their ends secured to the tank bearing ring 66 and describing opposite quarters of the circumference of the outer surface of revolution of the ring with their ends running tangentially from the tank to their points of securement in the shell inner surface bearing ring 62. The remaining opposite quarters of the circumference of the outer surface of revolution of the bearing ring 66 are traveled in a like manner by rods 6% and 6% which also lie in a common plane but rearward of the plane of rods 69:: and 600. The ends of rods tlb and 6nd also form tangent extensions running from the tank to their points of securement in the shell bearing ring. Securing the rod ends may be accomplished by welding as indicated in FIG. 8 at 75.

The three sets of rods shown are arranged to travel parallel paths in spaced relationship in six transverse planes, two for each set, along the outer surface of the tank ring 66 and through the vacuum space to the shell ring 62. At their points of tangency with the tank ring 66, the three cables or rods, one from each set, traveling corresponding parallel paths along the tank ring will become interspaced with three other cables, one from each set, also traveling corresponding parallel paths along the portion of the ring immediately extending from the portion of the ring traveled by the first three interspacing cables. This point of tangent interspacing of the cables is shown best in FIG. ll at the top, middle and lower locations along the inner or tank ring. The same parallel path traveling and interspacing arrangement is utilized for the rear bar suspension and is best shown in the rear segment of FIG. at the point of tangent spacers 72.

FIGURES 5 and 12 show the rear end suspension arranged in the same manner as the front end suspension to encircle and tangentially frame the tank for axial stability. The frontmost bars, 61:: and 610, lie in the same plane. Their inner surfaces intermediate the ends are retained at the tank bearing ring 67 and describe opposite quarters of the circumference of the outer surface of revolution of the ring. The ends run tangentially from the tank ring to their points of securement in slots provided in the shell ring, shown in FIG. 13, where they may be welded to the ring and to the lock pads 64.

Bars

61b and 61d also lie in a common plane rearward of the plane occuplied by bars 61a and die and in a like manner travel along the remaining opposite quarters of the circumference of the outer surface of revolution of the tank ring and form at their ends tangent extensions from the tank ring to the shell ring.

The purpose of providing encompassing radial support around the tank ends is to assure axial stability of the tank, that is, to hold the tank axis substantially fixed in relation to the shell axis. Tangential framing support around the tank adds to the strength of the suspension and allows a greater length along the support bars for heat conductivity impedance than would result if radial extensions from the tank to the shell were used. The use of elongated supports, to both bear the tank evenly around its circumference and provide tangential support extensions, which supports will shorten and lengthen with the contraction and expansion of tank due to temperature changes, results in a tank suspension which is compatible with radial temperature change movement of the tank and insures axial stability in any stage of temperature. It will be understood therefore that elongated supports may be arranged in many different ways to bearingly support the inner tank by their inner surfaces and provide tangent support extensions to the shell to provide even distribution of forces around the circumference of the tank to the surrounding suspension extensions to the shell. The preferred embodiment of the suspension of the in- 'vention shown is used to provide complete encircling of the tank and a plurality of radially oriented evenly spaced points of connection of the tangent extensions to the shell which are positioned for as even a distribution of the stresses and tensions as possible without increasing heat conductivity so as to afiect the commercial feasibility of the container.

When the inner tank is loaded with liquid oxygen it will reach a temperature of 297.4 F. when conditions have stabilized. To accommodate radial contraction during loading, and expansion when unloading, the nozzle 55 is preferably positioned centrally of the front end of the tank and is coaxial with the tank. This positioning of the rigid anchorage between the tank and the shell directs all longitudinal temperature change movements toward the rear end of the tank in such a manner that comparatively little or no longitudinal movement of the tank relative to the shell takes place at the front end, and the entire distance of longitudinal movement is traveled by the rear end of the tank. To accommodate the rear end longitudinal movement, the shell and tank rings of the rear suspension are preferably mounted when the tank is warm, and are offset from one another, the tank ring being displaced rearwardly relative to the shell ring as shown in FIG. 15. The support bars are flexed as a result of the displacement of the rings and flexure is imparted to the bars along their tangent extensions, designated T in FIG. 12. During the contraction of the tank, the tank ring also contracts because of its direct contact with the tank. The bars correspondingly shorten because of their direct contact with the ring. As a result of this and the longitudinal move ment of the tank relative to the shell, the displacement of the rear shell and tank rings gives way to radial alignment of the rings as shown in FIG. 5. Conversely, during unloading, heat gain in the tank, ring and support bars results in radial and longitudinal movement in the opposite direction, and the rear tank and shell rings are again dis placed and the bars again are put under fiexure.

