JP2002102966A - Long single barrel fabricating method for pressure vessel, repairing method, and manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture and repair even a large diameter pressure vessel with less man-hours and high quality and prolong the lifetime. SOLUTION: A steel plate 5 is cut in a prescribed length, bent parallel in the main rolling direction to fabricate a longitudinally curved piece 2, using a plurality of the longitudinally curved pieces 2, the curved pieces are juxtaposed in the circumferential direction in the linear state, the side rims of each longitudinally curved piece 2 are welded together to fabricate a ring-shaped longitudinal single barrel B, and the strain of the longitudinal single barrel B obtained is corrected. The longitudinal single barrel B is fabricated in the factory, transported to the site, where the deteriorated part of the existing pressure vessel is removed in a ring shape, and the new longitudinal single barrel B is peripheral-welded to the upper and lower barrel left in the existing pressure vessel to be joined together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The method of making the torso, the repair method and the manufacturing method using it
I do. In FIG. 5, FIG. I shows pressure vessel A before repair work.₀ 
Is shown. Pressure vessel A₀ Is a single cylinder b
Stacking and welding them together to join
A peripheral welding line c is formed. Pressure vessel A₀ Most of
An easily degraded part is located at the middle position of the trunk indicated by z in the figure.
Then, the upper and lower circumferential welding lines c ₀ , C₀ Even the other week
It deteriorates earlier than the welding line c. This degraded part
To repair the new body b₁ Figure II shows the new
Construction b₁ Above and below the new girth weld line c₁ , C₁ Ready
I have. The present invention is used for repairing such existing pressure vessels.
Technology for producing a single cylinder, and the existing pressure using that technology
On how to repair vessels and how to manufacture new pressure vessels.
You.

[0002]

2. Description of the Related Art A conventional method of completely removing and repairing a deteriorated girth weld line of an existing pressure vessel will be described with reference to FIG. First, as shown in I Figure, at the site where the pressure vessel A ₀ is installed to divide the body portion of the degraded peripheral weld line c ₀ vicinity several strip-like portion, by cutting the strip-shaped piece p ' After removal, as shown in Figure II,
A method is adopted in which new strip-shaped pieces p ₁ and p ₂ having the same dimensions are inserted and joined by welding. FIG. III shows a state in which all the strip-shaped pieces p ₁ , p ₂ , p ₃ .

[0003] However, the conventional method described above has the following disadvantages.
There is a problem. (1) A new torso using multiple strips
Welding work on site
And the workability is poor, requiring a long construction period.
You. (2) Stable quality welds due to large on-site welding volume
Risk of not being supplied. (3) Existing deteriorated girth weld line c due to repair₀ , C₀ Is excluded
But a new girth weld line c₁ , C_Two 
And this is the most easily degraded pressure vessel
As it exists in the part, like the existing deteriorated girth weld line,
New girth weld line c ₁ , C_Two Will deteriorate several years from now
Will need to be repaired again.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a method for repairing a girth weld line deteriorated during use, not only for a small-sized pressure vessel but also for a thin-walled large-diameter pressure vessel. ) Prolonged life of the pressure vessel by completely removing the deteriorated existing girth weld line and arranging a new girth weld line generated by repair work away from the easily deteriorated parts. (2) Installation of the pressure vessel The purpose of this project is to solve the two problems of minimizing the amount of work for on-site repair work and shortening the construction process. Another object of the present invention is to provide a pressure vessel having a long service life, in which even when a large-diameter pressure vessel is newly installed, a high-quality vessel can be manufactured with a small number of man-hours.

