JPS6361461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for replacing the bottom end plate of a storage tank.

Conventionally, in storage tanks such as petroleum tanks, corrosion tends to occur on the bottom end plates such as the annular plates, which receive the most load from the side plates, etc. Therefore, when it becomes necessary to replace the annular plates, After cutting out the side plate and annular plate, jack up the side plate using many jacks, replace the existing annular plate with a new annular plate,
The jack-up method is used, in which the side panels are jacked up first and then jacked down.
However, this type of jack up method requires a large number of expensive jacks, and when installing the jacks, it is necessary to create a mound for installing the jacks by cutting the slope of the tank foundation, and to use heavy jack bases and brackets. Furthermore, there are drawbacks such as a large bending moment acting on the side plates when jacking up. Therefore, as a way to replace the annular plate without jacking up the tank side plate, cut the joint between the tank side plate and the annular plate, pull out the annular plate to be replaced horizontally, and insert a new annular plate in the removed position. When welding the weld lines between the annular plates that are perpendicular to the side plates, the part directly below the side plates that cannot be welded is exposed by applying an external force in the radial direction to the side plates and partially deforming the lower part of the side plates inward or outward. There is a replacement method characterized by welding (see Japanese Patent Publication No. 56-18472), but even with this method, in the case of thick plates, it is difficult to deform the side plate, and when deforming the side plate, it is difficult to deform the side plate. This has the disadvantage that a large bending moment is applied to the side plate, and if the deformation exceeds the elastic limit of the side plate, the side plate itself may be destroyed.

Therefore, the object of the present invention is to provide a replacement for the bottom end plate of a storage tank, which eliminates such conventional drawbacks and makes it possible to replace the bottom end plate such as an annular plate easily and safely at low cost. The purpose is to provide a method.

According to this invention, the method for replacing a bottom end plate of a storage tank includes, in a storage tank, separating the bottom end plate to be replaced and the side plate, and separating the bottom end plate to be replaced and the adjacent bottom end plate except for the portion directly below the side plate. At the same time as cutting, a beveling process is performed on the lower end of the side plate at a position adjacent to the boundary between the bottom end plate to be replaced and the adjacent bottom end plate, so that the vertical cross section along the tank radial direction is approximately V-shaped. The bottom end plate to be replaced and the adjacent bottom end plate directly below the side plate are cut out.
Carry out the bottom end plate to be replaced outside the storage tank, replace it with a new bottom end plate, weld between the new bottom end plate and the adjacent bottom end plate, and weld between the new bottom end plate and the side plate. It consists of doing.

Other objects, features and advantages of the present invention will become apparent from the detailed description below, taken in conjunction with the accompanying drawings.

