US2289913A - Storage tank - Google Patents

Description

July 14, 1942. w. E, JQORQJR; i 2,289,913v

STORAGE TANK Filed May 1e, 1940- 4 sheets-sheet 1 July 14, 1942- l Y w. E. Joon, JR 2,289,913

STORAGE TANK 'Filed May 1e, 1940 4 Sheets-sheet 2 'l July 14,1942.

w.`E. ,looR,.JR 2,289,913

STORAGE- TANK Filed My 1e, 1940 l 4 sheets-sheet 5 July 14, 1942. w. E. JOOR, JR 2,289,913

STORAGE TANK Filed May 1,6, 1940 4 sheets-sheet 4` Y' Ik ZiZZzzmf/Z. JOOKJI:

Patented July 14, 1942 UNITE stares ii'l'hl'i OFFICE 15 Claims.

My invention relates to storage tanks and more particularly to storage tanks of large sizes intended for use in storing petroleum products and other volatile liquids and gases. The invention relates more specifically to tanks capable of maintaining superatmospheric internal pressures due to the vapor pressure or gas pressure of the Huid stored therein. The present invention may be considered as an improvement over the invention disclosed in my copending application Serial No. 140,132, led May 1, 1937, now matured into Patent #2,201,652.

Large tanks of the present type provide problems not met with in smaller tanks. These tanks are usually of comparatively large size, capable of storing from 1,000 to 100,000 or more barrels of liquid or its equivalent Volume of gaseous uids. Described briefly, the vessel mainly consists of a vertical cylindrical shell, a conical roof, and a conical bottom, all fabricated from steel plates. The lines of juncture between the roof and the shell and the bottom and the shell are supported by concrete rings which, because of their resistance to compression, prevent the failure of the tank at these po-ints. These concrete rings support a large part of the forces acting upon the juncture of the shell and roof and shell and bottom, and permit the vesselto be constructed of light and economical materials.

It is therefore an object of my invention to provide a novel liquid or gas receiver which may be constructed more economically than tanks for similar purposes now in use.

It is a further object of my invention to provide a tankwhich is an improvement over the tank shown in my copending application Serial No. 140,132;

A further object of the present invention is to provide a novel gas or liquid receiver which overcomes the disadvantages inherentin liquid and gas receivers as commonly constructed.

Further objects and advantages will appear from the following description, taken in conjunction with the accompanying drawings. In the drawings, in which similar characters of reference refer tosimilar parts throughout the several views:

Fig. 1 is a side elevation of a tank embodying my invention with portions thereof broken away to show in section the supporting rings and the juncture between the shell and bottom cone and shell and roof cone;

Fig. 2 is a sectional View on a larger scale of a portion of the upper concrete ring and the adjacent tank structure shown in Fig. .l with a force diagram applied thereto;

Fig. 3 is a View similar to Fig. 2, but showing a portion of the ring and tank structure at the juncture of the shell and lower cone;

Fig. 4 is a fractional View showing the top portion of a tank of somewhat different construction from that shown in Fig. l. In this view a portion of the tank is broken away to show the concrete ring and adjacent tank structure in section;

Fig. 4a. is a force diagram showing the principal forces acting in the `structure sh-own in Fig. 4;

Fig. 5 is a View similar to Fig. 4, but Showing a modified construction for joining the shell with a bottom cone;

Fig. 6 is similar to Fig. 4, but showing a still further modification of my invention;

Figs. 7, 8, 9 and l0 are views similar to Fig. 5, but showing additional modiiications of my invention.

Referring to Fig. 1, the tank indicated generally by the numeral 2li consists of a cylindrical shell 22 connected to a roo-f cone 24 and a bottom cone 26. As shown in Figs. 2 and 3, the roof and bottom cones are tightly secured and sealed tc the shell 22 by any suitable means such as by welding 0r riveting.

When a tank of this shape is filled with a gaseous fluid or a liquid and gaseous fluid under super-atmospheric pressure the stresses in the roof cone and bottom cone are of two general types. One of these is a stress in a circumferential direction which is usually called a hoop stress, and which acts so that failure brought about by this stress occurs along a slant height line from the base to the apex of the cone. The other type of stress acts within the roof and bottom plates in a direction parallel to the slant line of the cone. Failure caused by stresses of this type will become evident by rupture of the yplates of the roof or bottom in a circumferential line near the base of the cone where it is fastened to the end of the shell. Failure of this type may be more graphically described as the roof was blown ofi. Other important stresses which must be taken into consideration as affecting the strength of the line of juncture are the stresses which act in a Vertical direction in the side plates of the cylindrical shell and tendr to cause failure along a circumferential line and the hoop stresses which tend to split the shell vertically.