[0005]

According to a first aspect of the present invention, there is provided a method for producing a long single cylinder of a pressure vessel, comprising cutting a steel sheet into a predetermined length, bending the steel sheet in a direction parallel to the main rolling direction to form a vertically curved piece, Using a plurality of said longitudinally curved pieces, arranged in the circumferential direction in a vertically elongated state, welded the side edges of each vertically curved piece to create a ring-shaped long single cylinder, the obtained long single cylinder It is characterized by correcting distortion. The method for producing a long single cylinder of the pressure vessel according to claim 2 is the method according to claim 1, wherein a plurality of vertically curved pieces are welded to a temporary single cylinder in which side edges of the vertically curved pieces are temporarily welded to each other. Attach rails vertically,
An automatic MAG mounted on a bogie that runs up and down on this rail
The side edges of each vertically curved piece are joined by an automatic welding machine for welding, and then the rails are moved in the circumferential direction to sequentially weld the other side edges. According to a third aspect of the present invention, there is provided a method for producing a long single cylinder of a pressure vessel according to the first aspect of the present invention, wherein a method of correcting a distortion of a long single cylinder produced by welding a plurality of vertically curved pieces is used. A straightened portion of a long single cylinder is inserted between a straightening mold in which the molds are arranged in parallel and a hydraulic jack which is opposed to the two molds and is arranged so as to be movable up and down. And strain is removed by narrowing the pressure with the hydraulic jack. Claim 4
According to the method for repairing a pressure vessel, a long single cylinder is prepared in a factory according to the method of claim 1, and the long single cylinder is transported to the site, and the deteriorated portion of the existing pressure vessel is removed in a ring shape at the site. The new long single body is circumferentially welded and joined to upper and lower body portions remaining in the existing pressure vessel. According to a fifth aspect of the present invention, there is provided a pressure vessel manufacturing method, wherein a long single cylinder is formed in a factory by the method of the first aspect, and the long single cylinders are stacked up and down and welded to each other. It is characterized by producing a pressure vessel.

According to the first aspect of the present invention, since the cutting, bending, and welding operations required for producing a long single cylinder can be performed in a factory, it is possible to manufacture a quality-controlled long single cylinder. it can. In addition, a single cylinder with a large diameter can be easily created, and if a single cylinder with a long vertical dimension is created and replaced with a deteriorated body, the girth welding line can be located far away from the most susceptible part. Therefore, the life of the pressure vessel after the repair or the newly installed pressure vessel can be extended. According to the invention of claim 2, there are a plurality of welding lines for joining the side edges of the vertically curved piece, and the welding line length is long, but each of the automatic welding machines runs on a rail shape along the welding line. Since welding lines are welded, the welding quality is made uniform and the work efficiency is improved. According to the third aspect of the present invention, the distortion can be corrected by pressing the two vertically long molds, the hydraulic jack moving vertically and the long single cylinder, and the vertical movement of the hydraulic jack and the turning of the long single cylinder can be performed. In combination, the distortion of all parts of the long single cylinder can be removed. For this reason, since the roundness of the long single cylinder can be sufficiently ensured, it is possible to smoothly join the new long single cylinder and the existing trunk at the site, or to smoothly connect the new long single cylinders to each other. it can. According to the invention of claim 4, since the long single cylinder is completed at the factory, the amount of welding work on site in the repair work is reduced, the construction period can be shortened, and the roundness of the single cylinder can be sufficiently improved by straightening. Therefore, the connection with the existing trunk can be smoothly performed. According to the fifth aspect of the present invention, since a long, ring-shaped single body is used, the number of circumferential welding lines can be reduced, and a large-diameter pressure vessel can be easily manufactured. In addition, the life of the pressure vessel can be extended by using a long single cylinder having a vertical dimension in which the girth welding line is not located in a portion that is easily deteriorated in advance.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a work for producing a long single cylinder of the present invention, FIG. 2 is an explanatory view of a welding operation of the long single cylinder, and FIG. 3 is an explanatory view of a straightening operation of the long single cylinder.

