JPS5952268B2 - Bottom plate hanging method for flat bottom cylindrical tank - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for lifting and assembling a bottom plate in the construction of a flat-bottomed cylindrical tank, in which the bottom plate is suspended by wire to enable non-destructive inspection using X-rays, etc. In particular, in the wire configuration, by arranging a plurality of wires in the radial direction and connecting a plurality of ring-shaped wires to the radial wires in the horizontal direction, both the radial wire and the ring wire can be tensioned when the bottom plate is suspended. This invention relates to a construction method for lifting and assembling the bottom plate of a flat-bottomed cylindrical tank, which allows stable suspension of the bottom plate.

Conventionally, flat-bottomed cylindrical tanks were constructed by laying the bottom plate members on a foundation such as concrete, as shown in Figures 1a and lb, or in the case of double-shell low-temperature tanks, by laying the bottom plate members on the bottom cold insulation layer, and then placing the bottom plate members against each other. Fillet or backing butt welding is performed on the joints, but these welded joints often have a disadvantage in that the strength of the weld is significantly inferior to that of the base metal, but these days, the safety strength of tanks is It has received a lot of attention from this perspective.

Therefore, in the construction method of a flat-bottomed cylindrical tank based on the conventional technology, the bottom plate is welded on one side from the top surface as described above, and the inspection is performed by penetrant testing or vacuum testing from the top surface. Unavoidably, this method had the disadvantage that it was almost impossible to detect defects inside the weld.

The purpose of this invention is to solve the problem of the construction method of a flat-bottomed cylindrical tank based on the above-mentioned prior art, by assembling and welding the bottom plate on a temporary scaffolding at a certain height above the foundation, or by welding the bottom plate on one side of the top surface on the foundation. This relates to a construction method in which the bottom plate is later lifted to a certain height above the foundation and a space is temporarily created at the bottom of the bottom plate for upward welding or inspection. The present invention relates to a construction method for suspending a bottom plate, which eliminates the drawbacks of the prior art described above, and has the advantage of providing a high degree of safety when working on the underside of the bottom plate.

In other words, the bottom plate suspension construction method basically consists of a large number of radial wires connected to the side plate or roof of the tank, a plurality of ring wires connected to these wires, and the intersection of the radial wires and the ring wires. It consists of a plurality of hanging wires, and in particular, the radial wire is stretched by a ring wire in an upwardly curved shape.

With this wire configuration and wire shape, each wire is loaded with tension when suspending the bottom plate, making it possible to hang the bottom plate extremely stably. Even if the suspension wire is cut, the radial wire and ring wire are still under tension, so there is no instability or fluctuation in the shape of the wire, so the bottom plate can be suspended while maintaining its flat shape.

Therefore, there is no unnecessary deformation of the bottom plate, and not only can the quality of the bottom plate be maintained, but it is also safe to work on the bottom surface of the bottom plate. Embodiments of the present invention that meet the above objectives will be described below with reference to the drawings.

An annular plate 2 is mounted on a foundation 1 cast with concrete or the like, and side plates 3 as a shell are gradually assembled above it, and a temporary scaffold 4 for predetermined work is assembled on the foundation 1.

Next, a bottom plate 5 is formed on the temporary scaffold 4, and each member thereof is butted and welded on both sides as necessary, and a stiffener 16 is fixed above the side plate 3.

The stiffener 6 may be a temporary member, or if the tank has a roof, a roof structure may be used, or the stiffener 6 may be omitted in some cases. Appropriate pulleys 7 are attached to the stiffener 16, and each pulley 7 serves as a tensioning support point at equal intervals in the circumferential direction, and a winder such as a winch 8 is attached to the lower part of the side plate. . Then, from the winch 8, the radial wires 9 as actuating members are connected and passed through the pulleys 3a and 3b.
, 4, a ring wire 11 appropriately connected to the radial wire 9 and a hanging wire 10 as a hanging member are stretched, so that the hanging wire 10 is connected to the bottom plate 5. During this time, after the formation of the bottom plate 5 is completed, a non-destructive inspection of the welded part such as an X-ray inspection that requires work from the top and bottom of the bottom plate is performed to confirm the quality of the bottom plate and repair any defective parts.

In some cases, the winch 8 may be attached above the side plate 3.

