JPH0422798B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for repairing the bottom of a storage tank.
In particular, it relates to a method for replacing annular plates and repairing foundations.

[Prior Art] In a storage tank such as an oil tank, the annular plate that receives the most load from the side plates etc. is susceptible to corrosion, and therefore it is necessary to replace the annular plate. In addition, when replacing the annual plate, the foundation of the conventional storage tank, which is formed by spraying heavy oil on river sand or mountain sand, is replaced with a foundation made of asphalt mortar or asphalt sand with a thickness of about 30 to 50 mm. There are many things to do.

Conventionally, the so-called ``total jack up method'' has been used as a bottom repair method such as replacing the annular board or modifying the foundation. This whole jack-up construction method involves cutting the side panels and annular boards apart.
A large number of jacks are installed all around the outer circumference of the storage tank, and brackets that engage with each of these jacks are fixed on the outer peripheral surface of the side plate, and the entire side plate is jacked up to replace the annual plate. It is.

Another conventional annular board replacement method is generally called the "piece method." As shown in FIG. 4, this construction method involves cutting out the lower part of the side plate 3, cutting out the side plate 3 and the annular plate 2, replacing the required annular plate 2, and then applying a liner material 5 such as Kinya to the side plate 3. and the annular plate 2, and fix the support piece 6 to the side plate 3 to support the load of the side plate 3. After all the annular plates 2 have been replaced, the liner material 5 is removed and the lower part of the support piece 6 is fixed. This method involves cutting the side plate 3 little by little and gradually lowering it onto the annular plate 2.

[Problems to be Solved by the Invention] As described above, the two conventional construction methods have various problems as shown below.

In other words, in the case of the overall jack up method, a large number of expensive jacks must be used;
In addition, it is necessary to create a jack base etc. around the tank in order to install the jack, and furthermore, when lifting the side plate, it is necessary to reinforce or support the side plate to prevent it from deforming or tilting, and there are many people around the tank. This increases the construction period and costs as well. Furthermore, in the overall jack-up method, the side plate is generally raised to about 500 to 800 mm, so the joints with the piping around the tank must be cut, resulting in a lack of stability and the risk of earthquakes. Safety measures against strong winds are required.

On the other hand, although the piece method is an inexpensive construction method, it requires replacing the existing annular board with a new annular board immediately after removing it, making it difficult to modify the foundation directly below the side board, for example, due to uneven settlement. be. Additionally, because the support pieces are cut one by one and the side plates are lowered, excessive stress is generated around the last support piece, which may cause the tank to deform. Furthermore, since the lower part of the side plate is cut out, the height of the storage tank is reduced, resulting in a reduction in storage efficiency and the need to apply for structural changes. Additionally, since the mounting positions of nozzles, manholes, etc. change, the connection points with piping outside the tank must be changed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for repairing the bottom of a storage tank that eliminates the problems encountered in the prior art.

[Means for Solving the Problems] The method for repairing the bottom of a storage tank according to the first invention includes the steps of cutting the annular plate and the side plate apart around the entire circumference of the tank, and cutting the inner surface of the side plate at a predetermined height. This step involves fixing a plurality of brackets at appropriate intervals around the entire circumference of the tank, and dividing the storage tank into a plurality of zones in the circumferential direction and sequentially placing jacks between the annular plate and the brackets in each zone. Lifting the side plate with a jack, inserting the liner material between the side plate and the annular plate, removing the jack and moving it to the next area, and removing the liner material on the annular plate that needs to be replaced and replacing this annular plate with a new one. The steps include inserting a liner material between the new annular plate and the side plate, welding the annular plates, etc. together, and sequentially installing jacks between the annular plate and the bracket in each area. The process consists of the steps of placing the annular plate, removing the liner material, and lowering the side plate using the jack, and welding the annular plate and the side plate.

