JPS6337230B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for replacing the bottom plate of a liquid storage tank such as heavy oil.

Conventionally, for tank bottom plate replacement work, the so-called jack-up method, in which the side plate of the tank is lifted and supported using jacks, has often been adopted. In this conventional construction method, a jack cradle is attached to the side plate, and the jack cradle is pushed up by a jack installed on the foundation of the tank. , there is a risk that the side plates may buckle. Therefore, it is necessary to attach reinforcing materials not only to the mounting portion of the jack holder but also to the side plates for reinforcement. The installation of the jack cradle and the reinforcing material are done by welding, and the removal of the jack cradle and reinforcing material after the bottom plate replacement work is done by gas cutting. There were disadvantages such as distortion generation, residual stress, and damage to the side panels. In addition, a large number of jacks and control devices are required, and the tank foundation needs to be reinforced to install the jacks, which not only lengthens the construction period but also increases construction costs.

The present invention aims to solve the above-mentioned drawbacks by supporting the side plate with a jig combined with a taper liner installed directly under the side plate and replacing the bottom plate. There is no undesired bending moment applied to the side plate, and therefore there is virtually no need to attach reinforcing materials by welding, so there is no buckling welding distortion or residual stress on the side plate, and the bottom plate can be replaced safely and easily. The purpose of this study is to provide a tank bottom plate replacement method that can be used to shorten the replacement work period and reduce construction costs. This will be explained below with reference to the drawings.

1A and 1B are explanatory diagrams for explaining the structure of the tank bottom plate, in which FIG. 1A is a plan view and FIG. 1B is a sectional view taken along arrow A-A' in FIG. 1A.
Figures 2 A to C are explanatory diagrams of the bottom plate removal process, Figure 3
The figure is an explanatory diagram of the new bottom plate installation process, Figures 4 A to C
is an explanatory diagram of the liner jig installation process, Figures 5 A to C are explanatory diagrams of the misalignment prevention jig installation process, and Figure 6 A is an explanatory diagram of the liner jig installation process.
I to I show explanatory diagrams of the base down process and the fillet welding process. The code 1 in the figure is the bottom plate;
1a to 1l are the bottom plate sections, 1' is the new bottom plate, 1
a′ represents the new bottom plate section. Also, 2 is the side plate,
2' is a side plate opening, 3 is a liner jig, which is used for tapered liners 3a, 3b and height adjustment liner 3.
4 is a jig for preventing misalignment, which includes plates 4a, 4b and a taper.
5 is a magnetic holder, 6 is an auxiliary taper liner, 7 is an auxiliary taper liner with a vault, 7' is a vault,
Reference numeral 8 represents a liner extraction jig, 8' a nut, and 9 a backing plate.

Generally, the bottom plate 1 of a large tank is, for example, a first
As shown in Figure A, it is divided into a plurality of blocks (1a to 1l), and as shown in Figure 1B, a side plate 2 is provided upright on a bottom plate 1. In the bottom plate replacement method of the present invention, the bottom plate sections 1a to 1l are sequentially replaced, for example, in the order of the bottom plate sections 1a to 1l. The present invention will be explained below according to the construction procedure.

(A) Bottom plate replacement process (A-1) Bottom plate section to be replaced first (e.g. 1a)
In order to carry out and carry in the
As shown with diagonal lines in the figure, the side plate 2
A side plate opening 2' is created by cutting the lower part of the side plate.
The cutting width W ₁ and the cutting height H of the side plate opening 2' may be any size necessary to carry out the bottom plate section 1a. For example, the cutting width W ₁ may be slightly wider than the cutting width W ₂ (shown in FIG. 2C) of the bottom plate section 1a (described later), and the cutting height H may be
It should be around 20 to 50mm. Next, the second
As shown by the dotted line in Figure C, the bottom plate section 1a to be replaced is cut slightly outside the section line (for example, about 100 mm outside) and taken out from the tank through the side plate opening 2'.

(A-2) A new bottom plate section 1a' corresponding to the removed bottom plate section 1a is carried in through the side plate opening 2' and installed at a predetermined position as shown in FIG.

