JPS62127591A - Multilayer bellows joint - 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 [Industrial Application Field] The present invention relates to an improvement in the structure of a part of a pressure-resistant pounder in a bellows joint, and particularly to the structure of a multilayer bellows joint with improved soundness.

[Prior art and its problems] Piping used in nuclear power plants, for example, piping used in the primary cooling system of fast breeder reactors (hereinafter abbreviated as FBR), transports high-temperature sodium that can reach up to 500°C. , its resistant surface is coated with a heat insulating material to reduce the amount of heat dissipated. As a result, the material temperature of the piping system reaches approximately 500°C, which is almost the same as the fluid temperature, which increases thermal stress due to thermal expansion of the piping and reduces the allowable stress of the piping material, resulting in damage to the piping system. Danger arises. Relieving the thermal stress requires complicated piping, which increases the length of the piping, resulting in an increase in the number of hangers, damper insulation materials, etc., and an increase in pressure drop, which reduces the circulation pump capacity. This increase will cause an increase in plant construction costs. As a means of reducing the increase in plant construction costs, bellows joints are provided at predetermined positions of the piping system to absorb thermal expansion and make the piping system more compact.

However, in an atomic couplant, it is necessary to prevent radioactivity from leaking outside the system, so the bellows part, which forms the boundary for internal fluid leakage to the outside, is designed to prevent the safety of the plant from being compromised even if it is damaged. Attempts have been made to create a structure that maintains its soundness by using layered bellows. That is, by installing the boundary bellows and the backup bellows in a double layer in a concentric circle in a part of the boundary, even if the boundary bellows is damaged, the backup bellows will work to prevent the coolant from flowing out, and It is designed to stop between these two bellows.

However, further damage to the backup bellows will lead to the leakage of coolant to the outside, so in order to prevent chain accidents, it is necessary to shut down the plant at the same time as the boundary bellows breaks, increasing plant operating costs. becomes a factor. Therefore, there has been a demand for the development of a bellows joint that allows plant operation to continue without impairing the integrity of the bellows joint even if the boundary bellows is damaged.

[Object of the Invention] The present invention was made in view of the above-mentioned technical problems, and aims to provide a multilayer bellows joint with higher reliability by increasing the structural integrity of the bellows portion. .

[Structure of the Invention] The multilayer bellows joint of the present invention has one or more layers of backup bellows arranged concentrically inside or outside of a boundary bellows, and the peaks and valleys of the bellows between each layer are arranged alternately. The bellows joint parts are connected to both ends of each bellows to form a boundary part, and the number of threads on each bellows forming the boundary part is set to be larger than the number of threads on the outer bellows than on the inner bellows. Make more,
The positions of the bellows joint parts and the joints of each bellows are made so that they do not interfere with each other, and the joints can be butt welded, thereby making radiographic inspection possible.

An embodiment of the present invention will be described in detail regarding a case of a bellows joint that receives external pressure. FIG. 1 shows a sectional view of a gimbal type bellows joint showing one embodiment of the present invention, and is an example of a two-layer bellows joint. 1 is the backup bellows,
Boundary bellows 2 are arranged concentrically outside the backup bellows, and skirts 3 and 4 are welded to both ends of these bellows. Reference numeral 5 denotes a gas pipe connection nozzle for monitoring the health of the boundary bellows 2 by passing inert gas at a constant pressure into the space between the boundary bellows 2 and the backup bellows 1. 6. 6' is a flow sleeve installed inside the backup bellows 1, and one end of it is connected to the duct 7 and 7'.
The bellows joint is welded and connected so as to be integral with the bellows joint, and the other ends are in sliding contact with each other, which serves to reduce the flow resistance of the fluid within the bellows joint. As shown in FIG. 2, the backup bellows 1 and the boundary bellows 2 are arranged concentrically outside the backup bellows 1 with the mountain 1a of the backup bellows 1 and the boundary bellows 2.
The inner backup bellows 1 is arranged so that the valleys 2a of the inner bellows 1 are located at opposing positions, and the number of peaks of the inner backup bellows 1 is two fewer than that of the outer boundary bellows 2. Therefore, the welded part A between the skirt 3 and the backup bellows L, the boundary bellows 2 and the skirt 4
and the joint part B are relatively shifted by one mountain. Furthermore, even when the number of calendars is increased to create a multilayer structure as shown in the figure, the bellows arranged concentrically on the outside of the bellows have two more peaks than the inner bellows as described above. Then, shift the parts to be welded and joined at both ends by one thread from the inside.

Two opposing shells 8,8' are connected by direct welding to the ducts 7 and 7', which are connected via a connecting ring 9 to a pin 10. First, in the manufacturing procedure of the boundary part consisting of the pack-a-mum bellows 1 and the boundary bellows 2, as shown in Figure 2, first the backup bellows L and the skirt 3.3'
are butt-welded at points A and A' and perform the necessary predetermined tests and inspections. Boundary bellows 2 after passing inspection
The procedure is to weld the skirts 4 and 4' at points B and B'', respectively.At this time, the relative positions of A and B and A' and B' are shifted by one thread of the bellows, so when welding Not only will there be no adverse effects such as spatter on the backup bellows 1 installed on the inside, but also radiation inspection, which is an important inspection for welded parts, will ensure that the welded parts of each bellows and skirt have the same cross section. This is possible because there is no overlap with H.Also, even if the number of bellows is increased as shown in the figure, the bellows placed on the outside has one more thread at both ends than the bellows placed on the inside. Because of this, the welded portions of the bellows and skirt are shifted by one thread from each other, making radiographic inspection possible for the reason described above.

[Effects of the Invention] As detailed above, the multilayer bellows joint of the present invention has a structure in which each bellows is welded to the skirt connected to both ends of the boundary bellows and backup bellows in the boundary bellows portion. The bellows arranged on the outside have more threads than the bellows arranged on the inside, and each end has at least one thread more than the bellows arranged on the inside, so that the welded area between the bellows and the skirt is relatively at least one thread. Since the deviation is by the amount of the peak, not only is there no direct adverse effect on the bellows part during welding, but also radiological inspection is now possible, making it possible to provide a bellows joint with excellent soundness.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a multilayer bellows joint according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the contact area 'Id between the bellows and the skirt in the case of a multilayer bellows. 1...Backup bellows 2...
...Boundary Bellows 3.4...Skirt Applicant Kawasaki Heavy Industries, Ltd. Figure 1 Figure 2

Claims (1)

[Claims] One or more layers of backup bellows are arranged concentrically inside or outside the boundary bellows so that the peaks and troughs of each layer of bellows overlap alternately, and bellows joint parts are connected to both ends of each of these bellows to form a boundary section. 1. A multilayer bellows joint, characterized in that the outer bellows have a greater number of threads than the inner bellows.