JPS6333294A - Method of machining manhole of underground tank for storing dangerous substance - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Application The present application relates to a method for installing a manhole in a tank buried underground at a gas station or the like for storing dangerous substances such as petroleum.

(b) Conventional technology There are approximately 50,000 gas service stations across the country, each of which has three to four underground tanks. The majority of these tanks are of the type that does not have manholes installed, and those that are old and have the risk of forming holes, or those that are at risk of forming holes, are subject to internal inspection using Fiber Scope 7.
” etc.

(c) Problems However, sludge such as iron rust and viscous insoluble matter is deposited at the bottom of the tank, and it is necessary to scrape through this while inspecting. However, in tanks without manholes, there was a problem in that a tool for scraping the sludge could not be inserted into the tank, making it impossible to perform a sufficient inspection simply by visually inspecting the sludge using a fiberscope.

(B) Structure This application describes a method for safely additionally installing a manhole/I/ at a buried location in an existing tank where flammable hazardous materials were stored. ,
The process involves drilling a hole in the top of the tank where the manhole is to be installed, connecting a discharge pipe to the hole to allow the nonflammable fluid in the tank to overflow from the discharge pipe, and welding the body of the manhole to the tank, and closing the hole. This process consists of a step of inspecting the airtightness or liquidtightness of the space created by covering the manhole, and a step of cutting off the top of the tank inside the manhole.

(E) Example (2) is a cylindrical horizontal underground tank buried in the earthen floor (4) of a gas station, with a suction pipe (8) connected to the gas tank (6), and the inside of the tank exposed to the atmosphere at a high place. Ventilation pipe GO for communication.

Oil supply pipe QΦ extending into the pit (A) and measuring rod (not shown)
is connected to the metering tube 0e into which is inserted.

To administer moxibustion using the method according to the present invention, if there is oil remaining in the tank (2), which is a dangerous substance, first
) or by hanging a hose etc. from the oil supply pipe a4 or metering pipe aQ.

Then, fill the tank (2) with λ and non-flammable fluid using the ninth port (in this case, use the lubrication pipe (B)) to inject non-flammable fluid into the tank.
) to confirm that the inside is full (in this case, the measuring tube a.
Seal the open end of the other tube with a blind lid (T) and a wick.

After confirming that the tank is filled with nonflammable fluid,
Alternatively, in parallel with the above work, as shown in Figure 2, dig a hole (A) in the dirt floor where the manhole will be installed and install a barrier (2). At the top of this barrier, oil vapor (heavier than air) is leaking through a hole (
2) has a sufficient height to protrude from the earthen floor (4) to prevent oil from flowing into the soil, and there are joints to prevent oil that may have soaked into the soil from seeping into the ankan. are all sealed.

(E) is a waterproof and oil-resistant putty that prevents oil and water from seeping out from the soil below.

In this way, flammable and dangerous oil and oil vapor are prevented from entering the space (to) created by the barrier (goods), the putty (o), and the top of the tank (2), and the blower into the space (e) is prevented. After confirming the absence of oil or oil vapor in this space by blowing air with a gas detector, etc.,
A small hole (1) is drilled in the top f of the tank using a drill (not shown).

At this time, water is poured into the blade of the drilling machine or until the top of the tank is covered to prevent the temperature of the drilling part or the drilling machine from rising.In addition, the upper opening (to) of the barrier (c) is covered with Punto ■ to the space @. A nonflammable gas such as carbon dioxide or nitrogen gas is filled in to increase safety, and a perforated explosion-proof type is desirable.For example, if it is electrically driven, it is desirable to have a pressure-resistant explosion-proof type, and if it is an air-driven type, it is preferable. Even better.

Once the drilling is complete, thread the small hole (to) and connect a hose to it to allow the nonflammable fluid in the tank (2) to overflow. This is done to remove any air bubbles caused by oil or oil vapor remaining on the top of the inner surface of the tank where the manhole is to be machined, and to continue overflowing while the welding described later is being performed. is desirable.

Furthermore, when the nonflammable fluid is water, the tip of the hose (7) may be connected to an oil-water separation tank.

In this state, the lower edge of the body of the manhoe/L/(to) and the tank (2) are connected by welding the entire circumference. During these operations, safety can be ensured by filling the space (c) with nonflammable gas.

The installation of the manhole (to) to the tank (2) has been completed so far, so next, as shown in Figure 3, close the small hole with a blind stopper (6), and install the manhole (to) to the tank (2). 7 Cover the lunge with a lid and apply air or hydraulic pressure to the space to confirm that there are no leaks from the welded part. The reason why the small hole (to) is closed at this time is that it is better to inspect only the inside of the space to reduce measurement errors due to the influence of underground temperature and to shorten the inspection time. The ring is a gauge for confirmation, and the ring is a shutoff valve.

If there is no leakage from the welded part, the tank shown in Figure 4 (2)
) Now move on to cutting and removing the top part.

In Fig. 4, - is a rotary plate, which is made rotatable along the circumferential guide groove formed in the 7-ram leg of the cutting machine, which is fixed to the 7-lunge. There is a vertical column (2) with screws machined on the outer circumferential ring of the upper half. The ring is a gear formed around a rotating plate, and the ring is a frame)
The chuck Q3 at the tip of the rotating shaft has cutting teeth (7
A cutter 174 with a → is attached,
The large diameter portion I7 of the cutter QfJ passes through the rotary sheet metal and is slidably and rotatably inserted into the fixed tertiary guide pipe (e). (a) is a spring that urges the slide upward, the ring is a rotary handle that moves the slide 17'4 in the vertical direction, and the ring is a hand ρ for fixing the slide @.

To cut off the top of the tank (2) with this cutting machine, first rotate the motor 170 and operate the hand μ (b).
The tooth Q4 is inserted into the tank (2) by penetrating it to the position shown in the figure. Then, with the hand/I' (c) fixed on the slide (i.e., the position (height) of the gums) and motor 4 rotating, rotate the motor wheel to move the rotary plate. Rotate horizontally.

Then, the tooth Q4 will cut out the top of the tank closest to the body (6) in a circular shape along the inner circumference of the body (6).After this work is completed, remove the frame fi6' and attach the closure lid to the flange ■. n is good.

In FIG. 4, the space (goods) is filled with nonflammable fluid for safety, and the motors M and 90 are both explosion-proof.

Although the structure is as described above, welding between the tank (2) and the body part may be performed not only from the inside but also from the outside.
If only from the inside, it is a good idea to fill the outside with anti-corrosion putty. In addition, the nonflammable fluid is not limited to water, but may also be fire extinguishing foam, etc. The method of cutting off the top of the tank is to fill it with water and cut it underwater with a gas torch or the like. I can do this.

(f) Effects As described above, if the processing method of the present invention is adopted, it is possible to safely install a manhole even in a tank where flammable hazardous materials are stored. This makes it possible to carry out thorough inspections.

[Brief explanation of drawings]

Figure 1 shows the condition of a tank buried underground, and Figure 2.3.
Figure 4 shows the conditions during manhole welding, airtight inspection, and tank top cut-off.

Claims (1)

[Claims] A process of injecting nonflammable fluid into a tank buried underground, a process of drilling a hole at the top of the tank at the location where the manhole is installed,
The process of connecting a discharge pipe to the perforation and allowing the non-flammable fluid in the tank to overflow from the discharge pipe, and welding the body of the manhole to the tank, and sealing the space created by closing the perforation and covering the manhole. Alternatively, a method for manufacturing a manhole in an underground tank for storing hazardous materials, which consists of a process of inspecting liquid tightness and a process of cutting off the top of the tank inside the manhole.