JPH0211360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting welds of flat-bottomed cylindrical tank corner sections.

[Prior art and its problems] Large cylindrical tanks are generally used to store large quantities of liquids such as petroleum, LPG, and LNG. The construction method for this type of flat bottom cylindrical tank is
Annular plates are installed on the foundation (bottom cold insulator, etc.) constructed at the construction site, and then. Currently, the side plates and bottom plate are welded.

With this construction method, it is impossible to inspect the welding points between the annular plates, the welding points between the annular plate and the side plate, and the welding points between the annular plate and the bottom plate using radiation, and it is almost impossible to confirm the presence or absence of internal defects in the welded parts. In addition, large bending stress due to hydraulic pressure acts locally on the side plate, and furthermore, welding distortion that tends to warp the annular plate or bottom plate occurs when welding the side plate. However, it had serious drawbacks such as being easily damaged due to its structure.

In order to eliminate such defects,
As seen in Publication No. 51106, corner sections with curved corners of unequal thickness and convex end shapes are inserted between the lowermost side plate and the annular plate. Although techniques have been proposed to eliminate the above-mentioned drawbacks by doing so, at least the problem of radiological inspection of the welds between the corner sections remains unsolved.

However, although the applicant has proposed that this inspection method can be solved by having each corner section section suspended above the foundation,
With simple radiographic inspection, there is an element of uncertainty in the inspection in that uniform penetration of radiation cannot be obtained due to the uneven thickness of the corner sections as mentioned above, and this problem has not been resolved. .

The purpose of the present invention has been made in response to these circumstances, and by using a simple jig, uniform radiation penetration can be achieved, and accurate weld inspection can be carried out easily and quickly. The purpose is to provide an inspection method.

[Means for Solving the Problems] The configuration of the present invention that solves the problems of the prior art includes making the corners between the lowermost side plate and the bottom plate (including the annular plate) curved surfaces of unequal thickness, In addition, in the method for inspecting a welded part of a corner section of a flat-bottomed cylindrical tank in which a corner section with a convex end shape is inserted, By placing the corner sections on top of each other, or by providing a recessed part in the foundation corresponding to the joining weld between the corner sections, the corner section can be installed with a space formed below the joining weld between the corner sections. After welding the corner sections together, the welding points between the corner sections are made so that the corner sections conform to the unequal thickness curved surfaces of the corner sections and whose upper surfaces are shaped like the corner section. One parallel to the bottom of the material, or
A plurality of jigs are fitted to make the radiation transmittance uniform, and the corner part of the corner part is placed in contact with the bottom surface of the corner part using the above space. Perform non-destructive inspection of curved surfaces of unequal thickness and joint welds in a horizontal position, and then apply a film to one end face of the vertically uniform thickness part of the corner section without using a jig. In this state, a non-destructive inspection is performed on the joint welded portion of the corner section in a vertical position.

[Example] Fig. 1a shows a state in which the corner section material is raised above the foundation surface, that is, it is placed on a pedestal 17 disposed on the foundation surface, and is formed between this pedestal 17 and the foundation. Weld the corner sections 1 together using the space 18,
Furthermore, a construction method is shown in which the lowermost side plate 2 is welded and inspected on top of the lowermost side plate 2, and FIG. This figure shows means for welding the lowermost side plate 2 and the bottom plate 3 together using the space 18 formed by the concave portion 19 in the same manner as described above. After inspection, concrete is poured and filled into the depression.

FIGS. 2 to 5 show a welded part inspection when the unequal thickness curved surfaces 4a and 4b formed at both corners of the corner section 1 are irregular curved surfaces without being constituted by R. Shows the means.

In this case, as shown in FIG. 2, a jig 7 is provided with a curved surface 5a that fits a part of one curved surface 4a of unequal thickness, and has a surface 6 whose upper surface is parallel to the bottom surface of the corner section 1. are adapted as shown in the figure, and a radiation inspection is performed in the direction shown by the arrow with the film 8 in contact with the bottom surface of the corner section 1 using the space 18.

