GB842272A - Improvements in or relating to methods of and/or apparatus for constructing or reconstructing large tanks and/or large tanks so constructed and reconstructed - Google Patents

Abstract

842,272. Tanks. WARD, A. M. Nov. 21, 1957 [Nov. 22, 1956; Sept. 3, 1957], No. 36370/57. Class 69 (1). A method of contsructing or reconstructing the walls of a large tank comprises the steps of supporting the perimeter of the roof and the existing wall from within the perimeter thereof above the zone where the further construction or reconstruction is to be effected, raising such supported structures by raising means associated with the perimeter to a height sufficient to allow a wall strake 15 to be fixed in position below the supported structure, fixing the wall strake to the supported structure, repeating the aforesaid steps if and as desired, and fixing the lower strake of the supported structure to the floor of the tank. When constructing the tank shown in Fig. 2, roof trusses 5 (Fig. 8) and a centre drum 6 are welded together so as to form an assembly which is supported on blocks 7 at an appropriate height for welding the top strake 15 in position. A plurality of jacking supports 8 are provided within the perimeter of the tank. Each jacking support comprises an I beam 8a (Fig. 3) which is supported by two struts 9 and by braces 10. The I beams 8a are drilled at 12 to take jacking pads 13 which are adjustable up and down the I beams and supported at each hole 12 by a pin 12a as desired. An adjustable jacking pad is provided on each side of the I beams and a jack 14-14a is provided on each pad 13. A series of curved strakes 15 is welded together on the floor 2, the bottom edges being correctly positioned by being placed between spigots 3 and lugs 4. After welding the verticals the curb angle is placed in position and the trusses 5 attached to the strake 15. A roof 16 of steel plates is then completed, any plates which would be fouled by the jacking supports 8, being omitted. Compression members comprising channels 17, 17a are tack-welded to the walls of the tank on either side of the jacking supports 8 and a keeper bar 18 is welded across the base of each pair of channels. A jack 14 or 14a is placed on one of the pads 13, 13a at each jacking support 8 and the lifting head of the jack arranged below the lower ends of the channels 17, 17a. The jacks are then operated in an even manner by a gang of men who circulate around the jacks until each jack reaches the end of its jacking movement. The second jacking pad 13a or 13 at each jacking support is then positioned and a second jack 14a or 14 is placed thereon so that it can take up the lift against its associated channel 17 or 17a with its jacking screw in the retracted position. The jacks are then operated in an even manner. These jacking steps are repeated until the tank has been raised to a height sufficient to allow a further wall strake 15a to be placed in position. An existing tank may be enlarged by severing the supported structure from the floor of the tank or a part of the wall left associated with the floor before raising the supported structure to allow further strakes to be inserted in position. A damaged or corroded strake may be removed from below the supported structure before raising the latter.