PH12015000395A1 - Contruction method for cylindrical tank - Google Patents

Abstract

A construction method for a cylindrical tank having an inner tank and an outer tank, the construction method includes: a knuckle portion assembly step of assembling an annular knuckle portion inside a sidewall of the outer tank; a jack-up unit attachment step of attaching to the sidewall of the outer tank, a jack-up unit having a jack-up rod configured to be connected to the knuckle portion; an inner tank assembly step of hanging and lifting the knuckle portion by the jack-up unit, and of attaching an inner tank lateral plate to a lower side of the knuckle portion to assemble the inner tank; and a jack-up rod-lowering step, after the inner tank assembly step, of lowering the jack-up rod to a bottom surface of the cylindrical tank using a lowering device including a pulley group composed of a fixed pulley and a movable pulley, a wire bridging the fixed pulley and the movable pulley of the pulley group, and a drive unit configured to let out and pull back the wire.

Description

Next, concrete is poured onto the portion of the sidewall 3 as shown in FIG. 2 to form a sidewall of a sixth level (#6). Further, in construction of the sidewall 3, as the upper sides thereof are sequentially formed, the suspension scaffold 5 is also moved upward sequentially.

In addition, a plurality of inner tank lateral plates 7 serving as a portion of the sidewall of the inner tank are vertically placed on the legged stands 6 in the circumferential direction of the sidewall 3 simultaneously with the pouring, and the inner tank lateral plates 7 neighboring in the horizontal direction are integrally welded.

Accordingly, the plurality of inner tank lateral plates 7 are assembled in an annular shape.

Further, the inner tank lateral plates 7 assembled at this place finally constitute an uppermost level of the inner tank (in this embodiment, a ninth level (#9)) (hereinafter, may be referred to as “the inner tank lateral plate 7 of the uppermost level”). The inner tank lateral plate 7 is formed of a Ni steel material or the like having excellent toughness and strength.

In addition, a roofstand 8 is assembled at a central section of the base plate 1 inside the sidewall 3.

Next, plates of a knuckle plate 9 (a knuckle portion) are attached to an upper end of the inner tank lateral plate 7 of the uppermost level as shown in FIG. 3, and thus, the knuckle plate 9 is attached to the upper end of the inner tank lateral plate 7 while assembling the knuckle plate 9. The knuckle plate 9 is formed to be curved toward a lower side of an outer circumferential edge portion of an inner tank roof (to be described below), and an upper end of the inner tank lateral plate 7 of the uppermost level is connected to the lower end of the knuckle plate 9. That is, the knuckle plate 9 is curved to bulge outward in a radial direction of the tank when seen in a vertical cross-sectional view.

A knuckle support 10 is attached to the outer circumferential surface (the outside) of the knuckle plate 9 as shown in FIG. 4. In this embodiment, a plurality of (for example, 30) knuckle supports 10 are provided in a circumferential direction of the knuckle plate 9 at equal intervals. The knuckle support 10 is a member formed of steel plates forming a hanged part configured to be connected to a jack-up unit (to be described below), and has a pair of support plates 10a formed in a substantially triangular shape when seen in a side view, a hanged plate 10b sandwiched between the support plates 10a and having a substantially square shape when seen in a plan view, and a reinforcement plate 10c sandwiched between the support plates 10a and connected to an upper surface of the hanged plate 10b to reinforce the connection between the support plates 10a and the hanged plate 10b. The pair of support plates 10a adjoins each other in the circumferential direction of the knuckle plate 9.

One edge part of the support plate 10a formed to be curved to correspond to a curved shape of the knuckle plate 9 is connected to a curved surface of the knuckle plate 9 and then is attached and fixed thereto by welding or the like. The hanged plate 10b and the reinforcement plate 10c are attached and fixed between the support plates 10a by welding, bolt fixation or the like, in a state in which the hanged plate 10b and the reinforcement plate 10c are connected to each other by welding or the like. The hanged plate 10b is fixed between the pair of support plates 10a in a state in which an outer end (an end close to the sidewall 3) of the hanged plate 10b coincides with an outer end of the support plate 10a. A notch (not shown) opening toward the sidewall 3 of the outer tank is formed at a side of the hanged plate 10b opposite to the knuckle plate 9, and the notch becomes a hanged point which is connected to the jack-up unit (to be described below).

Next, as shown in FIG. 5, an inner tank roof block is loaded onto the roofstand 8, and an inner tank roof 14 (a tank roof section) is assembled.

In addition, a vehicle for high lift work (not shown) is driven onto the base plate 1.

In addition, a portion of an annular section 16 is constructed to form the annular section 16 in the annular region X under the legged stand 6.

In addition, the sidewalls 3 of the outer tank are also sequentially stacked, and the sidewalls 3 of the outer tank are constructed to the ninth level (#9) serving as the final level. Further, at this point, the suspension scaffold 5 used to form the sidewall 3 remains assembled in a range of, for example, sixth to seventh levels.

