US2436942A

US2436942A - Seal for floating roof tanks

Info

Publication number: US2436942A
Application number: US527689A
Authority: US
Inventors: Edgar E Shanor
Original assignee: General American Transportation Corp
Current assignee: General American Transportation Corp
Priority date: 1944-03-23
Filing date: 1944-03-23
Publication date: 1948-03-02
Anticipated expiration: 1965-03-02

Description

March 2,A 1948.

E. E. SHANOR SEAL FOR FLOATING ROOF TANKS Filed March 23, 1944 2 Sheets-Sheet 1 'Il' lll,"

March 2, 1948. E. E. sHANoR 2,436,942

SEAL FOR FLOATING ROOF TANKS Filed larch 23, 1944 2 Sheets-Sheet 2 www Patented Mar. 2, 1948 Edgar E. Shanor, Sharon, Pa., acsignor to General American Transportation Corporation, Chicago. IIL, a corporation oi New York Application March 23, 1944, Serial No. 527,889

This invention relates to improvements in storage tanks for oil. gasoline and other volatile liquids of the type in which the top or deck is not connected with the wall of the tank, but normally floats upon and is supported vby the liquid in the tank.

In this type of tank there is an annular space between the tank wall and the deck, in which the level of liquid rises above the bottom of the deck due to the displacement ofliquid by the deck.

z (ci. zzo-zc) Unless this space is properly closed, undue evaporation of the liquid and consequent loss and possible explosion results. The closure means, however, must yield to the drifting of the roof and must make sliding contact with the inner surface of the tank wall to allow for the rise and fall of the deck when the tank is being filled or emptied.

The object of the invention is to provide asealing or closure structure which meets the above requirements and at the same time remains gastight under all operating conditions. I

A furtherfobject 'is to provide for the adjustability of the closurestructure with respect to the level of the liquid in the annular space be tween the tank wall and the deck to minimize evaporation adjacent the sliding contact during summer temperatures and prevent freezing ofmoisture adjacent the sliding contact during winter temperatures.

Other objects of the invention will appear from the following description in connection with the of the closure structure illustrating several relative positions thereof resulting from the drifting of the deck out of concentricity with respect to the tank, and illustrating further the closure structure adjusted for summer operation; n

Fig. 3 is an inner face view of several adjacent suspension plates looking in the direction of the arrows on the line 3,-3 of Fig. 1; and

its upper margin. The floating deck B is circu.. lar in shape and, if of the pan type shown in the drawings. comprises a flat bottom wall 2 and a vertical'cylindrical wall 3 upstanding therefrom, this vertical wall generally being parallel with the wall of the tank. This invention is equally as well adapted to the types. of floating decks which are provided with air chambers or pontoons. The deck is of less diameter than the tank, so that there is anannular space C between c the tank wall and that of the deck. The deck is shown inthe drawings as close to the top of the tank, so that substantially the full capacity of the tank is utilized; but it is understood, of

course, that. the deck which floats on the body of E liquid in the tank rises and falls accordingly as the liquid level is raised or lowered in the tank. 'I'he deck.l due to its weight, displaces the liquid which rises in the annular space C to a normal level above the bottom of the tank and indicated by the line B.

'Ihe annular space C is closed or sealed by a flexible curtain or apron D ofsuitable material, such as asbestos fabric or synthetic rubber. which is gastight and iireresistant. This sealing or closure curtain extends continuously around the deck and bridges the gap between the deck and the tank wall. The upper inner edge of the curtain is clamped against the outer face of the deck wall 3 by means' of the straps l and a series of bolts 1, so as to make the joint gastight and securely hold the curtain in place. The outer and lower margin of the sealing curtain is attached to and supported by a series of suspension members E in close relation to the innereface of the tank wall. 'I'hese suspension members arein the form of rectangular plates which, for the most part of` their area, are substantially flat, but which'have their lower portions 8 curved on a suitable radius so that.their outer face makes substantially a line contact 9 with the inner face of the tank wall, this line contact shifting slightly along the curve of the plates as the plates swing about their fulcrums when the deck drifts into eccentric relation to the tank wall. These plates are also preferably slightly curved transversely in the vicinity of the contact with the tank wall, so that they conform to the curvature of the tank wall and thus maintain as close contact throughout their width as possible.

The lower portion ofthe sealing curtain is curved to conform to the inner face of the curved `portions 8 of the suspension members and are clamped against said faces by the curved clamping plates lll which are secured to the portions Aeach suspension member is closure curtain in close Contact with the susv @mten as necessary provided. but it been iound that' one clamping plate disposed in the center oi .1; cient to hold the pension members throughout their width.

The suspension members entend diagonally uns ward beyond the upper margin it? ci the wall of the deck and are supported on nilcrum helm or members iii which permits them to swing radially. They are spaced apart suciently to allow freedom ci? radial movement without inter-n ference with each other; in fact, the spacing such that fairly large openings are provided be tween the plates which render the suspension members themselves ineffective as a sealing or closure means for the annular space between the deck and the tank wail. Each suspension member is provided with a plate E' riveted on its inner,

face and extending downward to overlie the up@ per margin of the deck wall and serve as a watershed to minimize the possibility oi. water accumulation in the space between the member E and the sealing curtain D.

