US2696930A

US2696930A - Seal hanger for floating roof tanks

Info

Publication number: US2696930A
Application number: US243413A
Authority: US
Inventors: Frederick D Moyer
Original assignee: Chicago Bridge and Iron Co
Current assignee: Chicago Bridge and Iron Co
Priority date: 1951-08-24
Filing date: 1951-08-24
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14

Description

Dec. 14, .1954 F. D. MoYl-:R 2,695,930

SEAL HANGER FOR FLOATING ROOF TANKS Filed Aug. 24, 1951 5 Sheets-Sheet 1 f? y q@

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25 ,60

m WN DCC. 14, 1954 F, D, MOYER SEAL HANGER FOR FLOATING ROOF TANKS s Sheets-sheet 2 Filed Aug. 24, 1951 3 Shee'ts-Sheet 5 Filed Aug. 24, 1951 .ml H, 11

United States Patent@ HANGER FOR FLOATING ROOF TANKS Frederick D. Moyer, Chicago, lll., assignor to Chicago Bridge & Iron Company, a corporation of illinois Application August 24, 1951, Serial No. 243,413

1 Claim. (Cl. 220-26) This invention relates to a liquid storage tank, and more particularly to a new and improved shoe supportlng means for use in conjunction with a tloatmg root 1n a liquid storage tank.

VL iquid storage tanks having a floating roofr therein are 1n wide use. smaller diameter than the tank, leaving an annular space about the root'. This space is sealed by a flexible seal extending between the root` and a sealing ring. The sealing ring is generally a metal member made of one or more shoes each in sliding contact with the side walls of the tank.. Many devices have been proposed for supporting the shoes of the sealing ring against the side walls, however many have been cumbersome and complicated in nature while others have not given the simplicity of operation desired.

The present invention is concerned with a new seal hanger having in a single unit means for supporting the shoes and incorporated or separate means for centering the roof within the tank. ln accomplishing this result the hanger also supports the shoes'without vertical movement relative to the roof. One of the principal features of the hanger is that it permits the roof to rest on the bottom of the tank in its lowermost position and to oat higher in the tank so as to utilize more 'tank capacity.

The invention will be described with reference to an embodiment illustrated in the accompanying drawings in which Fig. 1 is a broken vertical sectional view through the side wall of the tank showing the floating roof, a shoe of the sealing ring and one of the hangers comprising this invention. The roof as shown is oating upon the liquid stored in the tank. Fig. 2 is a fragmentaryv elevational section taken as indicated by line 2-2 on Fig. l. Fig. 3 is like Fig. l showing a different spring arrangement, Fig. 4 is a fragmentary elevational section taken as indicated by line 4 4 on Fig. 3, Fig. 5 is like Fig. l showing a spring separate 'from the hanger, and Fig. 6 is a fragmentary sectional view taken along line 6--6 in Fig. 5.

Thev drawings illustrate a storage tank having a bottom -10 and side wallsy 11 secured together in a manner to contain a stored liquid 12. A iloating roof 13 having an upper deck 14 and a lower deck 15 is shown iloating in the stored liquid 12. The decks are joined at the periphery of the roof by a substantially vertically positioned rim 16 secured in liquid-tight relation to both of the decks. A sealing ring 17 extends around the lloating roof and comprises shoes 18 in sliding contact with the side walls 11 of the tank. The upper edges 19 of the shoes 18 are inclined inwardly in order to ride the sealing ring over any irregularities or protrusions in the tank shell 11. A ilexible fabric seal 20 is secured to the edges 19 of the sealing ring and to the upper peripheral edge of the roof at 21. The space between the floating roof and the tank shell is thus sealed by the fabric 20.

The particular hanger of this invention is adapted to support the shoes 18 against the side walls of the tank and to carry the sealing ring along with the roof as it rises and falls with the liquid level within the tank. The hanger comprises a supporting bar having two like

portions

26 and 27 as seen in Figs. 2 and 4. It is intended that the separate bars of the supporting bar 25 act as a unit, and to this end the upper ends of the individual bars are each pivoted to a supporting bracket or lugs 28 secured to the upper portion of the Generally the root is of slightly to the lugs 2S secured to the floating roof.

rim 16 of the floating roof.