1 to 9 of the drawings show an embodiment of a method for replacing the bottom end plate of a storage tank according to the present invention. In the storage tank bottom end plate replacement method of the present invention, first, the welded part 3 between the annular plate 1 and the side plate 2, which are the bottom end plates that need to be replaced, is removed by gouging, and then the welded part 3 adjacent to this welded part 3 is removed. A portion of the weld 3' is similarly removed. Next, as shown in FIG. 2, the welded portion 4 of the annular plates 1 and 1' is cut, and a bevel is made at the lower end of the side plate 2 at the location where it intersects with the welded portion 4 by gouging, a pencil grinder, etc. As shown in FIGS. 3 and 5, the grooved portion 5 is formed so that the vertical cross section along the radial direction of the tank is substantially V-shaped. At the same time, a proper root gap 12 is formed between the annular plates 1 and 1'. Since the wall thickness of this beveled part 5 becomes thinner toward the lower end,
The tip of a cutting tool such as a grinder can be inserted directly below the side plate 2. Therefore, by utilizing the shape of the grooved portion 5, the welded portion 4 between the annular plates 1 and 1' directly below the side plate 2 is cut, and the bottom plate 6 is also cut off. In this way, the separated annular plate 1 that requires replacement is cut into appropriate pieces and pulled out to the outside of the storage tank and removed. While the annular plate 1 is being removed, a new annular plate 1 is installed.
The edge of the existing annular plate 1' to be welded is beveled with a grinder, etc., and a backing metal 7 is placed under the edge.
Install. Next, the new annular plate 1, whose edges have been grooved in advance, is inserted under the side plate 2 and set in the desired position. Here, as shown as an example in FIG. 4, a jig 8 consisting of a top 9 and a gold arrow 10 is
is attached to the lower part of the side plate 2, and the annular plate 1 can be easily set in a desired position by driving a metal arrow 10 to lift the side plate 2 or pushing down the annular plate 1 using the lever block 13. Next, this jig 8 is removed, and the annular plates 1 and 1' are welded together, the annular plates 1 and the bottom plate 6 are welded, and the annular plates 1 and 1' are welded together in the appropriate order.
and weld side plate 2. At this time, it goes without saying that the quality of the welding is appropriately investigated by inspection such as dye penetrant testing. In the welding work in this embodiment, for example, as shown in FIGS. 5 to 9, the welding rod 11 is first inserted into the grooved part 5 from inside the tank, and the tip of the welding rod 11 is extended as far as possible to the outer side of the annular plate. Weld the first layer of 1 and 1' together. At this time, the work can be facilitated by widening the distance between the side plate 2 and the annular plates 1, 1' using a circular piece 14 and a metal arrow 15, as shown in FIG. In the same manner, welding is performed from the second layer to the finishing layer, and welding of the grooved portion 5 is performed (sixth layer).
figure). Next, as shown in Fig. 7, from the outside of the tank, the lower end of the side plate and the annular plate 1,
Process the welded part 1', weld the remaining parts of the annular plates 1 and 1' that have not been welded together, and then weld the lower end of the side plate and the annular plates 1 and 1', and perform the welding work. complete. In addition, in this invention, the groove shape and welding procedure are determined by the thickness of the side plate, etc., such as making the groove state of the side plate 2 double-edged, or welding the grooved part 5 after all the welding of the annual plates is completed. It can be changed as appropriate depending on the situation. Furthermore, although this embodiment shows partial replacement of the annular plates, in the case of replacing a plurality of annular plates or all of them, the above-mentioned partial replacement work can be repeated sequentially along the circumference of the storage tank. It's fine. Further, the cutting location between the annular plate to be replaced and the adjacent annular plate is not limited to the welded portion.

As described above, according to the present invention, when replacing a bottom end plate such as an annular plate of a storage tank, the lower end of the side plate is beveled and the side plate is made thinner toward the lower end, so that the part directly below the side plate of the annular plate can be replaced. This made it possible to cut and weld. That is, according to the present invention, in order to cut and weld the portion directly below the side plate of the annular plate, the lower part of the side plate is pushed outward or inward, or the side plate is jacked up to cut and weld the annular plate. There is no need to create a gap between the board and the board. Therefore, the annular plate of the storage tank can be replaced easily, safely, and at low construction costs. In addition, the welded part after the replacement is complete penetration welding has the advantage of being extremely strong.

[Brief explanation of drawings]

Fig. 1 is a plan view schematically showing the storage tank, Fig. 2 is an enlarged perspective view of the storage tank showing the opening provided in the side plate according to the present invention, and Fig. 3 is a partial side view showing the vicinity of the beveled part. Figure 4 is a perspective view of the storage tank showing a new annular plate being inserted in the position where the old annular plate has been removed, and Figures 5 to 8 are A-A in Figure 3 showing the welding order step by step. FIG. 9 is a sectional view taken along line A, and a perspective view showing a part where welding in the vicinity of the grooved part is facilitated. In the figure, 1, 1'... Annular plate, 2... Side plate,
3, 4...Welding part, 5...Beveling part, 6...Bottom plate, 7...Backing metal, 8...Jig, 11...Welding rod, 12...Root gap.

Claims (1)

[Claims] 1. In a storage tank, cut off the bottom end plate to be replaced and the side plate, and cut off the bottom end plate to be replaced and the adjacent bottom end plate excluding the part directly below the side plate, and also cut the bottom end plate to be replaced and the adjacent bottom end. A beveling is performed on the lower end of the side plate at a position adjacent to the boundary with the plate to form a beveled part whose vertical cross section along the tank radial direction is approximately V-shaped. Cut off the adjacent bottom end plate, carry out the bottom end plate to be replaced outside the storage tank, replace it with a new bottom end plate, and weld the new bottom end plate and the adjacent bottom end plate. A method for replacing a bottom end plate of a storage tank, comprising welding between a new bottom end plate and a side plate.