JPS5828187B2 - Liquid storage tank with inner bottom surface coated - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid storage tank in which the inner surfaces of a bottom plate and a lower side plate (hereinafter referred to as the bottom) are coated with a thin film.

In general, liquid storage tanks are not subjected to internal corrosion protection treatment except when storing specific chemicals, and are designed by taking the corrosion rate into consideration as a coefficient for determining plate thickness.

However, if there is a welding defect at the bottom corner,
This causes leakage accidents and poses a serious problem in terms of pollution prevention.

In other words, the cause of the leakage accident of stored liquid is that a very small primary crack occurs in a corner weld due to an earthquake or other cause, and a small amount of liquid leaks from that part and seeps into the storage tank foundation. Gradually, the ground supporting the bottom plate of the storage tank turns into a slurry and loses its supporting force, and as a result, when the corner becomes unable to withstand the head pressure of the stored liquid, it sinks all at once, causing a large tear in the storage tank. It is believed that a second major leak will occur instantaneously.

In order to prevent such accidents, the Fire Service Act was revised in 1976, making it mandatory for petroleum storage tanks of 4 out of every 10,000 or more to undergo periodic inspections every five years.

However, a large amount of oily sludge (sludge-like material) accumulates at the bottom of the tank over the course of five years, and this oily sludge must be removed for inspection, which is extremely difficult.

The current common method for removing oily sludge is to heat and circulate medium oil in a storage tank to dissolve or soften the sludge and discharge it outside the tank, and then clean the bottom using input. It is.

However, this method increases the volume of sludge to be treated by adding medium-dense oil, requires difficult waste oil treatment work, and also requires a large number of workers to be placed in the oily air that accumulates in the storage tank. This requires many days of work and reduces the operating rate of the storage tank.

In order to solve the above-mentioned problems, the present invention covers only the bottom of a liquid storage tank in which the entire inside of the tank is not subjected to anti-corrosion treatment with a thin synthetic resin film, etc., and by peeling off the thin film, the inner surface of the bottom can be easily cleaned. This enables inspection of

Embodiments of the present invention will be described below with reference to the drawings.

In the vertical cross-sectional view of FIG. 1, 1 is a bottom plate of the storage tank, 2 is a side plate, and 3 is a thin film made of synthetic rubber, synthetic resin, etc., and has extensibility, chemical resistance, etc.

In this example, three thin films are laminated, and each thin film has three layers.
is adhered to the lower part of the side plate 2 with an adhesive by sequentially shifting its peripheral edge in a liquid-tight manner.

3a, 3b, and 3c indicate the bonded portions.

Each thin film does not need to be a single piece, but only needs to be completely joined together, and the bent portions should have sufficient flare.

One type of thin film may be used, but it is also effective to combine several types by taking advantage of their characteristics, and the number is not limited to three, but may be one, two, or four or more. FIG. 2 shows an example of construction for a storage tank having a center pole 4.

The coating thin film covers the center pole 4 in close contact with the center pole 4 up to an appropriate height, and the periphery of the pedestal 5 is sufficiently flared to provide a margin to accommodate the deformation of the bottom plate 1.

Figure 3 shows an embodiment in which inspection holes are provided to detect liquid leakage between the coating thin films, and there are several small holes 6 around the bottom of the side plate.
A hole is drilled through the hole, and a plug 8 is screwed into the hole so that it can be opened and closed.

A thin tube 7 connected to the pore 6 is inserted between each coating thin film, and the plug 8 is pulled out at an appropriate time to check whether oil leaks from each layer.

Of course, the portion where the thin tube 7 penetrates the thin film is subjected to liquid-tight treatment.

The liquid storage tank of the present invention prevents the expansion of initial cracks at corners regardless of the presence or absence of anti-corrosion treatment on the inner surface, and even if initial cracks occur, cracks may occur due to subsidence of the bottom plate due to slurry formation of the ground due to shallow depth. It is possible to prevent the cracks from expanding and to make the cracks easily discoverable through periodic inspections, thereby preventing large-scale leakage accidents from occurring.

In addition, when inspecting the bottom of the storage tank, referring to the above embodiment, after the stored liquid is extracted, the sludge is pumped out to the extent possible, the first layer of the thin film is gradually peeled off, the sludge is collected, and the pump is pumped. The sludge spilled during the peeling operation of the first layer is removed by peeling off the second layer, and until the third layer is peeled off, the bottom of the storage tank is exposed, which is completely uncontaminated.

Therefore, there is no need for workers to clean with rags, etc., and inspection becomes easier, so a complete inspection can be carried out in a short time, without reducing the operation rate of the storage tank, and is effective in preventing pollution and saving labor. The effect is also strong.

Even when only one layer of thin film is provided, the effect of rapidly removing sludge from the inner surface of the bottom is extremely large compared to conventional methods.

[Brief explanation of the drawing]

Fig. 1 is a half longitudinal cross-sectional view of a storage tank showing an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of a storage tank showing another embodiment, and Fig. 3 is an enlarged longitudinal cross-sectional view of the vicinity of the leak inspection day. be. 1...Bottom plate, 2...Side plate, 3...
...Thin film, 3a. 3b, 3c---adhesion part, 4---center pole, 5---cradle, 6---pore,
7... Thin tube, 8... Plug.

Claims (1)

[Scope of Claims] 1. The entire surface of the upper surface of the bottom plate 1 and the lower inner surface of the side plate 2 is coated with a flexible thin film having extensibility and chemical resistance in a state where it can be easily peeled off, and the edge of the thin film is covered with the side plate 2. A liquid storage tank whose bottom inner surface is coated, characterized in that it is liquid-tightly adhered to the inner surface of the tank. 2 Covering the entire surface of the upper surface of the bottom plate 1 and the lower inner surface of the side plate 2 with a plurality of flexible thin films having extensibility and chemical resistance in a state where each layer can be easily peeled off, and the peripheral edge of the coating thin film is A liquid storage tank whose bottom inner surface is coated, characterized in that the inner surface of the bottom is coated in a layered manner by sequentially sliding it onto the side plate 2 and directly adhering it. 3 The entire surface of the upper surface of the bottom plate 1 and the lower inner surface of the side plate 2 is coated with a plurality of flexible thin films having extensibility and chemical resistance in a state where each layer can be easily peeled off, and the peripheral edge of the coating thin film is Laminated coating is applied by directly adhering to the side plate 2 in a sequentially shifted manner, and a thin tube is inserted between the laminated coating thin films, and a plug is used to freely open and close communication with the outside of the side plate to cover the inner surface of the bottom part, which makes it possible to detect liquid leakage. liquid storage tank.