Further, as shown in FIG. 3, the same radiographic examination as described above is performed using the same jig or another jig 9 having a curved surface 5b that matches the other curved surface 4b of unequal thickness. Further, the horizontal portion of the corner section 1 having the same thickness may be subjected to conventional radiation inspection without using this type of jig.

After this inspection, as shown in FIG. 4, curved surfaces 5c and 5b are provided that fit the remaining portions of the unequal thickness curved surfaces 4a and 4b, and each end surface is parallel to the vertical surface of the corner member 1. jig 12 having surfaces 10, 11;
13, the film 14 is brought into contact with the surface 10 of one of the jigs 12, and radiation is transmitted from the other side in the direction of the arrow, thereby completing the inspection of this curved surface portion. Note that for the equal thickness portions on the vertical sides of the corner section profile 1, conventional radiographic inspection is sufficient without using a jig.

FIG. 5 shows an embodiment in which the walls of the jigs 12 and 13 shown in FIG. 4 are made thinner to improve inspection accuracy.
13a and 13b are divided into four types and tested separately.

In the embodiment shown in FIGS. 6 to 8, both R-curved surfaces 15 and 15 of the corner section 1 have the same radius.
5, 15, and the same two jigs 1 are used to inspect the horizontal part and the vertical part of the corner section.
All tests are completed by using 6.
In addition, it goes without saying that for inspection of horizontal and vertical sections of equal thickness, conventional radiographic inspection can be performed without using a jig, as shown by the imaginary lines in Figure 8. be.

[Effects of the Invention] As described above, according to the configuration of the present invention, the following effects can be obtained.

Even when corner sections with curved surfaces of unequal thickness are used, the uniformity of the radiation transparency of the joint weld between the corner sections can be achieved using a jig, allowing accurate and error-free welding. It has excellent features such as being able to quickly carry out inspections, and combined with the effects of the corner section material, to further strengthen the corner sections of the flat-bottomed cylindrical tank.

[Brief explanation of drawings]

Figures 1a and 1b are partial longitudinal sectional front views showing the welded joints of the corner sections, and Figures 2 to 8 are cross-sectional views showing inspection means for the welded corner sections, respectively. be. 1...Corner section material, 2...Lowermost side plate, 3...
Bottom plate, 4a, 4b...unequal thickness curved surface, 5a, 5b...
...Curved surface, 6... Surface, 7... Jig, 8... Film, 9... Jig, 10, 11... Surface, 12, 1
3, 12a, 12b, 13a, 13b... jig,
14... Film, 15... R curved surface, 16... Jig, 17... Mount, 18... Space, 19... Recessed portion.

Claims (1)

[Scope of Claims] 1. Corner sections with curved corners of unequal thickness and convex end shapes are inserted between the lowermost side plate and the bottom plate (including the annular plate). In the method for inspecting the welded parts of flat-bottomed cylindrical tank corner sections, the above-mentioned corner sections are placed on a pedestal placed on the foundation surface, or the corner sections are attached to each other. By providing a concave part in the foundation corresponding to the joint weld,
After welding the corner sections to each other with a space formed below the joint weld between the corner sections, weld the corner sections together at the welded points between the corner sections. A jig consisting of one or more jigs that conforms to the unequal thickness curved surface of the corner section and whose top surface is parallel to the bottom surface of the corner section section to make the radiation transparency uniform, Utilizing the space above, non-destructive inspection of the unequal thickness curved surface of the corner section of the corner section and the joint weld in the horizontal position was carried out with the film in contact with the bottom surface of the corner section section. Then, without using a jig, the vertical equal-thickness part of the corner section was fixed with a film in contact with one end surface of the joint weld in the vertical position of the corner section. A method for inspecting a welded part of a corner section of a flat-bottomed cylindrical tank, characterized by carrying out a non-destructive inspection.