JPS6219296A - Method for fixing steel pipe cylindrical body for water treating apparatus in ultradeep layer - Google Patents

Abstract

PURPOSE:To easily repair-coating the part where paint is peeled off by inserting the leading end of a coating spray gun from the outer surface of a steel pipe through a small hole in the vicinity of the butt-joint welded part of the steel pipe and coating the welded part of the steel pipe on the inner surface side which has been butt-joint welded. CONSTITUTION:Steel pipes 20 of specified length whose inner surfaces are coated are successively connected by butt-joint welding to form an ultradeep- layer water treating steel pipe cylindrical body which is hung down in a vertical shaft 30 in the earth. In the fixing method, a small hole 23 is previously made in the vicinity of the butt-joint welded part 38 of the steel pipe 20. The leading end of a coating spray gun 40 is inserted from the outer surface side of the steel pipe 20 and the welded part on the inner surface side of the steel pipe which has been butt-joint welded is coated by the spray gun 40. Consequently, the part where paint is peeled off due to the welding can be easily repair-coated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for installing a steel pipe cylinder for an ultra-deep water treatment device.

[Conventional technology]

As shown in Figure 6, the ultra-deep water treatment equipment
An outer cylinder 1o and an inner cylinder 12 are provided at a depth of about m, and the water to be treated 14 is transferred to the outer cylinder 10.m. The water to be treated is primarily biologically purified by circulating it between the inner cylinders 12 and applying aeration or the like.

This equipment is compared to the conventional planar activated sludge method.

It has the advantages of high processing efficiency and requires a small amount of land area, so it has been adopted in many places in recent years.

By the way, when constructing this device, an important issue is how to install the outer cylinder 10 and the inner cylinder 12 underground. When these cylindrical bodies are manufactured by pouring concrete, installing the formwork becomes a difficult task. For this reason, in the past, steel pipes of a predetermined length (for example, I Im) with the necessary diameters (for example, an outer cylinder diameter of 3 m, an inner cylinder diameter of 2 m) were sequentially joined by butt welding, and the pipes were installed underground. The method used was to hang it down into the ditch.

However, in order to maintain corrosion resistance, this steel pipe has
Corrosion-resistant paint is usually applied to the inside and outside surfaces of steel pipes, and this paint melts and flakes off due to the heat during welding. For this reason, after welding the steel pipes together, it is necessary to repair and paint the vicinity of the welded portion.

Repair painting of the outer surface of steel pipes is relatively easy, but repair painting of the inner surface of steel pipes has been a challenge. Attempts have also been made to move a gondola suspended by a crane into a steel pipe barrel suspended underground and apply repair paint from the gondola, but this is extremely dangerous. Furthermore, in order to reduce the influence of earth pressure and prevent soil collapse, slurry liquid such as bentonite is often filled in the ditch. In this case, repair painting is not possible on the part of the cylinder submerged in the slurry liquid, so repair painting must be done at ground level.To do this, the steel pipes are welded together and then repaired immediately. Needs to be painted. For this reason, repeated welding and repair painting became complicated, which also caused problems in terms of work safety.

[Problem that the invention seeks to solve]

The object of the present invention is to repair and paint the welded parts on the inner surface of the cylinder even in a method of installing a cylinder for an ultra-deep water treatment system in which steel pipes are successively joined by butt welding and suspended into an underground ditch. An object of the present invention is to provide a method for easily installing the cylindrical body.

[Means for solving problems]

The present invention involves drilling a small diameter hole in advance near the butt weld of the steel pipe, inserting the tip of a spray gun for painting into this hole from the outside of the steel pipe, and welding the inner surface of the steel pipe after butt welding. The method is characterized in that the portion is painted with the spray gun.

If the tip of the spray gun can be inserted into the small diameter hole.

Preferably, the diameter is as small as possible, usually 4 to 6 diameters. It is preferable that three or more holes be provided along the circumferential direction of the steel pipe.

[For production]

A spray gun inserted into a small diameter hole can be used to repair and paint welds on the inner surface of steel pipes. After the repair painting is completed, sealing can be ensured by screwing a plug into the hole. For this reason.

Unlike the conventional technology, there is no need to lift the gondola inside the cylinder and perform repair painting, which is preferable in terms of work efficiency and work safety.

〔Example〕

Embodiments of the present invention will be described below based on one drawing.

FIG. 2 shows preparations for processing a steel pipe in advance in order to carry out the present invention.

The steel pipe 20 has a diameter that can be used as a cylinder for an ultra-deep water treatment device, and for example, the outer cylinder has a diameter of 3 m, and the inner cylinder has a diameter of about 2 m. For example, the length.

The 11m one is delivered to the construction site. Therefore, if the length of the inner and outer cylinders required for ultra-deep water treatment equipment is 110 m, using steel pipes of the above length, ten steel pipes can be joined by butt welding, and one inner and outer cylinder each can be joined. will be formed. The steel pipe 20 is coated with corrosion-resistant paint on its inner and outer surfaces, and a plurality of small-diameter holes 22 are bored in the vicinity of its lower end (right end in FIG. 2). The diameter of this hole is about 4 to 6α as described above. In addition, steel pipe 20
A plurality of rod members 24 are attached to the outer surface of the upper end (left end in FIG. 2) of the rod member 24 so that some of the rod members 24 protrude from the upper end.