Further, according to the second invention, the bottom repair method for a storage tank includes supporting the side plate with the liner material in the same manner as described above, and then removing the annular plates and the bottom plate other than the annular plate in the portion that supports the liner material. The stage of repairing the foundation, laying the bottom plate, removing the liner material and the part of the annular plate that supports this liner material for each part equivalent to one new annular plate, and laying the new annular plate, and installing the new annular plate and side plate. the step of inserting the liner material between the new annular plate and the bottom plate, the step of welding the new annular plate and the bottom plate together, and the step of sequentially placing jacks between the new annular plate and the bracket in each area, removing the liner material, and welding the new annular plate and bottom plate together. The process consists of the step of lowering the side plate with jacks and the step of welding the new annular plate and the side plate.

Other objects, features, and advantages of the first and second inventions will become apparent from the detailed description below in conjunction with the accompanying drawings.

[Embodiment] Figures 1 and 2 of the drawings show an embodiment of a storage tank bottom repair method, particularly an annular plate replacement method, according to the first invention. In the annular plate replacement method of this embodiment, first, the fillet weld between the side plate 3 and the annular plate 2 is removed by gouging, the side plate 3 and the annular plate 2 are cut away, and then a predetermined height is set on the inner surface of the side plate 3. Then, a plurality of brackets 10 are fixed by welding at a pitch of 3 to 4 m in the circumferential direction. Next, this storage tank 1 is circumferentially divided into a plurality of zones with a circumferential length of 30 to 50 m, and in one of the zones, a jack 11 is arranged between the annular plate 2 and the bracket 10 (the first figure),
The jack 11 is operated to lift the side plate 3 to a predetermined height. This lifting height is preferably about 50 to 70 mm so that butt welding and inspection of the annular plates 2 immediately below the side plates 3 can be performed. A liner material 12 such as gold arrow is inserted between the side plate 3 lifted by the jack 11 and the annular plate 2, and the side plate 3 is supported at that height. After the support of the side plate 3 is completed, the jack 11 is removed and moved to another area, and the side plate 3 is lifted and supported in the same manner as described above. This operation is repeated in sequence in all areas of the storage tank 1. The entire side plate 3 is supported by a liner material 12 (FIG. 2). Here, replace the annular plate 2 that requires replacement with the adjacent annular plate 2.
After removing the liner material 12, the annular plate 2 is dragged out, a new annular plate 2 is inserted, and the liner material 12 is again inserted between the annular plate 2 and the side plate 3. When replacing all the annular plates 2, this operation is repeated in sequence. After the replacement work is completed, the annular plates 2 are welded together and this welding is inspected. To lower the side plate 3 onto the annular plate 2, the jacks 11 are first placed between the bracket 10 and the annular plate 2 in one area, and the liner material 12 is pulled out and the side plate 3 is jacked down. After this, the jack 11 is moved to another area, and this operation is repeated to lower the entire side plate 3 to the annular plate 2.
lower it to the top. In this way, the bracket 10 is removed, the annular plate 2 and the side plate 3 are welded together, and a post-welding inspection is performed to complete the replacement of the annular plate 2.

In the case of modifying the foundation when replacing the annular plate, the second invention is applied, and an embodiment of the method for repairing the bottom of the storage tank according to the second invention is shown in FIGS. 1, 2 and 3. As shown in the figure. In this method, the side plate 3 is lifted to a predetermined height and supported by the liner material 12 in the same procedure as the annular replacement method described above. Here, as shown in FIG. 3, the annular plate 2 and the bottom plate are cut, leaving an annular plate (hereinafter referred to as liner material support plate 2') large enough to support the liner material 12. It will be removed and foundation 4 will be modified as appropriate. At this time, if the foundation 4 at the bottom of the liner material support plate 2' is also modified, even if any one set of the liner material support plate 2' and the liner material 12 thereon is removed, other liner material Considering that the side plate 3 is supported by the material support plate 2' and the liner material 12, the liner material support plate 2' and the liner material 12 thereon are shifted one by one onto the corrected foundation 4. After the foundation correction is completed, if necessary, replace the bottom plate with a new one and lay the bottom plate on the foundation 4. Next, remove the liner material 12 and liner material support plate 2' corresponding to one piece of the new annular plate 2, insert the new annular plate 2, and insert the liner material 12 between the new annular plate 2 and the side plate 3 again. to support the side plate 3. After repeating this operation and completing the installation of the new annular plate 2, the bottom plate and the annular plate 2 are welded and inspected. Thereafter, in the same manner as in the annular plate replacement method according to the first invention, the side plate 3 is jacked down in each area and lowered onto the annular plate 2, and necessary processing such as welding is performed to replace the annular plate. Complete basic corrections.

