JPH0154510B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method for replacing a bottom plate of a petroleum tank, that is, an annular bottom plate that is an annular bottom plate on the outer periphery of the tank bottom immediately below the side plate.

``Prior Art'' Tank bottom plates become corroded due to the influence of stored liquids such as petroleum, the influence of rainwater etc. infiltrating between the tank bottom plate and the tank foundation, and other factors, and must be replaced. In particular, the above-mentioned annular plate, which is made by welding multiple plates annularly around the outer circumference of the tank bottom plate and supports the side plates, corrodes first and determines the tank life, so the life of the tank cannot be extended. This is often done by replacing the annular plate.

As a method for replacing such a tank bottom plate, the so-called jack-up method illustrated in Fig. 1 is used.
This has been done traditionally. That is, a reinforcing ring 2 is attached to the upper end of the side plate 1 of the tank, a reinforcing material 4 is attached between this reinforcing ring 2 and a bracket 3 attached to the lower end of the side plate 1, and the tank is temporarily fixed using jacks 5. Hold it up,
Annular plate 6 was being replaced.

However, the side plate 1 is extremely thin and weak against external forces.
However, temporary materials such as the reinforcing ring 2, reinforcing material 4, and other reinforcing materials used to prevent deformation and buckling due to the moment of the tank load during jacking up are large, and the material costs and The cost of bending and other processing was considerable. In addition to the cost of temporary construction materials, welding at high places is required, the tank foundation needs to be reinforced to prevent jacking, and a large number of personnel are required to prevent the tank from losing its balance and tilting when jacked up. , problems with human cost, work efficiency, and safety were also pointed out. Therefore, in place of this jack-up method, a construction method that does not require lifting the entire tank was recently proposed in Japanese Patent Publication No. 55-41990. This construction method involves dividing the annular plate into multiple sections in the circumferential direction, cutting and removing the annular plate and the lower part of the side plate, temporarily joining the plate that constitutes the new annular plate to the section, and then a step of driving a first wedge between the upper part of the plate body constituting the new annular plate; and a step of joining adjacent plate bodies constituting the new annular plate; The step of fully joining the plate bodies constituting the annular plate: A support piece is fixed to the side plate from the inside, and a holding piece is attached to the plate body constituting the new annular plate on the outside of the side plate facing the support piece. and inserting a second wedge between the side plate and the holding piece; and removing the first wedge; cutting the lower part of the support piece at a position above the lower end of the side plate to remove the lower end of the side plate; After temporarily joining the plates forming the new annular plate, removing the support piece from the side plate and welding the inner surface of the lower part of the side plate and the upper surface of the plate forming the new annular plate; and extracting the second wedge. After that, remove the holding piece from the plate that makes up the new annual plate,
This process consists of welding the outer surface of the lower part of the side plate and the upper surface of the plate that makes up the new annular plate, so there is no need to reinforce the foundation ground around the tank or correct uneven settlement, and it is more effective than the jack-up method. The effect is that the work can be done in a short construction period by a small number of people.

The main parts of the described construction method are shown in Figures 6a and b.

In the figure, 14 is a side plate, 15 is a plate forming the new annular plate, 16 is a first wedge, 17 is a support piece, 18 is a holding piece, 1
Reference numeral 9 indicates a second wedge, and 20 indicates a support plate that may be interposed as necessary to improve the contact between the support piece 17 and the plate body 15.

Figure a shows a wedge 16 inserted in the gap formed between the lower part of the side plate 14 and the plate 15 constituting the new annular plate, and a support piece 17 attached to the side plate 14. This is a supported mode, and this treatment is applied to the entire circumference. Figure b shows wedge 16 and support piece 17.
In this embodiment, the side plate 14, which has been shortened by removing the side plate 14, is lowered onto the plate body 15 that constitutes the new annular plate. In other words, in this construction method, the side plate 14 has the characteristic that the lower end is cut and shortened, and while this shortening work is performed over the entire circumference, the side plate 14 is supported by the first wedge 16 and the support piece 17. It is said that it will.

