Floating deck for liquid-storage tanks

Application filed March 26, 1923. Serial No. 627,835.

This invention relates to liquid storage tanks of the type that comprise a movable top or deck which floats upon and is supported by the liquid in the tank, and is an Λ improvement upon the floating deck described in my U. S. Patent No. 1,493,091, ' dated May 6, 1924, which resulted from my application for patent Serial No. 540,847, filed March 3, 1922.

io One object of my present invention is to provide a tank of the general type above referred to for storing oil and other liquid, which is of such construction that permanent gases mixed with the liquid pumped 15 into the tank will not cause the liquid to be carried out of the tank and splashed onto the floating deck.

Another object of my invention is to provide a tank for storing volatile liquids so which is of such construction that the fire hazard and the evaporation losses are reduced to a minimum.

And still another object of my invention is to provide a liquid storage tank which is 25 of such design that relatively great variations in the diameter of the tank, due to expansion and contraction, will not influence or have any effect on the efficiency of the means that is employed to close the space 3 between the floating deck and the side wall of the tank.

To this end I have devised a liquid storage means, which, briefly described, consists of a tank provided with a cylindrical side 35 wall, a floating deck supported by the liquid in the tank and proportioned so that it covers the major portion of the surface of said liquid, and an annular chamber between the peripheral edge of said deck and the side 4(> wall of the tank constructed so that gases mixed with the liquid jumped into the tank will be trapped in said chamber, and subsequently allowed to escape from same through restricted openings. The annular 45 chamber and the restricted openings just referrred to are preferably of gas-tight construction, so as to reduce the fire hazard and the evaporation losses to a minimum. By' “gas-tight” I mean substantially gas-tight so when in normal operation. It is obvious that when, for any reason whatever, the internal gas pressure exceeds the safe limit, the vents will open and the annular chamber is no longer gas-tight. The outer side 55 wall of said annular chamber is formed by a shoe arranged parallel to the side wall of the tank with its lower edge portion submerged in the liquid in the tank, and in order to provide for a relatively great expansion and contraction of the tank, said 60 shoe is composed of segmental sections sustained by long hangers carried by the floating deck and joined to each other and to the floating deck by pieces of flexible material which are preferably substantially 65 gas-tight and fire-proof. Another annular chamber, which is open at its upper end, is formed by the outside surface of the shoe above referred to, by the inner surface of the side wall of the tank which extends par- 70 allel to said shoe and by the surface of the liquid in the tank. Said shoe is of relatively great depth, so that the open annular chamber between said shoe and the side wall of the tank will be comparatively narrow 75 with reference to its height, so that the oil vapors which collect in said chamber will remain at the lower end of said chamber, notwithstanding the fact that the upper end of said chamber is open, due to the fact that ⁸⁰oil vapors are about twice as heavy as air. With such a construction there is practically no circulation of air or vapor in the chamber referred to.

Figure 1 of the drawings is a top plan ⁸⁸view of part of the variable peripheral portion of a floating deck for liquid storage tanks constructed in accordance with my present invention.

Figure 2 is a vertical sectional view, 9° taken on the line 2—2 of Figure 1, looking in the direction indicated by the arrows.

Figure 3 is a vertical sectional view, taken on the line 3—3 of Figure 2, looking in the direction indicated by the arrows. °5

Figure 4 is an enlarged vertical sectional view, taken on the line 4—4 of Figure 1, looking in the direction indicated by the arrows.

Figures 5 and 6 are diagrammatic views, ¹⁰⁰illustrating slight modifications that may be made in the deck without departing from the spirit of my invention; and

Figure 7 is a detail sectional view, illustrating one way of producing gas-tight ¹⁰⁵joints between the various sections of the peripheral portion of a deck of the kind illustrated in Figure 6.

Referring to Figures 1 to 4 of the drawings, A designates the side wall of a liquid ¹¹⁰storage tank and B designates the central body portion of a movable top or .deck that , £3 1,662,225 floats upon the liquid in the tank, said central body portion being imperforate and so proportioned that it covers the major portion of the surface of the liquid in the tank. 5 The annular space between the side wall of the tank and the central body portion B of said deck is closed or protected from the atmosphere by a seal which is constructed in such a manner that it is capable of expand0 ing and contracting sufficiently to compensate for variations in the relative position and dimensions of the deck and the side wall of the tank. In the form of my invention shown in Figures 1 to 4, said seal consists of ¹⁵ the peripheral portion of the deck that is carried by the central body portion B of the deck and which is preferably composed of a number of segmental shoe members C that bear against the inner side of the side wall of ²⁰ the tank and horizontally-disposed elements

D that project inwardly from said shoe members towards a vertically-disposed annular rim E on the central body portion B of the deck, the shoe members C co-operating with ²⁵ each other to form an annular shoe arranged parallel to the side wall of the tank in sliding engagement with same and having its lower edge portion submerged in the liquid in the tank, as shown in Figure 4. The horizontally-disposed elements I) that project inwardly from the shoe members C may be formed in various ways, so long as they are of such construction that they pro_3B vide for the expansion and contraction of ⁰ the shoe formed by the members C and will also serve as a closure for the annular space between the side wall of the tank and the vertical rim E on the periphery of the central body portion B of the deck, that is gastight, in that it is sufficiently tight to retard or prevent the infiltration of air into said space and also retard or prevent the free escape of gases or vapors from said space.

One of the novel features of my present ⁵ deck consists of the means that is used for supporting or carrying the variable peripheral portion of the deck. Preferably said means consists of hinged or pivotally mounted hangers or supports F mounted on the central body portion B of the deck and combined with the various sections of the variable peripheral portion in such a way as to provide for the radial movement of said sections and insure the shoe members C remaining in parallel relationship with the side wall of the tank. As shown in Figure 1, two hangers F are provided for each section of the peripheral portion of the deck, _βθ each of said hangers consisting of a substantially elbow-shaped lever arranged with its vertical leg projecting upwardly from the central body portion B of the deck, and its horizontal leg projecting outwardly to_ω wards the side wall of the tank so as to overhang one of the sections of the variable peripheral portion or cue deck. The lower end of the vertical leg of each of tlie hangers F is pivotally connected at 1 to a bracket 2 on the annular rim E, and the horizontal leg of said hanger is connected by a swinging 7n link 3 or other suitable pivotal connection with the section of the peripheral portion of the deck with which it co-operates, thereby permitting the sections of the peripheral portion of the deck to move radially with- 7ft out destroying the parallel relationship between the shoe members C and the side, wall of the tank. In view of the fact that the vertical legs of the hangers F are comparatively long and are pivotally mounted on 8° brackets that are arranged in close proximity to the portion of the deck which floats upon the liquid in the tank, the sections of the deck carried by said hangers are capable of moving radially with only a slight rise ⁸⁸and fall. Such a construction is inexpensive to manufacture and it is reliable in operation, as there is very little possibility of any of the sections of the variable peripheral portion of the deck sticking in such a way as ⁰⁰to interfere with the radial movement of said sections. In order to hold the annular shoe and the central body portion of the deck in approximately concentric relation with each other and also insure the lower edge por- ⁰⁵tions of the shoe members C remaining in snug engagement with the side wall of the tank, the annular rim E on the central body portion of the deck is provided with a plurality of spring-pressed plungers G that ¹⁰⁰bear against said shoe members, as shown in Figure 4.

As previously stated, it is immaterial, so far as my present invention is concerned, what type or kind of horizontally-disposed ¹⁰⁵elements D are employed or used to form a closure for the annular space between the shoe members C and the rim E. In the form of my invention shown in Figures 1 to 4, inclusive, each of the shoe members C is ¹¹⁰provided with a horizontally-disposed plate D that projects inwardly from same and laps · over the upper edge of the rim E on the central body portion of the deck, the inner edge of said plate being turned downwardly ¹¹⁵so as to form a drip flange 4, as shown in Figure 4. It is essential that substantially gas-tight joints be formed between the adjacent shoe members C and horizontally-disposed plates D and between said plates and ¹²⁽¹the upper edge of the rim E on the central body portion B of the deck, so as to retard or prevent the free escape of gases or vapors that collect in the annular space between the _orrim E and the side wall of the tank and also ¹²⁵to retard or prevent the infiltration of air into said space. In the deck shown in Figures 1 to 4 each section of the variable peripheral portion is provided at one end with an angle-shaped metallic device H that forms ¹³⁰

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Q a lateral extension on one end of said section which laps over and slides upon the left hand end of the adjacent section of the variable peripheral portion of the deck, and the joints 5 between said devices H and the sections of the deck on which they slide are protected by flexible sealing devices I, as shown in Figure 2, which are preferably gas-tight and fire-proof. Preferably each of the flexible 10 sealing devices I is composed of a plurality of layers of canvas or other fabric, treated to make it impervious to gas, and permanently combined with angle-shaped attaching devices 5 which are secured by bolts or rivets 15 6 to the horizontally-disposed plates D and shoe members C of two adjacent sections of the peripheral portion of the deck. Such a construction permits the horizontally-disposed plates I) and the shoe members C to 20 move relatively to each other and it insures gas-tight joints between said parts, as each section of the peripheral portion of the deck· is provided at one end with a metallic extension, formed by an angle-shaped device 25 H, that laps over the opposite end of the adjacent section, and a flexible gas-tight sealing device I which extends over said extension and is connected to the end portion of the adjacent section on which said extension 30 slides. Owing to the fact that the fabric joint protecting devices I are arranged on the inside of the deck, they are protected from the elements and from fire by the angleshaped metal devices H which act as closures 35 for the radially-disposed joints between the various sections of the peripheral portion of the deck. Moreover, as said fabric joint protecting devices I are combined with the relatively movable parts of the deck in such 40 a way that no metallic parts rub against the same, said devices I will last for a long period.. In the form of my invention illustrated in Figure 4 I have shown a similar fabric gas tight sealing device 1' connected 45 to the upper edge of the rim E and to the underside of the horizontally-disposed plates D for protecting the joint between the said plates and rim, the device I' being formed preferably of treated fabric and con50 nected to the rim E and plates D in such a way that while it does not interfere with the movement of said plates relatively to each other, or radially with respect to the rim E, it does effectively prevent the free and un55 controlled escape of gases or vapors from the annular space between the rim E and the side wall of the tank.

Instead of using horizontally-disposed metal plates D to close the space between f the shoe members C and the annular rim E on the central body portion B of the deck, said space can be closed by a horizontallydisposed, flexible, gas-tight means D' formed of treated fabric or the like connected at its outer edge to the shoe members C and at its _0g inner edge to the upper edge of the rim E, as shown in Figure 5.

Another slight modification that Can be made without departing from the spirit of my invention is illustrated in Figure fi, ₇₀wherein the annular rim E on the intermediate portion B of the deck is provided with an annular trough 7 that contains a liquid 8 which co-operates with sealing devices 9 that project downwardly from the ₇₅underside of plates D which project inwardly from the shoe members C. Each of the plates D may be provided with one or more segmental shaped, depending sealing devices 9 that are submerged or partly submerged in ₈₀the liquid 8 in the trough 7 on the rim E, said sealing devices 9 effectively preventing gases from escaping from the annular space between the rim E and the side Avail of the tank through the joint between the upper ₈₅edge of said rim and the horizontally-disposed plates D. The radial joints between the plates D and shoe members C may be protected in the manner previously described in connection with Figures 1 to 4, and if de- 90 sired, flexible gas-tight devices 10 formed of treated fabric or the like can be connected to the sealing devices 9, as shown in Figure 7, so as to produce gas-tight joints between the adjacent sealing devices 9. In other 95 words, if the closure for the annular space between the side wall of the tank and the rim E on the central portion of the deck is formed by horizontally-disposed plates provided on their under sides with depending i₀₀devices that are sealed by a body of liquid, flexible devices 10 can be pro Added for joining the sealing devices 9 together in such a way that gas cannot escape through the joints betAveen the ends of same. 105

Due to the fact that the seal arranged between the deck and the side wall of the tank is constructed in the form of an inverted trough-shaped chamber whose lower end is open and in direct cornmuhication with the 110, interior of the tank, any gases that bubble upwardly around the edge of the rim on the deck will become trapped in said inverted trough-shaped chamber, and any liquid that is entrained in said gases will separate from 115 same before said gases are permitted to escape from said chamber, thereby reducing to a minimum the possibility of liquid being carried out of the tank with gases that escape to the atmosphere. In order to provide for 120 the escape of gases from said chamber and also to prevent an abnormal pressure from developing in said annular chamber the rim E on the peripheral edge of the body portion of the deck is provided with a number of ¹²5 outlets J equipped Avith liquid sealed closures K. Preferably each of said closures K is arranged in such a way that it is capable of

1,662,225 opening automatically whenever an abnormal pressure or pressure in excess of a certain degree exists in the inverted troughshaped chamber that constitutes the seal. As shown in Figure 4, each of the outlets J is formed by a horizontally-disposed tubular member projecting inwardly from the rim E and provided with a vertical discharge outlet that is surrounded by an annular well 10 11 which contains a liquid that will not evaporate rapidly. A hinged closure K is provided for said discharge outlet, which closure is equipped with a depending annular flange 12 that dips down into the sealing 15 liquid in the well 11. If an explosion occurs in the tank, due to the accumulation of a large quantity of gases between the rim E and shoe C, one or more of the closures K or “explosion doors” will be thrown upwardly 20 by the force of the explosion, thereby establishing communication between the atmosphere and the annular space between the rim E of the deck and the shoe C whose loweredge portion is submerged in the liquid in 25 the tank. ¹

One other feature of the construction above described that adds greatly to its commercial utility is the mounting of the shoe members C on the central body portion ³⁰ of the deck in such a way that it is impossible for said shoe members to move outwardly beyond a certain point, and thus cause the hangers for said shoe members to bind or fail to operate properly in instances ³⁵ where the side wall of the tank is abnormally out of round. In the form of the invention shown in Figure 4 the depending flanges 4 on the plates D co-operate with the upper edge of the rim E to limit the outward move40 ment of the shoe members C, and in the form of the invention shown in Figure 5 the gastight fabric D' that is connected to the shoe members and to the upper edge of the rim E functions as a means to limit the outward 45 movement of the shoe members. Obviously, various other means can be employed to attain this highly desirable result, and accordingly, I wish it to be understood that so far as this feature is concerned, it is immaterial 50 what means is used to limit the movement of the shoe members outwardly away from the rim E, so long as said means does not consist of the side wall of the tank, thereby insuring the shoe members and their support55 ing hangers remaining in an operative condition, even when the side wall of the tanx becomes abnormally out of round.