First, a description will be given of a method of forming a long single cylinder constituting the body of the pressure vessel. (1) First, the longitudinally curved piece 2 is made by the method shown in FIG. That is, as shown in FIG. 1 (I), a steel sheet S is cut at a right angle to the rolling direction R, and a flat piece 1 having a predetermined size is cut.
Then, as shown in (II), the plate piece 1 is bent and formed by a press machine in parallel with the rolling direction to form a longitudinally curved piece 2.
Create Heretofore, it was common sense on the part of the manufacturer that a single cylinder of a pressure vessel bends at right angles to the main rolling direction of the steel sheet. This is due to the limitation of the rolling width at the time of steel sheet production, which is generally limited to 4 meters, and the problem of the capacity of a forming machine called a bending roller.
Generally, the length of a single body is less than 4 meters,
It is common knowledge that bending to be performed in parallel with the main rolling direction of a steel sheet, which is necessary for manufacturing a single cylinder having a length exceeding this (ie, a single cylinder having a length of 4 meters or more). Because it was not considered in the area. However, due to recent advances in rolled steel sheet manufacturing technology, even if a steel sheet is bent parallel to its main rolling direction, the mechanical properties of the steel sheet, such as strength, ductility, and toughness, will not change even if it is bent parallel to the rolling direction. It is recognized that there is no difference in bending in the direction, and the problem is gone.

(2) Next, as shown in FIG. 1 (III), a long single cylinder B is prepared. Therefore, a plurality of vertically long curved pieces 2 obtained by the method (1) are used, and are arranged in the circumferential direction.
A long single cylinder B is formed by welding the side edges to each other. In addition, the single cylinder of the thin large-diameter pressure vessel having a diameter of about 8 meters is usually (ie, when the length of the single cylinder is 4 meters or less), as shown in FIG. A flat piece 51 is formed by bending the flat piece 51 into a semi-cylindrical shape with a bending roller at right angles to the rolling direction R to form two body plates 52, and joining the two copper plates 52 in the circumferential direction. Then, it is manufactured as a single body b. However, in the present invention, as shown in FIG. 1, six or more vertically curved pieces 2 formed by bending are assembled and manufactured. Therefore, in the conventional method shown in FIG. 4, only two longitudinal welding lines are required. However, in the present invention, the number is six or more, and the manufacturing cost is usually high. But,
As will be described later with reference to FIG. 2, by assembling the single cylinder B in an upright state and performing welding so as to form a container as it is, the setup and routing for welding can be simplified, and as a result, Production costs can be reduced. In particular, when the length of the single body is longer than 4 m, the cost reduction effect is large.

(3) Next, a method for welding a long single cylinder suitable for the present invention will be described. The pressure vessel that is the object of the production method of the present invention uses a base material of a low alloy steel called chromium-molybdenum steel and a clad steel whose inner surface is made of stainless steel as a composite material. Therefore, welding of the base material and overlay welding of the inner surface are required. Reference numeral 10 in FIG. 2 (A) indicates a welding device 10 used for welding a base material. A bogie 12 equipped with an automatic welding machine is mounted on a rail 11 which is vertically mounted on a temporarily welded single cylinder B. It is configured to run up and down. The welding method used is high-efficiency automatic MAG welding (metal arc gas welding), which has approximately twice the welding efficiency compared to covered arc welding, which is usually applied to vertical welding of chromium-molybdenum steel. . In addition, it has been confirmed by a construction method test that there is no problem in the tensile strength, bending performance, impact performance, and the like required for the deposited metal. In terms of quality, the use of an automatic welding machine can provide more uniform quality than covered arc welding performed manually by a welder. When the welding of one welding line is completed, the rail 11 is moved in the circumferential direction, and each welding tangent is sequentially welded. In addition, even when the length of the single body B becomes longer, the construction can be performed by adding the rails 11.