After completing the formation of the bottom plate 5, each winch 8 winds up each radial wire 9, and correspondingly,
Radial wire 9, ring wire 11. Hanging wire 10
Tension is applied to each wire, and each wire is stabilized in an extended state, and the bottom plate 5 is stably suspended in a constant flat state.

After dismantling and removing the temporary scaffolding 4 below the bottom plate 5, the winch 8 is returned, the bottom plate 5 is lowered onto the foundation 1, welded after adjusting the predetermined connection with the annealer plate 2, and inspected as appropriate. Complete tank formation.

According to design calculations, ring wire 11. The load on each wire at the node a where the radial wire 9 and the hanging wire 10 intersect is as follows: If the load applied to each hanging wire 10 is Wl, W2, W3, then the inner radial wire 9'' has a tension F1 corresponding to W1, W1+W2 for outer radial wire 9″″
If the tension F2 corresponding to is made to work so that ``θ2 - θ1, then F2>F1 will always hold.In this case, if the hanging wire 1
Even if the wire 0 is damaged or the load is unbalanced, the radial wire 9 is maintained in an upwardly curved shape by the ring wire 11, and θ2≦θ1 is maintained, resulting in F2 minus F1. The horizontal components H2 and Hl of F2 and Fl are also H2>H1, and the horizontal force difference H2-H1 is applied to the ring wire 11 as shown in FIG. In the case of wire 11, tension R2 will be applied. As a result, tension is applied to the radial wire 9, cylinder wire 11, and suspension wire 10 in accordance with Wl, W2, and W3, so that each wire does not sag, so that the wires always maintain a constant shape when hanging the bottom plate, resulting in a stable It is possible to suspend the bottom plate, which can completely eliminate the bottom plate sagging phenomenon seen in the example of FIG. 7, which is the commonly conceived wire tensioning method.

Further, even in the case of a double shell type flat bottom cylindrical tank, the bottom plates of the inner tank or the inner and outer tanks can be suspended in the same manner as in the above embodiment.

Furthermore, if the above wire tensioning method is used, the bottom plate that has been assembled on the foundation in advance is lifted to a certain height from the foundation, held, and after the necessary upward welding, inspection, etc., is stably lowered onto the foundation again. Furthermore, as an alternative method, it can also be used to simply hold the bottom plate in the air.

When this invention is applied, a turnbuckle or the like is used as an auxiliary material to adjust the wire length, or an angle material or the like is used to temporarily reinforce the bottom plate to keep the bottom plate even more flat, or
In place of the wire, a partially rod-shaped member may be used.

As described above, according to the present invention, by using the bottom plate hanging device formed by the upwardly curved radial wire, ring wire, and hanging wire, it is possible to work on the bottom surface of the bottom plate, and the bottom plate is welded from the bottom surface. This makes it possible to improve the strength and quality of welding.Also, internal defect inspection such as X-ray transmission method becomes possible for welding inspection, improving the strength of welded joints and maximizing tank safety. You can make it higher.

In addition, when the bottom plate is hung, the bottom plate maintains its flat shape well, and since there is no unnecessary deformation of the bottom plate, there is no damage caused by hanging, and it is safe to work on the bottom surface.

In addition, it is only necessary to use wire as the bottom plate hanging member, which has advantages such as ease, low cost, and good workability.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures A and lb are explanatory diagrams of a bottom plate construction method based on the prior art, and Figures 2a and subsequent figures show embodiments of the present invention. However, FIG. 7 is an explanatory diagram for comparatively explaining the effects of this invention. Figures 2a to 2g are explanatory diagrams showing the process, Figure 3a is a side explanatory diagram, Figure 3b is a schematic plan explanatory diagram thereof, Figure 4 is a partial explanatory diagram of the bottom plate hanging member, and Figure 5 is an explanatory diagram of the bottom plate hanging member. This is a schematic side view, and FIG. 6 is an explanatory plan view of the a node. 5...Bottom plate, 9...
・Radial wire, 11...Ring wire, a
...Connecting part (node), 10... Hanging wire.

Claims (1)

[Claims] 1. When inspecting the bottom plate assembly and welding of a flat-bottomed cylindrical tank, a radial wire stretched in an upwardly curved shape, a ring wire connected to the radial wire, and a hanger suspended from the joint of the radial wire and ring wire were inspected. A bottom plate hanging method that uses a bottom plate hanging device made of wire to suspend the bottom plate while maintaining its flat shape, thereby making it possible to work on the bottom surface of the bottom plate.