Next, as shown in FIG. 6, a scaffold 17 for the jack-up unit is assembled on the knuckle plate 9 in a state in which the scaffold 17 is spaced apart from the inner circumferential surface of the sidewall 3 of the outer tank and at a height at which the scaffold 17 does not interfere with the suspension scaffold 5. The scaffold 17 for the jack-up unit is formed in an annular shape in the circumferential direction of the knuckle plate 9 which is formed in an annular shape to prevent collapse in the radial direction.

In addition, in the assembly, as the scaffold 17 for the jack-up unit is almost entirely supported by the knuckle support 10 and further a falling prevention member (not shown) is provided between the scaffold 17 and the knuckle plate 9 or between the scaffold 17 and the inner tank roof 14, the scaffold 17 for the jack-up unit is formed in a state of being fixed to the knuckle plate 9 or to the inner tank roof 14. In this embodiment, the

I scaffold 17 for the jack-up unit is assembled to be substantially opposite to a fourth level (#4) to a fifth level (#5) of the sidewall 3 of the outer tank as shown in FIG. 6.

Then, a plurality of hanging stands 18 (hanging parts) are installed at a predetermined position of the sidewall 3, in this embodiment, the fifth level (#5), in the circumferential direction of the sidewall 3 at equal intervals using the scaffold 17 for the jack-up unit. That is, the hanging stand 18 is strongly and detachably fastened and fixed to, for example, an anchor plate or the like previously embedded in the sidewall 3, and protrudes from the sidewall 3 toward the inside thereof in a substantially horizontal direction.

Next, a jack-up unit 19 is attached between the hanging stand 18 and the hanged plate 10b of the knuckle support 10. That is, the jack-up unit 19 having a jack-up rod 20 (to be described below) configured to be connected to the knuckle plate 9 is attached to the sidewall 3 of the outer tank. The jack-up unit 19 is connected to the hanging stand 18 and the hanged plate 10b. The jack-up unit 19 is constituted as a center hole jack as shown in FIG. 7, and has a jack main body 20a engaged with and supported by the hanging stand 18, the jack-up rod 20 having an upper end attached to the jack main body 20a and a lower end attached to the hanged plate 10b of the knuckle support 10, and a nut 19a used to attach the lower end of the jack-up rod 20 to the hanged plate 10b. A male screw on which the nut 19a is screwed is formed at a lower end part of the jack-up rod 20.

Further, in FIG. 7, a description of the scaffold 17 for the jack-up unit is omitted in order to describe the jack-up unit 19.

In attachment of the jack-up unit 19, the jack-up rod 20 is suspended from the jack main body 20a in a state in which the jack main body 20a is engaged with and fixed onto the hanging stand 18, and further, the lower end part of the jack-up rod 20 is inserted into the notch of the hanged plate 10b of the knuckle support 10. Then, the lower end part of the jack-up rod 20 is fixed to the hanged plate 10b by the previously prepared nut 19a. The jack-up rod 20 is formed by connecting a plurality of rods 20b together in a lengthwise direction, the rod 20b having a length of about 4 m, and the rods 20b are detachably connected together by screw fixation or the like.

Further, a gondola rail 11 is installed at a lower side of the jack-up unit 19 as shown in FIG. 7. As the gondola rail 11 is attached to all the knuckle supports 10, the gondola rail 11 is disposed in an annular shape at the outside of the knuckle plate 9 in the circumferential direction thereof. A hook 12 movable in the circumferential direction and elevatable is hanged from the gondola rail 11. In addition, a knuckle inner surface rail 13 is annularly disposed inside the knuckle plate 9 in the circumferential direction thereof. An appropriate suspending tool (not shown) is also attached to the knuckle inner surface rail 13. As the gondola rail 11 or the knuckle inner surface rail 13 is used, various machine parts are elevated or conveyed in the circumferential direction.

A plurality of jack-up units 19 are installed in the circumferential direction of the sidewall 3 of the outer tank at predetermined intervals in this way and then each jack-up unit 19 is connected to the hanged plate 10b of the knuckle support 10, and thereafter, the roofstand 8 is removed as shown in FIG. 6. When the roofstand 8 is removed, the weight of the tank components (the inner tank lateral plate 7 of the uppermost level, the knuckle plate 9, the knuckle supports 10, the inner tank roof 14 and the scaffold 17 for the jack-up unit) is held by the plurality of jack-up units 19.

As shown in FIG. 6, since a position at which the hanging stand 18 is installed is the fifth level (#5) of the sidewall 3 and a position at which the knuckle support 10 is installed is a position facing the third level (#3) of the sidewall 3, the plurality of rods 20b are connected together in the lengthwise direction such that the jack-up rod 20 is formed to have a length greater than the distance therebetween. However, when the jack-up rod formed to have the above-mentioned length is lifted by driving the jack-up unit 19 as described below, the jack-up rod 20 may interfere with the suspension scaffold 5 disposed right above the jack-up rod 20.

