JPS6152067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an explosion structure for a closed container such as a fixed roof tank for storing crude oil or other flammable liquids at normal pressure.

(Prior art and its problems) In closed containers such as fixed-roof tanks that store liquid flammable hazardous materials such as crude oil and LPG at normal pressure, the liquid level may change due to changes in outside temperature or when the liquid is put in and taken out. The internal pressure in the upper space fluctuates. In order to absorb the fluctuating pressure and maintain the safety of the container itself, devices such as vent pipes such as emergency vents and safety valves are usually provided on the roof of the container. These safety devices function satisfactorily against the slow changes in internal pressure. However, if a fire occurs around the container and the container is affected by radiant heat, or if an explosion or fire occurs within the container for some reason and the pressure inside the container rises rapidly, the above-mentioned safety measures will be taken. It is difficult for the device to completely release the abnormal pressure to the outside,
As a result, the entire container structure was destroyed, making it inevitable that a secondary disaster would occur.

In other words, the damage is not limited to the roof of the container;
At the same time, a large amount of gas pressure and liquid pressure acts on the peripheral wall and bottom plate of the container, causing it to break down, causing the dangerous substance stored in the liquid to leak out over a wide area, causing a fire and potentially expanding the disaster. The sex was hot.

Therefore, in closed containers such as tanks for storing dangerous substances, it has been required to adopt an explosion structure to release abnormally high pressure to the outside.

In other words, it is the first conventional detonation structure.
As illustrated in the figure, the outer peripheral edge of the roof plate 2 is welded to the top peripheral wall plate or the top reinforcing plate 1 of the container with the shortest possible leg length to join them to each other. The mechanism of detonation when abnormal pressure rise occurs in this detonation structure will be explained below.

As shown by the broken line in FIG.
When the weld falls inward, bending stress concentrates on the fillet weld, which is the joint, and as a result, the weld breaks and internal pressure is released from the break to the outside.

In other words, by making the fillet weld, which is the joint between the roof plate 2 and the top reinforcing plate 1, the weakest part of the container structurally, if excessive internal pressure is applied, only that part will break. This system releases excessive pressure only upwards of the container to minimize accidents. In other words, the peripheral wall or bottom plate of the container is not destroyed, so secondary disasters due to the leakage of dangerous substances can be prevented.

In order for the roof joint to break easily in the above structure, the leg length of the fillet weld needs to be as short as possible. However, the top peripheral wall needs to be firmly welded and fixed to prevent buckling deformation even when subjected to external loads such as roof loads and snow accumulation. Furthermore, since the joint between the peripheral wall and the roof must be kept airtight, the fillet weld actually requires a certain weld leg length.

In other words, in order to make the roof plate joints easy to break and to improve the detonation function, it is necessary to reduce the weld leg length as much as possible in order to lower the roof plate joint strength. In order to completely satisfy the above, it is necessary to increase the welding leg length to some extent.

In reality, it is difficult to set and adjust the optimal welding leg length that satisfies these conflicting functions at the same time and actually perform the welding on site, and some kind of drastic countermeasure has been desired.

(Object of the Invention) The present invention was devised to solve the above-mentioned problems, and the joint between the top reinforcing plate and the roof plate of the closed container or the joint between the roof plates is easily destroyed. The object of the present invention is to provide a new detonation structure that maintains good airtightness at the joint.

(Structure of the Invention) Therefore, in the present invention, a thin plate is interposed in the above-mentioned joint to facilitate breakage, so that when the internal pressure acts above a certain pressure, only the joint of the roof sheets automatically breaks. , which provides a structure that avoids destruction of other parts of the container.

The gist of the invention is the joint between the top circumferential wall plate and the roof plate in an airtight container such as a fixed-roof tank, or the joint between the roof plates (hereinafter the top circumferential wall plate and the roof plate are simply referred to as plates). A breaker plate made of a thin plate is interposed between the plates, this breaker plate is interposed between the two plates to be joined, one edge of the breaker plate is joined to one of the plates to be joined, and the other edge is similarly joined to one of the plates to be joined. The detonation structure of a sealed container such as a fixed roof type tank is characterized in that one plate is joined to the other plate by welding.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings. Figure 2 shows the top reinforcing plate 11 and the roof plate 12.
A breaker plate 13 formed of a thin plate is superposed between the peripheral edge of the breaker plate 1
One end edge 14 of No. 3 is welded to the top reinforcing plate 11 side, and the other end edge 15 is welded to the roof plate 12 side to form an explosion structure.