The stresses described above would cause a rapid failure of the vessel at the line of juncture of the shell and roof or shell and bottom if the steel plates along these lines of juncture were not anchored securely to some rigid object, such as the concrete rings as provided and described in this specification.

The directions of the stresses in the roof plates and the shell plates are shown respectively by the arrows SI and S2 in Fig. 2, while the directions of the stresses in the shell plates and the bottom plates are shown respectively by the arrows S-'a and S4 in Fig. 3. No attempt is made to show the hoop stresses in either the bottom roof or shell. In these force diagrams the length of the arrows represents the magnitude of the forces while their direction indicates the direction in which the forces are acting. The resultants of these forces are indicated by the arrows Rl and R2, while the similar and opposite forces necessary to balance the forces RI and R2 are indicated by the arrows Fl and F2.

To supply the balancing force FI, I provide the reinforced concrete ring 28 which encircles .the tank opposite the line of juncture of the roof and shell. A similar ring 30 encircles the tank at the plane of juncture of the bottom cone and shell and supplies the force F2. These rings are connected to the lines of juncture at frequent intervals by rods 32 and 34, respectively. These rods are embedded in the concrete rings and form part of the reinforcing therefor, and have their ends welded to the tank roof or tank bottom as the case may be. Since the reinforced concrete rings 28 and 30 are constructed sufficiently massive to resist any compressional forces brought about by the radial forces acting through the rods 32 and 34, it will be seen that these rods effectively prevent any distortion of the line of the plates at the line of juncture between the roof and shell and the bottom and shell. Preferably the central portion of the rods extending into the concrete rings from one or more loops encircling the circumferentially arranged reinforcing rods 36.

Although the concrete rings are capable of supporting extremely high compressive loads, they must be supported at frequent intervals in a vertical direction such as by brackets 38 which support the upper ring 28. These brackets are spaced at intervals around the tank near its top and are securely attached to the ring. It will be appreciated that the number and spacing of these brackets will depend to a great extent upon the cross-sectional shape of the ring itself. That is, a comparatively thin ring will require support at more frequent intervals than a ring having a greater slenderness ratio, that is, ratio of breadth to unsupported length about the horizontal neutral axis. The similar ring 30 surrounding the tank at the juncture of the shell and lower cone may be attached to the tank by brackets 4B as shown in Fig. 5, for instance, or as shown in Fig. l, the lower ring may be attached to piling or piers 42 spaced circumferentially around the tanks and lying beneath the rings 3l). In general, the piling arrangement for anchoring the rings 30 is to be preferred, since it more strongly resists the tendency of the lower ring to turn inside out should the tank settle faster than the ring. This tendency of the tank to settle faster than the ring is brought about by the greater loading on the ground beneath the tank than beneath the ring. In any event, the lower ring should be spaced from the tank sufficiently sothat the portion of the rods 34 between the ring and the tank will be at least six inches long. This is done so that any settling of the tank yresultant force R5.

relative to the ring 39 will not produce as great a shearing action on these rods as would be the case if the rods were shorter.

'Io prevent water from accumulating in the space ybetween the ring 30 and the lower portion of the shell and the attendant destructive effects due to corrosion or to freezing of the water, a ashing strip 43 is provided as shown in Fig. 1.

In the building of extremely large tanks or tanks adapted to carry large internal gas pressures or liquids having high vapor pressures, it is preferable to provide a top and bottom of somewhat modied design. The roof of such a tank is illustrated in Fig. 4. In this instance, the portion 44 of the roof jointed to the top of the cylindrical shell constitutes a frustum of a right circular cone having a comparatively acute apex angle. The larger base of this frustum is tightly secured to the top of the shell while the upper or smaller base of the frustum is attached to a conical cap 46 having a considerably more obtuse apex angle. This structure, while being more conservative of materials than a simple cone of similar strength, should be supported by the ring 28 in a somewhat different manner. As shown in the force diagram Fig. 4a, the forces acting upon the conical cap d6 are balanced by a rod 32a extending obliquely upward and inward from the ring 23 and attached to the conical cap 46 along its slant height. The other end of the rod 32h extends downwardly and is attached on the outside of the shell.

