US2586813A

US2586813A - Floating roof seal

Info

Publication number: US2586813A
Application number: US218642A
Authority: US
Inventors: Fred L Goldsby; Clifford M Orr
Original assignee: Chicago Bridge and Iron Co
Current assignee: Chicago Bridge and Iron Co
Priority date: 1951-03-31
Filing date: 1951-03-31
Publication date: 1952-02-26
Anticipated expiration: 1969-02-26

Description

1952 F. GOLDSB'Y ET AL 86,813

' FLOATING ROOF SEAL Filed March 51, 1951 5 Sheets-Sheet l 1 7 6671. $011 5; 675' pref/71707");

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1952 F. L. GOLDSBY ETAL FLOATING ROOF SEAL 5 Sheets-Sheet 2 Filed March 51, 1951 J w H. 5 a 3 w 1%. WM

IIIHHM Feb. 26, 1952 Filed March 51 1951 F. GOLDSBY ET AL FLOATING ROOF SEAL 5 Sheets-Sheet Ll l.l

l atented F eb. 26, 1952 UNITED s'rATss PAT;

NT OFFICE FLOATING ROOF SEAL of Illinois Application March 31, 1951, Serial No. 218,642

15 Claims. 1

This invention relates to a floating roof tank, and particularly to a seal for sealing the area between the floating roof and the shell of the tank.

This application is a continuing application of our copending cases Serial No. 636,442 filed December 1, 1945 and Serial No. 639,947 filed January 9, 1946, both of which are now abandoned.

Floating roof tanks are generaly used for the storage of volatile liquids where the roof floats on top of the liquid. There is ordinarily an annular area between the edge of the floating roof and the shell of the tank. In order to avoid evaporation losses and to prevent contamination of the contents of the tank by dirt, rain water, and the like, it is necessary that a sealing means be provided, sealing off this area. Various types of sealing means have been proposed in the past but many of these have been unsatisfactory because of excess weight, bulk, and the like, and many have been diflicult to install and maintain.

A new type sealing means has been developed that employs a flexible sealing ring to contact the shell of the tank with hanger means to support the ring in sealing contact with the shell. The new sealing rin is so constructed that it readily slides up and down the tank shell, as the roof rises and fails, and is made quite flexible so as to follow the contour of the shell if the shell should get out of round. The new hanger means supports the sealing ring in position and provides outward pressureto holdthe ring against the shell at all times. The hanger means is preferably rotat-able so that sideways shifting of the ring may be accommodated. There is also preferably provided means tending to return the hanger means to its original position when the sealing ring has shifted from its normal position.

One of the chief advantages of the new sealing ring is that it provides very close contact with the shell of the tank, and this contact is maintained when the ring is supported at spaced points.

The invention will be described as related to the embodiments set out in the accompanying drawings. Of the drawings Fig. 1 is a fragmentary plan View of a floating roof tank embodying the invention; Fig. 2 is a vertical section taken along line 2--2 of Fig. 1; Fig. 3 is a horizontal section showing one curvature arrangement of the sealing ring when there is no outward pressure applied; Fig. 4 is a Vertical section taken along line 44 of Fig. 3; Fig. 5 to 8 inclusive illustrate individual steps of a preferred method of forming fiexures in the new sealing ring; Fig. 9 is a horizontal section taken along line, 99 of Fig. 2;;

Fig. 10 is an elevation showing a step in an alternate method of forming a sealing ring; Fig, 11 is an elevation showing the final step in said meth-' od; Fig, 12 is an elevation showing the completed sealing ring. formed by said alternate method; andFig. 13 is a section taken along line I3 3 of Fig. .12. i

The floating roof tank shown in the accompanying drawings comprises a shell I0. and a floating roof H therein. The space between the edge of the floating roof and'the shell of the tank is provided with a sealing means to prevent evaporation and contamination of the stored liquid.

The sealing means shown comprises an annular sealing ring l2 contacting the inner surface of the shell It and supported by hanger means it mounted around the edge of the floating roof I l. The annular sealing ring 12 is provided with spaced vertical flexuresl 4 extending between top [5 and bottom It marginal areas. Thesemarginal areas are preferably bent back from the vertical and away from the shellin order to permit the sealing ring to pass over raised sections on the inner surface of the shell.

