US2668634A - Spherical segment tank and method of making same - Google Patents

Description

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Feb. 9, 1954 Filed Feb. 25, 1950 c. ARNE 2,668,634

SPHERICAL SEGMENT TANK AND METHOD OF MAKING SAME 2 Sheets-Sheet l c. ARNE 2,668,634

SPHERICAL. SEGMENT TANK AND METHOD OF MAKING SAME Feb. 9, 1954 2 Sheets-Sheet? Filed Feb. 25, 1950 Patented Feb. 9, 1954' UNITED STATES PATENT OFFICE nois Application February 23, 1950,",Serial No. 145,770

6 Claims; I

This invention relates to improvements in pressure tanks and methods of making the same and more particularly segmental and multisphere tanks.

Large pressure tank are made of a plurality of steel plates usually welded together to form thecompleted enclosure, such as multisphere tanks shown in Boardman Patent No. 2,457,118. When such a tank is built up from a fixed foundation or support many of the welds must be vertical and'overhead welds which are much more diflicult to make accurately and sound than down hand welds. The present invention provides a method of making a pressure tank which obviates the difiiculties attendant with Welds made in positions other than down hand.

An embodiment of this invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a vertical cross section through a pair of ring members mounted on rollers and showing two'plates of the center segmental shell in place thereon;

Fig. 2 is an end view of a ring member illustrated'in Fig. 1 showing three plates of the center segmental shell in position thereon;

Fig. 3' is. a vertical view of a tank of this invention showing the plates of the center segmental shell inposition and a portion of one end semispherical shell;

Fig. 4' is, a view of the completed segmental tank partly in section;

Fig. 5 is a vertical viewv taken substantially along line 5-5 in Fig. l;

Fig. 6 is an enlarged sectional view of a section ofthe ring member and plates ofthe adjacent shells and the diaphragm; and

Fig. 7 is a view of the completed tank mounted on an earth foundation.

The first step in construction of a tank accord.- ing-to. this invention is the forming .of an'angle iron:into a-ring l8 and welding the. ends: of the angle iron together so that therring is continuous. One leg H of the ring should extend radially inward and the other leg 12 should. extend at an'angle thereto. The rings El mayrbeformed. on .the.- -ground.andadianhragm l3 welded:tothe Whilethe ring member ill is illustrated as formed from an angle iron, other structural shapes may be utilized. Tanks for different services have various sizes and shapes and in conformity with the individual tank design, the ring member may be made up of an angle, a T, an I-beam, abaror other section.

The next step-isto mount-a pair of rings In on a set of rollers l5 and 16, so that the rings extend in parallel'verticalplanes and may be rotated on the rollers I5, I61 While the ring members are held in position on the rollers individual plates H, I'Ia, llbetc. maybewelded to the base of the ring members asmore clearly illustrated in Fig. 6. Each center plate of the center spherical section is weldedto the ring members while the rings arerotated' to a position so that the weld between the plate and the ring member is a down hand weld. As illustrated in Fig. 6 a portion of the weld between the plates ll and the ring I0 is on the outside of the tank and another portion of the weldis on the inside. Each of these portions of'theweld are performed by down hand welding. Successive plates ll are placed between the upstanding ring: assemblies and welded in place sequentially while sequentially rotating ithe ring members on the roller supports sothat each weld'is a down hand weld. While rotating the. ring assemblies the ring members roll over the rollers much like .a wheel.

A' preferable methodof' Welding each of the plates tothe ringrmembers is to mount a welding station above the apex or the lowest point of travel of the ring members. The Welding station is-shown diagrammatically in Fig-'1 as a platform supported bya construction frame--v work (not shown).. The welder may weld the successive plates of the. spherical segments to the ringmembersas theyare rotated up to a position under the welding station.. A welding machine may bemountedabove the apexor the lowest point of travel of thering ,to weld each successive plate to the ring member or the welding may be done by hand. In either instance each weld will be a downv weld.

After. all...the:plates;of theeenterspherical sectionhaveheen weldedibetween the ringmembers; the individual platesulfi, 1.8a, I817, etc. ofian end semispherical section arewelded to the outstandinggleg 12.0fthe ring member. lllwhile sequentiallyarotatingtheiringmembers.onthe roller for making each weld in a down hand position; After one end spherical section has been welded to a ring member, the other end spherical section may be welded to the other ring member while sequentially rotating the rings for down hand welding to complete the segmental tank having three sections as illustrated in Fig. 4. An example of a tank made by this method, is one of approximately 15,000 barrels capacity and designed for a working pressure of about 80# per square inch.

A spherical tank may be constructed by the methods herein disclosed. A center section of the spherical tank is constructed with suitable rims, spokes and stiffeners and mounted on rollers for rotation about a horizontal axis. Plates of end sections of the spherical tank are then welded to the center section while sequentially rotating the center section to provide for down hand welding on each plate.

