JP2000064068A - Method and device for preventing corrosion in back face of bottom plate of flat bottom tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and economically prevent corrosion in the back face of a bottom plate by filling the gap part between a foundation part to be mounted with the bottom plate of a flat bottom tank and supporting it and the back face of the bottom plate with an inert gas from a gas feed tube while air is exhausted from plural gas exhaust tubes and holding it to a sealed state. SOLUTION: The peripheral part on the back side of the bottom plate 3 of an existing or new flat bottom tank is mounted with one or more gas feed tubes 31 and plural gas exhaust tubes 33 at suitable intervals. The gas feed tube 31 is connected to an inert gas feeding source 32 by a rubber hose 37, a stop valve 34 is opened to feed an inert gas such as dry nitrogen or the like, and, moreover, a stop valve 36 of the exhaust tubes 33 is opened to exhaust air at the inside. At the time when the inert gas is sufficiently substituted for the exhausted air, the stop valves 34 and 36 are closed. In this way, the gap part between at least the vicinity part of the back face of the bottom plate in the foundation part where the bottom place of the flat bottom tank is placed and supported and the back face of the bottom plate is filled with the inert gas, and it is held to a sealed state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottom plate back surface anticorrosion method for a flat bottom tank and an anticorrosion device therefor, and more particularly to a technique for anticorrosion using an inert gas.

2. Description of the Related Art A flat-bottomed cylindrical tank is widely used as a tank for storing liquids such as petroleum and water. For example,
A flat-bottomed cylindrical tank for storing petroleum (hereinafter referred to as an oil tank) is mainly composed of a bottom plate, a cylindrical side plate rising from the outer peripheral portion of the bottom plate, a floating roof body, and the like.

The tank foundation is a concrete foundation,
It has an oil sand layer piled up on this concrete foundation and an asphalt layer that hardens the surface of this oil sand layer, and an oil tank is constructed on the asphalt layer of this tank foundation, and the oil sand layer And the asphalt layer support the oil tank. As a sealing material to prevent the entry of rainwater etc. to the bottom plate back surface (bottom plate bottom surface) side of the oil tank, it covers the outer peripheral part of the annular plate which is a part of the bottom plate and the surface of the asphalt layer part on the outer peripheral side. An annular waterproof part formed by laminating a urethane resin film (or a silicon resin film) and a reinforcing fiber sheet is formed.

The bottom plate of the flat-bottomed cylindrical tank is constructed by welding and joining a large number of bottom plate materials to which anticorrosion coating has been applied in advance. The coating film is burned and easily corroded. In addition, there is a gap between the bottom plate and the base, and the moisture contained in the air that enters the gap and the base also condenses on the bottom of the bottom plate to cause corrosion. Conventionally, in relation to the capacity of an oil tank, it is necessary to emptied the inside thereof at regular intervals such as 5 years or 10 years and periodically inspecting it. At the time of this periodic inspection, it is usual to perform repairs such as partial replacement of the bottom plate on the portion of the bottom plate that is significantly corroded.

Conventionally, as the anticorrosion technology applied to the bottom plate of a new oil tank, etc., an anticorrosion method (galvanic anode method) in which a zinc plate or an aluminum plate is joined to the back surface of the bottom plate, and a tar epoxy resin or the like is applied to the back surface of the bottom plate. The coating film anticorrosion method is adopted. On the other hand, as an anticorrosion technology for the bottom plate of an existing oil tank, a paint injection method of injecting a resin-based paint to the back surface side of the bottom plate through a pipe arranged in advance in the foundation part, the above-mentioned cathodic protection method,
A coating film anticorrosion method and the like are known.

[0005]

[Problems to be Solved by the Invention] Among the anticorrosion technologies applied to the bottom plate of the new oil tank, etc., the electrocorrosion method requires a large amount of cost for the zinc plate or aluminum plate as the anode, which is disadvantageous in terms of equipment cost. However, if the zinc plate or aluminum plate is consumed, the anticorrosion function will be lost. In the coating film anticorrosion method using the tar epoxy resin or the like, the coating film in the vicinity of the welding line when the bottom plate is constructed burns down and the anticorrosion function deteriorates, and the cost of the paint and its coating work increases and There is a problem that the function deteriorates over the years.

