JPH0516159Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an explosion structure for a tank that stores crude oil or other flammable liquid.

[Conventional technology]

A tank for storing flammable liquids such as crude oil or LPG is a cone-shaped or dome-shaped tank with a central part protruding upward from the upper end of a peripheral wall 1 installed on the ground, as shown in the schematic cross section in Figure 4. Roofing board 2 is put on,
It is configured to store flammable liquid O such as crude oil inside.

In tanks that store this type of flammable liquid, if the internal pressure suddenly increases due to the effects of radiant heat from a fire near the tank and the entire tank explodes, the stored flammable liquid will be destroyed nearby. This will spill out and burn, causing a major secondary disaster. Therefore, in the event of an explosion, a structure is required in which only the roof plate 2 is torn off and the explosion is released upwards.

On the other hand, strong wind currents flowing above the tank generate a large negative pressure on the top surface of the tank's roof plate 2, but the roof plate must have the necessary strength to prevent the roof plate from being torn off by this negative pressure. installation is required.

Conventionally, as shown in an enlarged cross-section in FIG. The leg length l of this weld 4 part is made smaller than the thickness of the roof plate 2, so that when this tank explodes, the weld 4
The tank is ruptured first, and the explosion is carried out upwards to prevent the entire tank from being destroyed.

[Problem that the invention attempts to solve]

However, in the above-mentioned conventional structure, in order to make the roof plate 2 easily peel off in the event of an explosion, welding 4 is required.
It is desirable to reduce the cross-sectional area of the four welded parts by making the leg length l of the four welded parts as small as possible. It is desired that the leg length l be sufficiently large, and welding work to satisfy these contradictory demands requires extremely highly skilled techniques, making it difficult to attach the roof plate 2.

In particular, as shown in FIG. 5 above, when the outer peripheral end of the roof plate 2 is fillet-welded to the upper surface of the flange portion 3a, the roof plate 2 will move upward as shown by the chain line in FIG. 4 when the tank explodes. Even if it bulges out and its peripheral edge is pulled toward the center, the top flange 3 including the upper end of the peripheral wall 1 is pulled inward of the tank and the roof plate 2 and the flange are pulled together as shown in FIG. The angle β formed with 3a becomes smaller, and therefore only tensile force is applied to the weld 4, making it difficult for rupture due to the notch effect to occur, preventing it from breaking easily, and potentially causing damage to the peripheral wall 1. It was hot.

This idea focuses on the problems of the above-mentioned conventional technology,
This was developed with the aim of improving this, and it provides a tank explosion structure that makes it easier to break the roof plate welds in the event of a tank explosion, and ensures that the explosion occurs upwards. .

[Means for solving problems]

In order to solve the above-mentioned problems of the prior art, this invention has a thick annular detonation auxiliary plate attached to the outer edge of the flange formed horizontally at the upper end of the peripheral wall installed on the foundation. Butt the inner edges together,
The welding is smaller than the thickness of both of these plates, and the lower side from the upper side is fixed by seal welding, and the outer circumferential edge of the roof plate is fixed by seal welding at or near the outer circumferential edge of this auxiliary explosion plate. It is characterized by:

[Effect]

In the unlikely event that the pressure inside the tank suddenly increases and an explosion occurs, the diameter of the roof plate will shrink due to upward bulging deformation, and the radial tensile force acting on the roof plate at that time will cause the roof plate to expand. The outer edge of the auxiliary detonation plate is pulled upward, the angle between the roof plate and the auxiliary detonation plate gradually increases, and the notch effect causes the rupture to progress rapidly. As the inner circumferential edge is bent upward, the welded part of the roof plate will break when the inner edge is bent upward, and the blast wave will be emitted upward from this part, preventing the entire tank from being destroyed, and the blast wave will spread horizontally. At the same time, the outflow of flammable liquid due to destruction of the peripheral wall is prevented, thereby preventing the occurrence of secondary disasters.

〔Example〕

Embodiments of this invention will be described below with reference to FIGS. 1 to 3, with the same reference numerals assigned to the same members as those in FIG. 5.

FIG. 1 shows an enlarged cross-section of the joint between the peripheral wall 1 and the roof plate 2 of the tank according to this invention. In the figure, a top angle 3 is welded to the upper end of the peripheral wall 1. The horizontal flange portion 3a projects outward from the peripheral wall portion 1.

The outer edge of this horizontal flange portion 3a is abutted against the inner edge of an annular explosion auxiliary plate 5 that is the same or thicker than the roof plate 2, and is sealed by welding 6.
The upper surface of the flange portion 3a is fixed to the upper surface of the flange portion 3a so that the upper surface of the flange portion 3a is substantially flush with the upper surface of the flange portion 3a.