In the force diagram Fig. 4a, the forces S5 and S5 acting in the conical cap 46 have a resultant force R3 which is balanced by the force F3 acting through the rod 32a.. The forces S1 and S8, having a resultant R4 acting in the frusto-conical ring 44, and the force S9 in the shell, are balanced by the lower rod 32h, which supplies the force F4 acting oppositely from their Preferably as shown in Fig. 4, the rods 32a and 32h should intersect each other at approximately the neutral axis of the ring.

It may at times be desirable to use an end cap 45a. formed as a spherical segment, that is to say, the top and bottom are saucer-shaped. Such a structure is shown in Figs. 5, 6, and 8. When, as shown in Fig. '7, the end 4l' of the tank is formed as one half of an ellipsoid of revolution about its minor axle with the edge of the `ellipsoid being fastened to the end of the vertical cylindrical shell, the frusto-conical section 44a shown in Figs. 5, 6 and 8 may be omitted. The method of bracing this type of tank structure is similar to that shown in Fig. 4, excepting that a calculation of the stresses for each particular installation may show that the angle between the tie rods 34a and 34h should be slightly differently directed than those shown in Fig. 4. Figs. 5, 6 and 7 illustrate typical examples of arrangements adapted to the type of bracing shown in Fig. 4.

In Fig.v8 is illustrated an arrangement generally similar to that of Fig. 5, excepting that in Fig. 8, the frustoeconical ring 44a is a frustum of a cone having a considerably greater apex angle than that shown in Fig. 5. In this construction, the dome-shaped cap 46a is comparatively of considerably smaller diameter than the similar head shown in Fig. 5. For these reasons, the forces acting in the domed cap, in the frusto-conical ring, and in the cylindrical shell are more widely spaced apart than the similar forces acting in the tank shown in Fig. 5. I prefer, therefore, to use the Z-shaped concrete ring 30a with the top leg of the ring secured to the side wall of the tank by bars 34a, and to the frusto-conical section by bars 34D. The lower leg of the Z-shaped ring is similarly secured by bars 34e to the domed cap 46a to support the line of juncture between this head and the smaller base of the frustoconical ring 44a.

In Fig. 10 I have shown a tank having a base composed of an upper frusto-conical ring Md, an intermediate frusto-conical ring 44e, and a cap 44j. The cone of which the ring ddd is a frustum, has a smaller apex angle than the frusto-conical ring 44e while the cap 4f may be a cone of still greater apex angle, or it may be a segment of a sphere. In bracing such an arrangement, I prefer to use two separate concrete rings 30h and 3de. The ring 3th supports the line of juncture between the cylindrical side wall of the tank and the larger base of the ring Mid, and also the line of juncture beteween the frustoconical rings dfi-d and 44e in much the sarne manner as shown in Fig. 5. The ring @be is of smaller diameter and is located beneath the tank. This latter ring supports the line of juncture between the head llllf and the intermediate ring 4de.

In Fig. 9 I show a serviceable and practical design which may be manufactured at relatively low cost and which is particularly adapted for tanks intended to contain iiuids or gases under high pressures. drical side wall and a bottom closure member 453g shaped as a right circular segment of an ellipsoid of revolution about its minor axis. This end cap lilly is somewhat smaller in diameter than the diameter of the base of the shell so as to provide an annular opening between the two. The weight of this cap and the pressure of the liquid or gases bearing thereagainst are supported by the soil beneath the cap, while the cylindrical shell as supported by brackets $9 attached to the side walls of the shell and resting upon a concrete ring 4&3. This concrete ring serves both as a foundation to support the tank and as a radial load-bearing member. Tie rods extending through this ring are b-rought out and joined to the lower end of the vertical shell and along the slant height of the cap 44g in the manner previously described in connection with the other illustrated embodiments. To ll the annular space between the cap 4to and the cylindrical shell I provide a ring 5i) of comparatively light metal, shaped preferably as an approximation of a catenary. This ring is intended to carry only the weight or pressure ofy the material within the tank bearing thereagainst, and does not serve to support the cylindrical side wall or roof of the tank. I prefer that the brackets 49 be secured to the tank side wall and to the concrete ring by means of rods 52 and 54 respectively. The rods 52 are securely fastened to the tank wall at one end and extend outwardly horizontally through holes in the vertical leg of the bracket 49 and are welded at their opposite ends to the bracket at a distance of six inches or more from the tank shell. This arrangement securely holds the vertical leg of the bracket This tank consists of a cylinf against the shell wall while at the saine time slight horizontal sliding motion is permitted between the bracket and concrete ring, With this construction, the cylindrical tank is permitted to expand slightly within its elastic limits as greater pressures are brought to bear within the tank without the accompanying strong shearing stresses ordinarily set up at the line of juncture between the cylindrical shell and end wall of an ordinary tank.