The arrangement of the support bars to provide flexible tangent extensions between the tank and the shell while bearing the tank intermediate their ends results in a suspension which rides with contraction and expansion movements of the tank, both radial and longitudinal, without surrendering strength of construction and without the use of radially oriented tank-shell interconnections for rigidity, which would have to be separately connected within the suspension system, would not be truly flexible nor compatible with radial movements and would have the added disadvantage of being shorter and less resistive to heat conductivity. The bars are installed under flexure so that when the tank is chilled by the liquefied gas lading and the tank ring 67 becomes aligned with the padded shell ring, the supports will not be in danger of excessive strains which would occur if the rings were initially aligned and the bars shortened and became flexed under the influence of the cooling of the tank.

The tank rings of both front and rear suspensions are not attached to the tank but are fitted tightly allowing slippage particularly in the rear suspension where abnormal or non-uniform temperature change movements of the tank might cause excessive strain upon the support system. Obviously, where such slippage is deemed unnecessary, unimportant or detrimental the rings may be attached to the tank as by welding or otherwise.

The front end suspension is utilized in the preferred embodiment to impart to the container greater resistance to external forces. The rigid nozzle interconnection of the tank and shell at their front ends is thereby relieved for the most part, of tensions and stresses occasioned by the weight of the tank and by forcestending .to displace the tank from its normal axis. The nozzle acts principally as a resistance to longitudinal displacement of the tank relative to the shell and it directs longitudinal'temperature change movement of the'tank to the rear end of the tank. As the nozzle is rigidly positioned coaxially with the inner tank, it is further relieved of stresses and tensions which would otherwise be caused by displacement of the tank from its centered axis due to radial temperature change movements.

As shown in FIGS. and 6, the nozzle interconnection between the tank and shell has an annular section 55 extending coaxially with the tank rearward of the front end of the tank and forward of the front end-of the shell. Areducer 80 is provided to connect the shell and nozzle. Its reduced forward end connects the front end of the nozzle and may be secured by welding 95. It connects the shell at its rearward wide end for securement there. Gussets 99 .and the reducer act to reinforce the rigid connection of the shell and nozzle and also to allow the forward extension of the nozzle to provide greater distance between the tank and shell for heat conductivity impedance. The forward shell ribs 22 connect the reducer for further re-inforcement of the shellnozzle connection. The inner ends of the rib reinforce ments 20 of the tank connect with the rearward extension of the nozzle to reinforce the rigid tank and nozzle connection.

Direct entrance into the tank from outside the shell is provided by utilizing the rigid nozzle tank andshell interconnection as a manway. As the nozzle and the tank are coaxial, the liquid line of the load will normally fall above the nozzle structure. To provide against leakage of the liquid contained in the inner tank, the outer surfaces of revolution of two plate mounted rings are secured to the inner surface of the nozzle wall and placed in spaced relation to one another with one ring 81 positioned adjacent the rear end of the nozzle and the other ring 82 at a predetermined position forward of the rear ring. A cover plate 83 is secured bynut and bolt engagement at the front end of the nozzle to a flange 84 at the forward neck of the reducer 80. An O-ring 85 is provided between the flange and the cover for pressurized sealing. The plate 86 of the ring mounted adjacent the rear end of the nozzle closes the ring aperture at its rear face. Secured to the center of the plate and extending forward is a bolt 87 threaded at its end to receive a nut. A spider 88 is mounted on the bolt and its outer edges are forced against the forward face of the ring 81 by the application of pressure provided by the turning of the nut. This pressure acts to secure the plate to the ring. The plate 89 of the forwardly placed ring is secured to the ring at its forward face by nut and bolt engagement. There is provided in each ring and plate assembly an O- ring 90 for pressurized sealing between the ring face and the plate.

Although the O-ring pressurized seal provided in both ring and plate assemblies and between the nozzle cover and reducer flange, provides suificient resistance to gas leakage in the vapor phase, gas in the liquid phase may more readily escape past normal sealing. The provision of a compartment defined by the wall of the nozzle and the two ring and plate assemblies insures against leakage of liquefied gas. If liquid lading does seep past the rear ring and plate assembly, it evaporates in the compartment due to heat gain setting up a gas pressure which will effectively stop further liquid seepage between the plate and the ring. As a safety precaution against excessive vapor pressures in the compartment a spring loaded needle valve 91 has been set in the forward plate. For excess gases whcih pass through the valve, an egress is provided through diaphragm valve 92 placed in a short pipe circuit communicating with the forward chamber of the nozzle at the top of the nozzle adjacent its front end. This circuit may be used to interconnect the vacuum space with the forward chamber to provide evacuation of the forward chamber if desired.

