US2302904A - Explosionproof seal for floating roofs - Google Patents

Description

Nov. 24, 1942. J. H. WIGGINS EXPLOSION PROOF SEAL FOR FLOATING ROOFS Fi led Aug. 26, 1940 5 Sheets-Sheet 1 FIG].

- I INVENTOR; (JOHN H. W/GGINS 'HTTORNEY Nov. 24, 1942. J. H. WIGGINS 2,302,904

EXPLOSION PROOF SEAL FOR'FLOA'IING ROOFS Filed Aug. 26, 1940 s Sheets-Sheet 2 INVENTOB .r/OHN H. WIGGINS av ficawf W ATTORNEY Nov. 24', 1942.' J. H. WIGGINS EXPLOSION PROOF SEAL FOR FLOATING ROOFS Filed Aug. 25, 1940 S SheetS-Sheet 5 I0 J7 low v 7 #6 7 I0 29.

INVENTOR; JOHN H. WIGGINS 6r Wuwv hr? WM :4 TTORNE Y Patented Nov. 24, 1942 UNITED STATES PATENT OFFICE EXPLOSIONPROOF SEAL FOR FLOATING ROOFS '7 Claims.

This invention relates to floating roof seals of the type that comprise an annular shoe or equivalent element arranged so as to engage the vertical side wall of the tank, and a closure, commonly referred to as a primary seal, for the gas space between saidshoeand the peripheral edge portion of the floating roof.

One object of my invention is to'provide a floating roof seal, which, in addition to'having the desirable features and distinguishing characteristics of conventional seals now'in general use, is so constructed that in the event of an explosion in the gas space at the peripheral edge of the roof, the primary seal will automatically assume a position to produce a vent opening of variable size and sufiicient area to quickly relieve the pressure produced by the explosion, and thereafter will automatically resume its normal position and make said gas space gas-tight.

Another object is to provide a floating roof seal in which the primary seal and side wall shoe are maintained in gas-tight relationship in a novel manner that simplifies the construction and improves the operation of seals of the general type or kind referred to.

Another object is to provide a floating roof seal in which the means employed to force the shoe outwardly towards the tank side wall is also utilized to maintain a tight joint between said shoe and the primary seal.

Another object is to provide a floating roof seal, in which the side wall shoe and the primary seal are combined in gas-tight relationship in sucha way that said elements can slide and move relatively to each other without destroying the gas-tight joint or connection between said-elements.

Another object is to provide a floating roof seal, in which the primary seal and side wall shoe are combined in a novel manner that permits the primary seal to increase and decrease circumferentially as the shoe increases and decreases circumferentially, without disturbing the gas-tight joint or connection between said primary seal and shoe.

Another object is to provide a split, ringshaped side wall shoe that is provided with a novel means for producing a slidable, gas-tight joint between the ends of said shoe.

Another object of my invention is to provide a floating roof seal, in which the side wall shoe has circumferentially sliding lapped portions, and the primary seal has a continuous connection with said lapped portions.

And still another object of my invention is to provide a floating roof seal, whose co-acting parts that are in sliding engagement with each other and with the tank side Wall, are constructed in the form of continuous expansible and contractible rings, free from gaps or open spaces that are difiicult to maintain in a gas-tight condition. Other objects and desirable features of my invention will be hereinafter pointed out.

My improved seal is similar in general design to a type of floating roof seal that is now in general use, in that it comprises a circumferentially flexible, annular-shaped, split shoe disposed vertically in parallel, or approximately parallel, relationship with the side wall of the tank, a means for mounting said shoe on the floating roof in such a way that said shoe can move relatively to the roof and adapt itself to the tank side wall, a means for exerting outward pressure on said shoe in a direction tending to press it against the tank side wall, and a primary seal, preferably formed of gas-tight, fire-resistant fabric, arranged between said side wall shoe and the peripheral edge of the roof and combined with said elements in a gas-tight manner. It is distinguished from prior floating roof seals, however, in that the inner andouter edges of said seal are not directly attached or fastened to the floating roof and to the sidewall shoe, respectively. Instead, one edge of said primary seal is secured, attached or fastened to one of the parts with which it co-acts and the opposite edge of said seal is held in yielding engagement with the otherpart with which the seal co-acts. Accordingly, in the event of an explosion in the gas 7 space at the edge of the floating roof, one entire edge'of the primary seal is capable of separating or moving away from one of the parts with which it co-acts, thereby producing a vent opening of variable size, that is of ample area to quickly relieve the pressure produced by or resulting from the explosion. This highly desirable result can be attained in various ways, and while I prefer to fasten or attach the inner edge of the primary seal to the floating roof and maintain the outer edge of said seal in sliding, yielding engagement with the side wall shoe by spring pressural wish it to be understood that my invention is not limited to the particular structure herein illustrated. In addition to providing a quick-acting venting device having a variable outlet of ample size to afford instant relief for the gas space, the structure herein illustrated and described is highly desirable, in that it allows the primary sealto slide relatively to the side wail'shoe and permits said seal to increase and decrease circumferentially.