On the other hand, among the anticorrosion techniques for the bottom plate of an existing oil tank, the paint injection method of injecting the resin-based paint on the back side of the bottom plate requires a large amount of resin-based paint, resulting in high cost. Further, when the above-mentioned cathodic protection method is adopted, a large amount of cost is required for the zinc plate and the aluminum plate, and since it is necessary to jack up the tank, the construction period becomes long and the construction cost becomes expensive. Further, in the coating film anticorrosion method, since it is necessary to jack up the tank as in the above, the construction period becomes long and the construction cost becomes expensive.

The object of the present invention is to apply a corrosion protection technology to the bottom plate of the flat bottom tank applicable to both new tanks and existing tanks, corrosion protection technology to the bottom surface of the bottom plate of the flat bottom tank which can be economically implemented with a simple facility, and is simple in a short construction period. Another object of the present invention is to provide a bottom plate rear surface anticorrosion technology for a flat bottom tank that can be implemented.

[0008]

A flat bottom tank bottom plate back surface anticorrosion method according to claim 1, wherein at least a base portion for mounting and supporting the bottom plate of the flat bottom tank is installed in order to prevent corrosion of a back surface of the bottom plate of the flat bottom tank. It is characterized in that the vicinity of the back surface of the bottom plate and the space facing the back surface of the bottom plate are filled with an inert gas and kept in a sealed state. Here, the flat bottom tank stores petroleum, water and various other liquids and gases.
It may be a heavy structure tank, a double structure tank with an inner tank for storing LNG or the like, or a rectangular tank for storing water or the like. As the inert gas,
Nitrogen gas, carbon dioxide gas, argon gas, or the like can be applied.

When at least a portion of the base portion for mounting and supporting the bottom plate of the flat-bottomed tank near the back surface of the bottom plate and a space facing the back surface of the bottom plate are filled with an inert gas and are kept sealed, the bottom plate of the flat-bottom tank is filled. Since the back surface hardly contacts the air, the bottom plate back surface can be surely protected from corrosion. In the case of a new flat-bottom tank, if a gas supply pipe for filling the inert gas and a gas exhaust pipe for degassing the air are installed when constructing the tank, the tank The inert gas can be easily filled at the time of completion of the above, and at a predetermined time interval after the start of use of the tank.

Further, in the case of an existing flat-bottomed tank, a gas supply pipe for filling an inert gas, a gas discharge pipe for evacuating air, etc. are temporarily installed at the time of inspection and repair of the tank. If it is provided, the inert gas can be easily filled at the completion of the inspection and repair of the tank and at the predetermined intervals thereafter.

Here, the inert gas may be charged at predetermined intervals (claim 2 dependent on claim 1). The base that supports the flat-bottom tank is not completely sealed, and the inert gas gradually leaks. Can be kept high for a long period of time and can be reliably protected against corrosion. You may use nitrogen gas as said inert gas (Claim 3 depending on Claim 1 or 2). Since nitrogen gas is inexpensive, the material cost for anticorrosion can be reduced and the cost for anticorrosion can be reduced.

The flat-bottom tank may be an existing tank (claim 4 dependent on any one of claims 1 to 3).
Even with an existing tank, the back side of the bottom plate of the tank can be filled with an inert gas by a relatively simple facility, and it is not necessary to jack up the tank for anticorrosion work.

The flat bottom tank may be a new tank (claim 5 dependent on any one of claims 1 to 3).
Even with an existing tank, the inert gas can be filled on the back side of the bottom plate of the tank with a relatively simple facility. In this case, when constructing the tank, it is desirable to permanently equip a gas supply pipe for filling an inert gas, a gas discharge pipe for degassing air, and the like. It is desirable to provide an opening / closing valve on the gas discharge pipe.