This rod member 24 is used for mutual positioning of steel pipes to be butted,
The purpose is to facilitate skin matching. Further, a plurality of hanging fittings 28 are attached to the outer surface at a position approximately 1 m below the upper end (on the right side in FIG. 2). This hanging metal fitting 28
is used when lifting one steel pipe 20 or a cylindrical body made of connected steel pipes with a crane, and to engage with a support member 36 to be described later to transmit the load of the steel pipe or the cylindrical body to the support member.

The above-described machining of the holes 22 and installation of the rod members 24 and hanging fittings 28 can be carried out on the ground with good workability, and damage to the painted parts of the inner and outer surfaces of the steel pipe caused by these operations can be easily done on the ground as well. It can be repaired.

Figure 3 shows the general method of installing the cylinder. A bentonite slaly IJ liquid 32 is filled in a vertical trench 30 dug underground. First, the steel pipe 20 which is to constitute the lowermost end of the cylinder 10 or 12 is lifted up to a state by a crane 34, and then gradually inserted into the vertical groove 30 to bring it to state B. In state B, a cylindrical support member 36 is extended from a work platform 35 provided around the ground position of the vertical ditch 30, and the hanging fitting 28 attached to the steel pipe 20 is engaged with the support member 36. Therefore, the load on the steel pipe 20 is
4 moves on to the support member 36. After lifting the primary steel pipe 20 to state A using the crane 34 in the same manner as described above,
The upper end of the steel pipe 20 supported by the support member 36 and the lower end of the steel pipe 20 suspended by the crane 34 are brought close to a position where butt welding is possible. At this time, the rod member 24 attached to the upper end of the steel pipe 20 facilitates mutual positioning and skin alignment of the steel pipes.

FIG. 4 shows an enlarged view of the steel pipes 20 butted against each other. In the state shown in the figure, the butt portions 38 of the steel pipes are tack welded at several locations in the circumferential direction to integrate the steel pipes, and then the rod member 24
is removed from the steel pipe 20 by gas cutting or no-maring. Next, weld the entire circumference of the butt part. By this book welding.

The paint on the inner and outer surfaces of the steel pipe near the welds peels off. Therefore, as shown in Fig. 1, a small diameter hole 22 provided in the upper steel pipe
Insert the tip of the paint spray gun and repaint the peeled paint area. As shown in FIG. 5, the small diameter holes 22 are provided at multiple locations around the steel pipe 20.

Therefore, by sharing the painting area to be sprayed from each hole, it is possible to cover the inner peripheral surface (repair painting).The hole 22 can also be used by one person. From hole 22.

The internal spray status can be checked and this information can be communicated to the painter. Note that if the diameter of the steel pipe is large, a situation may arise in which the sprayed paint does not reach the opposing inner surface of the steel pipe. therefore.

In this case, a number of holes 22 may be provided and the positions near the holes 22 may be sequentially spray-painted, or the nozzle of the spray gun may be elongated and specially processed to extend the reach. After the repair painting work is completed, a blind plug is inserted into the hole 22. Therefore, it is preferable to make the hole 22 a threaded hole in advance so that the blind plug can be easily inserted.Also, when repairing the outer surface of a steel pipe, it is not necessary to follow the above-mentioned procedure. .

The work platform 35 also allows for easy work.

After all the repair painting is completed, the entire cylinder is lifted up by the crane 34 and suspended from the support member 36 by the hanging metal fittings 2.
8 apart and in this state.

Using gas cutting or other means for the hanging fittings 36.

Separate from the surface of the steel pipe 200. By separating the hanging fitting 28, the outer surface of the cylinder can pass through the penetration area of the support member 36. By lowering the rope of the crane, the hanging fitting 28 of the upper steel pipe 20 and the support member 36 are engaged.

Thereafter, by sequentially repeating the same operations as above, the installation of the cylinder can be completed.

〔Effect of the invention〕

According to the present invention, when steel pipes whose inner surfaces are painted are successively joined by butt welding and suspended into an underground trench, it is possible to easily repair and repaint the peeled-off portions of paint caused by welding. Therefore, there is no need to perform dangerous and complicated work using a gondola or the like as in the conventional technology.

[Brief explanation of the drawing]

1 to 5 are diagrams showing embodiments of the present invention,
Figure 1 is a side cross-sectional view showing the situation in which the inner surface of a steel pipe cylinder is painted, Figure 2 is a partially cutaway side view showing the preparation before processing into a steel pipe, and Figure 3 is the general installation method of the cylinder. Fig. 4 is a partially cutaway side view showing the steel pipes butted against each other, Fig. 5 is a plan cross-sectional view showing the position of small diameter holes in the steel pipes, and Fig. 6 is an ultra-deep water FIG. 2 is a side sectional view showing an outline of the processing device. 20...Steel pipe, 22...Small diameter hole 30
... Vertical groove, 38 ... Butt weld part 4
0...Spray gun. Figure 4

Claims (1)

[Claims] In a method for installing a steel pipe cylinder for an ultra-deep water treatment device, in which steel pipes of a predetermined length with painted inner surfaces are successively joined by butt welding and suspended into an underground ditch, the butt welded portion of the steel pipes is A small diameter hole is pre-drilled near the steel pipe, and the tip of a spray gun for painting is inserted into this hole from the outside of the steel pipe, and the welded part on the inside of the steel pipe that has undergone the butt welding is painted with the spray gun. A method for installing a steel pipe cylinder for an ultra-deep water treatment device, characterized by: