US2790574A - Floating-roof type liquid storage tanks - Google Patents

Description

April 30, 1957 GINO coNsANl FLOATING-ROOF TYPE LIQUID STORAGE TANKS .Filed Feb. 21, 1955 GINO CONSAN! ATTORNEYS United States Patent O i FLOATING-ROOF TYPE LIQUID STORAGE TANKS Gino Consani, Elsies River, Union of South Africa Application February 21, 1955, Serial No. 489,687

Claims. (Cl. 22026) This invention relates to floating-roof type liquid storage tanks and provides an improved and highly satisfactory means of both centralising and sealing the periphery of the roof to the tank wall to obviate evaporation of the contents, ut ilising-for forming the seal a manner generally known a s o-called shoe intended to fit slidably against the internal surface of the tank wall and borne against by the outer periphery of a flexible sheet rubber or like sealing element bridging the generally annular clearance space occurring about the ,roof, e. g. between the upper side of the roof-floating pontoon, and the inside surface of the shoe. The invention is more particularly an improvement upon roof-sealing and centralising arrangements of the kind in which a shoe is loaded outwardly from the roof into engagement with the tank wall by a weight-motivated variety of toggle linkage so devised and pivotally connected to the roof and to the shoe that, within required limits of movement of the latter, the locus of the shoe connection is substantially horizontal and lateral shoe displacements are practically eliminated.

According to the invention, the toggle linkage referred to comprises a first link member pivotally connected at one end to the shoe, a second link member pivotally connected at one end to an opposing point of the roof or pontoon, with the two members extending convergently downwards and pivotally connected to one another at a point short of the free end of the first of shoe-connected member, and a third link pivotally connecting the first member by its free or lower end with the roof or pontoon. at a point substantially below the first mentioned point; either the second or the third member being extended generally downwards from the remainder of the linkage and so formed as to experience a gravity produced turning moment, about its connection with the roof or pontoon, generally towards the shoe for application of force loading the shoe pivot outwardly from the others.

The foregoing and other features of the improved toggle linkage according to the invention are included in embodiments thereof hereinafter described by way of example with reference to the accompanying drawings, wherein:

Figure 1 is a fragmentary sectional elevation showing f the generally known arrangement of seal between the tank wall and the roof or pontoon, including a shoe support and linkage constructed according to one form of the invention;

Figure 3 is a fragmentary plan of the linkage shown in Figure l; and

Figures 2 and 4 are similar views to Figures 1 and 3 respectively but showing an alternative or further modified linkage construction.

In both Figures 1 and 2, the shoe 1 is shown in outward contact with the wall 2 of the tank, the flexible rubber seal at 3 spanning the annular clearance between the upper part of the shoe 1 and the upper part of the roof or pontoon 4.

2,790,574 Patented Apr. 30, 1957 'ice In Figures 1 and 3 the first linkage member 5 is a plain single link of suitable length between its two end pivot pins 6 and 7 and having a third pivot pin 8 located somewhat nearer to its free end than to its upper end which is pivoted to the bracket 9 on the inside of the shoe. The second member 10 is a twin link of substantially equal length to the distance of the third pivot pin 8 of the first link from the upper pin 6 thereof, and its upper end is pivotally connected at 11 in twin lugs or the like 12 to the side of the pontoon 4 while its lower end shares the aforesaid third pivot pin 8 of the first link 5. The third member 13 is also a twin link whereof the upper end is pivotally connected to the pontoon via the aforementioned lugs in a pivot pin or pins 14 whose axis is downwardly removed from the upper end connection of the second link at 11 and located somewhat nearer than the latter connection to the centre of the roof. The third member 13 is extended downwardly as at 13 beyond its pivotal connection 7 with the free lower end of the first link 5 to about level with the base 4 of the pontoon where it approaches the latter and turns, as at 15, under and clear of it to finish in a straight portion 15' provided with a preferably adiustably positionable weight 16.