One or a plurality of gas supply pipes and a plurality of gas discharge pipes are mounted on the back surface side of the outer peripheral side portion of the bottom plate of the existing flat-bottomed tank, and the inert gas is filled from the gas supply pipes. Alternatively, the back surface side of the bottom plate may be filled with an inert gas through the exhaust of air from the gas exhaust pipe (claim 6 dependent on claim 4). In this case, in parallel with the filling of the inert gas, the air is sequentially discharged from the plurality of gas discharge pipes, whereby the back surface of the bottom plate can be almost uniformly filled with the inert gas.

According to a seventh aspect of the present invention, there is provided a bottom plate rear surface anticorrosion device for a flat bottom tank, wherein the bottom plate rear surface of the flat bottom tank is prevented from corroding. And a bottom plate of at least the bottom part of the base part, and a gas supply pipe for filling the space facing the back surface of the bottom plate with the inert gas, an inert gas supply source for supplying the inert gas to the gas supply pipe. One or a plurality of gas exhaust pipes for exhausting air from a space near the back surface and the bottom plate back surface, and an on-off valve attached to each of the gas exhaust pipes. is there. The flat bottom tank includes various tanks described in the section of claim 1.

An inert gas is fed from the inert gas supply source to the gas feed pipe, and the inert gas is supplied to at least a portion of the base portion on which the bottom plate of the flat-bottom tank is placed and supported in the vicinity of the bottom plate rear surface. While supplying the air to the void portion facing the bottom plate back surface, the air is discharged from at least a portion near the bottom plate back surface of the base portion and the void portion facing the bottom plate back surface from one or a plurality of gas discharge pipes, thereby the base portion. Of these, at least the vicinity of the bottom plate back surface and the gap facing the bottom plate back surface can be filled with the inert gas. The on-off valve mounted on each gas discharge pipe is opened only when air is discharged from the gas discharge pipe. The air can be discharged only from the gas discharge pipe with the open / close valve opened, and the air can be prevented from flowing backward from the gas discharge pipe after the inert gas is filled. Therefore, the back surface of the bottom plate of the flat-bottom tank can be protected from corrosion as in the first aspect.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example of a case where the present invention is applied to an existing oil storage tank, which is an oil storage tank for storing petroleum, which is a flat-bottomed cylindrical tank. As shown in FIG. 1, the oil storage tank 1 includes a bottom plate 3 installed on a base portion 2, and an annular plate 3 of the bottom plate 3.
It is mainly composed of a cylindrical side plate 4 rising from the vicinity of the outer periphery of a, a floating roof 5 floating above the stored petroleum, and the like.

As shown in FIGS. 1 and 3, the foundation portion 2 has an oil sand 11 stacked on a foundation concrete 10 to a predetermined thickness, and the surface portion of the oil sand 11 has a thickness of about 30.
The asphalt layer 12 of about mm is formed.
The annular waterproof 13 is for sealing the back surface of the bottom plate 3 of the oil storage tank 1 so as to prevent rainwater and the like from entering, and has, for example, a structure in which a reinforcing fiber sheet is incorporated between a urethane resin layer or a silicone resin layer. This annular waterproof 13 liquid-tightly covers the outer peripheral portion of the annular plate 3a and the portion of the asphalt layer 12 outside the outer peripheral portion.

In the oil storage tank 1, a tank bottom heater 20, a rotation stop pole 21, a weather shield 22,
The weir board 5a, the rainwater drainage pipe 23, the roof support 24, the rotating ladder 25, the staircase 26, the top deck 27, etc. are also provided. FIG. 2 is a schematic plan view of the bottom plate 3 including the annular plate 3 a and the bottom plate back surface anticorrosion device 30.
Is formed by welding and joining a number of bottom plate materials at the welding line 28.