The outer circumferential edge of the roof plate 2 is fixed to the outer circumferential edge of the explosion auxiliary plate 5 or the upper surface in the vicinity thereof by seal welding 7.

FIG. 3 shows the top angle 3 of the upper end of the peripheral wall 1.
This is a modified example in which a horizontal flange portion 3a is provided to protrude inward of the peripheral wall portion 1, and the inner edge of the detonation auxiliary plate 5 is fixed to the outer edge of the flange portion 3a by seal welding 6. be.

In any of the above embodiments, if the pressure inside the tank suddenly increases and an explosion occurs, the pressure inside the tank will cause the pressure to concentrate on the inner surface of the central part of the roof plate 2 due to its medium-height shape, causing it to expand upward. The roof sheet 2 is deformed, and the peripheral edge of the roof sheet 2 receives a large tensile force toward the center. If tanθ=1/16, this tensile force q is 16P×D/
4 (here, P is the internal pressure and D is the internal diameter of the peripheral wall 1), so it is 16 times the upward force p (= P × D / 4) on the peripheral edge of the roof plate due to the internal pressure P of the tank, and this force Since the peripheral edge of the plate 2 is pulled upward and toward the center, the outer peripheral edge of the auxiliary detonation plate 5 is pulled deeply upward, and the roof plate 2 and the auxiliary detonation plate 5 are pulled together as shown in FIG. At the same time as the angle α between the
The seal welds 6 and 7 undergo a large amount of strain and breakage. In particular, the outer edge of the flange portion 3a and the detonation auxiliary plate 5 are joined by a seal weld that is smaller than the thickness of both plates to be welded and is open from the upper side to the lower side, so that the peripheral edge of the roof plate upward force p
The moment acts to bend the seal weld upward, and combined with the notch effect on the lower side (tension side) of the seal weld, it becomes easy to bend.
The rupture progresses steadily, and the explosion is carried out upwards from the rupture point. Therefore, the peripheral wall 1 is not destroyed, and the occurrence of a secondary disaster in which the flammable liquid in the tank leaks into the vicinity and causes a fire is prevented.

[Effect of idea]

As explained above, this device seal-welds and fixes the inner edge of the annular detonation auxiliary plate to the outer edge of the flange placed horizontally on the upper end of the peripheral wall, and the detonation The outer edge of the roof plate is sealed and fixed to or near the outer edge of the auxiliary plate, so even if the pressure inside the tank suddenly increases and an explosion occurs, the roof plate will not be damaged. The auxiliary detonation plate is rotated using the tensile force toward the center during the bulging deformation, and this causes a large bending moment to act on the seal welds on the inner and outer edges of the auxiliary detonation plate, causing distortion. However, this welded portion can be easily led to breakage, and the seal welded portion can be broken before the peripheral wall portion is destroyed, and the explosion can be emitted upward from this broken point.

In particular, since the detonation auxiliary plate is as thick as or thicker than the roof plate, when a large tensile force is applied to the roof plate and the detonation auxiliary plate is pulled upward, the detonation auxiliary plate may bend. Therefore, the tensile force of the roof plate is immediately transmitted to the seal weld on the inner peripheral edge of the detonation auxiliary plate, causing the weld to bend and leading to early rupture. Since the detonation auxiliary plate and the flange are sealed welded so that the lower side is open from the upper side as in the illustrated embodiment, it is easier to break due to bending, and reliable rupture can be achieved. These prevent the tank peripheral wall from being destroyed in the event of an explosion, and prevent the occurrence of a major secondary disaster due to the flammable liquid inside the tank spilling out.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the main part showing one embodiment of this invention, Fig. 2 is an explanatory diagram of the deformed state during the explosion, and Fig. 3 is equivalent to Fig. 1 showing another embodiment of this invention. Figure 4 is a schematic vertical sectional view showing an example of a tank to which this invention is applied, Figure 5 is a sectional view showing a conventional roof plate mounting structure, and Figure 6 shows the deformed state at the time of explosion. It is an explanatory diagram. 1... Peripheral wall part, 2... Roof plate, 3... Top angle, 3a... Flange part, 5... Auxiliary plate for explosion, 6, 7... Seal welding.

Claims (1)

[Scope of utility model registration request] The inner circumferential edge of the annular blasting auxiliary plate is butted against the outer edge of the flange formed in the horizontal direction at the upper end of the peripheral wall part established on the foundation, and the welding is performed with a thickness smaller than that of both plates. This explosion structure for a tank is characterized in that the lower side from the upper side is fixed by open seal welding, and the outer peripheral edge of a roof plate is fixed by seal welding to the outer peripheral edge of this auxiliary explosion plate or its vicinity.