Still another advantage of my invention is that it greatly simplifies the operation of cornbining a fabric primary seal with a side wall shoe. While my broad idea contemplates the use of any suitable means for holding the primary seal in gas-tight relationship with the side wall shoe, I prefer to build the structure so that the means which is employed to force the shoe outwardly towards the tank side wall, is also utilized to yieldingly hold the primary seal in engagement with the side wall shoe. This reduces the cost and simplifies the installation of the structure and it locates the metal parts subject to corrosion on the exterior of the gas space.

The side wall shoe, instead of being provided with a split or gap sealed by fabric attached to the end portions of the shoe, is constructed in 73118 form of a split ring provided with overlapped i or overlapping end portions that are machined or planed throughout the height of the shoe, so as to produce co-acting, sliding, metallic surfaces that remain in gas-tight engagement with each other when the shoe expands and contracts.

In addition to providing an efiicient expansion joint in the shoe, this type of construction makes it possible to produce and maintain a continuous gas-tight joint or connection between the primary seal and the side wall shoe.

Figure 1 of the drawings is a vertical, fragmentary sectional view through the tank side wall and shoe, illustrating the means employed to exert outward pressure on the shoe and also to hold the primary seal in gas-tight engagement with the shoe, and also showing how the auxiliary seal is mounted on the shoe.

Figure 2 is an elevational view of the parts shown in Figure 1, looking outwardly from the center of the tank.

Figure 3 is a vertical, fragmentary sectional view, through the tank side wall and shoe, illustrating the swinging hangers on the floating roof from which the side wall shoe is suspended.

Figure 4 is an elevational view of the parts Figure 7 is a side elevational view of the parts shown in Figure 6; and

Figure 8 is a plan view, more or less diagrammatic, for the purpose of showing the sliding overlapped end portions of the shoe that provide for the expansion and contraction of the shoe.

In the accompanying drawings, which illustrate the preferred form of my invention, A designates the circuit, vertically-disposed side wall of a liquid storage tank, and B designates a floating roof in said tank. The annular space between said tank side wall and the peripheral edge of the roof is sealed by a structure commonly referred to as a floating roof seal, that comprises a circumferentially flexible annular side wall shoe I, which is adapted to bear against the inner face of the tank side wall A, a primary seal 2, usually constructed from gas-tight, fireresistant fabric, disposed between the shoe I and the roof B and combined with said parts in a gas-tight manner, and an auxiliary seal or secondary seal 3, usually constructed of fabric, mounted on the upper edge portion of the shoe I and arranged so as to normally bear snugly against the inner face of the tank side wall. The shoe I may be mounted in any preferred or suitable way on the roof B, and is herein illustrated as being adjustably suspended by links 4 from swinging hangers 5 on the roof. Similarly, any preferred or suitable means may be used to mount the secondary seal on the upper edge portion of the shoe I. In the form of my invention herein shown, the fabric constituting the secondary seal 3 has its bottom edge clamped to the shoe I by clamping rod or ring 6, and the top edge of said fabric is positioned in and gripped tightly by carriers 1 carried by rock arms 8 mounted in bearings 9 attached to the inner side of the shoe I at the upper edge of same. Preferably, two rock arms are provided for each of the carriers I, and each carrier is associated with a spring arm I0 mounted on the shoe I and arranged so as to force the carrier outwardly, thereby causing the secondary seal 3 to be held pressed tightly against the inner face of the tank side wall. As shown in Figure 5, the carriers I are arranged end to end around the entire circumference of the shoe, and the secondary seal 3 is constructed in the form of a continuous ring that is cable of stretching and contracting sufficiently to accommodate itself not only to changes in the shape of the tank side wall, but also to variations in the circumferential length of said wall, which, in welded tanks, often ranges from one inch to three inches.

The fabric constituting the primary seal 2 has its inner edge or bottom edge secured in any suitable way in a gas-tight manner to the peripheral portion of the floating roof B. I have herein shown said fabric as being clamped to the roof by a clamping ring or rod II held in place by wedges I2 positioned in lugs I3 attached to a laterally-projecting portion of the roof that overhangs the annular gas space between the peripheral edge of the roof and the side wall shoe I, as shown in Figure 3. As previously stated, it has heretofore been the universal custom to bolt or otherwise securely fasten the primary seal to the side wall shoe. I have departed radically from said practice by combining the primary seal and side wall shoe in such a way that they are held yieldingly in engagement with each other, and are capable of sliding relatively to each other, both vertically and horizontally, or circumferentially, without destroying or disturbing the gas-tight joint or connection between said elements. As previously explained, one advance of such a construction is that if an explosion occurs in the gas space, the entire primary seal 2 will separate from the side wall shoe I, and will open as wide as necessary to relieve the pressure produced by the explosion, and thereafter will immediately snap shut or resume its normal position. Another advantage is that if the shoe I moves sideways relatively to the roof, the primary seal 2 will remain at rest or stationary relatively to the roof, or, in other words, will not move sideways with the shoe. This is of particular advantage with a tank side wall that is badly out of round.

I attain the desirable results just referred to by employing a plurality of spring-pressed arms I4 to fold or press the upper edge of the primary seal 2 against the inner side of the shoe I. Said arms M are pivotally mounted, or rockably mounted on the roof B at or adjacent the peripheral edge of said roof, and preferably the upper ends of said arms are attached to clips or carriers l5 which are securely fastened to the top edge of the primary seal 2, thus causing the primary seal to be suspended from rockable devices on the roof disposed so as to force the primary seal outwardly against the side wall shoe. In the form of my invention herein illustrated the top edge portion of the fabric constituting the primary seal 2, is folded over and positioned inside of U-shaped clips or carriers l5 that tightly grip said fabric. arranged end to end around the entire circumference of the primary seal, and each clip is combined with one or more spring-pressed arms 14. Preferably, and as shown in Figure 4, two

springs arms M are provided for each of the U- shaped members or clips attached to the top edge of the primary seal. The arms M are herein shown as being rockably mounted in the roof lugs l3, previously described, and each pair of arms It has associated with same a spring I6 that exerts an outward thrust on a cross bar l'! which bears against the arms, as shown in Figure l. One convenient and inexpensive way of fastening the upper ends of the spring-actuated arms M to the carriers or clips I5, is to provide each of said arms at its extreme upper end with a disk-shaped portion l3 that is embraced by bendable lugs or ears it on the carrier I5, as shown in Figure 2. In floating roof seals of conventional design springs or spring-actuated devices are commonly employed to force the shoe outwardly towards the side wall of the tank. In my improved seal the spring-pressed arms 14 perform the dual function of forcing the shoe I outwardly towards the side wall A of the tank, and also holding the upper edge portion of the primary seal 2 in gas-tight engagement with said shoe. In addition to being inexpensive and easy to assemble, the construction above described is desirable, in that the arms 14, the supporting means, and actuating springs for same, and the devices used to connect saidarms to the primary seal are all located on the exterior of the gas space at the edge of the roof.

The shoe l is made up of relatively long metal plates joined together by rivets 20, as shown in Figure 5, and said shoe is constructed in the form of a split ring having overlapped or overlapping end portions that are maintained in gas-tight sliding engagement with each other, as shown in Figure 8. Preferably, said overlapping portions are formed by two relatively heavy, smooth-surfaced plates 2! and 22. The plate 22, which is attached to one end of the shoe, extends throughout the entire height of the shoe, and projects laterally beyond the end of same, as shown in Figure 6, the inner side of said plate being machined or planed so as to produce a smooth fiat surface. The co-acting, smooth-surfaced plate 25. is attached to the opposite end portion of the shoe, and is arranged in overlapping relationship with the plate 2!, so as to produce a gas-tight sliding joint between the ends of the shoe that provides for the expansion and contraction of the shoe. Any suitable means may be used to hold the overlapping plates 2i and 22 in gas-tight relationship, but I prefer to attach a plurality of horizontally-disposed bars 23 to the plate 2| in spaced relationship with the inner side of same, and weld a vertically-disposed, round rod Said clips are :24 to said: bars, so. as to produce a guiding memher that bears against the inner side of the, plate 22 and holds it in gas-tight, sliding relationship with the plate 2 I. Said rod or guiding member 24 is preferably adjustably connected to the plate 2i and in the structure herein shown, the adjustment of said member24 is obtained by bolts 25 that pass through the bars 23. The terminal end of the inner surface of the plate 22 is beveled, as shown in'Figure 6, so as to facilitate introducing said plate into operative position between the plate 2i and the overlapping. vertical rod 24,

and if desired, cement or other suitable plastic material 28 can be arranged in the angles formed by the ends of the shoe and the plates 2| and 22, as shown in Figure 6, so as to eliminate sharp corners or angles on the inner side of the shoe I, and produce a substantially continuous surface for 'theprimary seal 2 to slide on.