(A-3) Next, as shown in FIGS. 4A and 4B, the liner jig 3 is installed between the side plate 2 and the new bottom plate section 1a'. Note that FIG. 4A shows a side view, and FIG. 4B shows a plan view. The liner jig 3 is composed of two tapered liners 3a and 3b and a height adjustment liner 3c. When installing the liner jig 3, first install the height adjusting liner 3c directly under the side plate 2, and then install the height adjusting liner 3c and the side plate 2.
There are two tapered liners 3a and 3b between
Insert from inside and outside of the tank. In the present invention, two taper liners 3a, 3
b is used, the upper surface of the taper liner 3a that comes into contact with the lower end of the side plate 2 is horizontal,
The side plate 2 can be supported horizontally. This is because the entire lower end surface of the side plate 2 contacts the taper liner 3a, so in the base down process (the process of pulling out the taper liners 3a and 3b and lowering the side plate 2 onto the new bottom plate), which will be described later. , there is an effect that the side plate 2 can be supported without strain. Also,
The arrangement interval of the liner jig 3 (arrow P shown in Fig. 4C) should be determined depending on the size and weight of the tank, but according to experiments conducted by the inventors, It has been found that it is sufficient to set the distance to about 1 m. It goes without saying that in order to equalize the load applied to each liner jig, it is desirable to equalize the arrangement intervals P of each liner jig.

(A-4) Next, a misalignment prevention jig 4 is used to maintain the roundness of the side plate 2 and to prevent misalignment of the side plate 2 in the circumferential direction during the base down process described later.
is installed as shown in FIG. 5A.
The misalignment prevention jig 4 is a misalignment prevention plate body 4.
It consists of a, 4b and a taper pin 4c. When installing the slip prevention jig 4, first set the slip prevention plates 4a and 4b.
As shown in FIG. 5B, the side plate 2 is clamped and fixed to the new bottom plate section 1a' by temporary welding. However, the slip-preventing plate 4b installed outside the tank is installed so as to have a gap of about 1 mm with respect to the side plate 2. This is done in order to remove the taper pin 4c and make the bottom plate as free as possible during the main welding process of the new bottom plate, which will be described later. Next, as shown in FIG. 5A and FIG. 5C which is a plan view of FIG. 5A, the taper pin 4c is attached to the side plate 2.
and the slippage prevention plate 4b. By doing this, the side plate 2 is held by the slippage prevention plate 4a and the taper pin 4c. It is preferable that the misalignment prevention jigs 4 are arranged at equal intervals, for example, at intermediate positions between the liner jigs 3 described above. Further, the taper pins 4c may be provided in the misalignment prevention jig 4 at approximately one out of three locations.

Above, we have explained the construction details for replacing the bottom plate section 1a shown in Figure 1A with the new bottom plate section 1a'.
The entire bottom plate 1 is replaced with a new bottom plate by replacing 1 in turn. The replacement order of the bottom plate sections a to l is, for example, bottom plate sections a, b,
Do this sequentially starting from the center like c,...,l. In addition, as the bottom plate replacement progresses, we will temporarily weld the adjacent new bottom plate sections one by one.
It is desirable to ensure that each new bottom plate section does not shift. Next, the main welding process for the new bottom plate will be explained.

(B) Main welding process of the new bottom plate After all of the bottom plate sections 1a to 1l mentioned above are replaced with new bottom plate sections 1a' to 1l' (although not shown, bottom plate section 1 shown in Figure 1A)
(It can be considered that sections a to 1l have been replaced with new bottom plate sections 1a' to 1l'), all of the previously mentioned temporary welding parts are fully welded to completely finish the new bottom plate as one piece. In addition, when performing main welding, use the aforementioned slippage prevention jig 4.
Remove the taper pin 4c to make the side plate 2 as free as possible with respect to the new bottom plate. This is to prevent the side plate 2 from being deformed due to shrinkage of the new bottom plate due to main welding. And the taper pin 4
c is set again at the end of main welding.