In addition, the first wedge 16 and support piece 1
7 are arranged alternately at intervals as equal support parts.

"The problem that the invention attempts to solve" The above construction method has the following problems.

(1) Temporary supporting materials such as support piece 17 and holding piece 18, which are to be removed, are welded and fixed to the inner surface of the lower end of the tank side plate and the bottom plate, respectively, and removal can also be done by cutting. This means that it cannot be reused at all, and unreasonable problems have been pointed out in terms of temporary material costs, personnel, and work efficiency.

(2) The final step, tank down, is performed by gas cutting in small portions of the support piece 17 directly near the annular plate surface.
There are problems in terms of cost, efficiency, etc. regarding the removal work and the quality inspection work of the annular plate after cutting.

(3) The first wedge 16 serves to quickly cut and remove the support piece 17 between two adjacent parts, that is, to serve as a temporary support when lowering the tank. It is impossible to raise the support level set by the support piece 17 later by driving the first wedge 16, since this would result in halving the support points and doubling the support load. Inconveniences can have a serious impact on quality.

That is, as shown in FIGS. 7a and 7b, the welding 24 between the plates 15 must be carried out by fully inserting the electric welding rod 21 from inside the tank to the depths of the gap 22 between the side plate 14 and the plate 15 (outside the tank). Must be. 23 in the figure indicates the backing money.

In addition, as shown in FIGS. 8a and 8b, a hand-type magnetic particle flaw detector 25 is used for the above-mentioned welded joint 24.
The inspection is performed by visual observation of the magnetic flux lines 26 using the above-described method, but the inspection beyond the gap 22 must be visually observed 27 by looking through the gap 22.

Incidentally, the same situation applies to inspection by penetrant testing.

In the above-mentioned welding and inspection, it goes without saying that mistakes can be reduced if the gap 22 is large.

However, there are circumstances in which this treatment is not permissible for tanks. That is, as shown in FIGS. 9a and 9b, at the lower end of the side plate 14, a nozzle 28 for putting in and taking out the stored liquid is installed through a reinforcing backing plate 29 so as to keep the dead zone in the tank as small as possible. However, the distance h that was initially maintained between the lower end of the corresponding plate 29 and the annular plate is greatly narrowed by cutting the gap 22, as shown in Figure b.

Then, in the side plate 14, the welded part of the contact plate 29 and the welded part to the annular plate become extremely close to each other as shown in the figure, and the distance between the welded wedge ends is at least twice the base metal thickness. However, it is not possible to avoid the adverse effects of strength reduction due to local concentration of residual stress due to welding, which is considered to be a good practice, and this disadvantage occurs.

Therefore, the gap 22 cannot be set unnecessarily large.

However, with conventional means that cannot lift up beyond the initial gap 22, which must be kept small, it is impossible to improve the integrity of welding and inspection.

"Means for Solving the Problems" In view of the above-mentioned circumstances, the present invention has been made to solve the above-mentioned problems of the conventional example. Therefore, we would like to propose a method for replacing the annular plate of a tank, which can easily support, lower, and raise the tank.

The tank annular plate replacement method according to the present invention involves partially cutting and removing the lower end of the side plate 1 of the tank at a predetermined width, and then removing the existing annular plate 6 near the cut and removal location A. is partially cut and removed, and a new annular plate 6 is installed and replaced in its place, and a thick plate with a substantially horizontal upper and lower surface is installed between the lower end of the rear side plate 1 and the new annular plate 6. The body is divided into upper and lower parts through a tapered surface, and an upper liner and a lower liner are used as a pair, with the head erected on the base end of the upper liner, and guided on both side edges of the lower liner. The system includes a replacement process in which a liner 8 having a lift function is inserted, in which the upper liner is housed between the guide plates by erecting the plates.

