US2768432A

US2768432A - Method for erecting roofs of tanks

Info

Publication number: US2768432A
Application number: US211098A
Authority: US
Inventors: Clarence W Hines
Original assignee: Chicago Bridge and Iron Co
Current assignee: Chicago Bridge and Iron Co
Priority date: 1951-02-15
Filing date: 1951-02-15
Publication date: 1956-10-30
Anticipated expiration: 1973-10-30

Description

Oct. 30, 1956 c. w. HINES METHOD FOR ERECTING RooFs oF TANKS 3 Sheets-Sheet l Filed Feb. l5, 1951 @www Oct. 30, 1956 c. w. HlNEs 2,768,432

METHOD FOR ERECTING ROOFS OF TANKS Filed Feb. l l5, 1951 5 SheetsSheet 3 Uflifed States Pattif r I 2,768,432 :MErHoD Fon ERECTING Roors F TANKS Clarence W. Hines, Chicago, Ill., assigner to `Clucago Bridge & Iron Company, a corporation of Illinois ,'.l'lhis invention relates to a method and apparatus for erecting roof structures of a` tank or the like and particularly to the methods and apparatus used in constructing and erecting the roof of an elevated storage tank.

The construction of elevated water tanks has previously been done with hoisting apparatus and a great amount of temporary'support. As the construction of the tank progressed, falsework was provided to hold the plates of the tank inproper position for welding or otherwise securing them to vpreviously positioned plates of the storage tank.` In roof structures a temporary support has been provided under the roof so that individual plates or sections of kplates may be'hoisted into position and temporarily` supported there while workmen weld them per-V manently to the structure. This invention eliminates the necessityfor temporary supports, thus reducing materially the cost of construction and the weight of steel previously used inthe supports. t

In the practice of this invention, the columns of the tank and the main'storage sidewalls may be constructed in accordance'withV the procedure outlined in mycopending application, Serial 99,507, led June V16, 1949, nou/.issued asA Patent No. 2,720,694,kr dated October 18,'

2,768,432 Patented Oct. 30, 1956 ice which projects upwardly from the bottom of the tank through the roof thereof. The central column portion -16 is Aprovided with a rotatable support 17 to whicha derrick boom is pivotedly secured in the manner described in myabove identified co-pending application. The support 17 for the boom 18 is provided with roller bearings to permit the boom to be swung through 360 about the central column portion 16. Suitable cables 19 are provided for positioning the boom 18 relative to the central column portion 16 land a hoisting cable 20 is provided at the end of the boom and controlled from the ground for hoisting sections of the tank structure to proper position.

As outlined in my co-pending application, the columns 12 and central column 14 are iirst constructed after which the bottom 11 of the storage tank is placed in position on the columns. The sidewalls 21 of the tank are hoisted by means of the derrick boom 18 and secured in position to the bottom 11 of the storage tank. After the sidewalls 21 are completed, a relatively large roof opening 22 remains. In previous constructions the roof was formed of plates hoisted onto a temporary supporting structurebuilt within the tank after the completion of the sidewalls 21 to the point where the roof opening 22 was ,reached Suchtemporary supports are dispensed with in the method in this invention.

igether on the ground. A radially aligned side-angle 36 extends from the outer end of the section to the inner end thereof. I extends from the Vouter end of the sectionto a point .beyond the inner end thereof to form an'arm 38 which 195,5.V Myco-pending application provides a derrick sppor'tedon the tank structure itself without the necessit'yof guy lines anchored at a great distance from the tank site. v This derrick is briey described herein as relatedvto the steps of construction to be described in detail,

In general, the method of this invention includes irst dividing theroof into a plurality of relatively largersections, each of which is formed in its prescribed shape on the ground beforeitis hoisted into ,position on the tank.y

These roof sections are somewhatin the shape of a section of a pie, hereindeiined as a truncated radial section, andfarep'rovided with means for temporarily supporting them 'onthe tank structure until each section is permanently welded or otherwise secured to the main portionv of the tank.