(C) Base down process The state of the side plate 2 at the end of the above process (B) is as follows:
As shown in FIG. 4, the liner jig 3 is placed on the liner jig 3, which is arranged at an interval P, as shown in FIG. 4, and as shown in FIG. It is in a state where it is held by the jig 4. The base down process is a process in which the liner jig 3 is removed and the side plate 2 is placed directly on the new bottom plate. The base down process will be explained below in the order of construction.

(C-1) The state in which the side plate 2 is supported by the liner jig 3 before the start of base down is illustrated in FIG. 6A. That is, the tapered liners 3a, 3 are arranged at equal intervals over the entire circumference of the side plate 2.
b and the height adjustment liner 3c, the side plate 2 has a height H (H=20 to 50
mm). Base down is performed by shifting the taper liners 3a and 3b in the directions of arrows a and b shown in FIG. 6A, respectively. 3b is not pulled out at once, but the amount of down is approximately 5 mm at one time, as shown in FIG. 6B. That is, sequentially from the predetermined liner jig 3 in both directions,
As shown in Fig. 6B, liner jig 3 in 5mm increments.
Lower the height H. In addition, liner jig 3
To lower the height H of the tapered liners 3a and 3b, as shown in FIG.
Each of these steps can be easily performed by repeatedly hammering in both directions of the arrows shown. In addition, in order to prevent the taper liners 3a and 3b from shifting when the height H of the liner jig 3 is lowered by 5 mm (the state shown in FIG. 6B), as shown in FIG. 6D, , and fix it using a magnetic holder 5.
In this way, by lowering the height H of all liner jigs 3, the side plate 2 can be lowered by 5 mm. At this time, in order to apply an equal load to all liner jigs 3, the height of the liner jigs 3 is adjusted so that the upper surface of the tapered liner 3a comes into close contact with the side plate 2. In this way, lower the base of the side plate 2 by 5 mm several times until the lower end of the side plate 2 is at a height of about 5 mm from the new bottom plate 1'.
Repeat.

(C-2) Next, as shown in Figure 6E,
After installing an auxiliary taper liner 6 near each liner jig 3 so that the load of the side plate 2 is evenly applied to the auxiliary taper liner 6, all the liner jigs 3 are removed. The situation is shown in FIG. 6F. When installing the auxiliary taper liner 6, as shown in FIG. 6G, a predetermined plurality of adjacent taper liners (four in the embodiment shown in FIG. 6G) Taper liner 6
Instead, an auxiliary taper liner 7 with a vault, which will be described later, is installed. Auxiliary taper with vault
As shown in FIG. 6H, the liner 7 is a bolt 7' fixed by welding or the like, and even if a considerably large load from the side plate 2 is applied to the vaulted auxiliary taper liner 7, By installing a liner pulling jig 8 and turning a nut 8', the vaulted auxiliary tapered liner 7 can be easily pulled out. Note that the patch plate 9 in FIG. 6H is the liner extraction jig 8.
This prevents the side plate 2 from coming into direct contact with the side plate 2. In this way, the auxiliary taper liner 6 and the vaulted auxiliary taper liner 7
After removing all liner jigs 3 as described above, all auxiliary taper liners 6 except for the auxiliary taper liner 7 with bold are removed. Thereafter, the vaulted auxiliary tapered liner 7 is removed using the liner extraction jig 8 as described above.
Note that even if the auxiliary taper liner 6 and the auxiliary taper liner 7 with vault are used, the side plate 2
As shown in FIG. 6F, the gap between the side plate 2 and the new bottom plate 1' is only about 5 mm around the entire circumference, and the auxiliary taper liner 6 Since it is removed gradually, the side plate 2 can be smoothly lowered onto the new bottom plate 1'. In addition, when the auxiliary taper liner 6 is removed, most of the lower end of the side plate is already in contact with the new bottom plate 1', and the load applied to the auxiliary taper liner 7 with the vault is small, so the above-mentioned The vaulted auxiliary taper liner 7 can also be easily removed using the liner extraction jig 8. Also, when pulling out the auxiliary taper liner 7 with vault, the side plate 2
The base can be lowered more smoothly by dividing the amount of down of 5 mm into two steps of 2 to 3 mm each. In this way, as shown in FIG. 6I, the base down of the side plate 2 is completely completed.