Next, on the rear surface side of the bottom plate 2 of the oil storage tank 1,
A bottom plate back surface anticorrosion device 30 for anticorrosion by filling with an inert gas (dry nitrogen gas in this embodiment) will be described. As shown in FIGS. 2 to 4, this bottom plate back surface anticorrosion device 3
Reference numeral 0 denotes a gas feed pipe for filling an inert gas into at least a portion near the back surface of the bottom plate 3 of the base portion 2 on which the bottom plate 3 of the oil storage tank 1 is mounted and supported, and a gap facing the back surface of the bottom plate 3. 31, an inert gas supply source 32 (which includes a plurality of nitrogen gas cylinders) for supplying an inert gas to the gas supply pipe 31, and a portion of the base 2 near at least the back surface of the bottom plate 3. For example, 13 gas discharge pipes 33 (33a to 33g) arranged at proper intervals in the circumferential direction for discharging air from the gap facing the back surface of the bottom plate 3, and an on-off valve mounted on the gas supply pipe 31. 34, a fine pressure gauge 35 and an opening / closing valve 36, etc., which are respectively attached to the respective gas discharge pipes 33.

The gas supply pipe 31 and the gas discharge pipe 33
Are each made of, for example, a 10 mmφ stainless thin tube.
When the gas feed pipe 31 and the gas discharge pipe 33 are installed in the existing oil storage tank 1, the gas feed pipe 31 and the gas feed pipe 31 and the gas discharge pipe 33 are installed in the place where the asphalt layer 12 and the oil sand 11 of the foundation part 2 are partially removed. The discharge pipes 33 are inserted and sealed with a sealing material 13a made of urethane resin or silicon resin.
The gas supply pipe 31 is connected to an inert gas supply source 32 by a gas hose 37. The inert gas supply source 32 includes
A flow meter 38, a pressure adjusting regulator (not shown),
A pressure gauge 39a, a micro pressure gauge 39b and the like are provided. Then, at a position where the gas supply pipe 31 and the gas discharge pipe 33 are not installed, the deteriorated portion of the annular waterproof 13 is repaired to complete the sealing function of the annular waterproof 13.

Next, an anticorrosion method for anticorrosing the back surface of the bottom plate 3 using the above bottom plate back surface anticorrosion device 30 will be described.
First, the regulator for adjusting the pressure of the inert gas supply source 32 is adjusted to a predetermined low pressure (for example, 50 mmAq),
When supplying the pressure of the inert gas, it is possible to supply a predetermined low-pressure inert gas, and the 13 gas exhaust pipes 3
All the on-off valves 36 in 3 are closed. In addition, at least two oxygen concentration meters (not shown) are prepared in order to measure the oxygen concentration when degassing air from the gas exhaust pipe 33.

With the on-off valves 36 of all the gas discharge pipes 33 closed, all of the gas supply pipes 31 are gradually filled with an inert gas (for example, at a flow rate of 30 liters / min) while The fine pressure gauge 35 of the gas discharge pipe 33 is monitored, and whether or not the bulge of the bottom plate 3 occurs inside the oil storage tank 1 is monitored. Even if a predetermined time (for example, 2 hours) elapses, the pressure of the inert gas on the back surface side of the bottom plate 3 does not abnormally rise, and the bottom plate 3 does not rise or the like. With only the on-off valve 36 opened, the inert gas is continuously filled and air is degassed from the two gas discharge pipes 33a. The oxygen concentration of the gas discharged during the degassing is measured, and the degassing from the gas discharge pipe 33a is continued until the oxygen concentration drops to a predetermined value. During this time, the filling of the inert gas is continued.

When the oxygen concentration drops to a predetermined value, the on-off valves 36 of the two gas exhaust pipes 33a are closed, and then only the on-off valve 36 of the two gas exhaust pipes 33b is opened, and the two gas exhaust pipes are opened in the same manner as described above. The air is deaerated from 33b. The oxygen concentration of the gas discharged during the degassing is measured, and the degassing from the gas discharge pipe 33b is continued until the oxygen concentration drops to a predetermined value. The on-off valve 36 of the pipe 33b is closed. The above operation is performed in the same manner as described above up to the gas exhaust pipes 33c, 33d, 33e, 33f, 33g.

Thus, at least in the vicinity of the back surface of the bottom plate 3 of the base portion 2 and in the gap facing the back surface of the bottom plate 3,
Filling with inert gas (nitrogen gas), all gas exhaust pipe 3
The on-off valve 36 of No. 3 and the on-off valve 34 of the gas feed pipe 31 are closed to keep the inert gas in a sealed state. After performing the above-described inert gas filling, the gas feed pipe 31 and the gas discharge pipe 33
The exposed portion on the ground is removed and removed, and as shown in FIG. 5, a sealing plug 41 is screwed onto the elbow 40, and the surface side thereof is sealed with a sealing material 42.

