JPS60192196A - Sealing structure of end section of hollow body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for closing an end of a hollow body, and particularly relates to a structure for attaching an end plate of a header that handles high-pressure fluid.

Thermal power plants, nuclear power plants, chemical plants, etc. often handle high-temperature and/or high-pressure fluids, so Figure 1 shows the structure of a commonly used header placed in the flow path. show. In this structure, an end plate 2 having the same outer diameter as the main pipe is arranged at the end of the main pipe 1, and both are joined by full-thickness butt welding 4a. Reference numeral 3 is a nozzle holder connected to the main pipe.

Here, if the end plate 8 is manufactured by the rolling method, layer defects (lamination) may occur along the rolling direction of the metal due to scratches, segregation of non-metals such as sulfur components (sulfur band), generation of air bubbles, etc. ) occurs. When actually using the header, the end plate tends to bulge outward due to the force of the internal fluid, but in this case, if there is a lamination 5 as shown in Figure 1, this stress will cause the lamination to peel off, preventing it from becoming healthy. Cracks may develop in other parts as well. For this reason, the effective thickness is the thickness t up to the lamination 5 with respect to the design required thickness T, and there is a risk that it will not be able to withstand the internal pressure and break, resulting in a major accident. There is a method to prevent this by using forged materials, but there is a problem that forged materials are considerably more expensive than rolled materials.

FIG. 2 shows a structure in which end plates of rolled material are used and the above-mentioned drawbacks are compensated for. In this case, the end plate 2 is inserted into the main pipe 1 and welded 4b for the entire required design thickness of the end plate 2.
That is.

This method increases the strength considerably, but the end plate 2 tends to bulge as shown in 2, which causes Ml, M2
Because of the bending moment acting, some progress of the lamination 5 is still unavoidable. Furthermore, stress tends to concentrate at the welded part due to this moment, so there is concern about the welding strength itself. Furthermore, if the main pipe 1 is made of rolled material, the weld 4b is a type of butt welding shown in FIG. .

This invention was constructed in view of the above-mentioned problems,
It is an object of the present invention to provide an end closing structure that does not advance lamination existing in a rolled material.

In short, the present invention is an end closing structure in which a welding groove is formed at the end of a hollow body such as a header so as to cover the entire thickness of both the hollow body and the end plate.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, the end of the main tube 1 is formed into a cylindrical main tube, for example, so that the inner circumferential wall thereof is inclined at a constant angle α with respect to the center line 6 of the main tube. On the other hand, the end plate 2 is also formed into a substantially trapezoidal shape to correspond to this shape, for example, a truncated cone shape for a cylindrical main pipe. By arranging this end plate 2 at the end of the main pipe 1, a welding groove is formed in the shape of a substantially truncated cone for a cylindrical main pipe and a trapezoidal shape for a square main pipe, and Join by welding. That is, welding is performed so as to cover the entire thickness of both the main pipe 1 and the end plate 2.

Therefore, when the wall thicknesses of the main tube 1 and the end plate 2 are approximately equal, the inclination angle α of the groove is approximately 45°.

FIGS. 4 and 5 schematically show the arrangement of the main pipe and end plates to show the difference in strength between the conventional structure and the structure according to the present invention.

Figure 4 shows the state of the end plate prepared by the method shown in Figure 2 (assuming that the wall thickness of the end plate and the main pipe are equal); in this case, the end plate 2 is centered at point P due to moment M. Try to rotate in the direction of the arrow. - The structure of the present invention shown in Figure 5 of the force cylinder attempts to rotate around point P, and the thickness of both is W. Since W2 is the W piece W2, the angle α formed with the axis 6 is approximately 45°, and the effective thickness at lamination 5* is 1
In contrast, the welding width is 1, which is approximately 1.4 times that in Fig. 4. Since stress is concentrated in this weld, an increase in the area of the weld increases the strength of the end plate attachment. This also applies to the main tube side, so even if lamination exists in the main tube 1, this lamination can be prevented.By implementing this invention, rolled materials that may have laminations can be prevented. There is no risk of lamination progressing when used on end plates or base metals, and the effective thickness up to lamination can be effectively increased, so it can increase not only the welding strength but also the strength of the member. can.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of the main pipe showing the conventional mounting structure of the end plate to the main pipe, Fig. 2 is a partially cutaway side view of the main pipe showing another conventional mounting structure, and Fig. 3 is a partially cutaway side view of the main pipe showing the structure according to the present invention, FIGS. 4 and 5 are conceptual diagrams showing the state of welding the main pipe and the end plates, FIG. 4 shows the conventional type, and FIG. 5 shows the conventional type. respectively show the methods according to the present invention. 1... Tube main tube 2... End plate 4...
・・・Welding part 5・・・Lamination 1. ,−
1. -,,-1. -1-〆〆\Figure 1 Figure 4 Figure 5 etc.

Claims (1)

[Claims] 1. In a structure in which the end of a hollow body such as a header main pipe is closed by an end plate, the weld groove is formed to include both the thickness of the hollow body and the thickness of the end plate. A hollow body with a closed end structure. 2. The hollow body according to claim 1, wherein the groove is formed such that the end cross section is substantially trapezoidal and the welding center line is located diagonally with respect to the hollow body center line. End closure structure.