US2740549A

US2740549A - Floating roof seals

Info

Publication number: US2740549A
Application number: US173762A
Authority: US
Inventors: Arthur H Graham; Saunders S Staley
Original assignee: J C WYNNE
Current assignee: J C WYNNE
Priority date: 1950-07-14
Filing date: 1950-07-14
Publication date: 1956-04-03
Anticipated expiration: 1973-04-03

Description

April 3, 1956 A. H. GRAHAM Ei'AL FLOATING ROOF SEALS 2 Sheets-Sheet 1 Filed July 14, 1950 Arthur H Graham Saunders 5. Sfa/ey ATTOR N 5Y8 P 3, 956 A. H. GRAHAM ET AL 2,740,549

FLOATING ROOF SEALS Filed July 14, 1950 I 2 Shets-Sheet 2 awe/WM Arfhur h. Graham Saunders $.Sfa/ey FLOATING ROOF SEALS Arthur H. raham and Saunders S. Staley, Dallas, Tex.; said S'l'aley assignor to J. C. Wynne, Tyler, Tex.

Application July 14, 1950, Serial No. 173,762

8 Claims. (Cl. 220-26) This. invention relates to new anduseful improvements in floating roofs for storage tanks and more particularly to means for sealing off between a floating roof and the wall of its tank.

One objectv of the invention is' toprovide improved means for sealing ofl between thefloating roof and shell of a large storage tank, such as a. tank used for storing crude petroleum and petroleum products, which is of such construction that the escape of volatile constituents is reduced to a minimum and the elements of the sealing means are protected from corrosion by the contents of the tank.

Another object of the invention is to provide in improved seal for the floating roof of. astorage tank which is self-adjusting so as to conform to the contour of the tank wall and which is constantly urged. into sealing, engagement with said tank wall to. reduce evaporation or vapor loss to a minimum.

A particular object of. the-invention is to. provide an improved fluid-tight seal,. of the character described, which includes expansiblc, flexible meansconnectedto the floating roof by resilientmeansso as to besupported and held in sealing conformity with the tank shell throughout the vertical travel of said root.

An important object of the invention is to provide an improved seal, of the character. described, wherein the flexible means includes a plurality ofupright metallic plates arranged circumferentially with adjacent plates being adjustable relative to one another so as to assure flexing of said means in conformity with the tank shell, and a flexible element extendingthe plates and the rim of the roof to seal the spacetherebetween.

A further object of the. invention is to. provide an improved seal, of the character described, wherein the adjacent edge portions of the. seal plates are. connected in such manner as to permit limited independent movement of said plates radially of the tank and to seal oft the joints therebetween.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

Fig. l is a transverse,,vertical, sectional'view of apertion of the shell and floating roof .of a storage tankhaving a seal embodying the. features of the invention,

Fig. 2 is a horizontal, cross-sectional view, showing the resilient mounting of the seal,

Fig. 3 is an elevational view, partly in section, showing one of the expansion joints between adjacent. sections of the shoe,

Fig. 4 is a horizontal, cross-sectional view,,taken on the line 4-4 of Fig. 3,

' Fig. 5 is a horizontal, cross-sectional. view, taken on the line 5--5 of Fig. 3,v

States Patent Patented Apr. 3, 1956 ice Fig. 6 is a view, similar to Fig. 3, showing a modified expansion joint,

Fig. 7 is. a horizontal, cross-sectional view, taken on the line 7--7 of Fig. 6.

In the drawings, the numeral 10 designates the upright cylindrical wall or shell of a. storage tank of the type used for storing crude petroleum, petroleum products and other volatile liquids. The tank 10 is of relatively large diameter and' has a floating roof 11 which includes a buoyant deck or cover 12 of less diameter than said tank and an annular, upstanding rim or flange. 13. It is noted that the deck 12 and the lower portion of the rim 13 are below the lever of the liquid, indicated by the broken line 14, in the tank, so as to be immersed in said liquid. In order to prevent corrosion of the major portion of the rim by hydrogen sulphide or other corrosive vapors rising from the contents of the tank, it is preferable to clad the exterior of said rim with stainless steel or other corrosion-resistant.metal; Due to the immersion of the deck, the .same is not subject to corrosion.