The asphalt layer 12 on the surface of the base portion 2
The annular waterproof 13 is not a completely airtight structure, and the inert gas filling the back surface of the bottom plate 3 gradually leaks, so the above inert gas filling is performed every predetermined period (for example, one month). However, this predetermined period is appropriately set depending on the capacity of the oil storage tank, the airtightness of the foundation portion 2, and the airtightness of the asphalt layer 12 and the annular waterproofing 13.

In this way, the back surface of the bottom plate 3 of the oil storage tank 1 is always kept in a state of being filled with an inert gas so that air is unlikely to contact the back surface of the bottom plate 3 and the back surface of the bottom plate 3 is reliably prevented from corroding. You can With the bottom plate back surface anticorrosion device 30 having such a simple structure, the inert gas can be easily filled, so that the facility cost does not increase, and the inert gas is inexpensive, so the material cost is low. Is also cheaper,
The work of filling the inert gas can also be performed in a short period of time.

Correspondingly to a newly installed oil storage tank, corrosion can be easily and inexpensively performed in a short period of time in the same manner as in an existing oil storage tank. The inert gas can be repeatedly and repeatedly charged at low cost in a short period of time. By filling the inert gas every predetermined period, the concentration of the inert gas can be kept high for a long period of time, and the corrosion can be surely prevented. Since inexpensive nitrogen gas is used as the inert gas, it is possible to reduce the cost of materials for anticorrosion and reduce the cost of anticorrosion.

Here, an example in which the above embodiment is partially modified will be described. 1] When the present invention is applied to a newly installed oil storage tank 1 or other flat bottom tanks, various changes are made to the arrangement of the gas feed pipe 31 and the gas discharge pipe 33 of the base portion 2 and the bottom plate back surface anticorrosion device 30. be able to. For example, in order to improve the airtightness of the surface of the base portion 2, an airtight layer is formed on the surface of the base portion 2. This airtight layer may be composed of a higher density asphalt layer similar to the conventional asphalt layer 12, and one or more airtight films having excellent weather resistance are fixed to the bottom, middle layer and surface of the asphalt layer 12. Can also be formed.

Instead of the gas supply pipe 31, a gas supply pipe may be arranged as shown in FIG. 6, for example. That is, the bottom plate 3
The gas discharge pipe 51a is arranged in a substantially annular shape in the central portion near the back surface side, the gas discharge pipe 51b is arranged in a substantially annular shape outside thereof, and the gas discharge pipe 51c is arranged in a substantially annular shape outside thereof.
A large number of discharge holes for discharging an inert gas are formed at appropriate intervals in each of these gas discharge pipes 51a to 51c. The gas discharge pipe 51a is connected to the gas supply source 32 via a gas supply pipe 53a with an open / close valve 52, and the gas discharge pipe 51b is connected via a gas supply pipe 53b with an open / close valve 52 to the gas supply source 3
2, the gas discharge pipe 51c is connected to the gas supply source 32 via a gas supply pipe 53c with an on-off valve 52. still,
The gas exhaust pipe 33 is the same as that of the above embodiment.

When the inert gas is filled, the open / close valves 36 of all the gas discharge pipes 33 are kept open, and the inert gas is first discharged from the gas discharge pipe 51a for a predetermined time.
Next, the inert gas is discharged from the gas discharge pipes 51a, 51b for a predetermined time, and then the gas discharge pipes 51a, 51b, 51 are discharged.
Inert gas is discharged from c for a predetermined time. afterwards,
All the on-off valves 36 and 52 are closed, and the back surface of the bottom plate 3 is kept filled with an inert gas. In this way, the gas discharge pipes 51a to 51c are uniformly arranged in the entire area on the back surface side of the bottom plate 3 and filled with the inert gas as described above, so that the back surface side of the bottom plate 3 is uniformly filled with the inert gas. Can be filled.
The arrangement of the gas discharge pipes is not limited to the above arrangement, but it is desirable that the bottom surface of the bottom plate 3 be uniformly filled with the inert gas.