Furthermore, it includes a process of performing such a replacement process on each location of the lower end of the side plate 1, and a tank down process of lowering the side plate 1 onto the new annular plate 6 by removing all the liners 8. It's summery.

"Operation and Examples" The method of the present invention will be explained in detail below based on the examples shown in FIGS. 2, 3, 4, and 5.

The tank is composed of a cylindrical side plate 1, a top plate and an annular plate 6 fixed to the upper and lower end surfaces of the side plate 1, and is installed on a foundation 9.

First, the outer surface of the lower end of the side plate 1 of the tank is divided into a plurality of sections with a predetermined width in the circumferential direction, and markings for cutting are performed using scribe lines and relief marks. The cutting height is approximately 20 to 50 mm from the lower end of the side plate 1, that is, the top of the annual plate 6, and the cutting width is:
Part 1 of annular plate 6 scheduled for subsequent replacement
The predetermined width is slightly longer than the circumferential length of the sheet.

Then, at the lower end of the side plate 1, an appropriate portion of the above-mentioned section is partially cut and removed to form an opening.

Next, the existing annular plate 6 near this cutting/removal point A, that is, the part that became the opening, is partially cut and removed, and a new annular plate 6 is laid in its place and replaced. In other words, the annular plate 6 near the cutting/removal point A of the side plate 1
was cut into approximately the same size as the new annular plate 6 that was scheduled to be replaced, taking into consideration the overlap, and the side plate 1 was cut.
Replacement is accomplished by removing the annular plate 6 to the outside through the opening at the cutting/removal point A, inserting and laying a new annular plate 6 in its place, and joining it with the surrounding annular plates 6. When removing the existing annular plate 6, the condition of the foundation 9 is checked, and if there is any unevenness, the ground is adjusted and leveled, and a new annular plate 6 is laid.

Thereafter, the end face of the side plate 1 that will form the cutting/removal location A is shaped using a grinder or the like. Taper a thick plate whose upper and lower surfaces are approximately horizontal as shown in FIGS. An upper liner 8' and a lower liner 8'' each having a vertically cut shape having 7' and 7'' are used as a pair, and a head 11 is erected on the base end of the upper liner 8'. At the same time, guide plates 12, 12 are erected on both side edges of the lower liner 8'', and the liner 8 is driven in so that the upper liner 8' is accommodated between the guide plates 12, 12.

Such a replacement process is sequentially performed at each location on the lower end of the side plate 1. In this way, the lower end of the side plate 1 is cut and removed over the entire circumference, and the annular plate 6 is replaced mainly in the vicinity immediately below the side plate 1. A large number of liners 8 are then inserted between the lower end of the side plate 1 and the installed new annular plate 6. These liners 8 are
Arrange them at equal intervals with a pitch of approximately 500mm.

In this way, the vertical load on the side plate 1 is received by these liners 8, and the liner 8 functions as a temporary supporting material that temporarily supports the tank, so no moment is generated on the side plate 1, and the side plate Deformation etc. of 1 are reliably prevented.

Although the tank is temporarily supported by the liner 8 in this way, it is also possible to raise the tank if necessary. In other words, the space for installing a non-destructive inspection device for the installed new annular plate 6 and performing other work is the opening between the lower end of the side plate 1 and the new annular plate 6, which is the cutting and removal point A. If this alone is not sufficient, the tank can be raised a little by further driving the liner 8 with a hammer or the like, making use of the lift function of the liner 8. This means that non-destructive testing, welding, and other work can be carried out without any problems and with sufficient reliability.

After that, by applying a blow to the liner 8 with a hammer or the like, all the liners 8 are pulled out using the descending function, and the side plate 1 is removed.
is lowered onto the new annular plate 6, and tank down is completed. In this way, tank down is
This can be easily and reliably carried out without any waste of materials or complicated work of fusing the temporary receiving material, and there is no additional effort of quality inspection of the fusing part.

