JPS5926543B2 - tank equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of a tank bottom plate, and more specifically, when constructing a tank, a conduit for injecting an anticorrosive agent is buried in the foundation of the tank in advance, and the anticorrosive agent is injected through the conduit. This invention relates to a method for effectively preventing corrosion of a tank bottom plate by applying the same to the tank bottom plate.

Currently, when constructing a tank to store petroleum or petroleum products, the bottom plate of the tank is assembled by arranging a number of steel plates on the tank foundation and welding the steel plates together. ing.

Conventionally, when assembling this tank bottom plate, each steel plate used for corrosion prevention purposes was coated with an anticorrosive agent in advance, and the steel plates were laid out on the tank foundation surface layer with the coated side facing downwards. Later, each steel plate was welded.

However, in the conventional method described above, the welding heat applied during welding the steel plates burns away the anticorrosive agent applied to the steel plate near the welded area, and it is not necessary to apply the anticorrosive agent to the underside of the tank bottom plate after welding. Since this is not possible, sufficient corrosion protection cannot be expected for the welded area and the steel plates around it.

Furthermore, since the welded portion of the tank bottom plate occupies a considerable proportion of the entire bottom surface, corrosion protection at and around the welded portion is an extremely important issue in extending the life of the tank. Therefore, the inventor of the present invention has conducted intensive research to overcome the shortcomings of conventional corrosion prevention methods and develop a simple and effective corrosion prevention method for tank bottom plates. They discovered a method of coating and completed the present invention.

That is, the present invention buries one or more conduits communicating with the surface layer of the tank foundation inside the tank foundation, provides an anticorrosive agent injection port at one end of the conduit, and then constructs the tank on the foundation. Further, the space between the periphery of the tank bottom plate and the base surface layer is closed, and then an anticorrosive agent is injected into the conduit through the injection port, and the anticorrosive agent is applied to the tank bottom plate. The present invention provides a method for preventing corrosion of a tank bottom plate. In the present invention, the tank foundation is usually formed by a layer of sand.

The surface layer of the tank foundation may be a sand layer, but is preferably finished with asphalt mortar. In addition, when finishing the tank foundation surface layer with a sand layer, in order to prevent moisture from penetrating into the foundation surface from inside the foundation or underground,
It is effective to impregnate the surface of the sand layer with heavy oil, waste oil, etc. The method of the present invention will be explained based on the drawings. As shown in FIG. 1, a conduit 2 is buried inside the tank foundation 1.

The number and location of the pipes can be determined in various ways depending on the shape and size of the tank. For example, as shown in Fig. It is necessary to install piping so that the agent can be applied. Further, the above-mentioned conduit must be connected to the tank foundation surface layer 5. As a result, the anticorrosive agent is ejected through the opening 3 of the conduit in the surface layer 5, and the anticorrosive agent is uniformly applied to the lower surface of the tank bottom plate 9. That is, the lower surface of the tank bottom plate and the upper surface of the tank foundation surface each have a considerably rough surface microscopically, and the contact between the two is constituted by a large number of contact points and voids. Therefore, the anticorrosive agent ejected from the opening 3 spreads through the gap to the lower surface of the tank bottom plate by capillary action or the like. If the tank foundation sinks due to the storage liquid entering the tank after the tank is constructed, the opening 3 of the conduit will push up the tank bottom plate 9, and an abnormal load may be applied to the conduit or the tank bottom plate. Therefore, in order to eliminate such an abnormal load, it is preferable to attach a disk 12 to the opening 3 of the conduit as shown in FIG. Since one end of the conduit becomes the anticorrosive injection port 4, it is arranged so as to pass through the ground at an appropriate position outside the tank. In the method of the invention, after the conduit is installed, the tank 8 is constructed. The tank bottom plate 9 is assembled by arranging predetermined steel plates on a tank foundation and welding the steel plates together in the same manner as in the past. However, in the present invention, it is not necessary to apply an anticorrosive agent to the lower surface of each steel plate used in advance. After the tank is constructed, the gap 10 between the periphery of the tank bottom plate 9 and the surface layer 5 of the tank foundation is closed.