Reference numeral 20 in FIG. 2B denotes a welding device used for overlay welding of the inner surface. The welding device 22 is mounted at the tip of a boom 21, and the boom 21 moves up and down on a column 23. It is. The welding device 20 is placed inside the single cylinder B. The welding method used is high-speed automatic TIG welding (tungsten-inert gas welding), which has a welding efficiency approximately five times that of manual TIG that is usually applied to vertical welding of stainless steel, nickel-based alloys, and the like. Further, it has been confirmed by a construction method test that there is no problem with respect to mechanical properties such as bending performance and chemical components required for the build-up deposited metal. In terms of quality, the use of an automatic welding machine will provide a more uniform quality than TIG welding performed manually by a welder. When welding of one welding line is completed, column 23
Is turned to build up each welding line in order. In addition, even when the length of the single body becomes long, the work can be performed by placing the column 23 on an appropriate base.

In the present invention, by applying such a welding method and apparatus, even if the length of the long single cylinder B becomes six or more, a long single cylinder satisfying the standard and the required quality can be manufactured at a low cost. It is possible to provide in.

(4) Next, a description will be given of a method for correcting distortion of the long single cylinder B obtained by the above method. Since the long single cylinder is joined by six or more longitudinal welding lines, it is difficult to ensure roundness. Since the pressure vessel is manufactured by joining the single cylinders with a girth welding line, if the roundness of the single cylinder is not ensured, the difference amount of the girth welding line exceeds the range allowed by the standard. Also, at the time of on-site repair work, the new torso is required to be a perfect circle in order to join the new single body and the existing torso smoothly. In the case of normal single cylinders, if distortion occurs due to longitudinal welding, it is possible to correct the distortion with bending rollers or press machines, but long single cylinders have dimensions where the length of the single cylinder does not fit into these machines. It cannot be corrected.

Accordingly, in the present invention, the straightening device 3 shown in FIG.
0 to correct distortion mainly caused by longitudinal welding. The straightening device 30 has two large columns 31 and 32, and a vertical rail-shaped mold 3 is provided on the inner surface of the outer column 31.
The straightening type is constituted by arranging 3, 34 in parallel, and a hydraulic jack 35 is mounted on the outer surface of the inner column 32 so as to be able to move up and down by a hydraulic cylinder or a chain. The single body B having undergone the longitudinal welding is put into the straightening device 30, the portion to be corrected is set in the span of the straightening dies 33 and 34, and the portion is pressed by the hydraulic jack 35 to correct the distortion.
In order to change the position of the hydraulic jack 35 up and down,
Can be corrected for the entire length. By correcting distortion using this correction device 30, it is possible to easily secure the roundness of the long single cylinder B having many longitudinal welding lines, which is originally difficult to correct.

The following method is used to use the long single cylinder B obtained by the above method for repairing an existing pressure vessel. the above
The long single cylinder B obtained by the manufacturing method of (1) to (4) is replaced with the single cylinder that has been removed due to deterioration of the existing pressure vessel, and the new long single cylinder B is left and right in the pressure vessel. It is repaired by welding to the torso.

According to the repair of the above-described embodiment, instead of welding all the divided new strip-shaped bodies at the site and correcting the bodies as in the prior art, a long single body of which quality is controlled is used. The following effects are obtained by being able to manufacture. (1) Since the vertical dimension of the long single cylinder B is long, the new girth welding line of the long single cylinder B is located farther away from the part where the deterioration of the pressure vessel is most likely to occur. It is possible to extend the life of the pressure vessel. (2) The amount of on-site welding work for repair work is reduced, and the work period can be shortened. (3) By automating welding in the manufacturing process of the long single cylinder B at the factory, high efficiency and labor saving can be achieved, and an inexpensive single cylinder can be supplied. (4) We can supply stable quality welds welded by automatic machines because the number of weldings performed in the factory increases. (5) The roundness of the long single cylinder B can be sufficiently secured, It is possible to smoothly perform a joint when joining a new single body and an existing body.

