JPS5828182B2 - The basics of the tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a corrosion protection method for the bottom plate of an existing oil storage tank.

Recently, oil storage tank leakage accidents have become a problem.

Leakage accidents are often caused by uneven settlement of the foundation ground or corrosion of the tank bottom plate.

By the way, the following may be the cause of the corrosion of the tank bottom plate.

In other words, the causes of corrosion on the inside of the bottom plate are ballast water, sulfides, dissolved oxygen, inorganic acids, etc. contained in the oil, and the causes of corrosion on the outside of the bottom plate include the corrosive nature of the foundation sand or soil, corrosion due to oxygen concentration battery action, and copper earth. This includes corrosion and galvanic corrosion caused by stray current.

On the other hand, in conventional tank foundations, sand mounds, oil sand, etc. are not necessarily impervious to water and have a relatively low resistivity, so they do not have sufficient corrosion protection.

Therefore, the main problem with such tanks is external corrosion.

As a corrosion prevention measure for the existing tank bottom plate, there is a method of removing the open bottom plate and replacing it with a new copper plate that has undergone anti-corrosion treatment on the outside, and at the same time improving the mound, but this is uneconomical as it takes a considerable amount of time and cost.

This invention was developed in view of the above circumstances, and embodiments thereof will be described below with reference to the drawings.

First, asphalt material A is kneaded at 100 to 200°C using a heating mixer 1 outside the tank.

By the way, as an example of this asphalt-based material A, the amount of asphalt is 20 to 30, and the dust-asphalt ratio (
An asphalt mortar for injection with D/A)=1.0 to 1.2 is suitable.

However, the physical properties of asphalt mortar vary depending on the type of asphalt, temperature, etc.

Therefore, the composition or injection temperature should be appropriately selected depending on the size of the tank, injection equipment, etc.

The injection temperature is determined according to the type and composition of asphalt so that the flow value is about 20±10 seconds.

The above asphalt-based material A is supplied to the injection device through a pipe 2 equipped with a heat insulating device, a transport vehicle 3, or the like.

As an injection device, a mobile pump 4 or an injection device 6 using compressed air from a compressor 5 is used, and an injection pipe 9 is connected to an injection hole 8 drilled in the bottom plate 7 of the tank, and the asphalt-based material A is injected. do.

The injected asphalt material is the bottom surface of the bottom plate γ and the foundation 1.
0, and the lower surface of the bottom plate 7 is covered with an asphalt-based material.

Radioisotope gap measuring device 1 is used to manage injection status.
1 is used to detect the filling thickness and uninjected areas, and re-inject according to the detected filling conditions such as insufficiently injected areas.

This invention has the above-mentioned structure, and with an appropriate combination, the
The asphalt-based material heated and mixed at 00℃ has no voids between the tank bottom plate and the base, and has a hydraulic conductivity of 1O after cooling and solidifying.
Provides sufficient water barrier properties of −10 cTL//SeC or less.

Further, the specific resistance of the asphalt-based material is 108 gCrl1 or more, which provides sufficient insulation.

Furthermore, since asphalt-based materials have viscoelasticity, they deform following the uneven subsidence of the ground and do not cause cracks.

It also has good adhesion to the bottom surface of the bottom plate.

Therefore, by injecting this asphalt-based material between the tank bottom plate and the base, corrosion on the outer surface of the bottom plate can be completely prevented.

By using an impeller type pump as the injection device, it is possible to inject asphalt mortar with sand added.

Also, the use of radioisotope gap measuring instruments (more on this,
Non-destructive (allows you to know the injection thickness and filling status,
Since uninjected areas and voids can be found, the corrosion-preventing effect of the injection material can be ensured.

[Brief explanation of drawings]

Figure 1 is a plan view showing an outline of the construction state of this invention, Figure 2 is a pump, Figure 3 is a compressed air injection device, and Figure 4 is a pump.
The figure is a diagram showing how the radioisotope gap measuring device is used. A: Asphalt-based material, 1: Heating mixer, 2: Pipe, 3: Transport vehicle, 4: Pump, 5... Compressor, 6... Compressed air injection device, 7.
...Bottom plate, 8...Injection hole, 9...
・Injection pipe, 10...Base, 11...
・Radioisotope gap measuring device.

Claims (1)

[Claims] 1 The asphalt-based material, which has been heated to make it fluid, is passed through the injection hole drilled in the tank bottom plate, and while the filling thickness and filling condition are detected by the gap measuring device, the filling device is used to insert the asphalt material between the tank bottom plate and the base. A corrosion-preventing construction method for the bottom plate of an existing tank, characterized in that the bottom plate of an existing tank is injected between the bottom plate and the bottom plate is coated with an asphalt-based material to prevent uneven settling of the tank and corrosion of the bottom plate.