In this case, when the jack-up rod 20 is lifted, as the rod 20b projecting upward from the hanging stand 18 is detached from the other rod 20b under the upwardly projecting rod 20b, the jack-up rod 20 can be prevented from interfering with the suspension scaffold 5. In addition, after the assembly of the inner tank is completed as described below, the jack-up rod 20 can be disassembled into the rods 20b and be collected. Further, a reference numeral 21 in FIG. 6 shows a hanging balance configured to lift or hang components of the jack-up unit 19 or to hang the detached rod 20b, and the hanging balance 21 is a known member configured by providing a weight 21b at one end of a carrying pole 21a. The hanging balance 21 is hanged by a crane (not shown), and thus, operations of elevation and of horizontal movement are controlled.

In addition, during the above-mentioned step, cold insulation construction of the annular section 16 and cold insulation construction of the central section of the base plate

1 are simultaneously performed on the base plate 1. As shown in FIG. 7, the cold insulation construction of the annular section 16 is performed under the legged stand 6 by assembling a pearlite concrete block 23a, a pearlite concrete block 23b and a structural lightweight concrete block 24 onto a bottom cold resistance relaxing material 22 and by attaching an annular plate 16a thereonto. The annular section 16 is a portion configured to finally support the assembled inner tank lateral plates 7, the annular plate 16a is thickly formed, and the cold insulation structure is also a rigid member such as a concrete block.

Next, as the knuckle plate 9 is lifted by the jack-up units 19 as shown in FIG. 8, tank components Y including the knuckle plate 9, the inner tank roof 14 supported by the knuckle plate 9, the inner tank lateral plate 7, the knuckle supports 10 and the scaffold 17 for the jack-up unit are lifted. Specifically, the jack-up rod 20 is moved upward by normally rotating the jack main body 20a, and thereby the tank components Y in the middle of the assembly are jacked up together with the knuckle supports 10.

Since the knuckle plate 9 lifted by the jack-up units 19 is a member connecting the inner tank roof 14 and the inner tank lateral plate 7, and the plate thickness of the knuckle plate 9 is sufficiently greater and strength thereof is higher than the inner tank lateral plate 7, deformation or the like of the knuckle plate 9 can be prevented even when the weight including the inner tank lateral plate 7 and the inner tank roof 14 and further the scaffold 17 for the jack-up unit is added thereto.

After the tank components Y are lifted by about one level of the inner tank lateral plate 7 by the jack-up units 19, a next inner tank lateral plate 7 is loaded into a space formed under the lifted inner tank lateral plate 7. The loading of the inner tank lateral plate 7 is performed through the construction entrance gate 4 provided in the sidewall 3.

A first conveyance device (not shown) is installed around the construction entrance gate 4, and the inner tank lateral plates 7 are sequentially conveyed onto the legged stand 6 from the outside of the sidewall 3 by the first conveyance device through the construction entrance gate 4. In addition, a second conveyance device (not shown) is installed on the legged stand 6 in the circumferential direction of the sidewall 3. The second conveyance device is configured to have a rail (not shown) or the like in the circumferential direction of the sidewall 3, and the inner tank lateral plates 7 conveyed onto the legged stand 6 are further sequentially conveyed in the circumferential direction of the sidewall 3.

Next, the inner tank lateral plates 7 conveyed by the second conveyance device are stood on the legged stand 6, and are annularly disposed under the jacked-up inner tank lateral plate 7. Then, as shown in FIG. 9, as inner tank lateral plates 7 conveyed and neighboring in the horizontal direction are integrally welded and inner tank lateral plates 7 neighboring in the vertical direction are integrally welded, these inner tank lateral plates 7 are integrally formed in a cylindrical shape. That is, an inner tank lateral plate 7 of the eighth level (#8) is attached to a lower side of the inner tank lateral plate 7 of the ninth level (#9) serving as the uppermost level.

Further, after the plurality of inner tank lateral plates 7 are previously connected together in the horizontal direction outside the sidewall 3 of the outer tank and are carried into the sidewall 3 to be formed in an annular shape, the inner tank lateral plates 7 neighboring vertically may be welded. As the connection of the plurality of inner tank lateral plates 7 is performed outside the sidewall 3 at which restriction of a work space is

Co small, welding work can be easily performed and the inner tank can be efficiently assembled.

When jack-up is performed in this way, as shown in FIG. 9, the upper end of the jack-up rod 20 of the jack-up unit 19 projects upward from the hanging stand 18, and if lifted more, the upper end interferes with the suspension scaffold 5 disposed right above the jack-up rod 20. For this reason, while the welding or the like of the above-mentioned inner tank lateral plate 7 is performed, among the plurality of rods 20b that constitute the jack-up rod 20, the rod 20b projecting upward from the hanging stand 18 is detached. Then, the rod 20b is lowered onto the inner tank roof 14 by a davit (not shown) previously installed at the apex of the scaffold 17 for the jack-up unit.

Detachment of the rod 20b is performed using the scaffold 17 for the jack-up unit. In addition, upper parts of the scaffold 17 for the jack-up unit are also sequentially removed using the hanging balance 21 to not interfere with the suspension scaffold 5.

