JPS6152075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of the lower surface of a steel tank bottom plate.

Conventionally, anti-corrosion materials painted on the underside of the bottom plates of large tanks built underground or semi-underground are susceptible to heat caused by fusing, welding, etc. of construction materials during tank construction.
There was a problem that the effect was lost due to deterioration or decomposition. As a result, the bottom plate of the tank corrodes due to moisture seeping into the base material.
In some cases, the tank bottom plate had to be replaced several years after construction.

In addition, due to ground subsidence, the asphalt sand of the tank foundation becomes deformed, causing cracks and gaps to form, causing moisture seeping through the cracks and corroding the tank bottom plate. It was wanted.

The present invention was made in response to these demands, and will be described below based on the drawings showing one embodiment thereof.

FIG. 1 shows a steel tank 1, which is installed on a foundation 2.

FIG. 2 is an enlarged view of section A in FIG. 1, and the lower surface 3a of the bottom plate 3 of the steel tank 1 is anti-corrosion treated by the method described below. In other words, (a) excavate the soil at a predetermined location and construct a concrete frame 4.
and pour tank foundation sand 5 such as asphalt sand.

(b) The tank foundation sand 5 is shaped so that the center part 5a is high and the peripheral part 5b is low, making the whole tank smooth.

(c) A waterproof sealing material 6 having watertightness, flexibility, elasticity, and compression resistance is laid on the upper surface of the tank foundation sand 5, and the peripheral edge 6a of the waterproof sealing material 6 is brought into close contact with the concrete frame 4.

(d) A suitable hole 8 is drilled in advance in the waterproof sealing material 6 at a position where the foundation bolt 7 passes through, and after the foundation bolt 7 has passed through, the waterproof sealing material 6 and the foundation bolt 7 are connected to each other by the waterproof sealing material 6. Glue using batch 9 of the same material as material 6. 10 is mortar, 11 is foundation concrete, 12 is pile,
13 is a nut, and 14 is a washer.

(E) When constructing the steel tank 1 by welding, a protective material 15 such as dry sand is laid on the waterproof sealing material 6 in order to protect the waterproof sealing material 6 from the heat.

(F) Install the tank bottom plate 3 on top of the protective material 15, and construct the steel tank 1 including the tank body plate 16.

(G) A drain hole 17 is provided in the concrete frame 4 at a location where the drain in the foundation (mainly from surrounding concrete placement) can be easily drained.

(H) Drill holes 18 at appropriate locations on the installed tank bottom plate 3, blow dry air through the holes 18 from inside the tank 1 to dry the protective material 15, and then open the holes 18 by appropriate means. Seal tightly.

(li) Surrounding concrete 19 is placed between the outer periphery 3b of the tank bottom plate 3 and the concrete frame 4, and after the surrounding concrete 19 dries, the outer periphery 3b of the tank bottom plate 3 and the surrounding concrete 19 are made watertight and weatherproof. It is integrally covered with a waterproof sealing material 20 having elasticity, flexibility, and stretchability.

FIG. 3 shows another embodiment based on the present invention. That is, the peripheral portion 6 of the waterproof sealing material 6
b is closely attached to the lower surface 3c of the outer periphery 3b of the tank bottom plate 3, and the lower surface 3a of the tank bottom plate 3 is isolated from the outside world. Perform step 15 drying.

According to the present invention described above, the protective material laid on the top surface of the first waterproof sealing material is sealed by the surrounding concrete and the second waterproof sheet covering the outer periphery of the surrounding concrete and the tank bottom plate, and when the tank is installed. A hole is made in the tank bottom plate, dry air is injected through the hole to dry the protective material, and the hole is then sealed, preventing water, moisture, and outside air from entering the bottom of the tank bottom plate, ensuring a dry state at all times. The lower surface of the tank bottom plate will not corrode, and the bottom plate sealing material has elasticity, so even if the foundation is deformed due to ground subsidence, it will always adapt to the shape of the foundation, preventing cracks from entering the tank foundation sand. Tsutari,
Even if a gap is created, moisture will not infiltrate, and the tank bottom plate will not be corroded, which is a significant effect.

[Brief explanation of the drawing]

The drawings show an embodiment based on the present invention; FIG. 1 is a longitudinal sectional view showing a steel tank and foundation, FIG. 2 is an enlarged detailed view of section A in FIG. 1, and FIG. FIG. 3 is an enlarged detailed view of the main part of the embodiment. 1... Steel tank, 3... Bottom plate, 3a... Lower surface, 5...
Tank foundation sand, 6,20...Waterproof sealing material, 15...
Protective material, 19...surrounding concrete.

Claims (1)

[Claims] 1. A first waterproof sealing material having elasticity is laid on the tank foundation sand which is shaped so that the tank installation part is high and the peripheral part is low, a protective material is laid on the first waterproof sealing material, and the protective material is A tank bottom plate is installed on top, the outer circumference of the tank bottom plate and the surrounding concrete cast around the protective material are integrally covered with a second waterproof sealing material, and holes are drilled at appropriate locations on the tank bottom plate. A method for preventing corrosion of a lower surface of a steel tank bottom plate, comprising: drying the protective material by injecting dry air through the hole, and then sealing the hole.