The annular sealing ring is preferably made of ordinary sheet metal. but may be madeof stainless steel if desiredand in the latter case may have a thickness of not more than about fg inch. The stainless steel used can be any one of a. wide variety of different type alloys. The stainless steel is a chromium-iron-nickel alloy that has been heat-treated to make a true solid-solution alloy. Stainless steel has been found to make a superior type sealing ring because it is very hard, and thus resists frictional wear. It is also quite flexible and will bend and slide around welding protuberances, rivets, and the like. It is resistant to corrosion, which resistance is a very important feature, as many of the volatile liquids stored in floating roof tanks are somewhat corrosive. Stainless steel is very strong and has a yield point considerably greater than that of mild steel and only a little less than that of spring steel.

The flexures M are formed in the sealing ring i2, and they extend away from the body portion of the sealing ring. The flexures have the form of loops formed in the sheet metal with inner portions ll adjacent each other in order to allow for expansion and contraction of the sealing ring. The flexures may be generally rounded, as indicated .at 14. These flexures not only permit expansion and contraction of the ring, but also permit the ring to bend easily. One method of making the flexures is shown in Figs. to 8 inclusive. In this method a cutout portion I9 is formed at one edge of the ring. A second similar cut-out portion is formed on the opposite edge of the ring and opposite the first portion. A third cut-out portion is formed extending from the inner end of the first portion, and a fourth cut-out portion similar to the third is formed adjacent the other edge of the ring. The third and fourth cut-out portions have one edge 2| substantiall parallel to its edge of the ring, and have another edge 22 of arcuate shape with the are extending away from its edge of the ring. The fourth cut-out portion is formed in the same manner. The flexure I4 is formed by bringing the opposite ends of the third and fourth cut-out portions adjacent each other to form a fold. The overlapping

edges

23 and 24 adjacent the first and second cut-out portions are left free so as to have sliding movement relative to each other.

:This method forms a flexure l4 having top 25 and bottom 26 edges sloped toward each other at an acute angle to the main body portion of the ring. It is preferred that the top and bottom ends be thusly sloped, although such construction is not absolutely necessary and in some forms only one end, such as the top, will be sloped.

Any type of hanger means desired may be used to support the new sealing ring. The hanger means shown comprises a T bar 21 extending between adiacent fiexures l4 and attached to the sealing ring l2 by means of short brackets 28. The T bar 21 is loosely held by the brackets 23 in order to permit bending of the section 2:) ,of the sealing ring between adjacent flexures horizontal pipe 33 is provided having a yoke end 34 with one leg of the yoke above and the other leg below the horizontal portion. A threaded bolt 35 is loosely held in the yoke 34 and engages threads in the horizontal portion 32. The

bolt 35 extends above the yoke 34, and a spring 36 is located between the upper end of the bolt and the top surface of the upper yoke leg. There is also provided a second pipe 31 of larger diameter than the first pipe 33, and through which the first pipe extends. The first pipe 33 is provided with a roller 38 held in top and botton slots 39 in the first pipe 33 and mounted by means of pin 40 for rolling contact with the inside surface of the second pipe 31. On the end of the first pipe 33, opposite the yoke 34, there is located a cap 4| closing this end of the pipe. On the corresponding end of the second pipe 31 there is located an annular cap 42 having a hole 43 therein through which the first pipe 33 extends. The hole 43 is of such size that the cap 4| on the end of the first pipe will contact the annular cap 42 when the first pipe has been extended its full distance toward the shell of the tank. Between the annular cap 42 and the roller 38 there is provided an annular collar 44 on the first pipe 33. This collar is of such diameter that it slides freely within the second pipe 31. Between the annular cap 42 and the collar 44 there is provided a spring 45 normally urging the first pipe 33 toward the shell of the tank.