Next, the tank components Y are lifted by substantially one level of the inner tank lateral plate 7 by the jack-up units 19, a next inner tank lateral plate 7 is further loaded into the space formed under the lifted inner tank lateral plate 7, and subsequently, like the case of the inner tank lateral plate 7 of the above-mentioned eighth level (#8), an inner tank lateral plate 7 of the seventh level (#7) is attached to the lifted inner tank lateral plate 7 as shown in FIG. 10. At this time, the rod 20b projecting upward from the hanging stand 18 is also detached and lowered onto the inner tank roof 14 by the davit.

After the inner tank lateral plates 7 from the ninth level (#9) to the seventh level (#7) are attached to the knuckle plate 9 in this way, as shown in FIG. 11, the suspension scaffold 5 on the inner circumferential surface side of the sidewall 3 is removed. That is, since a sufficient time has elapsed before this point, the sidewall 3 of the outer tank is completed to the ninth level (#9) serving as the uppermost level and thus the mold or the like can be removed, the suspension scaffold 5 on the inner circumferential surface side of the sidewall 3 can be removed. Further, the suspension scaffold 5 on the outer circumferential surface side of the sidewall 3 remains without being removed because it is used for a later step.

Next, in order to relocate the jack-up unit 19 to an upper position, as shown in

FIG. 11, a second hanging stand 25 is installed on the apex of the sidewall 3 of the outer tank. In addition, the jack-up unit 19 installed on the hanging stand 18 is jacked down, and the tank components Y (including also the inner tank lateral plates 7 of the eighth and seventh levels) are lowered onto the legged stands 6.

Next, the jack-up rod 20 of the jack-up unit 19 shown in FIG. 7 is detached from the hanged plate 10b of the knuckle support 10 using the hanging balance 21, a crane or the like. In addition, the jack main body 20a of the jack-up unit 19 is detached from the hanging stand 18. Accordingly, the jack-up unit 19 is detached from the sidewall 3 of the outer tank and the knuckle plate 9. Further, the hanging stands 18 are removed from the sidewall 3.

Then, the jack main body 20a of the jack-up unit 19 is attached to the second hanging stand 25 shown in FIG. 11. In addition, while the rod 20b of the upper side of the jack-up rod 20 is detached and lowered onto the inner tank roof 14 to avoid interference with the suspension scaffold 5, since the suspension scaffold 5 on the inner circumferential surface side of the sidewall 3 is removed and the interference with the jack-up rod 20 does not occur, the rod 20b lowered onto the inner tank roof 14 is attached to the jack-up rod 20 again and the jack-up rod 20 is elongated. Further, in this embodiment, as shown in FIG. 11, since the jack-up rod 20 has to be suspended from the ninth level (#9) serving as the uppermost level of the sidewall 3 of the outer tank to the fifth level (#5), the jack-up rod 20 is adjusted to have a desired length by adding a previously prepared spare rod 20b to the jack-up rod 20.

After the jack-up rod 20 is adjusted to have a desired length in this way, the lower end side thereof is inserted into the notch of the hanged plate 10b of the knuckle support again. Then, the lower end part of the jack-up rod 20 is fixed to the hanged plate 10b by the nut 19a. Accordingly, the jack-up unit 19 is relocated to an upper position (i.c., from the hanging stand 18 to the second hanging stand 25). After the relocation of the jack-up unit 19 to the apex of the sidewall 3 of the outer tank is completed in this way, the scaffold 17 for the jack-up unit is removed as shown in FIG. 11.

Next, as shown in FIG. 12, the knuckle plate 9 is lifted by the jack-up units 19 : installed at the second hanging stands 25, and the tank components Y are lifted by about one level of the inner tank lateral plate 7.

Next, a next inner tank lateral plate 7 is further loaded into the space formed under the lifted inner tank lateral plate 7, and subsequently, like the case of the inner tank lateral plates 7 of the above-mentioned eighth level (#8) and seventh level (#7), an inner tank lateral plate 7 of the sixth level (#6) is attached to the lifted inner tank lateral plate 7 as shown in FIG. 13.

Next, an outer tank roof 26 is attached onto the inner tank roof 14. Attachment of the outer tank roof 26 is performed by attaching to the inner tank roof 14, a connecting member (not shown) formed of a plurality of channel type steels or the like, and by attaching the outer tank roof 26 to the connecting member.

In addition, a work of affixing a side liner (not shown) to the inner circumferential surface of the sidewall 3 of the outer tank is started.

Subsequently, the lifting of the tank components Y by the jack-up units 19, the loading of a next inner tank lateral plate 7 to the lower side of the lifted inner tank lateral plate 7 (the tank components Y) and the attachment of the loaded inner tank lateral plate 7 to the tank components Y (the lifted inner tank lateral plate 7) are repeated, and as shown in FIG. 14, the inner tank lateral plate 7 of a first level (#1) of the lowermost level is attached thereto. Accordingly, the sidewall of the inner tank is completed.

Further, during the above-mentioned attachment of the inner tank lateral plate 7 of each level, i.e., while the tank components Y are lifted to form a space thereunder, various kinds of materials 27 are loaded onto the base plate 1 in the sidewall 3 separately from the loading of the inner tank lateral plate 7. In addition, a work scaffold 28 is assembled on the outer tank roof 26.