Thereafter, the lower end surface of the side plate 1 and the new annular plate 6 are fixed by welding, all temporary materials are removed, and the surface of the installation site is reshaped.

Furthermore, when such a special upper liner 8' and lower liner 8'' are used in combination, it becomes possible to slide using the mutual tapers 7' and 7''.
Tanks will now move up and down more smoothly. The upper liner 8' is combined and restrained with the lower liner 8'' and will never shift, so there is an advantage that the side plate 1 can be supported without shifting. Using a flat guide piece 13 as a temporary member erected on the new annular plate 6, in a substantially straight line with the side plate 1 in the vicinity of where the liners 8' and 8'' are inserted, When the liners 8' and 8'' are placed opposite each other on the annular plate 6, there is an advantage that the side plate 1 can be held without being displaced in the radial direction of the tank when the liners 8', 8'' are driven in and pulled out.

"Effects of the Invention" As explained above, the tank annular plate replacement method according to the present invention is a temporary material that cannot be attached or detached by welding or fusing, and the tank does not increase even after temporary mounting at all points. By exclusively utilizing the liner, which has the characteristic of being reusable, temporary construction material costs, personnel costs, and
It is excellent in terms of work efficiency, safety, and quality maintenance. Furthermore, tank down is carried out efficiently, tank up is possible as needed, ancillary work such as non-destructive inspection can be carried out satisfactorily, and problems that existed in conventional examples of this type are avoided. Its effects, such as being wiped out in one fell swoop, are remarkable and great.

[Brief explanation of drawings]

FIG. 1 is a front center vertical cross-sectional view of a tank for explaining a conventional tank annular plate replacement method, and FIGS. 2 and 3 are tank annular plate replacement methods according to the present invention. This is for explaining the method. Figure 2 is a vertical cross-sectional view of the front center of the tank, Figure 3 is an enlarged view of the main part of Figure 2, and Figure 1 in Figure 3 shows the initial stage of the method. The figure shows each of the next steps. FIG. 4 shows a liner used in the present invention, with FIG. 1 being a side sectional view of the main part thereof, and FIG. 2 being a cross sectional view thereof. Figure 5 shows each liner shown in Figure 4, Figure 1 is a plan view of the upper liner, Figure 2 is a side view of the same, Figure 3 is a plan view of the lower liner, and Figure 4 is a side view of the same. , Fig. 6 a, b is an explanatory diagram showing the conventional construction method, Fig. 7 a, b
Figure 8 is a cross-sectional view and a plan view to explain the welded part of the new annular plate, Figures 8a and b are cross-sectional views and a plan view to explain the inspection of the welded part, and Figures 9a and b are a diagram showing how to take in and out the stored liquid in the tank. FIG. 4 is an explanatory diagram of the relationship between the nozzle and the side plate. 1... Side plate, 2... Reinforcement ring, 3... Bracket, 4... Reinforcement material, 5... Jacket, 6... Annular plate, 7, 7', 7''... Taper,
8... Liner, 8'... Upper liner, 8''... Lower liner, 9... Foundation, 11... Head, 12... Guide plate, 13... Guide piece, A... Cutting and removal location.

Claims (1)

[Scope of Claims] 1. After partially cutting the lower end of the side plate of the tank at a predetermined width and removing it, partially cutting and removing the existing annular plate near the cutting and removal point, Instead, a new annular plate was installed and replaced, and then between the lower end of the side plate and the new annular plate, a thick plate with an approximately horizontal upper and lower surface was divided into upper and lower parts via a tapered surface. An upper liner and a lower liner each having a different shape are made into a pair of upper and lower parts, and a head is erected on the base end of the upper liner, and guide plates are erected on both side edges of the lower liner,
A replacement process of inserting a liner such that the upper liner is stored between the guide plates, a process of applying such a replacement process to each location of the lower end of the side plate, and a process of removing all the liners. A tank annular plate replacement method, comprising: a tank down step of lowering the side plate onto a new annular plate.