2] The gas supply source is not limited to the cylinder, but an inert gas storage tank and a piping system connected to this tank may be applied, or an inert gas storage tank or an inert gas may be used. A permanent piping system extending from the source may be applied. As the inert gas, in addition to nitrogen gas,
Carbon dioxide gas, argon gas, etc. can be applied. Further, it goes without saying that the present invention can be applied to flat-bottomed tanks of various structures for various purposes other than the oil storage tank. In addition, it goes without saying that various modifications can be made to the embodiment without departing from the spirit of the invention.

[0033]

According to the first aspect of the present invention, an inert gas is filled in at least a portion of the base portion for mounting and supporting the bottom plate of the flat-bottomed tank, which is near the bottom plate rear surface and the space facing the bottom plate rear surface. Since the back surface of the bottom plate of the flat-bottomed tank is hardly contacted with the air because it is kept in the sealed state, the back surface of the bottom plate can be reliably protected from corrosion. Moreover, since the inert gas can be easily filled with a simple facility, the facility cost does not increase. Further, since the inert gas is inexpensive, the material cost is low, and the work of filling the inert gas can be done in a short period of time.

Almost the same as the existing flat-bottom tank, corrosion protection can be performed easily and inexpensively in a short period of time, and the pipes for filling the inert gas can be installed once. By doing so, the inert gas can be repeatedly charged easily and inexpensively in a short period of time.

According to the second aspect of the present invention, the inert gas is filled every predetermined period, so that the concentration of the inert gas can be kept high for a long period of time, and the corrosion can be surely prevented. In addition, the same effect as that of the first aspect is provided.

According to the third aspect of the invention, since inexpensive nitrogen gas is used as the inert gas, the material cost for anticorrosion can be reduced and the cost of anticorrosion can be reduced. Other effects similar to those of claim 1 or 2 are achieved.

According to the invention of claim 4, even if the flat bottom tank is an existing tank, the back side of the bottom plate of the tank can be filled with an inert gas by a relatively simple facility, and anticorrosion work can be performed. Therefore, there is no need to jack up the tank. In addition, the same effect as that of any one of claims 1 to 3 is achieved.

According to the fifth aspect of the present invention, even if the flat bottom tank is a new tank, the inert gas can be filled on the back side of the bottom plate of the tank with a relatively simple facility. In particular, when constructing this tank, if a gas supply pipe for filling inert gas and a gas exhaust pipe for degassing air are permanently equipped, it is necessary to use the tank at the time of tank completion or when the tank is used. It is possible to simply and inexpensively fill the inert gas at every predetermined period after the start. In addition, the same effect as that of any one of claims 1 to 3 is achieved.

According to the invention of claim 6, one or a plurality of gas supply pipes and a plurality of gas discharge pipes are attached to the back surface side of the outer peripheral side portion of the bottom plate of the existing flat-bottomed tank to install the gas supply pipes. The back side of the bottom plate is filled with an inert gas through the filling of the inert gas from the supply pipe and the discharge of the air from the gas discharge pipe. By sequentially discharging the air from the gas discharge pipe, the back surface of the bottom plate can be almost uniformly filled with the inert gas. In addition, the same effect as in claim 4 is obtained.

According to the invention of claim 7, a gas feed pipe for filling an inert gas, an inert gas supply source, one or a plurality of gas discharge pipes, and each gas discharge pipe are attached. By using a device having a simple structure equipped with an open / close valve, an inert gas is filled in at least the vicinity of the bottom plate rear surface and the void facing the bottom plate rear surface of the base portion for mounting and supporting the bottom plate of the flat bottom tank. Therefore, the same anticorrosion effect as in claim 1 can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram of an oil storage tank according to an embodiment of the present invention (left half is a front view, right half is a vertical sectional view).

FIG. 2 is a schematic plan view of a bottom plate of the oil storage tank and a bottom plate back surface anticorrosion device.

FIG. 3 is a front view of a main part of an oil storage tank and a gas supply pipe.