Next, the legged stands 6 are removed as shown in FIG. 15, and thus, a space is formed under the tank components Y. Then, the tank components Y are jacked down by the jack-up units 19, and the outer circumferential end of a roof skeleton (not shown) of the outer tank roof 26 is connected and fixed to an attachment end (not shown) embedded in an inner circumferential surface of the apex of the sidewall 3 of the outer

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- TTT ee tank. Further, at this time, the lower end of the lowermost level of the inner tank lateral plate 7 does not contact the annular section 16.

Next, the connecting member (not shown) connecting the outer tank roof 26 and the inner tank roof 14 is removed, and the connection therebetween is released.

Next, the tank components Y are further jacked down by the jack-up units 19, and the lower end of the lowermost level of the inner tank lateral plate 7 is lowered onto the annular section 16. Then, the inner tank anchor strap 2 installed on the base plate 1 is connected to the lowermost level of the inner tank lateral plate 7. Accordingly, assembly of the inner tank is completed. In addition, since the support of the tank components Y by the jack-up unit 19 is released, no load is applied to the jack-up rod 20 of the jack-up unit 19.

When the assembly of the inner tank is completed in this way, in the jack-up unit 19, the jack-up rod 20 extends above the inner tank roof 14 and the outer tank roof 26.

Accordingly, when the jack-up unit 19 is disassembled and collected, the jack-up rod 20 should be previously collected. For this reason, in order to collect the jack-up rod 20, first, the jack main body 20a is detached from the second hanging stand 25 and is lowered to a position close to the knuckle support 10 using a crane or the like as shown in

FIG. 16.

Then, at the position, the jack main body 20a is fixed to an upper side of the hanged plate 10b of the knuckle support 10 by a plurality of bolts 30. Here, the bolts 30 are attached to the hanged plate 10b via an annular plate-shaped attachment member 31 provided on a lower surface of the hanged plate 10b and via a spacer (not shown).

Accordingly, the attachment member 31 is attached to the hanged plate 10b in a state of surrounding the jack-up rod 20 without contacting the jack-up rod 20. Further, the nut 19a shown in FIG. 7 is detached from the lower end of the jack-up rod 20 at an appropriate timing after the assembly of the inner tank is completed.

That is, the construction method for a cylindrical tank of this embodiment may include a step of fixing the jack-up unit 19 to the knuckle support 10 (or to the knuckle plate 9) after the assembly step of the inner tank and before a lowering step of the jack-up rod 20 as described below.

After the jack main body 20a (the jack-up unit 19) is fixed to the hanged plate 10D in this way, the jack-up unit 19 is driven again, the jack-up rod 20 is slightly lowered as shown in FIG. 16, and the lower end of the jack-up rod 20 extends downward from the attachment member 31. Further, the above-mentioned removal of the nut 19a, attachment of the attachment member 31 and the bolts 30 before the removal, or the like are performed using, for example, a temporary scaffold 32 attached to an upper end part of the outer surface of the inner tank lateral plate 7 by welding or the like.

In addition, a lowering device 40 is attached to the knuckle support 10 and the attachment member 31 as shown in FIG. 17A, separately from lowering the jack-up rod 20.

Further, in FIG. 16, in order to describe the fixing of the jack main body 20a, description of the lowering device 40 is omitted. As shown in FIG. 17A, the lowering device 40 includes a winch 41 (a drive unit), a pulley group 42, and a wire 43 bridging the winch 41 and the pulley group 42. In other words, the lowering device 40 includes the pulley group 42 composed of a fixed pulley and movable pulleys that are to be described below, the wire 43 bridging the fixed pulley and the movable pulleys of the pulley group 42, and the winch 41 configured to let out and pull back the wire 43. As shown in FIG. 17B being a view taken along line A-A of FIG. 16, the winch 41 is a relatively small and lightweight device attached to one support plate 10a of the knuckle support 10 via an attachment tool 44.

As shown in FIG. 17A, the pulley group 42 is disposed under the attachment member 31. The pulley group 42 includes a fixed pulley 42a hanged from the attachment member 31 through a wire 49 or the like and held by the attachment member 31 in this state, and a pair of (a plurality of) movable pulleys 42b disposed at both sides (both sides in the horizontal direction) of the fixed pulley 42a. At the time of installation of the movable pulley 42b, for example, the movable pulley 42b is hanged from the lower end of the bolt 30 through a wire 45, and then, after the wire 43 is bridged and supports the movable pulley 42b, the wire 45 is removed, and the movable pulley 42b becomes movable in the vertical direction. However, if the length of the wire 45 for suspension is formed to a sufficient length such that the wire 45 does not interfere with movement of the movable pulley 42b in the vertical direction, the wire 45 may be provided between the movable pulley 42b and the bolt 30 as it is, separately from the wire 43, as shown in FIG. 17A.

