JPS604950Y2 - Field assembled tank - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a field-assembled tank.

When it comes to large tanks, the bottom plate may be damaged due to uneven ground, etc., and the liquid inside the tank may leak out from the damaged area, causing a leakage accident. However, in this case, it is relatively easy to detect, so However, most major accidents involving tank destruction occur at the joints between the tank side plate and the annular plate, and the joints between the annular plate and the bottom plate. In view of the experience and fact that such leaks occur, we designed a field-assembled tank structure that enables early detection of leaks at the joints mentioned above, and that can reinforce existing large tanks with a bark that allows for easy early detection of the above-mentioned leaks. It is related to.

In the structure of a field-assembled tank as shown in Fig. 1, the fillet weld C between the side plate a of the cylindrical tank and the annular plate
It has also been pointed out that the fillet welds e between the annular plate and the bottom plate d are structurally weak points in the assembled tank.

Once a crack forms in such a weak spot and the contents begin to leak, the foundation of the tank will be weakened by the contents in a short period of time and will be partially washed away, which will reduce the supporting capacity of the annular plate or bottom plate. It is easy to imagine that this will cause the cracks to further progress, eventually leading to large-scale destruction of the tank and a major leakage accident.

To explain the situation in a little more detail, the structure of a normal on-site assembly large cylindrical tank is as shown in Figure 1, and the annual plate has fillet welds on the tank side plate a and the bottom plate d. It is welded by C and e, and the side plate a
A concrete block f (rarely a bearing plate with a small width) is placed directly under the.

In such a tank, due to internal pressure or other forces, the included angle θ between the side plate a and the annular plate shown in Fig. 2 may become large, or stress corrosion cracking may occur, causing the fillet weld C to If cracks occur near the sandy ground
As the contents leak towards the tank, the supporting capacity of the sandy ground G weakens or disappears, and the annual planks are no longer able to withstand the internal pressure, resulting in large-scale destruction of the tank, as shown in Figure 3. .

Furthermore, if a crack occurs in part i of the fillet weld e between the bottom plate d and the annular plate as shown in Fig. 4, and leakage begins, the tank will eventually leak as shown in Fig. 5. resulting in large-scale destruction.

Moreover, in the case shown in Figure 2, the time from the occurrence of cracks to the state shown in Figure 3 is relatively short, 1 to 2 hours.
It is extremely difficult to prevent accidents from occurring during that time.
In the case shown in FIG. 4, since the leakage location is deep in the tank, it is extremely difficult to detect the leakage before it becomes a serious problem.

Therefore, in order to prevent the fillet weld C between the side plate a and the annular plate from being destroyed, a bearing plate f' is used instead of the concrete block f, and the fillet weld is made between the annular plate and the side plate a, as shown in Fig. 6. 1. Fillet weld the reinforcing plate k to the annular plate as shown in Figure 7.
Although it is conceivable to attach it with m, both still have the following drawbacks.

Namely, 1. No consideration was given to the destruction of the welded part e between the annular plate and the bottom plate d.

2. The time between the discovery of a leak and the large-scale destruction of the tank is short.

3. It is difficult to detect local uneven settlement of the ground, which is one of the causes of cracks in the fillet weld C between the side plate a and the annular plate.

4. If a leak were to occur, the foundation would still be easily destroyed and large-scale destruction of the tank would likely occur.

In particular, the type shown in FIG. 7 has a fillet weld between the side plate a and the annular plate b1 or between the side plate a and the reinforcing plate.
Although there is an advantage that even if cracks occur in C/ and the contents leak, the annular plate and reinforcing plate are welded to each other, so leakage to the tank foundation ground G is prevented. ,
Note that this method can only be applied to newly constructed tanks, and since there are many welded parts, the distortion of the bottom plate may become large.
Since no consideration has been given to cracks and leakage at the welded portion between the above-mentioned annular plate and the bottom plate d, there have been drawbacks such as a crack accident as shown in FIG. 8.

This idea overcomes the shortcomings of the construction, and in addition, it can be easily implemented on existing field-assembled tanks without significantly changing the design standards of current tanks and without increasing the welding strain. Its purpose is to provide configuration.

The structure of the on-site assembly tank of this invention will be explained based on an embodiment shown in FIG. , at the corner portion of the bottom of the tank where both side edges of the annular auxiliary plate 3 which is wide in width and which are not lap-jointed at least in the circumferential direction protrude sufficiently long from both side edges of the annular plate 2. The annular auxiliary plate 3 is joined to the outer peripheral edge of the annular plate 2 by temporary welding without continuous welding.

In Fig. 9, 4 is the tank side plate, 5 is the tank outer protrusion,
6 is the inner protrusion of the tank, p is the width of the outer protrusion of the tank, q is inside the tank inner protrusion, 8 and 9 are fillet welds, p is sufficiently long, for example, 100 or more, and q is also sufficiently long, for example. 5007FEll1 or more, the thickness of the annular auxiliary plate 3 is preferably made thicker than the annular plate 2.

Further, the annual auxiliary plate 3 is laid by welding the auxiliary plates together by butt welding, without lap welding.

Also, the welded portion 7 between the annular plate 2 and the annular auxiliary plate 3
This is only temporary welding and should never be continuous welding.

Further, FIG. 10 shows another embodiment in which the annular auxiliary plate 3, which is wider than the annular plate 2, is not a single piece, but is made up of additional pieces.

Since these embodiments have a configuration like Narukami, the first
As shown in Fig. 1 and Fig. 12, even if a crack occurs for some reason and leakage occurs, the auxiliary annular plate 3 will remain intact.
If the width is wider than the plate 2 and the tank outer protrusion 5 and tank inner protrusion 6 are sufficiently long, the foundation sand will be scooped out in a short time and the tank will not be destroyed.