Although I have shown several alternative types of tank construction in the drawings together with several alternative concrete supporting ring shapes, it will be appreciated that other shapes, types and forms are practical, and that the forms shown are given merely for the purpose of illustrating what may be considered as typical embodiments of my invention.

Having described typical preferred embodiments of my invention, what I claim as new and useful and desire to secure by Letters Patent of the United States is:

l. A storage tank comprising a cylindrical shell, an end cap secured and sealed to one end of the shell, said end cap having the form of a non-hemispherical surface of revolution, a reinforced concrete ring surrounding the line of juncture between the end cap and the shell and spaced outwardly therefrom, said ring being secured to the end cap and to the shell by radially arranged spaced-apart rods extending inwardly from the ring, said concrete ring together with said rods serving to oppose the slant height stresses in the end cap and the vertical stresses in the 4cylindrical shell.

2. A storage tank comprising a vertical cylindical shell, an end cap forming aroof secured and sealed to the upper end of the shell, said roof having the form of a non-hemispherical surface of revolution, an upper reinforced concrete ring surrounding the line of juncture between the roof and the shell and spaced outwardly therefrom, said ring being secured to the roof and to the shell adjacent the line of juncture therebetwen by radially arranged spaced-apart rods extending inwardly from the ring, a second end cap forming a bottom for the tank secured and sealed thereto, said bottom having the form of a non-hemispherical surface of revolution, a lower reinforced concrete ring surrounding the tank at the line of juncture between the cylindrical surface and the bottom and spa-ced outwardly from the cylindrical surface, said lower reinforced concrete ring being joined to the bottom and the shell adjacent the line of juncture therebetween by means of radially arranged spaced-apart rods extending inwardly from the ring, said concrete rings together with said rods serving to oppose the slant height stresses in the top and bottom and the Vertical stresses in the cylindrical shell.

3. A tank as called for in claim 2 wherein the reinforced concrete ring is so spaced vertically that the horizontal neutral axis of a vertical cross-section of the ring lies substantially in the plane of the resultant of the vertical stresses in the 4cylindrical shell and the slant height stresses in the end cap'.

4. A storage tank comprising a vertical cylindrical shell, a roof secured and sealed to the upper end of the shell, said roof having the form of a surface of revolution and intersecting said shell at an angle, an upper reinforced concrete ring surrounding the line of juncture between the roof and the shell and spaced outwardly therefrom, said ring being secured to the roof and to the shell adjacent the line of juncture therebetween by radially arranged spaced-apart rods extending inwardly from the ring, a bottom for the tank secured and sealed thereto, said bottom having the form of a surface of revolution and intersecting said shell at an angle, a lower reinforced concrete ring surrounding the tank at the line of juncture between the cylindrical surface and the bottom and spaced outwardly from the cylindrical surface, said lower reinforced concrete ring being joined to the bottom and the shell adjacent the line of juncture therebetween by means of radially arranged spaced-apart rods extending inwardly from the ring, said concrete rings together with said rods serving to oppose the slant height stresses in the top and bottom and the vertical stresses in the cylindrical shell, and means secured to the cylindrical shell to support the upper ring.

5. A storage tank comprising a vertical cylindrical shell, a roof secured and sealed to the upper end of the shell, said roof having the form of a surface of revolution and having a portion thereof oblique to'said shell, an upper reinforced concrete ring surrounding the line of juncture between the roof and the shell and spaced outwardly therefrom, said ring being secured to the roof and to the shell by radially arranged spacedapart rods extending inwardly from the ring, a bottom for the tank secured and sealed thereto, said bottom having the form of a surface of revolution and having a portion thereof oblique to said shell, a lower reinforced concrete ring surrounding the tank at the line of juncture between the cylindrical surface and the bottom and spaced outwardly from the cylindrical surface, said lower reinforced concrete ring being joined to the bottom and the shell adjacent the line of juncture by means of radially arranged spacedapart rods extending inwardly from the ring, said concrete rings together with said rods serving to oppose the slant height stresses in the top and bottom and the vertical stresses in the cylindrical shell, and means to support the lower ring.

6. A tank as called for in claim 5 wherein the means to support the lower ring comprises a row of piling or piers fixed in the ground beneath the ring.

7. A tank as called for in claim 5 wherein the means to support the lower ring comprises brackets attached to the ring and xed to the vertical side wall of the cylindrical shell.