The proportioning of the links and the ratios of lengths between pivotal connections are made such that the locus of outward movement of the upper end connection 6 of the first link with the shoe 1 is in a horizontal plane substantially level with or slightly below the upper pivotal connection 11 of the second member with the pontoon 4; and furthermore the two lines x and y respectively joining the upper and lower pivotal axes of the second and third members (as medial lines between the twin link components) when downwardly produced are made to intersect in a point 2 contained in a vertical line z dropped from the axis of the upper connection 6 of the first link with the shoe; the effects of which arrangements, within the limits of radial shoe movement in relation to the pontoon, being to dispose of vertical forces through the last mentioned connection (6) otherwise than would cause lateral shoe displacement; such effects moreover being obtained without the aid of or reliance upon sliding connections.

The force motivating the linkage and thus translated thereby into outward pressure of the shoe against the tank is a function of the effective moment of the weight 16 and is readily variable by adjusting the mass of the weight and/or its position along the part 15' of the extension of the third link 13.

In the modification of the device shown in Figures 2 and 4, functioning in an equivalent manner to the first construction, it is the second-mentioned member 10 (i. e. the first of the aforementioned two twin links, of which the lower is modified as shown in Figure 4tto a convergent form) which is extended downwardly and inwardly under the pontoon (like the parts 13', 15 and 15' in Figure l) and Weighted suitably to motivate the linkage in the required manner.

What I claim is:

1. In a liquid storage tank having a floating roof, a plurality of shoes adapted to slidably contact the inner side walls of the tank and an annular seal between the shoes and the roof, a toggle linkage for connecting the floating roof and the shoes comprising a first link member pivotally connected at one end to a shoe, a first connecting link pivotally connected at one end to an opposing point of the floating roof, with the link member and the link extending convergently downwardly and pivotally connecting to each other at a point between the ends of the first link member, and a second connecting link pivotally connecting the lower end of the first link member with the floating roof at a point substantially below the point at which said first connecting link is attached, one of said connecting links being extended generally downwardly from the linkage and formed to cause a gravityproduced turning moment about the pivotal connection of the linkage with the floating roof in a direction generally towards the shoe, whereby a force is applied to the shoe which loads the shoe pivot outwardly against the tank side wall, the instantaneous center of rotation of said linkage being in a vertical line beneath the pivotal connection of said first link member to the shoe.

2. A linkage as claimed in claim 1 in which the first connecting link is extended downwardly beyond its pivotal connection with said first link member and is turned under and beneath the base of the floating roof, and a weight thereon for applying the turning moment to said linkage.

3.- A linkage as claimed in claim 1 in which the second connecting link is extended downwardly beyond its pivotal connection with said first link member and is turned under and beneath the base of the floating roof, and a weight thereon for applying the turning moment to said linkage.

4. A linkage as claimed in claim 1 in which the two axial lines joining the upper and lower pivot points of the first and second connecting links when downwardly extended intercept at a point in a vertical line beneath the axis of the pivotal connection of said first link memher with the shoe, and the proportioning of the links and the ratios of lengths between pivotal connections are such that the outward movement of the pivotal connection or" the first link member with the shoe is in a horizontal plane substantially level with the pivotal connection of the first connecting link with said floating roof.

5. A linkage as claimed in claim 1 in which the first link member is a single link having end pivot pins and having a third pivot pin located nearer its lower end than to its shoe-connected end, the first connecting link is of substantialequal length to the distance of the third pivot pin from the shoe-connected end of said first link member, and the lower end of said first connecting link is pivotally connected to the third pivot pin on said first link member, the second connecting link having the upper end thereof pivotally connected to the floating roof at a point downwardly removed from the connection of the first connecting link to said floating roof and located nearer to the vertical axis of the roof than the connection of the first connecting link to said roof.

References Cited in the file of this patent UNITED STATES PATENTS 1,931,551 Larson Oct. 24, 1933 2,536,019 Allen Jan. 2, 1951 2,587,508 Meyer Feb. 26, 1952

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