JPS60252090A - Method of fire-preventive repair in oil tank - Google Patents

Abstract

PURPOSE:To easily and surely take fire-preventive measures for repair in an oil tank, by coating the surface of oil sludge in the tank with a viscous aqeous solution containing a surface active agent. CONSTITUTION:After oil in an oil tank is all conveyed out thereof, a viscous aqueous solution 11 containing a surface active agent is applied by a spray gun 12 to the surface of oil sludge 10 residual in the tank. To prepare the aqueous solution, about 0.5% of the surface active agent such as a polyethylene glycol fatty acid sodium compound and a sodium dodecylbenzenesulfonate is added to an aqueous solution contaning 1% of a high-molecular coagulant such as a polyacrylamide and an acrylic polymer. The oil sludge 10 is coated with the aqueous solution 11. Fire-preventive measures for repair in the oil tank are thus taken easily and surely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for repair work inside oil tanks of tankers, etc., and particularly improves the work efficiency and improves the safety of hot work such as cutting and welding. This invention relates to a method for fireproof repair work inside an oil tank.

[Conventional technology]

Conventionally, when repairing tanker oil tanks, even if all the oil is removed from the tank, flammable oily sludge remains on the tank's inner wall, so repair work that involves hot work such as cutting and welding has not been done. Before proceeding, such oily sludge must be removed to ensure safety.

For this reason, conventionally, repair work inside tanker oil tanks was
This is done by the following means:

First, after all the oil in the oil tank formed below the deck is removed using a cargo pump, the oily sludge adhering to the side walls and side wall reinforcement materials around the repair area in the oil tank is removed using a tank cleaning machine (swivel type). The flammable gas in the oil tank is removed using a ventilation fan.

Then, a large number of workers entered the oil tank and used shovels or other tools to remove the oily sludge that had accumulated on the side wall reinforcements and the bottom of the tank in areas where there was a risk of scattering sparks from cutting or welding around the repair area. The oily sludge is collected and placed in a container, and the container is lifted onto the deck using an air winch, etc., and the oily sludge is carried out of the tank.

After ensuring the safety of the area around the repair area from fire in this way, repair work inside the oil tank can be carried out.

[Problem that the invention seeks to solve]

However, with conventional repair work methods like this, it takes a lot of manpower and time to remove oily sludge from around the repaired area in the oil tank, resulting in a long construction period and high construction costs. There is a problem with this.

The present invention aims to solve these problems, and makes it possible to perform repair work inside an oil tank efficiently, and to improve the safety of hot work.
The purpose of this invention is to provide a method for fire-proof repair work inside oil tanks.

[Means for solving problems]

For this reason, in the fireproof repair work method for an oil tank of the present invention, when repair work is performed inside an oil tank, the surface of the oily sludge in the oil tank is coated in advance with a viscous aqueous solution containing a surfactant. The system is characterized in that the repair work inside the oil tank is then carried out.

[For production]

According to the above-described fireproof repair work method for an oil tank of the present invention, during construction, the surface of the oily sludge in the spoiled oil tank is coated with a viscous aqueous solution containing a surfactant that has good adhesion to the oily sludge. Because the oil tank is covered, even if sparks fall during work such as welding inside the oil tank, there is no risk of a serious disaster due to a fire.

〔Example〕

Hereinafter, a fireproof repair method for an oil tank as an embodiment of the present invention will be explained with reference to drawings, taking an oil tank of a tanker as an example. Reinforcing materials 4 and 5 are welded to the side wall 2 and tank bottom 3, respectively, and manholes 7 are formed in the ceiling (upper deck) 6 of the tank 1, and some of the manholes 7 have ventilation holes 77 and 8. Ready to be installed.

A work scaffold 9 is erected around the repair area A in the tank 1, and a spray gun 12 applies a coating liquid 11 as a dry viscous aqueous solution containing a surfactant to the surface of the oily sludge 10.
The work tool 13 that sprays water with a spray gun, and the work tool 15 that performs repair work such as cutting and welding with a tool 14 such as a welding torch can enter from the manhole 7 into the vicinity of the repair point A in the tank 1. There is.

Further, a coating liquid tank 16 and an airless pump 17 are installed on the upper deck 6, and a spray gun 12 held by a working tool 13 in the tank 1 is connected through a coating liquid transfer hose 18.
A tool 14 carried by a working tool 15 that performs repair work is connected to a power source (not shown) outside the tank 1 by a cabtyre cord 19.

The coating liquid 11 as a viscous aqueous solution containing a surfactant used in the fire prevention repair method of the present invention is an aqueous solution in which a surfactant is added to an organic compound such as a polymer flocculant.

Polyacrylamide polymer is used as a polymer flocculant.

An aqueous solution of acrylic polymer, water-soluble anionic polymer, carboxylmethyl cellulose, etc. having a concentration of about 1% or less is used.

In addition, as surfactants to be added, polyethylene glycol fatty acid soda, dodecylbenzenesulfonic acid sodium, polyoxyethylene 7ylphenol ether, etc. are used, and these are added to the aqueous solution at a concentration of about 0.5% or less. be done.

Since the coating liquid 11 prepared in this manner has fluidity, it can be applied to the surface of the oil-based sludge 10 or sprayed with a spray gun 12 to coat the surface of the oil-based sludge 10.