FIG. 4 is a front view of a main part of an oil storage tank and a gas discharge pipe.

FIG. 5 is a diagram showing a sealed state of a gas supply pipe and a gas discharge pipe after gas filling.

FIG. 6 is a view corresponding to FIG. 2 according to a modified example.

[Explanation of symbols]

1 oil storage tank 2 foundation 3 bottom plate 30 Bottom plate backside anticorrosion device 31 gas supply pipe 32 Inert gas supply source 33 gas exhaust pipe 36 open / close valve 51a to 51c Gas discharge pipe 53a to 53c Gas supply pipe

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[Procedure amendment]

[Submission date] August 23, 1999 (1999.8.2
3)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

A flat bottom tank bottom plate back surface anticorrosion method according to claim 1, wherein the bottom plate back surface of the flat bottom tank is prevented from corroding.
One or more gas supply pipes and multiple gas discharge pipes on the side
Install the gas while filling it with an inert gas from the gas supply pipe.
The air is discharged from the discharge pipe , and at least the vicinity of the back surface of the bottom plate and the voids facing the back surface of the bottom plate of the base plate for mounting and supporting the bottom plate of the flat bottom tank are filled with an inert gas to maintain the sealed state. It is a feature. Here, the flat-bottom tank may be a single-layer tank for storing petroleum, water, various other liquids or gases, or a double-layer tank with an inner tank for storing LNG or the like. It may be a rectangular tank for storing water, etc. As the inert gas, nitrogen gas, carbon dioxide gas, argon gas, or the like can be applied.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

When at least a portion of the base portion for mounting and supporting the bottom plate of the flat-bottomed tank near the back surface of the bottom plate and a space facing the back surface of the bottom plate are filled with an inert gas and are kept sealed, the bottom plate of the flat-bottom tank is filled. Since the back surface hardly contacts the air, the bottom plate back surface can be surely protected from corrosion. here
Then, send one or more gas to the back side of the bottom plate of the flat bottom tank.
Install the gas supply pipe and multiple gas discharge pipes
Eject air from the gas exhaust pipe while filling with active gas
Since it is filled with an inert gas, it is almost uniform on the back side of the bottom plate.
Can be filled with an inert gas. In the case of a new flat-bottom tank, if a gas supply pipe for filling the inert gas and a gas exhaust pipe for degassing the air are installed when constructing the tank, the tank The inert gas can be easily filled at the time of completion of the above, and at a predetermined time interval after the start of use of the tank.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Delete

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

According to a sixth aspect of the present invention, there is provided a bottom plate rear surface anticorrosion device for a flat bottom tank, wherein the bottom plate rear surface of the flat bottom tank is prevented from corroding. And a bottom plate of at least the bottom part of the base part, and a gas supply pipe for filling the space facing the back surface of the bottom plate with the inert gas, an inert gas supply source for supplying the inert gas to the gas supply pipe. it is characterized in that it comprises a multiple gas discharge pipe for discharging air from the gap portion facing the portion near the bottom plate back surface of the back surface, and each loaded closing valve to the each gas exhaust pipe . The flat bottom tank includes various tanks described in the section of claim 1.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

An inert gas is fed from the inert gas supply source to the gas feed pipe, and the inert gas is supplied to at least a portion of the base portion on which the bottom plate of the flat-bottom tank is placed and supported in the vicinity of the bottom plate rear surface. while feeding the air gap which faces the bottom plate rear surface, by discharging the air from at least the bottom plate rear surface void portions facing the vicinity of the bottom plate back surface of one of said base portion through a gas discharge line of multiple, of the base portion At least a portion near the bottom plate back surface and a space facing the bottom plate back surface can be filled with an inert gas. The on-off valve mounted on each gas discharge pipe is opened only when air is discharged from the gas discharge pipe. The air can be discharged only from the gas discharge pipe with the open / close valve opened, and the air can be prevented from flowing backward from the gas discharge pipe after the inert gas is filled. Therefore, the back surface of the bottom plate of the flat-bottom tank can be protected from corrosion as in the first aspect.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