When the tank is empty of lading, access to its inside is a matter of disengaging the nut and bolt arrangements at the nozzle plate and the forward and rear ring and plate assemblies.

In the container of the invention a rigid or stable anchorage interconnects the shell and tank at one end of the container with coaxial alignment of the anchorage and tank thereby providing an anchorage which resists relative tank and shell instability, is compatible with radial movements of the tank due to wide range temperature changes, directs longitudinal temperature change movements to the opposite end of the container substantially eliminating longitudinal movement of the tank at its anchored end, and by the inclusion in its structure of effective resistance to liquefied gas seepage provides amanway access to the inside of the tank without the necessity of breaking the vacuum between the tank and the shell. A tank suspension is provided for bearing and tangential support of the tank against axial displacement. Preferably, elongated support elements substantially circumferentially bear the weight of and forces imparted to the tank by their inner surfaces with their end extensions running tangent from the tank to the shell inner surface and provide flexibility along the tangent extensions to accommodate longitudinal temperature change tank movement. Tank and shell inner wall bearing rings are utilized as positioners of the support elements, and are restrained against forward movement along the tank and shell wall to prevent excessive fiexure and compressive stresses of the supports. Slippage of the tank forwardly through the tank ring during contraction may be permited for the same reason and to allow for non uniform or abnormal temperature change movement of the tank during cooling. On the other hand it may be desirable to weld the ring to the tank to avoid such slippage. The use of ring bearings is also advantageous in that it permits sub-assembly and facilitates installation of the suspension.

The anchorage cooperates with the suspension system to achieve substantially total tank and shell relative stability against external forces normal to such containers when used as railroad tank cars. The cooperation of the anchorage .and suspension system further results in axial stability of. the tank within the shell as both the anchorage and the suspensions are compatible with radial temperature change movements of the tank, the anchorage and the tank being held substantially coaxial and the suspension support elements being flexible in a direction radial of the tank due to their long and curved shape. As the support elements of the suspension system are both long and curved between their anchor points, these elements will also be capable of flexing in an axial direction with respect to the tank, the suspension system further cooperates with the anchorage to receive and ride with the longitudinal temperature change movements of the tank.

This anchorage-suspension cooperation results in a comparatively maintenance free support of the tank within the shell thereby eliminating the necessity of breaking the vacuum between the shell and the tank for maintenance care resulting from normal operations of the container. With the usual necessities for breaking the vacuum eliminated the container of the invention provides economical filtering of insulation material in its evacuating system by the positioning outside of the evacuation space of large efficient filters impractical for use in containers in the past where complete evacuation of the space necessitated replacement of insulation contaminated filters after each evacuation.

Various changes in the details and construction of the liquid gas container of the invention may be made without departing from its spirit and scope. It is therefore intended to limit the scope of the invention only by the following claims.

What is claimed is:

1. A container for storing and transporting liquid lading at extreme temperature comprising an elongated cylindrical outer shell having a front and a rear end, a similarly shaped inner tank, said inner tank being in spaced relation to and suspended in vacuo within said outer shell and having a front and a rear end, a nozzle extending coaxially with said inner tank between and rigidly connecting said outer shell and inner tank at said front ends, a front end tank suspension and a rear end tank suspension, said suspensions supporting said inner tank adjacent said front and rear ends respectively and securing the same to said outer shell, each said suspension comprising a tank bearing ring and a shell bearing ring, said bearing rings being in radial spaced relationship and circumferentially bearing against said inner tank and said outer shell respectively, a plurality of elongated support elements, each said support element having ends and an intermediate portion, said intermediate portion being formed to describe and bear along a portion of said tank bearing ring, said elongated support elements being arranged in at least two adjacent transverse planes to substantially circumferentially encompass said tank bearing ring by said intermediate portions, said ends of said elongated supports extending tangentially of said tank bearing ring and being secured to said shell bearing ring, said elongated supports being flexible and due to their arrangement permitting axial and radial movement of said tank while holding said tank axially stable, said tank bearing ring of said rear end tank suspensions being positioned in a transverse plane rearward of said shell bearing ring of said rear end tank suspension when said inner tank is at ambient temperature, whereby said ends of said elongated supports of said rear end tank suspension are flexed axially rearward of the tank to accommodate forward temperature change movement of the rear end of said inner tank.

2. A container as provided in claim 1 wherein said tank bearing ring of said rear end tank suspension is rearwardly slidable and stop means are secured to the tank forward of and adjacent to said tank bearing ring to prevent forward slippage thereof.

3. A container as provided in claim 1 wherein said nozzle provides a continuous manway access to inside said inner tank from outside said outer shell.