Therefore, it is possible to take some measures before large-scale destruction occurs.

In addition, cracks occur and leakage occurs, as shown in Figure 13.
Even if the tank sinks unevenly locally, the side plate 4 and annual
There is little effect on the fillet weld 8 between the plate 2 and the fillet weld 9 between the annular plate 2 and the bottom plate 1, and the annular
The auxiliary plate 3 acts as if it were a cushion.

In addition, since there is a protrusion 5 on the outside of the tank, as shown in FIGS. 11 and 12, if there is a leak, the fillet weld 7 between the annular plate 2 and the annular auxiliary plate 3 will be removed. As mentioned above, continuous welding is never done at the level of tack welding, and the annular auxiliary plate is not lap welded, so the contents are transferred from between the annular auxiliary plate 2 and the annular auxiliary plate 3 to the annular auxiliary plate. 3, and the leakage can be easily detected.

Furthermore, if there is uneven settlement as shown in Figure 13, by measuring the angle θ between the horizontal foundation ground surface and the annular auxiliary plate 3, the uneven settlement as shown in Figure 14 can be determined. If there is subsidence, by measuring the gap t between the annular plate 2 and the auxiliary annular plate 3, it is possible to detect local uneven subsidence inside the tank near the tank side plate 4. .

Furthermore, these embodiments can be implemented without changing the design of conventional on-site assembly tanks, and as is clear from the above explanation, the annular auxiliary plate 3 is not continuously welded to the annular plate 2 and the bottom plate 1. Therefore, it can also be used as a reinforcement structure for an existing tank.Compared to the improved structure that requires fillet welds] and m as shown in Figure 7, the welding points are only temporary fillet welds. Since there is only one section 7, there is little welding distortion on the bottom plate, and it is no different from conventional on-site assembly tanks.

Furthermore, since a wide auxiliary annular plate is provided on the back side of the original annular plate 2 and bottom plate 1, it is useful for corrosion prevention.

Experience has shown that leakage of contents near the center of the tank bottom does not result in large-scale destruction of the tank.

Therefore, there is no need to double the entire tank bottom, and the fillet weld 8 between the side plate 4 and the annular plate 2 (see Fig. 9) is where cracking and leakage are most likely to occur, leading to large-scale tank destruction. ), it is necessary to pay special attention to the fillet weld 9 (see Fig. 9) between the annular plate 2 and the bottom plate 1 to ensure the safety of this part, and for this reason, as shown in Fig. 15, By using a concrete block 10, one end 3' of the auxiliary annular plate 3 is connected to the tank foundation 1 as shown in FIG.
As shown in FIG. Place the end of the upper layer 3' on the annular plate 2.
It may be pulled inward and fillet welded there (12), or a depression angle α may be added to one end of the annular auxiliary plate 3 from the inside of the outer edge 13 of the annular plate 2, as shown in Fig. 17. , as shown in FIG. 18, the entire annular auxiliary plate 3 is given a depression angle β, and in some cases, the annular auxiliary plate 2 and the annular auxiliary plate 3 protrude outward from the tank side plate 4. It is even more effective to provide a rain shield over the area.

It should be noted that in these cases, the annular auxiliary plate 3 and the annular plate 2 are not joined by continuous welding, but only by temporary attachment.

Since this idea has the structure and function similar to Narukami's, it requires almost no changes to the design of conventional on-site assembly tanks, and with a simple structure, it can quickly prevent leakage of contents that occurs near the tank side panels and local uneven subsidence of the ground. This is an extremely effective on-site assembly system that can be used to prevent large-scale tank destruction, detect cracks leaking between the annular plate 2 and the bottom plate 1, and serve as a reinforcing structure for existing on-site assembly tanks. Tank configurations can be provided.

Furthermore, if welding is performed, welding distortion may occur, the number of man-hours will increase, and costs will increase.Furthermore, the structure of the tank body will change due to this welding, resulting in damage to the annular plate joint and the annular plate joint. - In addition to excessive welding strain, stress caused by the internal pressure of the liquid reservoir is added to the joint between the plate and the bottom plate, resulting in complex mechanical behavior that threatens the safety of the tank body. Since no welding is required and only temporary attachment is required, the above concerns can be resolved.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of the main parts of a conventional on-site assembly tank;
Figures 3 and 3 are explanatory diagrams of one pattern of large-scale destruction of a tank, Figures 4 and 5 are illustrations of another pattern of large-scale destruction of a tank, and Figure 6 is an illustration of conventional on-site assembly. An improved example of the tank, Fig. 7 (a), another improved example of the opening, Fig. 8 (a), an explanatory diagram of the opening shown in Fig. 7 but with cracks occurring, and Fig. 9 shows an on-site assembly tank according to the present invention. FIG. 10 is a longitudinal sectional view of the main part of the first embodiment, FIG. 10 is a longitudinal sectional view of the main part of another embodiment, FIGS.
14 are explanatory diagrams of effects, and FIGS. 15 to 18 are longitudinal cross-sectional views of main parts of other embodiments, 1 is a bottom plate, 2
3 indicates an annular plate, and 3 indicates an auxiliary annular plate.

Claims (1)

[Scope of utility model registration request] The width is wider than the thickness of the annular plate 2 which is joined to the bottom plate 1 by using only one plate or by adding a plurality of plates.
At least at the corner of the bottom of the tank where both side edges of the annular auxiliary plate 3 that are not lap-jointed in the circumferential direction protrude sufficiently long from both side edges of the annular plate 2, the outside of the annular plate 2 is The on-site assembly tank is characterized in that the annular auxiliary plate 3 is not continuously welded to the periphery but is joined to the extent of temporary attachment.