Furthermore, since it is viscous, it can completely coat the uneven surface of the oily sludge 10, and can also coat oily sludge (not shown) attached to vertical surfaces such as walls in the oil tank.

Furthermore, since a surfactant is added, the adhesion to the oily sludge 10 increases.

Note that when the surface of the oil-based sludge 10 is coated, the coating liquid 11 may contain at least one of a coloring agent, a fluorescent agent, and a luminescent agent in order to improve the visibility of the covered area.

Then, the coating liquid 11 coated on the surface of the oil-based sludge 10
It has fire resistance against the high-temperature cut pieces and sparks that scatter and try to sprinkle on the oily sludge (10) as a result of cutting or welding the repaired area, and it also has the following properties (a) to (t). Fireproof.

(A) By covering the oily sludge 10 and shielding it from the outside air, generation of flammable gas from the oily sludge 10 is suppressed, and the concentration of flammable gas in the atmosphere is reduced.

(b) Captures and cools cut pieces and sparks that fall during work, making them nonflammable.

(1) Moisture in the liquid evaporates due to the falling pieces and sparks, becoming water vapor. When vaporizing, heat is taken away from the pieces and sparks, and the concentration of water vapor in the atmosphere is increased, making it non-flammable.

Repair work inside an oil tank using the coating liquid 11 as a viscous aqueous solution containing a surfactant as described above is carried out in the following steps (1) to (4).

(1) After all oil is removed from the oil tank 1 using a cargo pump or the like, the side wall 2 and side wall reinforcing material 4 inside the oil tank 1 are cleaned using a tank cleaning machine (not shown). Then, the oily sludge (not shown) adhering to the sidewall 2 is washed off, and oily sludge () 10 accumulates on the tank bottom 3 and the sidewall reinforcing material 4. In addition, in order to promote the peeling of the oily sludge adhering to the side wall 2 at this time, cleaning with hot water containing a surfactant is desirable.

(2) A ventilation 7 amp 8 is attached to a manhole 7 formed in the upper deck 6 as the ceiling of the oil tank 1 and activated, and the flammable gas remaining in the oil tank 1 is discharged to the outside of the tank.

(3) After confirming that the flammable gas concentration in oil tank 1 is low enough to pose no risk of explosion, and that the oxygen concentration is high enough to allow workers to perform the work, work will be carried out around repair area A in tank 1. A working tool 13 enters the tank 1 by constructing a scaffold 9 and spraying a coating liquid 11 as a viscous aqueous solution containing a surfactant onto the surface of the oily sludge 10.

Then, side wall reinforcement material 4 in areas where there is a risk of fire spreading around or below the repair area A due to cutting or welding work.
The work tool 13 uses a spray gun 12 to spray the coating liquid 11 onto the surface of the oily sludge 10 accumulated on the tank bottom 3.
The surface of oily sludge 10 is coated with coating liquid 11.

In this way, there is no need to scrape up the oily sludge 10 and carry it out of the tank 1, and it is only necessary to coat the surface of the oily sludge 10 with the coating liquid 11 using the spray gun 12, so it can be done quickly and easily by a small number of workers. This time-consuming work ensures fire safety during repair work.

(4) The work tool 15 for performing repair work such as cutting and welding enters the tank 1, and the tool 14 is used to perform repair work on the repair area A.

At this time, even if high-temperature cut pieces or sparks are scattered to the oil-based sludge 10 around or below the repair area A due to cutting or welding, the coating liquid 11 covering the surface of the oil-based sludge 10 may Such fire resistance prevents fires from occurring and allows repair work to be carried out safely.

If the repair work is carried out according to the steps (1) to (4) above, the oil tank can be repaired safely in a short time using a small number of tools.

The fireproof repair method of the present invention can be used not only for oil tanks of tankers, but also for oil storage tanks installed on land or at sea.

〔Effect of the invention〕

As detailed above, according to the fireproof repair work method for an oil tank of the present invention, when repair work is performed inside an oil tank, the surface of the oily sludge in the oil tank is treated with a surfactant. By coating the oil tank with a viscous aqueous solution containing it and then performing repair work inside the oil tank, fire prevention measures against hot repair work can be reliably carried out in a short time using a small number of tools. As a result, the entire repair work period is shortened and construction costs are reduced.
It has the advantage of increasing construction safety.

[Brief explanation of the drawing]

The figure is a vertical sectional view of an oil tank illustrating a fireproof repair method for an oil tank according to an embodiment of the present invention. 1. Oil tank, 2. Side wall, 3. Tank bottom, 4°5
... Reinforcement material, 6. Tank ceiling (upper deck), 7. Manhole, 8. Ventilation fan, 9. Work scaffolding, 10.
- Oily sludge, 11... Coating liquid as a viscous aqueous solution containing a surfactant, 12... Spray gun, 13...
Working tools, 14... Tools, 15... Working tools, 16... Coating liquid tank, 17... Airless pump, 18... Hose for transferring coating liquid, 19... Cabtire cord, A... Repair points. Sub-Agent Patent Attorney Yoshihiko Iinuma

Claims (1)

[Claims] When carrying out repair work inside the oil tank, the surface of the oily sludge in the oil tank is coated in advance with a viscous aqueous solution containing a surfactant, and then the repair work inside the oil tank is carried out. A method for fireproof repair work inside oil tanks.