Individual pivot pins

29 and 30 are provided on the lugs 28 for pivotally securing the individual members of the supporting bar 25. The lower end 31 of the supporting bar is positioned adjacent to but slightly spaced from the shoe 18. The surface of the bar facing the shoe is curved as indicated at 32 so that movement of the bar about its pivot will maintain the spacing of the lower end from the shoe.

The shoes are supported and carried by the supporting bar 25 to the floating roof. To accomplish this a shoe bar 35 is pivotally connected at 36 to a lug 37 secured to the shoe. The shoe bar is an individual metallic bar which extends from its pivotal connection to the shoe downwardly in the space between the roof and shoe to the lower portion of the roof. A rod 38 is secured in the lower end of the shoe bar 35 so as toV extend outwardly from either side of the bar. This rod 384s positioned between the legs of a fixture 39 secured to the lower portion of the root' for the purpose of guiding the lower end of the shoe bar in a vertical path with respect to the roof. The lixture 39 is constructed so as to have a vertical slot 40 formed of either side of the shoe bar 35 for the reception of the rod 38. The slot 40 is of suicient length to insure that the rod 38 will remain therein and yet not bind against the rod to limit relative movement of the roof and shoe bar.

The supporting bar and shoe bar above described are pivotally connected intermediate their ends by a pivot pin 43 extending between the

members

26 and 27 of the supporting bar and through the shoe bar 35. The pin 43 `isplaced at substantially equal distances from the pivotal connection of each of the bars to the roof and shoe respectively. Thus the weight of the shoe is carried by the shoe bar to the pivot pin and from there The shoes will not move vertically with respect to the roof with horizontal movement of the roof within the tank since the lower ends of both bars may move vertically without restricting the horizontal movement of the pivotal connections of the respective bars. It will be understood n that the sealing ring comprising the shoes 18 is supported at intervals by hangers such as illustrated in the figures of the drawings.

It is desirable that the roof be centered within the tank. Due to wind pressure and unequal loading, however, the roof often has a tendency to move toward one portion of the side wall of the tank. In the present 1nvent1on means are incorporated within the hangers to exet a force tending to center the roof within the side wa s.

ln Figs. l and 2 this force is supplied by means of a coil spring Sil wound about the pivot pin 43 securing the supporting bar to the shoe bar. The

free ends

51 and 52 of the spring 50 engage the

separate members

26, 27 of the supporting bar. A center portion 53 of the spring is positioned to engage the shoe bar in opposition to the force supplied by the coils of the spring to the

free ends

51, 52. The coils of the spring thus supply a force which tends to bring the bars into horizontal parallelism while at the same time forcing the shoe and roof apart. The spring is so chosen that small movement of the relative positions of the ends with respect to the center portion 53 changes the force applied by the spring against the bars. Thus as the roof moves toward the side wall of the tank the spring is wound tighter, thus permitting it to exert a greater force on the bars. On the diametrically opposite side of the tank the ends and center portion of the spring on the hanger bars are moved in the opposite direction, thereby lessening the force applied by that spring against the hanger bars. This combination of increasing the force on one side of the roof, with the roof moving toward the side wall at that point, and a decreasing of the force of the spring on the opposite side of the roof provides unbalanced forces acting to return and maintain the roof centered within the tank.

In Figs. 3 and 4 of the drawings, the force for pressing the shoes against the side walls and for centering the roof Within the side walls is provided by a spring 55 which is secured to a lug 56 on the rim 16 of the floating roof and a similar lug 57 secured to the lower portion of the shoe supporting bar 35. The spring 55 acts in tension and attempts to bring the shoe supporting bar 35 and supporting bar 25 into horizontal parallelism. The action of the spring S is substantially the same as the coil spring 50. The hanger, by the action of the levers, supports the weigh-t of the sealing ring regardless of the position of the ring from the roof, and the springs each acting' in its own manner provide the outward push to press the sealing. ring against the sidey wall and at the same time provide the forces necessary to center the roof within the tan-k.

Since the pivotal connections of the shoe supporting bar to the sealing ring and of' the supporting bar 25 to the root arey in substantially the same horizontal plane, the force applied by the springs in pressing the sealing ring outwardly'` against the side wall is independent of any vertical force in the plane of the shoe.. Thus, an increase in the vertical weight of the shoe'v due to friction or of freezing of moisture between the shoe and side Wall will not increase or decrease or otherwise affect the outward force pushing the sealing ring against the side wall.