The invention will be described in connection with the exemplary embodiment illustrated in the accompanying drawings, in which Fig. l is an elevation of a large storage tank illustrating two steps in the. hoisting of a roof section ofnthis `invention to position on the tank structure. Figt 2 is a top plan view of the tank shown in Fig. 1.4 Fig; is aV fragmentary top plan view of the completed roof. Fig. 4 is a fragmentary radial section through the roof Vof the tank showing one roof section in position on the tank structure. Fig. 5 is a plan view of the roof sec tion shown in Fig. 4, as formed on the ground prior to its being hoisted into position on the tank.

The particular elevated tank chosen for purposes of illustration comprises a spheroidal shaped storage portion 10 having a radial cone bottom 11 and supported uponV a pluralitylofy columns 12'restingy upon4 foundations 13 at the bottom of each column. A central column 14 having a foundation 15 supports an extension 16 thereof joined to the side angle irons 36 vand 37 and eachare..

'-froof plates .4 4 are placed over the framework and forced= is of suicient length to'reach from the section to'the central'column portion 16 withinthe tank. .'.These radially aligned angle irons are leach curved to the prescribed camber .of theroof. `Cross-members 39, 40 and 41 are curved alongan arc having its center at the center of the roof.'v These cross-membersare each an angle. ironas are the-,radially aligned members. .-Additional radially-v aligned members 42 may beprovided as desired to ex Vtend between adjacent cross-members to further-strengthen the frame of each roof ,.section.v -Care is exercised inl assembling the framework to secure and maintain thecorrect curvature vof the. members. f

After the framework lis assembled, substantially -ilat to a curvature corresponding to thaty of the framework. The plates are welded to each other and tacked to the upstanding legs of the angle irons whichy comprise-the` framework. The `plates -extend from the inner cross- 1 member 39 to the outer cross-member 41 and cover 'the In addition, the plates are so posientire framework. tioned that vthey extend a short distance over theangle irons 37 and beyond the cross-member 41 at the larger.' These overhanging portions are of;` use in temporarily Supporting the section on theshell of` the ltank and thepreceding roof section as will be described below, This, section of the roof is in theformof a truncatedradial section of the Aroof as viewed in plan end of the section.

V(Fig..5).

Afterwthe requisiteY number of roof sections are as. sembled on the groundat spaced positions about the,V

tank site,each section is hoisted in4 turnrto its proper position on thetank. As illustrated'in Fig. l, the derrick boom 18 is lowered to the dotted line position so that the hoisting cables 20 may clear the edge of the A second radially aligned angle iron 37- sidewall 21 ofthe tank. Av sling 46 having two equal legs is secured to spaced points on the inner end of the truncated section and passed over the hook 47 carried by the hoisting cables (Figs. 1 and 2). The section is-hoistedfroniltle ground as indicatedin-the-dotte'd lines of Fig.- 1. Asthe section nearsthe top offthI tank, the derricleboom is raised vtovvard thecentral column? portion 16 until theouter edge portion ofgthe sectionl 25 may be i positioned with the plates 44 overlapping the sidewalls 21 of the tank as is more Clearly seen in Fig. 4. The section 25 is maneuvered into position so that the arm 38 may be bolted at 48 in a pin and'slot connection with a lug 49 secured to the center column 16; In this position the derrick boom is in? alignmentfin the space be tween the radial edges of the roof section. The arm 38 is suticiently strong to carry onev side of the section on the central column. While in this position, one leg of. the sling 46 is disengaged from the side of the section nearestthe leg 38, after which the boom is swung about the central column 16 to move it out of alignment with the section. The opposite side of the section is supported during such movement by the other leg of the sling 46 which remains secured to the roof section. Once the hoorn is out of such alignment, the strut S0, which is pivoted to the roof section at S1, is connected with a lug 52 on the column. A substantially horizontal spider' rodi-3 is connected to the lug 52 and a ring-member 54 adjacent the roof opening 22. A turnbuckle 55 is provided in the spider rod S3 to provide the desired amount of tension in the rod.