In installing the seal above described, the shoe i is lowered into operative position between the floating roof B and the side wall A of the tank, and after it has been pressed firmly against the tank side wall, the plates 2i and 22 are bolted to the end portions of the shoe. The shoe isv then mounted on the hangers 5, and set at the proper level by adjusting the links 4 which suspend the shoe from the hangers, and thereafter the lugs 53 are welded to the top surface of the roof. The next step of the installation is to fasten the U- shaped metal clips iii to the top edge portion of the primary seal 2, after which the upper ends of the rock arms M are fastened to said clips by bending the ears or lugs [9 over the disk-shaped portions i8 011 the said arms. The arms It can now be set in slots provided for same in the lugs iii, and combined with the cross bars H and springs l6 that are used to force the shoe I outwardly and hold the primary seal in gas-tight engagement with said shoe. After the angles between the ends of the shoe and the attached plates 2| and 22 have been filled with cement 26, as previously explained, the nuts on the bolts 25 of the bars 23 are tightened so as to produce suincient pressure between the plates 2| and 22 to maintain a gas-tight joint between the same, but still permit said plates to slide on each other when the shoe expands and contracts, due to variations in the shape and circumferential length of the tank side Wall. Subsequently, the bottom edge of the primary seal is fastened in a gas-tight manner to the floating roof, and the secondary seal 3 is mounted on the upper edge portion of the shoe i in such a way as to produce a continuous tank side wall contacting element that stretches and contracts sufficiently to accommodate itself to changes in the shape and in the circumferential length of the tank side wall.

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

l. The combination of a floating tank roof, an annular shoe surrounding said roof and adapted to engage the side Wall of the tank in which the roof is positioned, a primary fabric seal for the gas space, having its inner edge attached to the roof and its outer edge arranged in sliding, yielding engagement with said shoe, means carried by the roof for so supporting the outer edge of the primary seal, and separate and distinct means also carried by the roof for supporting the shoe.

2. A structure of the kind described in claim 1, in which the supporting means for the shoe and for the seal are located on the exterior of the gas space.

3. The combination of a floating tank roof, an annular shoe surrounding said roof and arranged vertically in sliding engagement with the side wall of the tank in which the roof is positioned, said shoe having a substantially continuous surface at the inner side of same, swinging hangers on the roof, means for suspending the shoe from said hangers, a primary seal having its inner edge fastened or attached to said roof, spring-actuated devices on the top side of the roof that support the outer edge of the primary seal and force it outwardly into tight engagement with the inner side of the shoe, and a, spring-pressed secondary seal mounted on said shoe adjacent the top edge of same for protecting the joint between said shoe and the tank side wall.

4. In a floating roof seal, the combination of a floating roof, an annular side wall shoe carried by the roof and arranged with its lower end spaced away from the peripheral edge of the roof, a closure for the gas space between said shoe and roof, formed from a substantially annular-shaped, flexible element extending unbrokenly around the entire circumference of the gas space, said closure element having one of its edge portions attached by a gas-tight joint to one of said parts and having its free edge portion, arranged in horizontal, sliding contact with said other parts, and means for normally maintaining said closure element in yielding, sliding engagement with the part with which the free edge portion of said closure element is in horizontal, sliding contact.

5. A floating roof seal of the kind described in claim 4, in which the part contacted by the free edge portion of said closure element has a substantially continuous surface engaged by the free edge portion of said closure element and arranged so as to be capable of moving horizontally relatively to same.

6. In a floating roof seal, the combination of a side Wall shoe, a floating roof, a seal for closing the gas space between said shoe and roof, said seal having its inner edge portion attached or fastened to the roof and having its outer edge portion arranged in yielding, sliding engagement with the shoe, means on the roof for supporting the shoe, and an independent means for supporting the outer edge portion of said seal and normally maintaining the same in separable relationship with said shoe.

'7. A floating tank roof seal of the kind described in claim 6, in which the means that supports the outer edge portion of the seal for the gas space, presses said seal against the shoe and also forces the shoe outwardly toward the tank side Wall with which said shoe co-acts.

JOHN H. WIGGINS.

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