8. A storage tank comprising a vertical cylindrical shell, a roof secured and sealed to the upper end of the shell, said roof having the form of a surface of revolution, an upper reinforced concrete ring surrounding the line of juncture between the roof and the shell and spaced outwardly therefrom, said ring being secured to the roof and to the shell adjacent the line of juncture therebetween by radially arranged spaced-apart rods extending inwardly from the ring, a bottom for the tank secured and sealed thereto, said bottom having the form of a surface of revolution, a lower reinforced concrete ring surrounding the tank at the line of juncture between the cylindrical surface and the bottom and spaced outwardly from the cylindrical surface, said reinforced concrete ring being joined to the roof and the shell adjacent the line of juncture therebetween by means of radially arranged spacedapart rods extending inwardly from the ring, said concrete rings together with said rods serving to oppose the slant height stresses in the top and bottom and the vertical stresses in the cylindrical shell, and brackets extending between one of the rings and the cylindrical side wall of the tank, securing means to secure the brackets to the ring and to the cylindrical side wall of the tank, said securing means adapted t-o permit slight relative motion between the ring and the side wall of the tank.

9. A tank as called for in claim 2 wherein at least one of the end caps is formed as a cone.

10. A tank as called for in claim 2 wherein at least one of the end caps is formed as a frustum of a cone joined at its smaller base to a different surface of revolution.

11. 4A tank as called for in claim 2 wherein at least one of the end caps is formed as a frustum of a cone joined at its smaller base to a cone, said cone having a larger apex angle than the apex angle of said frustum.

12. A storage tank comprising a Vertical cylindrical shell, an end cap secured and sealed to one end of the shell, said end cap having the form of a surface of revolution composed of a plurality of surfaces of revolution joined together, a reinforced concrete ring surrounding the tank at the line of juncture between the cylindrical surface and the end cap and spaced outwardly from the cylindrical surface, said reinforced concrete ring being joined to the end cap and the shell adjacent the line of juncture therebetween by means of radially arranged spaced-apart rods extending inwardly from the ring, a second and smaller reinforced concrete ring surrounding the line of juncture between contiguous sections of the end cap and spaced outwardly therefrom, the last said reinforced concrete ring being joined to the tank by means of radially arranged spacedapart rods extending inwardly from the ring and joined to the end cap adjacent the said line of juncture, said concrete rings together with said rods serving to oppose the slant height stresses in the end cap and the vertical stresses in the cylindrical shell.

13. A storage tank comprising a vertical cylindrical shell, an end cap secured and sealed to one end of the shell, said end cap having the form of a surface of revolution composed of a plurality of surfaces of revolution joined together, a reinforced concrete ring surrounding the tank and having a portion thereof opposite the line of juncture between the cylindrical surface and the end cap and spaced outwardly from the cylindrical surface and a second portion opposite the line of juncture of contiguous sections of the end cap and spaced outwardly therefrom, the first said portion being joined to the end cap and the shell adjacent the line of juncture therebetween by means of radially arranged spaced-apart rods extending inwardly from the ring and the second portion of said ring being joined to the tank by means of radially arranged spaced-apart rods extending inwardly therefrom and joined to the end cap adjacent said line of juncture of contiguous portions, said concrete ring together with said rods serving to oppose the slant height stresses in the end cap, and vertical stresses in the cylindrical shell.

14. A storage tank comprising a vertical cylindrical shell, a bottom for the tank, said bottom being supported upon the ground beneath the tank and having the form of a right circular segment of an ellipsoid of revolution about its minor axis, the diameter of said bottom being less than the diameter of the shell to provide an annular space therebetween, a reinforced concrete ring of the shell by the ring, tie rods extending from said ring to said shell and to said bottom to oppose the stresses in the bottom and shell, and a relatively thin annular member secured to the shell and to the bottom to close said annular space, said annular member having a curvature l0 in a radial plane approximating a catenary.

15. A storage tank comprising a vertical cylindrical shell, a bottom for the tank, said bottom being supported upon the ground beneath the tank and having a diameter less than the diam 15 eter of the shell to provide an annular space therebetween, a reinforced concrete ring supported upon the ground and surrounding the lower end of the shell and spaced radially outwardly therefrom, means mounted on the ring and secured to the shell to support the Weight of the shell by the ring, tie rods extending from said ring to said shell and to said bottom to oppose the stresses in the bottom and shell, and a relatively thin annular member secured to the shell and to the bottom to close said annular space, said annular member having a curvature in a radial plane approximating a catenary.

WILLIAM E. JOOR, JR.

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