The above sequence of operations are sufficient to secure a single roof section in its proper position on the tank shell. The section is supported on the tank shell at the roof opening 22 by the overlapping of the roof plates 44 and the shell 21. The inner end of the section is supported by the arm 38 against the central column 1'6 and a truss which includes the roof section, the strut 50, and the spider rod 53. It will be noted that the section is supported without the necessity of temporary roof supports and may be hoisted directly from the ground to its position on the tank without any fitting up of adjoining plates.

After one section of the roof has been secured in position, adjoining sections are sequentially hoisted and placed in position to complete the roof, starting from the first section and continuingrabout the roof, and ending with a section adjoining thevrst. The spider rods 53 are all placed between the root opening and center column prior to hoisting any of the roof sections. The inner end of the rods may be dropped temporarily to allow the derrick boom to pass. Since each roof section has plates overlying and extending beyond the radial member 37, the preceding sectionmay help support the next section. The plates of adjoining sections are generally lapwelded to make the roof weather-tight. The spider rods may be used for scaffold supports for painters after the roof is completed.

The inner cross-members 39 of each section are welded together after all sections of the roof are in position to form a small compression ring 57 near the top of the roof. The center opening about the central column 16 is of relatively small size compared with the larger portion ofthe roof covered bythe roof sections 25. After the derrick boom has served its purpose, it is lowered through Van opening in the bottom 11 of the tank and the rotatable support member 17 may be ren'ioved from the central column. If desired, the central column may remain within the tank to serve as an access tube. The small opening 'about th'e central column is closed by plates 58 hoisted from the ground by hand.

As an example of an elevated storage tank-constructed by the use ofroof sections of the character described and utilizing the methods of erection described,A a .C11/2A million gallon water spheroid may be constructed with a roof opening 22 of approximately 98 feet in diameter. The small opening about the central column is about 15 feet in radius and the roof sections span the remaining portion of the roof opening. The roof itself may be divided into twelve individual sections, each weighing in the neighborhood of 10,000 pounds. Fewer or more sections of the roof may be made as desired within the limits of capacity of the particular hoisting device.

The foregoing description is given for clearnessl of understanding only and no unnecessary limitations should be understood therefrom. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

l claim: A Y

l. The method for erecting the roof of an elevated tank which includes the steps of providing a central column in the tank and a derrick boom secured 'to the column, formingl a major annular portion of the roof into a plurality of truncated radial sections on the ground, providing a sling having a pair of legs joined respectively to said section at the inner corners thereof, hoisting the section to proper position on the tank with said boom, bracing one side of said section against the column, removingv the leg of the sling joined to said braced side, swinging the boom out of radial alignmentl with the section while supportingV the unbraced side of the section, and then bracing the other side of the section against the column and removing the remaining leg of the sling from the section.

2. The method for erecting the` roof of an elevated tank which includes the steps of providing a central column in the tank, forming a plurality of similar roof sections on the ground which when assembled on the tank form an annular portion of the roof, hoisting the sections successively into position on the tank shell, providing each section so formed with a radially extending arm along one radial edge of the section and of sufcient length to support one side of the section against the center column when the section is in position on the tank shell, providing a strut hingedly connected to the other edge of the section for supporting the other side of the section against the center column below the inner end of the roof section and securing a substantially horizontal spider rod between the column end of said strut and the tank shell adjacent the outer end of the section to form a truss including the section and the strut.

3. The method of claim 2 including the step of providing each roof y section with a framework having roof 'plates secured thereto and extending said plates outwardly over the frame along one radial edge to overlap the plates of the adjoining section.

References Cited in the tile of this patent UNITED STATES PATENTS OTHER REFERENCES Construction Methods, January 1947, pp. -112.