FIG. 3 is a side sectional view showing an embodiment in which a breaker plate 13 is interposed at the joint between the roof panels 12, 12. When the breaker plate 13 is provided in the middle of the roof plate 12, each end face of the plate 13 is connected to the adjacent roof plate 1 as shown in this figure.
Join to 2 and 12.

Figures 4 and 5 show the breaker plate 13.
FIG. 3 is a plan view showing an example in which the containers are arranged over the entire roof of a sealed container.

FIG. 4 shows an example in which the breaker plates 13 are arranged at the circumferential joints of the roof panels 12 as indicated by broken lines, and in FIG. An example of the arrangement is shown. Note that the arrangement of the breaker plate 13 is appropriately determined depending on the material, shape, storage capacity, pressure rise degree, etc. of the closed container.

In the above description, the detonation structure of the present invention is also exemplified in the case where it is applied to the roof of a closed container such as a tank, but the application is not limited thereto. In other words, it goes without saying that if this structure is adopted for the lid of a nozzle with a diameter of several meters, it can also be used as an emergency pressure release lid called a love hatch.

(Function) According to the explosion structure of the present invention, when the internal pressure of the container becomes abnormally high, the roof plate 12 bulges upward as shown by the broken line, and at the same time the breaker plate 13 stands up. At this time, bending stress acts on the welded portions at both ends of the plate 13, easily leading to breakage, and the internal pressure is released upward to the outside from the broken portion. Even if the overall rise of the roof plate 12 due to abnormal internal pressure is small, the amount of displacement of the breaker plate 13 is large, and the bending moment with the width of the plate 13 as the length of the arm around the welded part becomes a large value. Even fillet welds with long legs break easily.

(Effects) According to the explosion structure of the present invention, the following effects can be obtained.

(i) Only the joints of the roof panels can be easily broken and the internal pressure can be safely released. The roof plate 12 is less likely to be deformed, and disordered destruction of the roof can be avoided.

Moreover, the breaker plate 13 can be repaired simply by readjusting it.

(ii) only the roof joint ruptures, other parts of the container;
In other words, since destruction of the peripheral wall and the bottom plate can be avoided, secondary disasters due to leakage of the stored liquid can be prevented.

(iii) Since the breaker plate 13 is inserted, the force to break the weld is strong, and the plate 13
When joining, the welding leg length can be used as normal. In other words, when abnormal internal pressure acts on the roof,
Although the breaker plate 13 stands up, the amount of deformation at this time is large and it can be easily broken even if the weld leg length is large.

Therefore, when welding and joining during assembly, there is no need to reduce the weld leg length as much as possible as in the conventional method, and the construction does not require a high level of skill.

(iv) Furthermore, since the weld leg length can be increased, the function of seal welding at the joint can be sufficiently performed, and a container with excellent airtightness can be provided.

As described above, the explosion structure according to the present invention exhibits extremely superior effects compared to conventional structures.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a conventional explosion structure. FIG. 2 is a side sectional view showing one embodiment of the present invention, and shows an example in which the structure of the present invention is adopted at the joint between the top reinforcing plate and the peripheral edge of the roof plate. FIG. 3 is a side sectional view showing another embodiment, and shows an example in which the structure of the present invention is adopted at the joint between roof panels. Figures 4 and 5
The figure is a plan view of the roof of the closed container showing the arrangement of the breaker plate 13. 1...Top peripheral wall plate or top reinforcing plate of airtight container,
2... Roof plate, 11... Top reinforcing plate, 12... Roof plate,
13...Breaker plate, 14...One edge of the breaker plate, 15...The other edge of the breaker plate.

Claims (1)

[Claims] 1. In an airtight container such as a fixed roof tank, a breaker plate made of a thin plate is interposed at the joint between the top circumferential wall plate and the roof plate, or at the joint between roof plates (hereinafter referred to as the top circumferential wall plate or roof plate simply as a plate). and insert this breaker plate between the two plates to be joined, one edge of the breaker plate to one of the plates to be joined, and the other edge to the other of the plates to be joined. , an explosion structure for sealed containers such as fixed roof tanks, each of which is joined by welding.