The iulcrum bolts are i.shaped and have their upper portions It turned radially outwardly be yond the wall S oi' the' deck where they extend through holes I in the suspension members and holes lia in the watersheds E'. Their outer end portions I8 are reduced to provide shoulders it against which the suspension members bear as fulcrums, the holes Il being sumciently large to provide for the free movement oi" the members. The members are retained on these fulcrum bolts against displacement by the pins I8. There are preferably two of these fulcrum supports for each suspension member to prevent them from any rocking movement in their own. planes. The bolts are positioned adjacent the margins of the suspension members and are mounted on a continuous angle I! which extends around the deck wall 3 and is secured by welding or otherwise to the inner face of the deck wall adjacent the upper margin thereof.

The verticalportions of the fulcrum bolts extend through holes in the horizontal ange o1' the crevice di to present the sims ci mais ture which may accumulate 'in the crevice and ireese the suspension members to the tank wall.

The upper portions ci the suspension members it entend in their same plane above lthe fulcrum bolts and are acted upon by spi-ins devices which ursethe members yieldinsly outwardly to maintain constant contact with. the tank wall the angle I9 and are threaded for the locking nuts 2l, one of which is positioned on each sidel of the ilange and screwed up tightly thereagainst to firmly hold the fulcrum bolt in position, This construction provides a considerable adiustment by which the suspension members E may be bodily raised or lowered to-adiustlthe contact lines l of the suspension members with respect to the liquid level 5 in the annular space between the deck and the tank wall.

The lower portions l of the suspension members and the clamped lower portions of the elosure curtain are always submerged in the liquid, but the position of the contact l with respect to the liquid level is important. During summer or warm weather temperatures, it is desirable to adjust the suspension members so that the contact line 8 of the suspension members coincide substantially with the liquid level I in the annular space, as indicated in Fig. 2. This leaves a minimum of' liquid in the crevice 22 between the tank wall and the suspension member exposed to evaporation or ilre. On the other hand, during the winter or freezing temperatures. the suspension members are bodily lowered so that the contact 9 is positioned considerably below the liquid level 5, as shown in Fig. 1, whereby a body of non-freezing liquid will be maintained sion member.` The spring device consists oi the rcel iii, the coil spring and the supporting bracket liti. The outer end ci the rod entends through a hole in the member it and has a i or cross-head 2d which hears against the outer face ci the member E. The spring is mounted on the inner end portion of the rod and is posh tioned between the bracket 2d and a nut il? which is threaded on the rod so that the spring may be placed under the proper degree of compression for the purpose. e outer end of the spring' bears against a washer member @il which has a bearing face t@ normal to the airis or the spring. This washer member is clamped to the bracket *Zit by means of the bolt il and a nut ti. The boi-t extends through an elongated slot di in the bracket 2u, so that the position oi the spring device can be adjusted vertically in the bracket 2t to conform to thefvertical adjustment of the fulcrum bolts ior the suspension members E. The base oi' the bracket 25 is turned horizontally and is secured to the horizontal :flange oi the angle member l@ by means of the bolt @il and nut 3|.. 'I'he spring device for each suspension meinber E is preferably positioned substantially in the center thereof between the two fulcrum bolts.

I claim:

1. The combination of a storage tank for liquid having a vertical cylindrical wall, a roof deck floated upon the liquidin the tank and having a peripheral vertical wall annularly spaced from the tank wall, an annular series of plates disposed in said annular space and having their lower ends curved for contact with the tank wall and their upper ends extending above the deck wall, a pair of fulcrum bolts having outwardly turned upper ends extending through said plates for pivotally supporting the plates and having vertically disposed vshank portions adjustably mounted on the inner side of said deck wall to adjust the contact of said plates with the tank wall relatively to the liquid level, a ilexible continuous curtain secured at its inner edge to the deck wall and at its outer edge to the said plates below the liquid level, and spring devices acting upon said plates above said fulcrum bolts for yieldingly urging the plates in contact with the tank wall. y

2. The combination of a storage tank for liquid having a verticalcylindrical wall, a roo! deck floated upon the liquid in the tank and having a peripheral vertical wall annularly spaced from the tank wall. an annular series of plates disposed in said annular space and having their lower ends curved for contact with the tank wall and their upper ends extending above the deck wall, a pair of i'ulcrum bolts having outwardlyturned upper v at its inner edge to the deck wall and at its outer m' edge to the said plates below the liquid level, n mans mm 5px-mg devices acting' upon said plates bwegidy The following references are oi' record in the fulcrum bolts for' yieldingly urging the plates in `ille 0f this patent:

contact with the tank wall, said spring devices 5 UNITED STATES pAmrx-s including rod members engaging `the plates above l 2,313,856 Wiggins Mar, 18. 1943