For sealing off the annular space between the roof and the tank shell, an expansible, flexible seal in the form of a circular shoe or skirt 15 is provided and includes a plurality of substantially arcuate sections or plates 16 spaced radially from the roof rim in upright, parallel relation thereto. Although the number of plates employed is subject to variation, said plates preferably are of considerable length. The plates 16 are arranged circumferentially ot the roof rim and have their adjacent edge portions connected by expansion joints 17 (Fig. '3) to permit limited, independent movement of said plates relative to one another in conformity with the contour of the tank shell which frequently is out of round. Angularly and inwardly directed lips or

flanges

18 and 19 are formed on the upper andlower margins, respectively, of each plate to minimize binding, or-hanging of the shoe. it is preferable-for the plates to be of greater height than the roof rim so as to extend thereabove and therebelow. A suitable angle bar or other stiffening member 26 is secured to the upper portion of each plate immediately below its upper flange 1% by stud bolts 21 and nuts 22 and extends longitudinally of the plate with the ends of adjacent angle bars spaced from one another.

Asismost clearly shown in Figs. 3, 4 and 5, each expansion joint 1-7 includes an" elongate clip 23 having its longitudinal margins bent inwardly upon themselves to provide inwardly directed, substantially co-extensive flanges or keepers 24. The clip-23 extends longitudinally of the adjacent edge portions of the plates, which edge portions are bent inwardly upon themselves to provide marginal, flanges or keepers 25 extendingparallel to their respective plates for coactingwith the keepers 24 of said clipv (Fig. 5). It is noted that the vertical keepers 25 extend from the lower margins of the angle bars to the lower flanges 19 of said plates. and that the clip is coextensive with said keepers. The upper portion of the clip is flat and bent complementary to the plate flanges 18 so as to overlie the gap therebetween as shown in Figs. 3 and 4. In order topreventdisplacementof thec'lips, the endportionsof thelower flanges l9 are. bent inwardly to provide radially directed lugs 26 for underlying; and supporting said clips. Manifestly, the construction of the expansion joints seals off between the adjacent edge portions ofthe plates. in addition to permitting limited, independent movement of said. plates relative to each other.

The shoe is resiliently supported and urged outwardly into sliding engagement with the tank shell by resilient members, such as leaf or plate springs 27,, one or more springs being provided for each. of the plates 16. Each spring. 27 is preferably semi-elliptical and. has, reverse curves and substantially straight end portions. Zli which upstanding, angular bracket 30 is welded or otherwise secured to a. circumferential angle bar or reinforcing member 31, which is secured internally to the upper peripheral edge portion of the roof rim, for confining the medial portion of the spring in cooperation with clamping plates 32. Suitable bolts 33 and nuts 34 fasten the plates 32 to the bracket 30 above and below the spring so as to confine said spring therebetween. Due to this arrangement, it is manifest that the plates of the shoe are. resiliently mounted on the roof rim so as to be suspended therefrom and that said plates are constantly urged radially outward into sliding, sealing engagement with the tank shell. This mounting of the plates permits installation and removal of the same from above while the tank is in use.

Lower springs 35, similar to the spring 27 but preferably of lighter gauge, are carried by the lower portion of the roof for engaging and urging the lower portions of the shoe plates outwardly into sliding, sealing engagement with the tank shell. Each spring 35 is supported by an angular bracket 36 and coacting clamping plates 37 which are fastened to the bracket by suitable bolts 38 and nuts 39. The brackets 36 are similar to the brackets 35) and are welded or otherwise secured to the underside of the deck 12 of the roof so as to depend therefrom. Although not shown in detail, the springs 35 are of substantially the same shape as the springs 27 and have substantially straight end portions for bearing against the lower portion of the shoe plate. Although no connection between the lower springs and plates is shown, the same may be connected in the same manner as the upper springs so as to assist in supporting the plates. In some installations, it may be desirable to offset the lower springs relative to the upper springs so as to distribute the outward pressure exerted against the shoe plates.

In order to seal the annular space between the roof rim and the shoe, an annular flexible element or sheet 41?, of synthetic rubber or other suitable material, which is preferably elastic and impervious to petroleum and petroleum products, extends therebetween. The outer periphery of the flexible element 40 is clamped beneath the angle bar so as to be positively connected to the inner surfaces of the plates 16. A flat, annular member or ring 41 overlies and is secured by suitable bolts 42 and nuts 4-3 to the outer periphery of the angle bar 31 for confining the inner peripheral margin of the flexible element. It is noted that the radial width of the unconfined portion of the element 4% is greater than the distance between the roof rim and shoe so as to facilitate radial movement of said shoe relative to the roof. In addition to providing a fluid-tight seal between the roof and the shoe so as to prevent the evaporation or escape of vapors or volatile constituents, the flexible element functions to protect the upper springs 27 and their mountings as well as the angle bar 29 from the corrosive effect of said vapors or constituents. Since the lower springs 35 and their mountings are immersed in the contents of the tank, the same are not subject to corrosion. The plates 16 of the shoe and their expansion joints 17 are preferably formed of stainless steel or other corrosionresistant metal, since these members are exposed and subject to corrosion. Manifestly, a metal-to-metal seal is provided by the engagement of the shoe with the tank shell.