In the` device as illustrated in Figs. 5 and 6i, the force for pressing the shoes against the side walls is provided by safety pin-like springs 60k which have one leg 61 pivotally secured to the rim 16 ofthe roof at 62 extending downwardly from the point of pivotal connection to the roof to a coil 63. The other leg 64 extends upwardly from the coil 63 and is biased against a hook 65y secured to the end of the mounting bar 66 which is pivotall'y secured to the. arm 36 of the hanger. This spring has its

legs

61 and 64 extended downwardly generally in a ver tical radial plane betweeny the roof and shoes and exerts an outward force against the shoe reacting against the: rim of the roof to press the shoes against the side walls 11.

The hangers are generally used with a mounting bar 66 so that the hanger will support the sealing ring 18 adjacent ilexuresI therein.. ln Fig'. 6 these ilexures are clearly shown at 67 with a mounting bracket 68 secured to the shoey adjacent the flexure. The arm 35 of they hanger is secured by means of a clevis 69 to the center of the mounting bar 66, and in all other respects operates in the same manner as described with relation to Figs. 1-4. Ordinarily a spring 60S will be secu-red to each end of the mounting bar 66 so that two springs will be used with each hanger.

In the operation.. of the embodiment of' Figs. 5 and 6, the hanger serves to support the shoes with relation to the roof and the springs act independently of the shoes to press the sealing ring against the side walls. Asthe roof moves toward the` side Walls, the force. applied by the springs 60 increases, thereby providing a centering. action or force to maintain the roof in a generally concentric position within the side walls of the tank. By removing the fabric seal 20 the springs 60 and hanger' may be independently removed and'. replaced.

An important feature of this invention is the provision of a hanger which permits the oating roof to rest in its lowermost position on the bottom of the tank. This is possible since both the supporting bar and the shoe bar are positioned entirely within the space between the peripheral rim of the roof and the side wall of the tank.

At the same time the hanger may be completely beneath the seal fabric 20' and is thus' out of Contact withthe ele ments. Also important is the fact that the hanger not only supports the shoes but maintains a pressure forcing the shoe tightly against the side walls of the tank. This is accomplished without permitting relative vertical movement of the shoes with respect to the roof. The lower ends 31 of the supporting bar previously mentioned are maintained a short distance from the shoe and will contact the shoe to limit its movement outwardly from the sidey wall.` AlsV the shoe moves over any irregularities or protuberances in the side wall, it will sometimes tip; and in such cases the shoe may contact the lower ends 31. When the roof is in its uppermost position with the tank substantially full of liquid, the shoes may project above the side wall of the tank in which case the lower ends 31 of the supporting bars prevent the shoes from tipping substantially out of vertical position.

While we have shown and described our invention in itsl preferred embodiment, it is` to be understood that it is capable of' many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed inthe appended claim.`

I claim:

In a liquid storage tank having a floating roof and one or more shoes adapted to slidably contact the inner side walls of the tank, means for supporting the shoes against the side walls including as supporting bar pivotally attached to the roof and extending' downwardly in the space between. the. root and the tank from the point of attachment tol the roof to adjacent said shoe, a shoe bar pivotally attached to the shoe at one end in substantially the same horizontal plane as the point of connection of said supporting bar to the roof, said shoe bar extending downwardly from the shoe connection and connected at the other end to the roof', said' connection to the roof permitting vertical movement and preventing horizontal movement of saidother end with respect' to the roof, a pivot pin swingably connecting said supporting bar and shoe bar intermediate their respective ends and a tension spring extending upright along the side of the roof having one end secured to the roof and the other end secured to the lower portion of the shoe bar, said spring exerting a force on said bars tending to move said roof andk shoeaway from each other.

References Cited in the file of -this patent UNITED STATES PATENTS Number Name Date 1,426,998 Leland et al Aug. 22, 1922 1,668,792 Wiggins May 8, 1928 1,673,984- Kuhl lune 19, 1928 1,930,953 Hampton Oct. 17, 1933 2,318,135 Wiggins May 4, 1943 2,471,404 Boberg May 31, 1949 2,542,444 Wilkin Feb. 20, I 2,587,508 Moyer et al Feb'. 26, 1952 2,660,237 Graham Iune 10, 1952