US 3811598 A
A covering for a collecting tub defining an annular channel around an aboveground storage tank intended to hold an inflammable liquid having a predetermined combustion temperature comprises an annular roof consisting of a plastics material which tends to disintegrate rapidly and substantially without formation of a flame at said combustion temperature.
Description (OCR text may contain errors)
United States Patent 91 Schwarz [111 3,811,598 [451 May 21, 1974 1 STORAGE TANK INSTALLATION  Inventor: Karl Schwarz, Linz, Austria  Assignee: Verelnigte Osterreichische Eisen-und Stahlwerke Aktiengesellschaft, Linz,
Austria 22 Filed: Aug. 5, 1971 21 App1.N0.:169 ,174,
 Foreign Application Priority Data Sept. 22, 1970 Austria 8541/70 52 us. Cl. 220/88 R, 220/18 51 1m.c1.....- B65d'25/00, B65d 25/24  Field of Search....; 220/85 R, 85 s, 85 on,
220/85-P, 88 R 5A,,24 GT, 89 B, 1 B, 18, 26 S, 26 D, 315, DIG. 6
 References Cited UNITED STATES PATENTS 2,546,573 3/1951 Wiggins 220/26 S 3,669,302 6/1972, Markarian...
7/1957 Staber 9/1957 Wiggins ..-......'220/26 o 986,395 3/1911 King 220/23.4 3,687,329 8/1973 Baum.... 220/88 R 1,823,256 9/1931 Clark 220/1 B 1,943,191 l/1934 Schwemlein 220/1 B 1,844,961 2/1932 Kramer 220/1 B 1,974,034 9/1934 Pelleriti 220/85 S FOREIGN PATENTS OR APPLICATIONS 1,806,186 7/1969 Germany 220/18 1,282,344 12/1961 France 220/26 S 929,723 6/1963 Great Britain 220/26 S Primary ExaminerWilliam 1. Price Assistant Examiner-Allan N. Shoap Attorney, Agent, or Firm-Kurt Kelman [5 7] ABSTRACT A covering for a collecting tub defining an annular channel around an aboveground storage tank intended to hold an inflammable liquid having a predetermined combustion temperature comprises an annular roof consisting of a plastics material which tends to disintegrate rapidly and substantially without formation of a flame at said combustion temperature.
3 Claims, 4 Drawing Figures QATENTEDMAY 21 lHN- 3, 8 I1, 5 9 8 PATENTEMY 21 m4 3,811 ,598
- sum 2 0f '2 STORAGE TANK INSTALLATION This invention relates to a covering for annular collecting tubs of high-capacity, aboveground storage tanks which hold inflammable liquids, which covering comprises an annular roof, which preferably terminates over a gutter carried by the outer wall of the collecting tub.
High-capacity, aboveground storage tanks. which serve to hold petroleum products or the like must be surrounded by a protective bank or better by a collecting tub so that in case of a leakage of the tank or an overflow of its contents an uncontrolled flow of the escaped liquid and a risk of a contamination of the underground water can be prevented. The collecting tubs are often made from steel and have such'a high capacity that they can hold a large part of or the entire contents of the tank.
inner edge portion extending between two continuous peripheral flanges carried by the wall of the highcapacity storage tank and have ,a downturned outer edge portion having parts which bear on the bottom of the gutter. The annular roof can then be formed from prefabricated plates of plastics material which can easily be made and there is no need for a special design of the covering to conform to the annular configuration of the gutter. Because parts of the downturned outer edge portion of the plates of plastics material bear on the bottom of the gutter, a special support for the covering 7 is not required. When the plates of plastics material have been placed on the tub, openings are left between It has been known for a long time to surround such high-capacity tanks with earth banks or protective area so that the fire-fighting equipment can be moved quickly to the source of the fire and the fire can be suppressed with relatively small amounts of fireextinguishing foam.
If such collecting troughs are open-topped, any precipitated water can freely enter the annular collecting channel between the outer wall of the tank and the outer wall of the collectingtub and can collect ,in that space. To avoid such collection of precipitated water, it is known to provide the collecting tubs with a sheet steel covering and with means to conduct the rainwater outwardly. In case of a fire, however, such covering of sheet steel preventsa rapid supply of fire-extinguishing foam to the burning surface so that it is very difficult to extinguish the fire. v Hence. it isan object of the invention to eliminate these disadvantages and to provide a covering for collecting tubs defining an annular channel around highthe supporting parts of the plates and enable an equalization of pressure so that any air flow cannot produce suction. These openings ensure also that any leakage liquid draining over the roof will enter the interior of the collecting tub.