In Figs. 6 and 7, a slightly modified foim of seal or shoe 60 is shown and includes a plurality of sections or plates 61 similar to the plates 16 of the shoe 15. Similar, angularly, inwardly-directed

flanges

62 and 63 are formed on the upper and lower margins, respectively, of the plates 61. The upper portion of each plate is reinforced by a longitudinal angle bar or member 64 which fastens a flexible element or sheet 65, similar to the elements 40 and 56, to the shoe 60, and which is adapted to have 4 slidable connection with a supporting spring (not shown) similar to the spring 27. Instead of the expansion joints 17, the vertical edge portions of adjacent plates overlap one another and are fastened together by coacting slots 66, bolts 67 and nuts 68. The slots 66 are formed in the underlying or inner edge portion 69 and extend hOI izontally thereof, while the bolts 67 extend inwardly through said slots from the inner surface of the overlying or outer edge portion 70 with their nuts 68 overlying the inner surface of said edge portion 69. Thus, the vertical edge portions of adjacent plates are adjustably connected so as to permit limited independent movement of said plates relative to one another.

For sealing off between adjacent plates, the edge portion 69 is offset inwardly to provide a vertically-extending pocket or recess 71. A hollow, cylindrical sleeve or tube 72, of synthetic rubber or other elastic material, is confined in the recess 71 by the edge portion 70 of adjacent plates. It is preferable to terminate the upper margin of the underlying edge. portion 69 immediately below the element 65, whereby the upper ends of the recess 71 and tube 72 are closed by said element. The remainder of the vertical edge portions of the plates, ineluding their

marginal flanges

62 and 63, preferably are disposed in spaced relation. This type of joint is of primary use when the plates of the shoe are formed of heavy gauge metal which does not lend itself readily to the reverse bends required by the expansion joint 17.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What we claim and desire to securelby Letters Patent is:

1. In a floating roof storage tank having an upright cylindrical shell and a buoyant roof vertically movable in the shell and having a deck and an annular upright rim of slightly smaller diameter than the shell, a seal for the annular space between the roof and shell including, an annular flexible metal shoe in sealing engagement with the shell and consisting of a plurality of circumferential plates, metallic sliding joints connecting adjacent edge portions of theplates whereby limited relative movement of one plate with respect to adjacent plates is permitted, a curved leaf spring disposed in a substantially horizontal plane connecting each plate to the roof for supporting and urging the plate radially outward,.each spring being rigidly attached to the upper portion of the roof rim and having its ends directed outwardly, means carried by the upper portion of each plate and slidably confining the ends of the spring associated with said plate in a direction radially of the shell to prevent disconnection of the plate from the spring in the event the plate moves upwardly into a plane above the shell, an annular flexible element extending and sealing off betweenthe roof and shoe plates below the springs, and a plurality of horizontal curved leaf springs rigidly secured to the lower portion of roof below the annular flexible. element and immersed in the contents of the tank, the springs having their ends directed outwardly and bearing against and urging the lower portion of the shoe plates outwardly,

2. In a floating roof liquid storage tank having an upright cylindrical shell and a buoyant roof movable axially within the shell and having anannular wall surface which is of lesserdiameter than the shell, :1 seal for the annular space between the roof and shell including, an annular flexible metal shoe in sealing engagement with the shell and composed of a plurality of ar'cuate plates, means for connecting the adjacent edge portions of the plates for limited relative movement of one plate with respect to adjacent plates, an annular flexible element spanning the annular space between the roof and the shoe plates for sealing said space at a point above the liquid within the shell, flexible leaf springs attached to the roof and having their ends slidably connectedto the shoe plates for urging said plates radially outwardly into sealing engagement with the shell, said springs being locat d above the annular flexible element, and additional leaf springs attached to the roof below the level of the liquid within the shell and engaging the shoe plates for additionally urging said plates into engagement with the wall of the shell.

3. A seal as set forth in claim 2 wherein each metallic sliding joint is formed by overlapping the adjacent edge portions of the shoe plates, means connecting and permitting limited sliding movement of the overlapping edge portions, the inner edge portion of each plate being offset inwardly to provide a recess substantially coextensive with said overlapping edge portions, and a tubular sealing element of elastic material confined in the recess and deformed into sealing engagement with said overlapping edge portions.