Hooks 46 are attached to the lower ends of the pair of movable pulleys 42b, and a wire 47 is hooked on the hook 46. The wire 47 is connected via a holding tool 48 to the jack-up rod 20 extending downward from the attachment member 31 in accordance with lowering of the jack-up rod 20. The holding tool 48 includes a cylindrical holding part

48c configured to surround and hold the jack-up rod 20, and a pair of (a plurality of) attachment plates 48a integrally formed on a side of the holding part.

Then, the wire 47 passes through an attachment hole 48b formed in the attachment plate 48a, and thereby the holding tool 48 is connected to the movable pulley 42b via the wire 47 and the hook 46. Accordingly, the jack-up rod 20 held by the holding tool 48 is held in a state of being hanged from the pair of movable pulleys 42b.

[0054]

After one end of the wire 43 is let out from the winch 41, the wire 43 is bridged in sequence of one movable pulley 42b, the fixed pulley 42a and the other movable pulley 42b, and then, the one end of the wire 43 is fixed to the attachment member 31.

Accordingly, when the wire 43 is let out by the winch 41, the pair of movable pulleys 42b are gradually lowered. In addition, when the wire 43 is pulled back (rewound) by the winch 41, the pair of movable pulleys 42b are gradually lifted.

After the lowering device 40 having the above-mentioned configuration is attached to the knuckle support 10 and the attachment member 31, and the jack-up rod 20 is lowered to cause the lower end thereof to extend downward from the attachment member 31, the holding tool 48 is attached to the lower end of the jack-up rod 20. Here, in this embodiment, since the jack-up rod 20 is formed by connecting the plurality of rods 20b together, the holding tool 48 is attached to the jack-up rod 20 at a slightly lower position than the joint between the lowermost rod 20b and the other rod 20b connected to the upper end of the lowermost rod 20b.

Next, the lowermost rod 20b is detached from the other rod 20b disposed thereon as shown in FIG. 16. Therefore, the lowermost rod 20b is hanged from the pair of movable pulleys 42b via the holding tool 48 shown in FIG. 17A. Accordingly, as the winch 41 is driven and the wire 43 is let out to lower the pair of movable pulleys 42b, the lowermost rod 20b can be lowered onto the base plate 1 (onto the bottom surface of the tank).

After the holding tool 48 is detached from the lowermost rod 20b lowered onto the base plate 1 and the lowermost rod 20b is collected, the winch 41 pulls back the wire 43, and the pair of movable pulleys 42b are lifted.

Subsequently, the above-mentioned steps are repeated, and the rods 20b at the lower end side of the jack-up rod 20 are sequentially lowered onto the base plate 1 and are collected. Then, after all the rods 20b are collected, the lowering device 40 is disassembled and collected, and further, the knuckle supports 10 are removed from the knuckle plate 9.

After that, as shown in FIG. 18, strain construction of the sidewall 3 of the outer tank is performed. In addition, polyurethane foam (PUF) serving as a cold resistance relaxing material is sprayed onto the side liner (not shown) affixed to the inner circumferential surface of the sidewall 3 of the outer tank. Further, the jack main body 20a, the second hanging stand 25 and the like are also removed. Then, after closing of the construction entrance gate 4 and installation of a pump barrel (not shown), water is filled in the inner tank and a pressure/airtightness test is performed.

Finally, a cold insulation material (a foam body, not shown) such as pearlite is filled between the inner tank and the outer tank to perform cold insulation construction between the inner and outer tanks, and further, a cylindrical tank 100 is constructed through painting construction and piping cold insulation construction.

According to the construction method for a cylindrical tank of this embodiment, since the jack-up rod 20 of the jack-up unit 19 is lowered by the lowering device 40 having the pulley group 42, the weight of the disassembled rod 20b can also be supported by the pulley group 42, and thus, the load on the winch 41 can be reduced. Accordingly, the jack-up rod 20 can be lowered onto the base plate 1 (onto the bottom surface of the tank) and be collected using the small winch 41, without using a large winch or the like serving as a drive unit. Therefore, when the large winch or the like serving as the drive unit is used, while elevation of or attachment place of the large winch cannot be easily secured, elevation of or attachment of the winch can be easily secured by using the small winch 41.

In addition, in this embodiment, the pulley group 42 has the pair of (the plurality of) movable pulleys 42b. For this reason, a support ratio of the weight of the rod 20b (the jack-up rod 20) by the pulley group 42 can be increased, and the load on the winch 41 can be further reduced. In addition, since the mechanical magnification by the pulley group 42 becomes four times (four times or more), the winch 41 having a small output can be employed. Accordingly, the winch 41 having a small size and a low output can be used. :

In addition, in this embodiment, the winch 41 is attached to the knuckle support attached to the outside of the knuckle plate 9. For this reason, since the winch 41 is

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26 disposed outside the inner tank roof 14, handling or installation thereof can be easily performed.

Hereinbefore, while the preferred embodiment of the present invention is described with reference to the accompanying drawings, the present invention is not limited thereto. Shapes, combinations and the like of all the components shown in the above embodiment are examples, and various modifications based on design requests or the like can be adopted within the scope of and not departing from the gist of the present invention.