[Effect of the invention] As described above, according to the first and second inventions,
Since the side plate is partially and continuously lifted or lowered with a jack over a certain width, stress is not concentrated at one point in the storage tank, and the number of jacks used is reduced, thereby reducing costs. I can do it. In addition, since the amount of lifting of the side plate is small, stability is high, and only small jacks and brackets are required, which can be easily installed and removed.In addition, the amount of lifting and lowering is small, and the tank capacity does not change. Therefore, there is no need to cut or modify the joints of piping around the tank, or apply for structural changes. Furthermore, since the annular board is used as the jack base or liner base, construction can be performed without modifying the foundation around the tank, which has the effect of greatly improving economical efficiency and construction efficiency.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the method for repairing the bottom of a storage tank according to the first and second inventions.
The figure is a partial sectional view of the storage tank showing the side plate being jacked up, Figure 2 is a schematic explanatory view showing the side plate being supported by liner material, and Figure 3 is the implementation of the bottom repair method according to the second invention. A schematic explanatory diagram showing the removal of the annular plate and the bottom plate in an example, and FIG. 4 is a partial sectional view of a storage tank showing a conventional annular plate replacement method. In the figure, 1... storage tank, 2... annular plate, 2'... liner material support plate, 3... side plate, 4
...Basic, 5,12...Liner material, 6...Support piece, 10...Bracket, 11...Jet.

Claims (1)

[Scope of Claims] 1. Cutting off the annular plate and side plate over the entire circumference of the tank, and fixing a plurality of brackets at appropriate intervals to the inner surface of the side plate at a predetermined height over the entire circumference of the tank. At the stage, the storage tank is circumferentially divided into a plurality of zones, a jack is placed between the annular plate and the bracket in each zone, the side plate is lifted up by the jack, and a liner material is inserted between the side plate and the annular plate. removing the jack after inserting the jack and moving it to the next area; removing the liner material on the annular plate that needs to be replaced and replacing the annular plate with a new annular plate;
The steps include inserting liner material between the new annular plate and side plate, welding the annular plates, etc. together, sequentially placing jacks between the annular plate and the bracket in each area, and then inserting the liner material. A method for repairing the bottom of a storage tank, comprising the steps of removing and lowering the side plate with the jack, and welding the annular plate and the side plate. 2 Cutting off the annular plate and side plate all around the tank, fixing a plurality of brackets to the inner surface of the side plate at a predetermined height at appropriate intervals all around the tank, and fixing the storage tank. Divide it into a plurality of zones in the circumferential direction, sequentially place a jack between the annular plate and the bracket for each zone, lift the side plate with the jack, insert the liner material between the side plate and the annular plate, and then lift the jack. a step of removing the annular board and moving it to the next area; a step of removing the annular board and bottom plate other than the annular board in the part supporting the liner material and modifying the foundation;
Lay the bottom plate, remove the liner material and the part of the annular plate that supports the liner material for each part equivalent to one new annular plate, lay a new annular plate, and insert the liner material between the new annular plate and the side plate. a step of welding the new annular plate and the bottom plate together; a step of sequentially arranging jacks between the new annular plate and the bracket in each of the areas, removing the liner material and lowering the side plate with the jacks; A method for repairing the bottom of a storage tank, comprising the steps of welding a new annular plate and a side plate. 3. In the step of modifying the foundation, in order to modify the foundation of the lower part of the annular plate in the part that supports the liner material, remove the liner material, move the annular board, and insert the liner material again for each annular board in turn. 3. The method of repairing the bottom of a storage tank according to claim 2, which is carried out after the repair is performed.