Although various methods can be considered for the closure, it is usually accomplished by filling a space between the periphery of the bottom plate 9 and the base surface layer 5 with a sealant (for example, an asphalt-impregnated chute) as shown in FIG. As a result, the small gap between the tank bottom plate 9 and the tank foundation surface layer 5 is completely cut off from the outside air.
At this time, it is preferable to provide openable and closable air vents 6 at several locations in the seal portion 7 on the periphery of the tank bottom plate, as shown in FIG. After constructing the foundation and the tank in this way, an appropriately selected anticorrosive agent such as waste oil, heavy oil, asphalt, or synthetic resin is injected through the anticorrosive injection port 4 of the conduit 2. Note that if the anticorrosive agent does not have sufficient fluidity, it may be used by heating or by adding a solvent. At this time, if the installed air vent 6 is left open, the anticorrosive agent will pass through the conduit 2 and open through the opening 3.
At the same time, the air that had entered the small gap 10 between the tank bottom plate 9 and the tank foundation surface layer 5 is absorbed by the anticorrosive agent that blows out from the opening 3 of the conduit. As a result, it is pushed out from the air vent 6, and eventually,
The air within the void 10 is completely replaced by the anticorrosive agent. After completely expelling the air, the air vent port 6 is closed. The anticorrosive agent is injected using a pump or by using the differential pressure (head pressure) created by the drop in the liquid level.

When injecting the anticorrosive agent, fill the tank with water or storage liquid so that the injection pressure does not lift the bottom plate of the tank inward. This is preferable because it reduces the volume of the gap between the tank bottom plate and the foundation surface and saves the amount of anticorrosive agent used. For example, when the surface layer of the tank foundation was finished with asphalt mortar and waste oil was used as an anticorrosive agent, the amount of waste oil used could be reduced to approximately 51/Rrl. As described above, by using the method of the present invention, the anticorrosive agent can be sufficiently and uniformly applied to the entire lower surface of the tank bottom plate, and as a result, an excellent anticorrosion effect can be obtained. Moreover, the air gap 1 between the tank bottom plate 9 and the tank foundation surface 5 is
Since there is no air present in the 0, it is considered that this is an extremely advantageous situation in terms of corrosion prevention. Furthermore, by pouring the anticorrosive agent according to the present invention not only at the time of tank construction, but also periodically thereafter as needed, it is possible to significantly extend the life of the tank. Further, the method of the present invention can be applied not only to the construction of a new tank, but also to the case of replacing and repairing the bottom plate of an existing tank.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of the piping in the tank foundation and the entire tank used in the method of the invention. FIG. 2 shows one embodiment of the arrangement of conduits in a tank foundation. FIG. 3 is a partial sectional view of the opening of the conduit and the vicinity of the tank bottom plate, and FIG. 4 is a partial sectional view showing a state in which the space between the periphery of the tank bottom plate and the tank foundation surface layer is closed. In the figure, 1 is the tank foundation, 2 is the conduit, 3 is the opening of the conduit,
4 is a corrosion inhibitor injection port, 5 is a tank base surface layer, 6 is an air vent, 7 is a seal around the tank bottom plate, , the tank body, 9
1 is a tank bottom plate, 10 is a gap, 1 is a tank side plate, 12 is a disk, and 13 is a socket.

Claims (1)

[Claims] 1. Bury one or more conduits inside the tank foundation to communicate with the surface layer of the tank foundation, provide an anticorrosion agent injection port at one end of the conduit, then construct the tank on the foundation, and then A tank characterized in that the space between the periphery of the bottom plate of the tank and the base surface layer is closed, and then an anticorrosive agent is injected into the conduit through the injection port, and the anticorrosive agent is applied to the tank bottom plate. Corrosion prevention method for bottom plate.