In order to support the second pipe 31 and the first pipe 33 there is provided a third pipe 46,

attached near the front end of the second pipe 31 and extending downwardly therefrom. This third pipe abuts the edges of a hole 48 in a horizontal base plate 41. The third pipe 46 is rotatably held concentric to the hole 48 by providing a smaller concentric. pipe 49 extending through the hole 48- with the concentric pipe being attached to the third pipe as by welding 50. On the bottom of the concentric pipe 49 there are located three lugs 5| in order to hold the assembly in place. In assembling the structure the lugs 5| may be inserted through cut-out portions 52 at the edge of the hole 48. The lugs 5| and cut-out portions 52 are arranged so that they will not coincide when the hanger means is in use.

The base plate 41 is supported on vertical threaded posts 53 mounted on the deck of the floating roof. The base plate is held on the post by means of nuts 54 on either side of the base plate so that the position of the plate may be easily regulated.

In order to take up some of the load of the sealing ring l2 a spring 55 is provided extending substantially vertically from the rear of the base plate 41 to the second pipe 31. The spring is attached to the base plate by means of a hole 56 at the rear of the plate and is attached to the pipe 31 by means of a downwardly extending eye 51. Any type sealing means may be provided between the sealing ring l2 and the edge of the floating roof ll. As shown, this sealing means comprises a flexible sealing member 58 made of fabric impregnated with a flexible impervious material. The sealing member 58 is attached to the sealing ring by means of bolts 59 extending through a washer bar 60 and the sealing ring E2. The roof edge of the sealing member 58 is attached to the roof by means of hooks 6| holding wedges 62 pressing against a circular rod 63 in contact with the roof edge of the sealing member 58. Any other means of fastening may be used if desired.

The sealing ring 12 may also be provided with any type of secondary seal (not shown) for sealing any areas between the shell I0 and the sealing ring I2.

The spring 36 around the top end of bolt 35 is provided so that each of the hanger means l3 will carry its proportionate share of the load of the sealing ring. the position of the T bar 21 with respect to the first pipe 33 and may be used to even up the load on all hangers. The spring 45 around the first pipe 33 serves to hold the sealing ring tightly against the shell [0. The spring 55 between the base plate 41 and the second pipe 31 applies a vertical load to the inner end of the second pipe and serves to at least partially balance the load of the sealing ring. If the sealing ring should move to one side of its normal position the spring 55 also applies a force tending to res-tore the pipe 31 to a radial position. The spring 55 reduces the bending moment at the base plate 41 and helps to prevent breakage of the hanger. The spring 55 is of such strength that the moment when the roof is moving up is approximately the same but of opposite sign as the moment when the roof moves down. This is accomplished by providing a spring that would resist a load equal to the weight of the sealing ring. This, of course, is not essential, and the spring load could be made such that the moment at the connection at the base The bolt 35 serves to adjust varying magnitude. The spring, or any similar connectingmeans, may be omitted if desired.

The base plate 4! is mounted onthe threaded posts 53* so that each plate can be levelled and adjusted vertically. Forproper operation it is necessary that all the hanger means be in a substantially horizontal plane. Since the top of the floating roof may vary somewhat from a hori- Zontal plane the vertical adjustment is required. Since the pipe 37 is mounted for rotational movement in a horizontal plane it is necessary that the base plate be kept substantially level, and thus a minimum of three posts 53 is required.

The sealing ring is preferably constructed so that portions of the ring between adjacent flexures should have radii of curvature, when unrestrained, difiering from the radius of the shell. The hanger means will then be arranged to press against the ring at points substantially adjacent where the distance between the shell and the ring tends to be the greatest. points adequate contact may be maintained over substantially the entire surface of the sealing ring. This principle of construction is shown in Fig. 3, where the radius of the portion 29 is less than the radius of the shell and the hanger means press against the ends of the portion 29. If desired, however, the sealing ring may be of substantially the same radius of curvature as the radius of the shell. Although the sealing means has been shown with the hanger pressing against the shoe at areas between flexures the hangers may be constructed to press at the fiexures themselves if desired. As shown, one hanger means is shown operating between two adjacent flexures. If desired, however, one may be used for each flexure or for any combination of flexures. It is preferred, however, that at least one hanger be provided for not more than three flexures.