The following method is used to use the long single cylinder B obtained by the above-mentioned manufacturing method for manufacturing a new pressure vessel. In a factory, two or three or more long single cylinders B are vertically stacked and welded to each other, and this is repeated to produce a pressure vessel having a predetermined height. By joining the long single cylinders B manufactured in the factory in this way, the circumferential welding line can be reduced as compared with a container manufactured by a general single cylinder manufacturing method. For example, when the length of the body is a container having a length of 24 meters, in a general manufacturing method, six single bodies having a length of 4 meters are spliced together. And the number of circumferential welding lines can be reduced by three. In the case where the girth weld line of the pressure vessel deteriorates selectively, manufacture a pressure vessel using a long single cylinder with a long vertical dimension in advance, and separate the girth weld line from the easily degraded part. Thus, the life of the pressure vessel can be extended.

[0018]

According to the first aspect of the present invention, it is possible to manufacture a long single cylinder controlled in quality in a factory, and to extend the life of a repaired or newly installed pressure vessel. According to the second aspect of the present invention, by automating the welding of the long single cylinder, the welding quality is made uniform and the work efficiency is improved. According to the third aspect of the present invention, since the roundness of the single body can be sufficiently secured by correcting the distortion, it is possible to smoothly perform the joint when the long single body is joined. According to the invention of claim 4, since a long single cylinder is completed in the factory, the amount of welding work on site in the repair work is reduced, and the work period can be shortened. According to the fifth aspect of the present invention, the life of the pressure vessel can be extended by using a long single cylinder having a size in which the girth welding line is not located in a portion which is easily deteriorated in advance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an operation for producing a long single cylinder of the present invention.

FIG. 2 is an explanatory view of a welding operation of a long single cylinder.

FIG. 3 is an explanatory diagram of a straightening operation of the long single cylinder.

FIG. 4 is an explanatory diagram of a conventional method for producing a single cylinder.

FIG. 5 is an explanatory view of a problem in a conventional pressure vessel repair method.

FIG. 6 is an explanatory view of a conventional method for repairing a pressure vessel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate piece 2 Vertically curved piece B Long single cylinder 10 Welding device 20 Welding device 30 Straightening device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B21D 51/10 B21D 51/18 B 51/18 G21C 13/00 X

Claims (5)

[Claims] 1. A steel sheet is cut into a predetermined length, and bent in a direction parallel to a main rolling direction to form a vertically curved piece, and a plurality of said vertically curved pieces are arranged in a circumferential direction in a vertically elongated state.
A method for producing a long single cylinder of a pressure vessel, characterized in that a side edge of each vertically curved piece is welded to form a long single cylinder of a ring shape, and distortion of the obtained long single cylinder is corrected. 2. A method of welding a plurality of vertically curved pieces, wherein a rail is vertically attached to a temporary single body in which side edges of the vertically elongated pieces are temporarily welded to each other, and attached to a bogie traveling up and down on the rail. 2. The automatic welding machine according to claim 1, wherein the side edges of the longitudinally curved pieces are joined by an automatic welding machine for welding, and then the rails are moved in the circumferential direction to sequentially weld the other side edges. How to make a long single cylinder for a pressure vessel. 3. A straightening method for a long single body made by welding a plurality of vertically curved pieces, wherein a straightening type in which two vertically long dies are arranged in parallel and a two-type die are opposed. The straightened portion of the long single cylinder is inserted between hydraulic jacks that are vertically movably disposed, and the straightened portion is narrowed by the straightening die and the hydraulic jack to remove distortion. Item 2. A method for producing a long single cylinder of the pressure vessel according to Item 1. 4. A long single cylinder is produced in a factory according to the method of claim 1, the long single cylinder is transported to a site, and a deteriorated portion of an existing pressure vessel is removed in a ring shape at the site. A method for repairing a pressure vessel, characterized in that a new long single body is circumferentially welded and joined to upper and lower body parts left in an existing pressure vessel. 5. A long single cylinder is produced in a factory according to the method of claim 1, the long single cylinders are stacked up and down and welded to each other, and this is repeated to produce a pressure vessel having a predetermined height. A method for producing a pressure vessel, comprising: