US2314805A - Floating tank roof seal - Google Patents

Description

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Mam@ 23, @43 J. H. WaGexNs FLOTING TANK RO-OF SEAL 2 sheets-sheet 1 Filed May 24, 1940 INVENTOR;

l N5 .n o 'N Y Mwah 23, E943. Jl H. wxGGlNs 314,5

FLOATING TANK ROOF SEAL Filed May 24,- 1940 2 Sheets-She 2 .2 mr mfr/w .M 6. /7 NJB/97@ m fu. I MM Hf @uw Patented Mar. 23, 1943 UNITED STATES PATENT ortica FLOATING TANK ROOF SEAL John H. Wiggins, Chicago, Ill.

Application May 24, 1940, Serial N0. 337,022

(Cl. B20-26) 4 Claims.

This invention relates to oating tank roof seals .of the general type or kind that comprise an annular shoe carried by hangers on the floating roof, and arranged vertically in sliding engagement with the side wall of the tank, and a closure for the space between said roof and side wall shoe constructed so as to provide for the relative movement between the roof and the shoe and still function as a primary seal for the annular space y'between the shoe and the peripheral edge portion of the roof.

In llc-ating tank roof seals of conventional construction, the primary seal above referred to is usually constructed from an annular shape piece of gas-tight fabric of substantial width, attached Vto the side wall shoe and to the rim on the peripheral portion of the roof, and made full enough so as to permit the shoe to have some radial and vertical movement relatively to the roof and also be capable of exing circumferentially, so as t 'follow the shape of the side wall, or conform to the curvature of the side wall. Due to the relatively high cost of gas-tight fabric, the expense of replacing the primary seal or maintaining the primary seal in an operative condition, is an Vitem of considerable importance in the cost of maintenance of the conventional floating tank roof seal. One objectof my present invention is to reduce this maintenance cost, and also produce a oating roof seal whose initial cost is no greater than the cost of structures of conventional design.

Another `object of my invention is to provide an inexpensive and perfectly satisfactory primary seal or closure for the annular space between a tank side wall shoe and a floating roof, which is of such construction or design that the gas-tight fabric portion of same has no open ended pocket or looped portion in which rain water and dirt can collect.

And still another object of my invention is to provide a primary seal or annular closure of the general kind above mentioned, that is easy to install and replace, and which is of good mechanical appearance. Other objects and desirable features of my invention will be hereinafter pointed out.

Figure 1 of the drawings is a fragmentary top plan View of a floating tank roof seal constructed in accordance with my invention7 taken on the line I-'| of Figure 2.

Figures 2 and 8 are vertical sectional views, taken on the lines 2 2 and 3-3 of Figure l.

Figure 4 is a fragmentary horizontal sectional view, taken on the line 4 4 of Figure 3.

Figure 5 is a fragmentary elevational viewof said seal, looking from the center of the tank outwardly towards the side wall, as indicated by the arrow 5 in Figure 4; and

Figures 6 and 7 are detail sectional views, illustrating the kmethod of combining and installing the plates constituting the metal frustum.

`Briefly described, the primary seal or annularshaped closure of my improved floating tank roof seal, is composed of a limber or highly flexible sheet metal structure projecting laterally from the rim of the roof and proportioned so that its peripheral edge is in such close proximity to the side wall shoe that said structure practically closes the annular space between said shoe and the rim of the roof, and a relatively narrow, annular-shaped gas-tight fabric member or element attached to the top edge of said metal structure and to the upper end portion of the side wall shoe,

said metal structure being preferably made up of a plurality of light-weight sheet metal members of simple design, that can be easily combined with each other to produce a gas-tight structure of inverted frusto-conical form, or of inverted frusto-pyramidal form, that can be easily installed. on or joined in a gas-tight manner to a floating roof and which projects laterally or outwardly beyond the peripheral edge of the roof. In order to reduce the cost and simplify the operation of installing and replacing the fabric element of the seal, the side wall shoe is preferably provided at its upper end with an integral portion that embraces the top edge of said fabric element and serves as a securing means for same, and the inverted frusto-conical or frusto-pyramidalshaped structure carried by the rim of the-roof is provided at its upper end with a similar integral portion that embraces the bottom edge or'inner edge of the fabric element and serves as a securing means for the same. In the normal operation of the seal, the outwardly-flared, upwardly-projecting sheet metal structure on the floating roof, constitutes a closure for the major portion of the annular space between the rim of the roof and the side wall shoe, and a comparatively slight lateralV movement-, of the shoe relatively 'to the roof, or vice versa, causes the peripheral edge of said sheet metal structure to contact with the side wall shoe, whereupon said peripheral edge will ex and then spring back to its former shape, when the normal` concentric relationship between the shoe and the rim of the roof is re-established. It also serves as a supportA for the fabric element that spans the gap between said structure and the side wall shoe, and prevents said fabric element from assuming the shape or form of an open-ended pocket or loop in which rain water and dirt can collect.

In the accompanying drawings which illustrate the preferred form of my invention, I designates the circular side wall of a liquid storage tank, and 2 designates a floating roof of circular form that is normally supported by the liquid in the tank. Practically all types and kinds of floating tank roofs are provided at their peripheral edge with an upwardly-projecting part that prevents the liquid on which the roof fioats, from overiiowing onto the top side of the roof, said part consisting of a rim that projects upwardly from the top side of the roof at the peripheral edge of same, or a pontoon mounted on the top side of the roof at its peripheral edge, so as to function as a rim. My improved seal comprises an annular-shaped metal shoe A carried by the roof and arranged vertically in sliding engagement with the side wall I of the tank, a sheet metal structure of approximately inverted frusto-conical shape or form, or of inverted frusto-pyramidal form, designated as an entirety by the reference character B and mounted on the rim of 2a of the roof in such a way that it .projects upwardly and outwardly from said rim andagas-tight fabric element C of annular shape attached to the top edge of the sheet metal structure B and t'o the upper end portion of the side wall shoe A, so as to seal the space between said parts, the sheet metal structure B being separate and distinct from the rimbf the roof and so proportioned and arranged that it serves as a closure for the major portion of the annular space between the shoe A and the rim of the roof, thereby permitting the use of a relatively narrow fabric element C. The side wall shoe A is herein illustrated as being sustained by swinging hangers 3 on Vthe roof, provided with vertically-adjustable rods or links 4 that are used to suspend the shoe A from the hangers 3, the hangers being provided at their upper ends with rollers or other suitable friction-reducing devices 5 that bear against the inner face of the tank side wall I. The side wall shoe A may either be composed of a plurality of segmental-shaped shoe members connected together by flexible sealing devices, or it may be constructed in the form of a split ring that eX- tends unbrokenly around the: entire circumference of the tank sidewall and provided at its meeting ends with a conventional sealing device.

In the form of my invention herein illustrated the outwardly and upwardly iiared structure B on the roof is of inverted frustro-pyramidal form and is made up of a plurality of substantially flat or straight pieces of light gage sheet metal, such as galvanized sheets, whose ends or vertical edge portions arejoined together by `gas-tight joints produced during the operation of fabricating the metal structure B and attachingV it to the roof 2. The sheets or plates from which the structure B is formed have their lower end portions positioned between and sealed `to co-operating clamping members that comprise ends by clamping plates la, as shown in Figure 4. Any suitable means may be used to force the movable clamping members 'I towards the stationary clamping means 6 on the roof, so as to cause said co-acting means to embrace and securely hold the lower end portion of the sheet metal structure B. I prefer to use for this purpose a plurality of bolts 8 that project inwardly through aligned holes in the co-acting clamping elements 6 and "I, and which are of such length that when their nuts 8a are loosened, the movable clamping members I can be arranged in spaced relationship with the stationary clamping means Ii to form a trough in which plastic cement 9 can be placed preparatory to installing the sheet metal structure B. When the nuts 8a on the bolts are tightened, the movement of the clamping members 1 towards the stationary clamping means 6 on the roof causes the' cement 9 to be forced upwardly into the joints or spaces between the parts 6 and 'I and the lower end portion of the sheet metal structure which said parts embrace, in such a way as to produce a reliable gas-tight connection between the lower end of the sheet metal structure B and the floating roof 2, the cement 9 operating to seal the holes in which the bolts 8 are positioned, as well as the opposed faces of the clamping means that receives and holds the lower end portion of the sheet metal structure B. The side wall shoe A, which is preferably made of metal plates of such thickness as to produce a shoe that will iiex circumferentially, and thus follow the shape or curvature of the tank side wall when said side Wall goes out of round, as is usual with metal liquid containers of relatively great diameter, is provided at its upper end with a doubled portion or turned over portionV I0 that serves asa re-.enforcing or strengthening means for the top edge portion' of the shoe and is also preferably used to attach the top edge of the fabric element C to the shoe. After said fabric element has been inserted under the turned over top edge portion Alil of the shoe, it is clamped or clawed to same by bending or de-forming said portion I0 in such a way as to cause integral claws or prongs Il thereon (see Figure 3) to tightly grip the fabric. The links or rods 4 that suspend the shoe A from the roof hangers can be attached in any suitable way to the upper edge portion of the shoe, without departing from the spirit of my invention. The lower edge or inner edge of the fabric element C is also preferably attached to the upper end of the metal frustum B in the same manner that said fabric element is attached to the side wall shoe. Thus, as shown in Figures Sand 5, the metal plates which constitute the frustum B, are provided at their upper ends with integral, angularly-disposed, U-shaped parts or folded parts I2 into which the bottom edge portion of the fabric element C can be inserted and then permanently secured by deforming the parts I2 in such a way as to cause claws or spurs I3 thereon to bite into and grip the fabric C.

The vertical edges or the ends of the metal plates from which the frustum B is fabricated are arranged in overlapped relationship and clamped together by bolts or other suitable fastening devices after gaskets have been positioned between the overlapped portions of said plates.

Figures 5,'6 and 7 of the drawings illustrate one method of joining the plates of the frustum B. In Figure 5 :r and x' designate-two adjacent plates of the frustum B, whose ends or vertical edge portions overlap, the channel-shaped or U- vshaped part I2 at the upper end of one plate being cut away so that after the plates have been assembled or combined, there will be a substantially continuous fabric gripping means at the upper end of the frustum B that extends around the entire circumference of same. The overlapped portions of the plates r and :c are clamped together by a round shank bolt I4'arranged adjacent the upper ends of said plates and positioned in round holes formed in the overlapping portions of the plates. Additional bolts or fastening devices I5 are located at the lower end of said plates and at approximately the center of said plates, the bolts I5 having square Shanks that fit in horizontally-disposed slots or elongated openings I 6 in the plates.

For convenience in combining the plates, the

. interposed between the plates a: and x in such a way as to produce a gas-tight seal extending throughout the entire height or depth of the plates :1: and :lr after the connecting bolts of said plates have been tightened.

The plates or sheet metal members which constitute the frustum B are provided at their lower ends with angularly bent portions or flanges I8 (see Figure 3) disposed at such an angle that the upper end portion of the frustum B will be arranged in close proximity to the side wall shoe A', but under normal conditions, will be spaced far enough away from said side wall shoe so as to not bear against the same. At the lower ends of said plates, one end of the flanged portion i8 of each plate is cut away at the point where adjacent plates overlap so that the vertically-disposed flange at the lower end of the frustum B which is engaged by the co-acting clamping members 6 and I on the roof, will be of such shape or form as to lie snugly between and be gripped tightly by the clamping members 6 and l. lf desired, closure pla-tes I9, made of very thin metal, can be positioned over the cut-outs or cut away portions of the flanges I8 and combined with cement 20 in such a way as to produce an effective seal between the frustum B and the clamping members 6 and 'I on the roof, at the lower ends of the vertical joints or radial joints in said frustum. As shown in Figures 6 and 7, the closure plates I9 extend upwardly above the top edge of the movable clamping means 'I on the roof and lap over the adjacent plates and at at the points where the bottom bolts I5 project upwardly through said plates, each of the closure plates il being maintained in spaced relationship with the plates :c and by a sleeve or tubular spacing device 2l mounted on said bolt, as shown in Figures 6 and 7. Before the movable clamping means 'i on the roof is tightened, a quantity of plastic cement 2i) is spread over the overlapped lower end portions of the plates :l: and so as to lie between said plates and the closure plate i9, and also to cover the bottom bolt I5 and the spacing sleeve 2i through which it passes. Thereafter, when the nut I5a of said bottom bolt is tightened, and the nuts 8a on the bolts 8 are tightened, the cement that was previously applied to the lower end portion of the frustum and to the clamping means for same carried by the roof; will be thoroughly distributed over the co-acting surfaces and forced into all of the joints or interstices in such a way on the roof.

as to effectively clamp and seal the lowers-nd portion of the structure B to the roof. l e

While the procedure of installingr the seal vor combining the co-acting parts of same may vary to suit existing conditions, or at the preference of theworkmen installing the seal, I have found the following method to be perfecthT satisfactory:

(l) Cement is put into the trough formed by the co--acting parts E and 'I on the rim 2a of the roof. The top edge of the fabric element C'is then clamped to the integral U-shaped portion or turned over portion ill at the upper end of the shoe.

(2) The next step is to position one platej or section of the frustum B between the clamping members i and 1 on thereof, so as to see thatit properly iits against the particular segment or section of the clamping means 6 with which it is to co-act'. The bottom edge or inner edge of the fabric element C is then pushed into the doubled or folded U-shaped portion i2 at the upper end of the said fitted section of the frustum, after which said fitted section is raised out of the space between the co-acting clamping means E and 'I' on the roof and turned into such a position that the portion I2' of said section can be deformed so as to tightly grip the-fabric. Another section or plate of the frustum B is then attached in a similar way to the bottom edge of the fabric element C, after which said additional section is attached to the previously iitted section of the frustum by the bolt. I4, which is tightened after one of the gaskets i7 has been positioned between the overlapped ends or overlapped vertical edge portions of said two sections. After a plurality of the sections of the frustum have been attached to the sealing element C and pivotally joined together by the top bolts I5, as above described, said sections are turned over or arranged in their approximately normal position, andthe bolts I5 are inserted in the elongated openings or slots It provided for same in the overlapped portions ofthe sections of the frustum. In this way, the metal plates that constitute the sections ofthe frustum B are attached to the bottom edge of the fabric element C and progressively bolted together, not in a perfectly tight manner, but in such a way as to permit the plates or sections constituting the frustum B to be rocked or turned on the top bolts Ill sufficiently to produce a structure whoseflanged lower end portion I8 will conform to the shape and size of the stationary clamping means 6 on the roof.

'Before the wing nuts I5a of the bolts I5 are tightened, the spacing devices 2I are slipped over the bottom bolts i5, and the coverl plates i9 are mounted in proper position on the frustumv with gobs of cement 20 spread over the under sides of said closure plates. Thereafter, the nuts of the bolts I5 are tightened so as to seal all of the radial seams of the frustum B, whereupon, the frustum is then dropped into operative position between the coacting clamping members 6 and 'I Subsequently, the nuts 3a on the bolts 8 are tightened so as to cause the members 'I to tightly clamp the vertically-disposed flanged portion at the lower end of the frustum tightly against the stationary clamping means 6 on the roof.

`When it becomes necessary to replace the fabric element C, this operation can be eected quickly and easily by removing the retaining bolts from one radial seam of the frustum B, loosening the bolts 8 so as to open the trough-like clamping means on the roof, formed by the co-acting members 6 and 1, and thereafter, progressively unbolting the sections or plates of the frustum B and swinging them upwardly into a position where the U-shaped portions I2 of said sections can be easily opened, to disengage the same from the bottom edge portion of the fabric element C. After the new fabric element has been replaced in the channel-shaped portion Hl of the side wall shoe, the sections or plates of the frustum B are progressively attached to the new fabric element and bolted together in the way previously eX- plained.

Due to the fact that the fabric element C is relatively narrow, usually about 8 inches in width, the cost of replacing the gas-tight fabric part of the seal is substantially less than the cost of replacing the fabric of a floating tank roof seal of conventional construction. Notwithstanding the fact that the element C is relatively narrow, it is wide enough to seal the gap between the side wall shoe and the upper end of the metal frustum B on the roof and provide for the necessary relative movement between the side Wall shoe and the iioating roof. Figure 3 of the drawings shows the metal frustum B in its normal position, i. e., when the side wall l of the tank is round, and when the roof 2 is in the center of the tank. If now the shoe A has to move outwardly away from the roof, then this movement is accomplished or permitted by the straight flexing of the fabric element C. If, however, the shoe must move inwardly towards the roof, the shoe will bear on the upper end of the metal frustum B and push it inwardly. Since the upper circumference of the metal frustum musi; remain the same, its upper edge moves outwardly in the places where the shoehas moved away from the roof. If later, at the same point, the shoe moves away from the roof again, the point on the metal frustum B that had been pushed in, will now spring back, out tov its original position. Thus, it will be seen that, in addition to forming a, part of the closure between the roof and the side wall shoe, the metal frustum B tends to maintain the roof in the geometrical center of the tank.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent:

1. In a iioating tank roof seal, the combination of an annular, circumferentially flexible side Wall shoe provided at its upper end with a doubled or folded portion, a floating roof, a substantially annular-shaped fabric sealing element whose outer edge is embraced by and gripped tightly to the doubled portion of said shoe, a sheet metal structure of substantially inverted frustum form mounted horizontally on the roof with its lower end portion sealed to the roof, and a portion at the upper end of said sheet metal structure that embraces and tightly grips the inner edge of said fabric sealing element.

2. In a floating tank roof seal, the combination of an annular side wall shoe, a oating roof provided at its peripheral edge with an upwardlyprojecting rim, a limber or highly flexible sheet metal member removably mounted on said rim and projecting upwardly and outwardly therefrom towards said shoe, the peripheral edge of said member being in such close proximity to said shoe that in the normal use of the apparatus said peripheral edge may contact with and be flexed by said shoe, and a fabric sealing element having one of its edges attached to the upper end of said sheet metal member and having its other edge attached to said side wall shoe in a horizontal plane higher than the upper end of said sheet metal member, whereby said member prevents said fabric element from assuming the shape or form of an open-ended pocket in which dirt and water can collect. y

3. A structure of the kind described in claim 2, in which the rim of the roof carries opposed clamping members that grip the lower end of said sheet metal member and produce a tight joint between said member and rim.

4. A structure of the kind described in claim 2, in which said sheet metal member is of substantially inverted frusto-pyramidal form and is composed of a, plurality of metal plates joined together by radially-disposed, gas-tight joints.

JOHN H. WIGGINS.

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