Where secondary seals are used these seals may be attached to the top marginal area [5 of the sealing ring. They may be held on the sealing ring itself, or may be held by upstanding brackets attached to the ring. Joints between individual sections of the sealing ring may be joined in any manner desired. Thus the ends of adjoining sections may be welded, riveted-or bolted together; they may be bent and welded, riveted or bolted; they may be interlocked and clamped; or may be joined by flexible sealing members.

In most tanks it is desirable to provide guide "means so that the sealing ring will travel in a substantially vertical path only. These guide means may be any type desired. One form is to provide a vertical bar attached to the inner surface of the shell and toprovide a crimped portion in the sealing ring passing around the bar. The combination of crimped portion and'bar will prevent any substantial lateral movement of the sealing ring. Such arrangements may not be necessary on all tanks, however.

The sealing ring may be formed with the fiexures terminating short of the top bent marginal area, if desired, and the overlapping portions 23 and 2d at the marginal areas may be eliminated if desired. An alternate method of forming sections of the sealing ring is shown in Figs. to 12, inclusive. Here the sheet metal 64 is formed with relatively deep slots 65 along its top edge and extending below the bend line 56. Shallow slots 6? are formed along the top edge and extend substantially to the bend line 63. On the bottom edge slots 6& are formed immediately below the wide top slots 55 but these bottom slots extend only substantially to the By pressing at these v bottom bend line 69; Narrow slots 10 are formed between wide bottom slots 68. The fiexures H are then formed by bringing the sides of the wide top and bottom slots 55 and 68 adjacent each other. The top and bottom marginal areas are bent back along the bend lines 66 and $9. In this form of construction it is preferred that the'top edge of the ring be turned over, as shown in Fig. 12, so as to remove sharpedges.

In the above method of making a sealing ring there will be a long narrow slot 72 above each fiexure ll. It is preferred that these slots be sealed over with a sheet of flexible impervious material 13 such as neoprene. The sheets may be cemented, bolted, riveted, or otherwise attached to the ring.

In all forms of flexures it is sometimes preferred that the opening in each fiexure be closed with a resilient closure. Thus in Fig. 12 there is shown a plug 14 ofneoprene sponge or the like extending into the fieXure ll. A flap 15 of neoprene or the like is cemented or otherwise attached to the top of the plug 14.

Where a secondary seal is desired for use with the sealing ring of this invention the secondary seal may have substantially the same form as the sealing ring but will preferably be smaller in width. It should be of some resistant material such as stainless steel.

Where the shell of the tank has a flat side the section of sealing ring on this portion will also be flat. Thus all sections of sealing ring may be considered to have a curvature between zero and a finite distance.

Having described the invention as related to the embodiments shown in the accompanying drawings, it is intended that the invention be not limited to any of the details of description unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

We claim:

1. A seal for a floating roof tank or the like, comprising a sealing ring of flexible sheet metal to be located around the floating roof, a plurality of circumferentially spaced substantially vertical flexures formed in said ring and extending in the aggregate from a point near one edge to a point near the other edge of the ring to render said sealing ring difierentially expansible horizontally and rigid vertically, the portion of the ring between adjacent pairs of flexures constituting a shoe extending substantially from one marginal edge of the ring to the other marginal edge and adapted to have rubbing engagement with the shell of the tank, and said shoe having a radius of curvature when unrestrained difiering from the radius of curvature of the shell.

2. The seal of claim 1 in which said sheet metal is stainless steel.

3. The seal of claim 2 in which said stainless steel has a thickness of not substantially greater than inch.

4. A seal-as set forth in claim 1 in which the ring is supported by hangers having points'of attachment at each flexure.

5. A seal as set forth in claim 1 in which the sealing ring is supported by hangers spaced apart by one to three fiexures.

6. A seal as set forth in claim 1 in which the sealing ring is supported by supporting means immediately adjacent the flexures.

7. A seal as set forth in claim 1 in which the sealing ring is supported by supporting means immediately adjacent the flexures and a support is provided immediately adjacent each fiexure.