4. The container provided in claim 1 wherein the space between said inner tank and said outer shell is loosely packed with particles of insulation material and an evacuation pipe line is provided in said space, said evacuation pipe line has an inner intake end and an outer end, said intake end projects above the level of said material and extends from said intake end to said outer end outside said outer shell, and said evacuation pipe line has shut-off means between said outer shell and said outer end and insulation material filtering means between said shut-ofi and said outer end is provided.

5. A container for storing and transporting liquid lading at extreme temperatures comprising an elongated inner tank, an elongated outer shell housing said inner tank and providing a vacuum space therebetween, a manway nozzle interconnecting said tank and said shell coaxially at one end of said tank and operable to permit access to said tank from outside said outer shell while retaining the vacuum, supports located in spaced relation axially along said tank, each support including at least four elongated support elements, each said support element having straight ends, a curved intermediate portion joining said ends, said curved intermediate portion being formed to describe and encompass substantially one quarter of the circumference of said tank, said elongated support elements being arranged in at least two adjacent planes transverse of the tank to collectively circumfercntially encompass said tank, said straight ends extending tangentially from the tank into engagement with said outer shell, said elongated support elements during shortening and lengthening due to temperature changes permitting both axial and radial contraction and expansion of said tank within said shell With minimum heat transfer between said tank and shell while holding said tank and shell in coaxial relationship.

6. A container for storing and transporting liquefied gas at extreme temperature comprising an elongated cylindrical outer shell, an inner tank of corresponding shape, said inner tank being suspended in vacuo within said outer shell, a manway nozzle rigidly connecting said inner tank centrally of one of its ends to the corresponding end of said outer shell, said manway nozzle extending coaxially with said inner tank between said inner tank and said outer shell ends, said inner tank being suspended by tank supports, said tank supportsbearingly encompassing said inner tank at its other end and having flexible tangential extensions to circumferentially spaced points of connection to said outer shell, said manway nozzle having detachably sealed closures adjacent its ends, and having an intermediate detachably sealed closure intermediate its ends, said sealed closures forming with said nozzle a first vapor pressure sealing compartment adjacent said tank and a second compartment adjacent said shell, and pressure relief means carried by said intermediate closure to vent pressure from said first compartment into said second compartment.

References (Zited in the tile of this patent UNITED STATES PATENTS 2,587,204 Patch Feb. 26, 1952 2,814,410 Hansen Nov. 26, 1957 2,858,136 Rind Oct. 28, 1958 2,864,527 Altman et al Dec. 16, 1958 2,925,934 Hampton Feb. 23,1960 2,926,810 Yeager Mar. 1, 1960 FOREIGN PATENTS 26,817 Denmark of 1919 254,220 Great Britain July 1, 1926 697,222 France Oct. 27, 1930

Claims

6. A CONTAINER FOR STORING AND TRANSPORTING LIQUEFIED GAS AT EXTREME TEMPERATURE COMPRISING AN ELONGATED CYLINDRICAL OUTER SHELL, AN INNER TANK OF CORRESPONDING SHAPE, SAID INNER TANK BEING SUSPENDED IN VACUO WITHIN SAID OUTER SHELL, A MANWAY NOZZLE RIGIDLY CONNECTING SAID INNER TANK CENTRALLY OF ONE OF ITS ENDS TO THE CORRESPONDING END OF SAID OUTER SHELL, SAID MANWAY NOZZLE EXTENDING COAXIALLY WITH SAID INNER TANK BETWEEN SAID INNER TANK AND SAID OUTER SHELL ENDS, SAID INNER TANK BEING SUSPENDED BY TANK SUPPORTS, SAID TANK SUPPORTS BEARINGLY ENCOMPASSING SAID INNER TANK AT ITS OTHER END AND HAVING FLEXIBLE TANGENTIAL EXTENSIONS TO CIRCUMFERENTIALLY SPACED POINTS OF CONNECTION TO SAID OUTER SHELL, SAID MANWAY NOZZLE HAVING DETACHABLE SEALED CLOSURES ADJACENT ITS ENDS, AND HAVING AN INTERMEDIATE DETACHABLY SEALED CLOSURE INTERMEDIATE ITS ENDS, SAID SEALED CLOSURES FORMING WITH SAID NOZZLE A FIRST VAPOR PRESSURE SEALING COMPARTMENT ADJACENT SAID TANK AND A SECOND COMPARTMENT ADJACENT SAID SHELL, AND PRESSURE RELIEF MEANS CARRIED BY SAID INTERMEDIATE CLOSURE TO VENT PRESSURE FROM SAID FIRST COMPARTMENT INTO SAID SECOND COMPARTMENT.