To prevent a sagging or bending of relativelylarge plates of plastics material, radial stiffening ribs are provided on the plates of plastics material.
An illustrative embodiment of the invention is shown byway of example on the accompanying drawings, in which I FIG. 1 is a fragmentary vertical sectional view showing a portion of a high-capacity storage tank provided with a collecting tub and a covering according to the invention.
FIG. 2 is an enlarged fragmentary top plan view showing a portion of the covering.
FIG. 3 is an enlarged sectional view taken on line III- III in FIG. 2 and capacity storage tanks, which covering prevents an in- I object essentially in that the roof consists of a plastics material which at the combustion temperature of the liquid stored in the tank melts repidly or burns whereas it is inflammable with difficulty. Hence, the covering will be destroyed soon after the'outbreakof a fire so that the surface of the burning liquid is freely accessible and fire-extinguishing foam can be applied quickly and in a simple manner to the surface of the burning liquid. In accordance with the invention the roof consists of a plastics material which burns but is difficultly inflammable so-that in case ofa fire there will be no burning roof portions which by the wind created by the fire are carried into the area around the fire, which would thus be propagated. At the present time, the plastics material industry is aware of certain admixtures which can be added to almost all plastics materials concerned so that they burn in a flame whereas the combustion ceases when there is no external source of fire.
A simple covering according to the invention will comprise a roof consisting of overlapping, preferably trapezoidal plates of plastics material. which havean FIG. 4 is an enlarged sectional view taken on line IV-lV of FIG. 2.
A high-capacity, aboveground storage tank 1 for holding combustible liquid is placed in a collecting tub 2 having a sheet steel bottom 2 and a sheet steel outer wall 3. The channel between the outer wall 4 of'the tank and the outer wall 3 of the collecting tub is covered by a roof 5, which terminates over a gutter 6 carried by the outer wall 3 ofthe collecting tub. The gutter 6 is provided with a plurality of U-shaped drainpipes 7 regularly spaced around its periphery. The drainpipes 7 have outlet openings which are disposed outside the outer wall 3 of the tub and below the overflow rim of the inner wall of the gutter so a pool of water will always be left in the gutter 6 and the drainpipes 7 will be filled with water. A sight glass may be inserted in the drainpipes 7. Any water flowing from the roof 5 will enter the gutter6 and will drain outwardly through the drainpipes 7.. Liquid which has flown over from the tank 1 or leakage liquid emerging from the high capacity tanks 1 through any leaks disposed above the roof 5 will also be conducted into the gutter 6 from the roof but as these liquids are in most cases lighter than water they will flow over the inner wall of the gutter into the collecting tub.
The roof 5 consists of overlapping trapezoidal plates 8 of plastics material. The inner edge portions of these plates extend between peripheral flanges 9 provided on the wall 4 of the high-capacity storage tank. Parts of the downturned outer edgeportions of the plates 8 bear on the bottom of the gutter. Radial stiffening ribs 11 are provided to prevent a bending or sagging of the plates 8 of plastics material.
When a fire has broken out, the plates 8 of plastics material melt or burn without forming a flame, e.g., at
a temperature of 150 C. so that the covering is destroyed and the surface of the burning liquid is exposed to receive the fire-extinguishing foam.
What is claimed is:
1. In a storage tank installation which comprises a collecting tub having an outer wall, a gutter carried by the outer tub wall, the gutter having a bottom, an above-ground storage tank for an inflammable liquid having a predetermined combustion temperature, the tank having an outer wall and being placed into the tub, the outer tub wall and the outer tank wall being spaced from each other to define an annular chamber around the tank for collecting therein any of the inflammable liquid coming from the tank, and a covering for the annular collecting chamber of the tub, the covering consisting ofa rigid annular roof having an inner edge adja- 2. An installation as set forth in claim 1, in which said plates are trapezoidal.
3. An installation as set forth in claim 1, in which said plates are provided with radial stiffening ribs.