8. A seal for a floating roof tank or the like, comprising a sealing ring of flexible sheet metal to be located around the floating roof, a plurality of circumferentially spaced substantially vertical flexures formed in said ring and extending in the aggregate from a point near one edge to a point near the other edge of the ring to render said sealing ring differentially expansible horizontally and rigid vertically, the portion of the ring between adjacent pairs of flexures constituting a shoe extending substantially from one marginal edge of the ring to the other marginal edge and adapted to have rubbing engagement with the shell of the tank, and said shoe having a radius of curvature when unrestrained substantially less than the radius of curvature of the shell.

9. A seal for a floating roof tank or the like, comprising a plurality of substantially rectangular flexible sheets of metal, a substantially vertical fiexure formed in each sheet and extending from near one edge of the sheet to near the other edge of the sheet to render each sheet differentially expansible horizontally and rigid vertically, said sheets being secured together at their edges to form a sealing ring with the portions of the ring between adjacent pairs of flexures constituting shoes adapted to have rubbing engagement with the shell of the tank, with each of said shoes having a radius of curvature when unrestrained diiiering from that of the shell.

10. A seal for a floating roof tank or the like, comprising a plurality of substantially rectangular flexible sheets of metal, a substantially vertical fiexure integrally formed in each sheet and extending from near one edge of the sheet to near the other edge of the sheet to render each sheet difierentially expansible in horizontal planes and rigid in vertical radial planes, said sheets being secured together at their edges to ring between adjacent pairs of flexures constituting a shoe adapted to have rubbing engagement with the shell of the tank, with each of said shoes having a radius of curvature when unrestrained substantially less than the radius of curvature of the shell, and supporting means for maintaining the shoe in sealing contact with the shell, said supporting means contacting each shoe only at points lying substantially in a single horizontal plane intermediate the top and bottom of the shoe.

12. In a storage tank having side walls and a floating roof, a seal for the floating roof comprising a plurality of substantially rectangular flexible sheets of metal, a substantially vertical flexure integrally formed in each sheet and extending substantially from one edge of the sheet to the other edge of the sheet to render each sheet differentially expansible in horizontal planes and rigid in vertical radial planes, said sheets being secured together at their edges to form an annular sealing ring extending horizontally around form a sealing ring with the portions of the ring between adjacent pairs of flexures constituting shoes adapted to have rubbing engagement with the shell of the tank, and supporting means for maintaining the shoes in sealing contact with the shell, said supporting means contacting each shoe only at points lying substantially in a single horizontal plane intermediate the top and bottom of the shoe.

11. A seal for a floating room tank or the like, comprising a plurality of substantially rectangular flexible sheets of metal, a substantially vertical fiexure formed in each sheet and extending from near one edge of the sheet to near the other edge of the sheet to render each sheet difierentially expansible horizontally and rigid vertically, said sheets being secured together at their edges to form a sealing ring with the portion of the the tank with the portions of the ring between adjacent pairs of flexures constituting shoes having rubbing engagement with the side walls of the tank and supporting means for maintaining the shoes in such sealing contact with the walls, said supporting means contacting the ring only at points spaced from each other around the ring.

13. The seal of claim 12 in whichsaid sheet metal is stainless steel.

14. The seal of claim 13 in which said stainless steel has a thickness of not substantially greater than it? inch.

15. A storage tank as set forth in claim 12 in which said points are located only immediately adjacent the flexures which serve as vertical beams to transfer the supporting pressure vertically across the sealing ring.

FRED L. GOLDSBY. CLIFFORD M. ORR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,668,792 Wiggins May 8, 1928 1,775,758 George Sept. 16, 1930 1,859,632 Pheteplace May 24, 1932 1,865,969 Schurmann July 5, 1932 1,900,904 Berger Mar. 14, 1933 2,054,693 Einbeck Sept. 15, 1936 2,082,194 Wiggins June 1, 1937 2,327,083 Wiggins Aug. 17, 1943 2,381,396 Kuhn Aug. 7, 1945