4. A seal as set forth in claim 2 wherein the upright edge portion of one plate overlaps the upright edge portion of the adjacent plate and is offset to form a vertically extending recess which is in facing relationship to said adjacent plate, a flexible tubular sealing member disposed within the recess for sealing the joint between the adjacent plates, means for connecting the overlapping portions of the plates to permit limited movement of the plates relative to each other in a horizontal plane, said tubular sealing element maintaining the joint sealed during the movement of the plates with respect to each other, an annular flexible element attached to the upper end of the roof and spanning the space between the roof and the shoe plates and secured to said plates, said element overlying the flexible tubular member to close the bore thereof, spring means attached to the roof and engaging the metal shoe for urging said shoe into sealing engagement with the shell, said spring means being disposed above the annular flexible element, and additional spring means attached to the roof in a plane below the liquid level in the tank and engaged with the metal shoe for also urging the shoe into sealing engagement.

5. A seal as set forth in claim 2 wherein the flexible metal shoe includes a plurality of arcuate plates disposed in a generally circumferential path, the upright edge portion of one plate overlapping the upright edge portion of the adjacent plate and being oifset to form a Vertically extending recess which is in facing relationship to said adjacent plate, a flexible tubular sealing member disposed within the recess and in sealing engagement with the Walls of said'recess and with the contiguous wall of the adjacent plate for sealing the joint between said plates, and means for connecting the overlapping portions of the plates to permit limited movement of the plates relative to each other in a horizontal plane, the tubular sealing element maintaining sealing contact with the plates during such relative horizontal movement of the plates with respect to each other.

6. In a floating roof storage tank having an upright cylindrical shell and a buoyant roof vertically movable in the shell and having a deck and an annular upright rim of slightly smaller diameter than the shell, a seal for the annular space between the roof, and shell including, an annular flexible metal shoe in sealing engagement with the shell and consisting of a plurality of circumferential plates, metallic sliding joints connecting adjacent edge portions of the plates whereby limited relative movement of one plate with respect to adjacent plates is permitted, a curved leaf spring disposed in a substantially horizontal plane connecting each plate to the roof for supporting and urging the plate radially outwardly, each spring being rigidly attached to the upper portion of the roof rim and having its ends directed outwardly, means carried by the upper portion of each plate and slidably confining the ends of the spring associated with said plate in a direction radially of the shell to prevent disconnection of the plate from the spring in the event the plate moves upwardly into a plane beyond the shell, an annular flexible element extending and sealing off between the roof and shoe plates below the springs, each metallic sliding joint being formed by bending the adjacent edge portions of the shoe plates inwardly upon themselves to provide flanges in parallel relation to said edge portions, and a complementary clip engaged with and connecting the adjacent flanges to provide expansion joints between the plates for permitting limited lateral movement of said plates while preventing separation of the plates from each other.

7. The combination with a liquid storage tank having an upright cylindrical shell and a buoyant roof movable axially within the shell which roof has an annular wall surface of a lesser diameter than the shell, of a seal for the annular space between the roof and shell, said seal including, an annular metal shoe in sliding sealing engagement with the inner wall of the shell, an annular flexible element spanning the annular space between the annular wall of the roof and the shoe and secured to said roof and said shoe for sealing said annular space, a plurality of flexible leaf springs attached to the roof and having their ends slidably connected with the metal shoe and exerting a pressure radially outwardly to urge the shoe into sealing engagement with the shell, said springs being attached to the roof above the annular flexible element whereby said element protects said springs from contact with vapors rising from the liquid, and additional spring means attached to the roof in a plane below the liquid level in the tank and engaged with the metal shoe for also urging the shoe into sealing engagement.

8. The combination as set forth in claim 7, wherein the slidable connection between each flexible leaf spring and the metal shoe comprises apertured members through which the ends of the springs extend, said members functioning to connect the springs to the shoe while permitting limited movement of the springs relative thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,509,218 Walsh Sept. 23, 1924 1,514,116 Wiggins Nov. 4, 1924 1,816,124 Patterson July 28, 1931 1,900,904 Berger Mar. 14, 1933 1,994,477 Kramer Mar. 19, 1935 2,159,346 Welch May 23, 1939 2,402,253 Macleod June 18, 1946 2,495,742 Lebedetf Jan. 31, 1950 2,519,633 Brown Aug. 22, 1950 2,538,067 Wilber Jan. 16, 1951 FOREIGN PATENTS 487,774 Great Britain June 24, 1938