According to the first aspect of the present invention, an inert gas is filled in at least a portion of the base portion for mounting and supporting the bottom plate of the flat-bottomed tank, which is near the bottom plate rear surface and the space facing the bottom plate rear surface. Since the back surface of the bottom plate of the flat-bottomed tank is hardly contacted with the air because it is kept in the sealed state, the back surface of the bottom plate can be reliably protected from corrosion. And behind the bottom plate of the flat bottom tank
One or more gas supply pipes and multiple gas discharge pipes on the surface side
The gas supply pipe, and fill it with inert gas.
Exhaust the air from the exhaust pipe and fill it with an inert gas.
The bottom surface of the bottom plate can be filled with an inert gas almost uniformly.
You can Moreover, the inert gas may be filled in one or more
Since it can be easily performed with simple equipment such as the gas supply pipe and a plurality of gas discharge pipes , the equipment cost does not become expensive. Further, since the inert gas is inexpensive, the material cost is low, and the work of filling the inert gas can be done in a short period of time.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Delete

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

According to the invention of claim 6, and a gas feed pipe for filling the inert gas, and an inert gas supply source, and the gas discharge tube several, each mounted to the each gas exhaust pipe By using a device having a simple structure including the open / close valve, it is possible to fill an inert gas into at least a portion near the back surface of the bottom plate and a space facing the back surface of the bottom plate of the base part for mounting and supporting the bottom plate of the flat bottom tank. Therefore, the same anticorrosion effect as that of claim 1 can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoru Noboto             3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture             Kansai Electric Power Co., Inc. (72) Inventor Hiroshi Itaya             8th Niijima, Harima-cho, Kako-gun, Hyogo Prefecture Kawasaki Heavy Industries             Harima factory (72) Inventor Mitsuhiro Miyazaki             8th Niijima, Harima-cho, Kako-gun, Hyogo Prefecture Kawasaki Heavy Industries             Harima factory F-term (reference) 3E070 AA03 AB02 AB03 BA10 BB02                       DA01 QA04                 3E073 AA01 AB02 BA21                 4K062 AA03 BA01 FA02 FA18 GA10

Claims (7)

[Claims] 1. In order to prevent corrosion of the bottom surface of the bottom plate of the flat-bottomed tank, at least a portion of the base portion on which the bottom plate of the flat-bottom tank is placed and supported is inactive at least in the vicinity of the bottom plate back surface and in the space facing the bottom plate back surface. A method for preventing corrosion from the back surface of a bottom plate of a flat bottom tank, which is characterized by filling gas and maintaining the sealed state. 2. The flat bottom tank bottom plate back surface anticorrosion method according to claim 1, wherein the inert gas is charged at predetermined intervals. 3. The flat bottom tank bottom plate back surface anticorrosion method according to claim 1, wherein nitrogen gas is used as the inert gas. 4. The flat bottom tank bottom plate rear surface anticorrosion method according to claim 1, wherein the flat bottom tank is an existing tank. 5. The flat bottom tank bottom plate rear surface anticorrosion method according to claim 1, wherein the flat bottom tank is a newly installed tank. 6. An inert gas from the gas supply pipe, wherein one or a plurality of gas supply pipes and a plurality of gas discharge pipes are attached to the back surface side of the outer peripheral side portion of the bottom plate of the existing flat bottom tank. 5. The flat bottom tank bottom plate back surface anticorrosion method according to claim 4, wherein the back surface side of the bottom plate is filled with an inert gas through the filling of (1) and the discharge of air from the gas discharge pipe. 7. A device for preventing corrosion of a bottom plate rear surface of a flat bottom tank, wherein an inert gas is present in at least a portion of a base portion on which the bottom plate of the flat bottom tank is mounted and supported, and a space facing the bottom plate rear surface. A gas feed pipe for filling the gas feed pipe, an inert gas supply source for feeding an inert gas to the gas feed pipe, and a void portion facing at least the bottom plate rear surface of the base portion and the bottom plate back surface. A bottom plate back surface anticorrosion device for a flat bottom tank, comprising: one or a plurality of gas discharge pipes for discharging air from the tank; and an on-off valve attached to each of the gas discharge pipes.