In addition, in the base down process, the taper pin 4c in the jig for preventing displacement mentioned above is
remains inserted. Therefore, the base
Even during the down process, it is possible to prevent the side plate 2 from shifting in the circumferential direction and maintain its roundness.

(D) Fillet welding process Next, the new bottom plate 1' and side plate 2 are welded, that is, the 6th
Perform fillet welding as indicated by arrows C and C' in Figure I.
First, fillet welding on the inside (arrow C shown in Fig. 6I) is performed, but before welding, loosen the taper pin 4c of the slip prevention jig 4 explained with reference to Fig. 5, and remove the slip prevention plate. While removing the body 4a,
The fillet welding indicated by the arrow C in FIG. 1 is performed sequentially over the entire circumference. After completing the inner fillet welding, the outer fillet welding (arrow C' in Fig. 6I) is sequentially performed around the entire circumference while removing the slippage prevention plate 4b. Once the fillet welding is completed, the bottom plate replacement work is essentially complete.

It goes without saying that various necessary inspections in the above-mentioned bottom plate replacement work are performed in the conventional manner in accordance with a predetermined construction order.

Although the tank bottom plate replacement method according to the present invention has been described above, the present invention is not limited to only tank bottom plate replacement work;
This method can also be applied as is to the tank annular plate replacement work disclosed in No. 30521.

As explained above, according to the present invention, a liner jig constructed by combining two tapered liners, an auxiliary taper liner, an auxiliary taper liner with a vault, and a liner extraction jig are used to remove the base down. At the same time, the bottom plate is replaced using a misalignment prevention jig, so the bottom plate can be replaced safely, easily, and smoothly without damaging the roundness of the tank. In addition, since there is no need to weld the various jigs and reinforcement materials mentioned above to the side plate,
There is no distortion or residual stress caused by welding on the side plates, and there is no need to reinforce the foundation. Therefore, it is possible to significantly shorten the construction period and reduce construction costs.

[Brief explanation of the drawing]

Figures 1A and B show the structure of the tank bottom plate.
Figures A to C are explanatory diagrams of the bottom plate removal process, Figure 3 is an explanatory diagram of the new bottom plate installation process, Figures 4 A to C are explanatory diagrams of the liner jig installation process, and Figures 5 A to C are for preventing slippage. An explanatory diagram of the jig installation process, FIGS. 6A to 6I show explanatory diagrams of the base down process and fillet welding process. In the figure, 1 is the bottom plate, 1' is the new bottom plate, 2 is the side plate, 3
4 is a liner jig, 4 is a jig for preventing displacement, 5 is a magnetic holder, 6 is an auxiliary taper liner, 7 is an auxiliary taper liner with a vault, and 8 is a liner extraction jig.

Claims (1)

[Claims] 1 In the tank bottom plate replacement method, (A) one bottom plate section of a tank bottom plate divided into multiple sections and the lower part of the side plate above the one bottom plate section are cut and removed, and a new bottom plate section is placed in the removed position. After that, the process of installing a liner jig that supports the lower end of the cut side plate and a slip prevention jig that clamps the inner and outer surfaces of the side plate on the new bottom plate section is repeated for each bottom plate section. (B) a bottom plate main welding process of welding the joint parts of each of the replaced new bottom plate sections to form an integral new bottom plate; C) Base-down process in which the liner jig is removed and the side plate is placed on the new bottom plate, and (D) The corner between the lower end of the side plate and the new bottom plate is removed while the jig for preventing displacement is removed. A fillet welding process is performed to join the side plate and the new bottom plate together by performing fillet welding, and in the bottom plate replacement process, a first The side plate is supported at a predetermined height position relative to the new bottom plate by the liner jig, and in the base down process, the side plate is supported at a predetermined position by the first liner jig. A second liner jig made of a tapered liner is inserted between the side plate and the new bottom plate, and then the first liner jig is removed, and then the second liner jig is inserted between the side plate and the new bottom plate. A tank bottom plate replacement method characterized by removing the jig.