For example, in the above embodiment, while the pulley group of the lowering device is constituted of the one fixed pulley and the pair of (two) movable pulleys, the movable pulleys may be three or more, and a plurality of fixed pulleys may be provided to correspond thereto. In addition, a single movable pulley may be provided, and a plurality of fixed pulleys may be provided.

In the above embodiment, while the plurality of legged stands 6 configured to support the inner tank lateral plate 7 during the assembly of the inner tank are installed at the inner circumferential surface side of the sidewall 3 of the outer tank, the present invention is not limited thereto. That is, the inner tank lateral plate 7 may be supported by the base plate 1, specifically, the bottom liner installed on the upper surface of the base plate 1 without using the legged stand 6.

In the above embodiment, while the rods 20b are lowered one by one using the lowering device 40, if rods 20b can be supported by the knuckle plate 9 (the knuckle ——

support 10) or by the winch 41 (the drive unit), two or more rods 20b may be lowered together.

In the above embodiment, while the attachment member 31 is used to fix the jack main body 20a (the jack-up unit 19) to the knuckle plate 9 (the knuckle support 10) or to hold the pulley group 42, the present invention is not limited thereto. The jack main body 20a may be capable of being fixed to the knuckle plate 9 or the knuckle support 10 without using the attachment member 31, or the pulley group 42 may be directly held by the knuckle plate 9 or by the knuckle support 10.

In addition, while the winch 41 of the above embodiment is attached to the knuckle support 10, the winch 41 may be attached to the knuckle plate 9. The winch 41 may have any configuration as long as the wire can be let out and pulled back.

In the above embodiment, while the jack-up unit 19 (the jack main body 20a) is fixed to the knuckle support 10 after the assembly step of the inner tank and before the lowering step of the jack-up rod 20, the present invention is not limited thereto. For example, the lowering device 40 may be attached to the second hanging stand 25, and the jack-up rod 20 may be lowered from the second hanging stand 25 to the bottom surface of the tank using the lowering device 40.

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CONSTRUCTION METHOD FOR CYLINDRICAL TANK

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a construction method for a cylindrical tank.

Priority is claimed on Japanese Patent Application No. 2014-234543, filed

November 19, 2014, the content of which is incorporated herein by reference.

Description of Related Art

A cylindrical tank of a double shell structure having an inner tank and an outer tank is used to store a low temperature liquid such as a liquefied natural gas (LNG), a liquefied petroleum gas (LPG) or the like. In Patent Document 1 (Japanese

Unexamined Patent Application, First Publication No. 2012-149416), a construction method for a cylindrical tank having an inner tank formed of metal and an outer tank formed of concrete is disclosed.

In Patent Document 1, in order to reduce a construction period of the cylindrical tank, a technique of simultaneously constructing the inner tank formed of the metal and the outer tank formed of the concrete is employed. Specifically, a stand is installed along an inner circumferential surface of a lower level of the outer tank, and then, lifting of an inner tank lateral plate by a jack-up unit and welding of a next inner tank lateral plate to a lower side of the lifted inner tank lateral plate are alternately repeated on the stand to assemble the inner tank. In addition, simultaneously with the above-mentioned

4 ¥ , . ‘ ’ 2 assembly of the inner tank, the outer tank is also sequentially constructed from a lower level to an uppermost level.

In the related art, the jack-up unit having a jack-up rod is used to assemble the inner tank formed of the metal. When the inner tank lateral plate is lifted by the above-mentioned jack-up unit in stages and the assembly of the inner tank is completed, the jack-up rod extends above the roof of the tank. Accordingly, after the assembly of the inner tank is completed, when the jack-up unit is disassembled and collected, collecting the jack-up rod becomes a big challenge.

That is, the jack-up rod is formed by detachably connecting a plurality of rods together in a lengthwise direction, and for example, one rod having a length of 4 m has a weight of 400 to 500 kg. For this reason, it is preferable to provide a method of lowering the jack-up rod onto a bottom surface of the tank and of collecting the jack-up rod without using a large winch (drive unit).

In consideration of the above-mentioned circumstances, the present invention is directed to provide a construction method for a cylindrical tank capable of lowering a jack-up rod of a jack-up unit onto a bottom surface of a tank and of collecting the jack-up rod without using a large winch or the like after assembly of an inner tank is completed.

SUMMARY OF THE INVENTION

A first aspect of the present invention is a construction method for a cylindrical tank having an inner tank and an outer tank, the construction method including: a knuckle portion assembly step of assembling an annular knuckle portion inside a sidewall of the outer tank; a jack-up unit attachment step of attaching to the sidewall of the outer tank, a jack-up unit having a jack-up rod configured to be connected to the knuckle portion; an inner tank assembly step of hanging and lifting the knuckle portion by the jack-up unit, and of attaching an inner tank lateral plate to a lower side of the knuckle portion to assemble the inner tank; and a jack-up rod-lowering step, after the inner tank assembly step, of lowering the jack-up rod to a bottom surface of the cylindrical tank using a lowering device including a pulley group composed of a fixed pulley and a movable pulley, a wire bridging the fixed pulley and the movable pulley of the pulley group, and a drive unit configured to let out and pull back the wire.