A multisphere tank such as shown in Fig. 4 may be supported on cradles at the center sections under each ring member or may be supported on a foundation 2| of sand, concrete or the like, in the manner illustrated in Fig. 7. The diaphragms [3 may have openings l3a therethrough if desired.

Each of the segments are spherical in their layout to withstand a greater pressure with a lesser thickness of metal. The method described above for constructing the tank has several advantages in that it permits down hand welding of all the plates and allows complete drainage both inside and outside the tank.

The end spherical sections join the center section at such an angle that liquid may drain by gravity from the end sections into the center section where the inlet and outlet pipe 22 is usually connected with the tank. The slope of the adjacent portions of the sections at the lowest point on the intersection is downwardly toward the center of the segmental shell having the greatest diameter. The diaphragm is so constructed to permit the drainage to the lowest point in the tank. In the same manner, gas may flow without obstruction from the top of the end sections to the highest point in the tank. Water will run oil the outside of the tank since there are no pockets to retain it.

In liquid containing tanks, the plate thickness on the bottom of the tank must be greater than the plate thickness at the top of the tank because the pressure is greater at the lower level. Plates extending generally upwardly on the tank thus have excess thickness to a degree increasing with the height above the lower edge of the plate. As best seen in Fig. 3, the plates of' the spherical sections are arranged with their sides extending along meridians of the spherical section as determined by the intersection of planes passing through the polar axis of the section, with the surface of the section. Each plate has it greatest length in a generally horizontal direction and allows successive plate thickness to be selected to effect economy of construction. Also, plates arranged as illustrated in Fig. 3, have their edges deviating the least from parallel lines, thus providing for the least amount of waste in fabricating the individual plates for a tank.

It will be noted from Fig. 6 that the ring member I0 provides a three-way connection between the plates l8 of the end semispherical section, the plates 11 of the center section and the diaphragm l3. However, all welds at the joint illustrated are two-way welds since the plates [8 are welded to the leg H of the ring members and the diaphragm is welded to the other leg H and the plates [1 of the center section are welded to the base of the angle iron with which the ring member is formed.

In the completed structure as illustrated in Figs. 4 and 7 the three segments of the tank have a common horizontal axis with the center section having a greater radius than the end semispherical sections. The intersection between the spherical sections lies in a plane passing through the ring members iii.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom.

I claim:

1. A multisphere tank comprising a plurality of spherical segmental shells intersecting along parallel vertical planes, a ring girder interposed between adjacent shells and welded to the shells,

each of said shells being welded to a separate portion of said ring girder, and a diaphragm welded to each ring girder, said shells having a common horizontal axis and each of said shells being less than a hemisphere with one shell having a radius greater than the other shells.

2. A three-segment multisphere tank comprising a pair of spaced parallel vertically aligned ring girders, a spherical segmental shell welded to the girders to enclose the space therebetween, a first semispherical shell welded to one girder and a second semispherical shell welded to the other girder, all of said shells having acommon horizontal polar axis and said segmental shell having a greater radius than the semispherical shells.

3. A tank as claimed in claim 2 in which the shells are made up of a plurality of plates welded together and in which all of said welds are down welds.

4. A tank as claimed in claim 2 in which said shells comprise a plurality of plates each having its longitudinal edges spaced along a meridian of the shell determined by a plane passing through the poles of the shell.

5. A tank as claimed in claim 2 in which the portion of the spherical segmental shell and semispherical shell adjacent the ring girder slope downwardly toward the center or" the spherical segmental shell at the lowest point on the shells.

6. The method for constructing a three-segment tank having spherical segments which comprises forming an angle iron into a ring with one leg of the angle projecting radially inwardly from the angle, mounting a pair of rings so formed in spaced relationship for rotation in parallel vertical planes, positioning a welding device above a portion of the path of said rings, positioning an individual plate to extend between the spaced rings to be aligned thereby and welding the ends of the plate to the rings, successively positioning additional plates between the rings in similar manner and welding the ends of said plates to the rings and to the previously welded plates at the longitudinal edges after rotation of the rings to position the plates under the welding device to complete the inner spherical segment, aligning individual plates of the end segments with the rings, and then sequentially welding the individual plates forming the end spherical segments to another portion of the rings while sequentially rotating the rings.

CHRISTIAN ARNE. 7

(References on following page) I References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Phillips Jan. 6, 1903 Wentworth Mar. 3, 1908 Fraser Aug. 8, 1911 Kaarbo Aug. 19, 1919 Bell Apr. 29, 1924 Pinckney Dec. 17, 1929 Spence Jan. 26, 1932 Wiggins Feb. 23, 1932 Anderson May 9, 1933 Boardman Dec. 26, 1933 Werder May 8, 1934 Number Number Name Date Catlett Aug. 31, 1937 Debar Jan. 25, 1933 Sandberg June 23, 1942 Sandberg June 23, 1942 Jackson et a1. Feb. 8, 1944 Jackson Oct. 15, 1945 Kercher Dec. 10, 1946 Branson Apr. 4, 1950 Branson Apr. 4, 1950 FOREIGN PATENTS Country Date France May 1, 1914

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