A second aspect of the present invention is that in the construction method for a cylindrical tank of the first aspect, the pulley group includes a plurality of movable pulleys.

A third aspect of the present invention is that in the construction method for a cylindrical tank of the first or second aspect, in the knuckle portion assembly step, a knuckle support configured to be connected to the jack-up unit and to be lifted is attached to an outside of the knuckle portion. In addition, the drive unit of the lowering device is attached to the knuckle support.

According to the construction method for a cylindrical tank of the present invention, the jack-up rod is lowered to the bottom surface of the tank using the lowering device including the pulley group composed of the fixed pulley and the movable pulley, the wire bridging the fixed pulley and the movable pulley of the pulley group, and the

‘ ¢ ] s ‘ ’ 4 drive unit configured to let out and pull back the wire. For this reason, as the jack-up rod is held by the wire bridged on the pulley group and is lowered by letting out the wire using the drive unit, the weight of the jack-up rod can also be supported by the pulley group, and thus, the load on the drive unit can be reduced. Accordingly, the jack-up rod can be lowered onto the bottom surface of the tank and be collected using, for example, a small winch, without using a large winch or the like serving as a drive unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a tank during construction showing a construction method for a cylindrical tank of an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a major part of the tank showing an attachment state of a knuckle support.

FIG. 5 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of the major part of the tank showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 11 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 12 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention. :

FIG. 13 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 14 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

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FIG. 15 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 16 is a vertical cross-sectional view of the major part of the tank showing the construction method for a cylindrical tank of the embodiment of the present invention.

FIG. 17A is a schematic configuration view of a lowering device of the embodiment of the present invention.

FIG. 17B is a view taken along line A-A of FIG. 16.

FIG. 18 is a vertical cross-sectional view of the tank during construction showing the construction method for a cylindrical tank of the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of a construction method for a cylindrical tank according to the present invention will be described in detail with reference to the accompanying drawings. Further, in the following drawings, in order to allow members to have recognizable sizes, scales of the members are appropriately varied. In the following description, a ground type prestressed concrete (PC) double shell storage tank configured to store liquefied natural gas (LNG) is described as an example of the cylindrical tank. An inner tank of the cylindrical tank of this embodiment is formed of metal, and an outer tank thereof is formed of concrete (prestressed concrete).

First, as shown in FIG. 1, construction of a base plate 1 (a bottom portion of an outer tank) having substantially a disk shape is performed, and a bottom liner (not shown) is formed on an upper surface thereof. Here, in this embodiment, an inner tank anchor strap 2 is installed inside an outer circumferential edge portion of the base plate 1 in a circumferential direction of the base plate 1.

Next, a portion of a sidewall 3 (a PC wall) of the outer tank, for example, to a fifth (#5) level of the sidewall 3 stacked to 9 levels as a whole, is formed outside the inner tank anchor strap 2 at the outer circumferential edge portion of the base plate 1.

Further, a construction entrance gate 4 is formed at a portion of the sidewall 3 of the outer tank formed at this place at a lower level side thereof, for example, second to third levels. In addition, since the sidewall 3 finally formed is constituted of 9 levels by stacking sidewalls of remaining levels on the portion of the sidewall 3, a suspension scaffold 5 used to assemble a mold for the remaining levels is installed at an upper side of the portion of the sidewall 3, for example, an area of a fourth level or more.

After the portion of the sidewall 3 of the outer tank is formed in this way, a plurality of legged stands 6 used for assembling inner tank lateral plates are installed at an inner circumferential surface side of the sidewall 3 in a circumferential direction thereof. The legged stand 6 is a gate-shaped stand configured to support the inner tank lateral plate (to be described below). The legged stand 6 is installed on the base plate 1 to span an annular region X serving as a region in which a cylindrical inner tank formed by combining the plurality of inner tank lateral plates is finally lowered.

Claims (3)

What is claimed is:

1. A construction method for a cylindrical tank having an inner tank and an outer tank, the construction method comprising: a knuckle portion assembly step of assembling an annular knuckle portion inside a sidewall of the outer tank; a jack-up unit attachment step of attaching to the sidewall of the outer tank, a jack-up unit having a jack-up rod configured to be connected to the knuckle portion; ! an inner tank assembly step of hanging and lifting the knuckle portion by the jack-up unit, and of attaching an inner tank lateral plate to a lower side of the knuckle portion to assemble the inner tank; and a jack-up rod-lowering step, after the inner tank assembly step, of lowering the jack-up rod to a bottom surface of the cylindrical tank using a lowering device including a pulley group composed of a fixed pulley and a movable pulley, a wire bridging the fixed pulley and the movable pulley of the pulley group, and a drive unit configured to let out and pull back the wire.

2. The construction method for a cylindrical tank according to claim 1, wherein the pulley group includes a plurality of movable pulleys.

3. The construction method for a cylindrical tank according to claim 1 or 2, wherein, in the knuckle portion assembly step, a knuckle support configured to be connected to the jack-up unit and to be lifted is attached to an outside of the knuckle portion, and the drive unit of the lowering device is attached to the knuckle support.