JPH0313472B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in the pressure-resistant boundary structure of an external pressure type double bellows joint.

[Conventional technology]

Pipes used in nuclear power plants, such as those used in the primary cooling system of fast breeder reactors (hereinafter referred to as FBR), transport sodium at temperatures as high as 500°C, so the piping system is The material used is stainless steel or nickel alloy steel with high high temperature strength, and the outer surface is coated with a heat insulating material to reduce the amount of heat dissipated. The temperature of such piping during operation reaches 500°C, which is almost the same as the temperature of the fluid, which increases thermal stress due to thermal expansion of the piping and reduces the allowable stress of the piping material, resulting in the risk of damage to the piping system. will arise. Therefore, as a method to alleviate thermal stress, complicated piping is required, resulting in an increase in piping length, an increase in the number of hangers and dampers, an increase in insulation material, and an increase in pressure drop in the piping system. This causes an increase in plant construction costs, such as an increase in the pump capacity. In order to alleviate this increase in plant construction costs, it is necessary to provide expansion-contraction joints at predetermined positions in the piping system to absorb thermal expansion and make the piping system more compact. Since it is necessary to form a boundary against internal fluid leakage in order to prevent radioactivity from leaking out of the system, a bellows joint that maintains complete airtightness is used as an expansion-deflation joint. Furthermore, nuclear power plants are designed to maintain their integrity by using double bellows so that even if the bellows should be damaged, the safety of the plant will not be compromised. In other words, by installing the boundary part of the bellows in a double concentric circle with a boundary bellows and a back-up bellows, even if the boundary bellows is damaged, the back-up bellows will prevent the coolant from flowing out. At the same time, a leak detection device installed between the boundary bellows and the back-up bellows can immediately detect damage to the boundary bellows, prevent chain accidents in the plant, and improve plant safety. keeping. Therefore, quality control during the manufacturing of bellows joints is extremely important, and the manufacturing method requires sufficient testing and inspection. In particular, inspection of welded parts is necessary because the material used is stainless steel or nickel alloy steel.
Radiographic inspection is required as ultrasonic testing is not applicable.

The basic structure of the conventional external pressure type double bellows joint is
As shown in Fig. 3, a boundary bellows 1 and a back-up bellows 2 are arranged concentrically, and short pipes 3, 3' and 4, 4' are connected to both ends of these bellows. The ring plates 5 and 6 are connected by welding to form a boundary part, and the structure is such that the pressure of the fluid inside the pipe is applied as external pressure from the outside of the boundary bellows 1.

[Problem to be solved by the invention]

By the way, in the bellows joint as described above, the short pipes 3, 3' at both ends of the boundary bellows 1 and the short pipes 4, 4' at both ends of the back-up bellows 2 are welded to a common ring plate 5, 6. Therefore, the expansion-contraction of the boundary bellows 1 and the expansion-contraction of the back-up bellows were restricted to each other, and they could not be freely deformed individually, making it impossible to sufficiently absorb the thermal expansion of the piping. In addition, the welding shapes of the connecting portions A, B, C, D, E, and F between the short pipes 3, 3', 4, and 4' and the ring plates 5, 6 are fillet welds, and radiographic inspection is not possible.

Therefore, the present invention provides an external pressure type bellows joint in which the expansion-contraction of the boundary bellows and the expansion-contraction of the back-up bellows are not constrained by each other and can be freely deformed individually, and can sufficiently absorb the thermal expansion of piping. The present invention aims to provide a highly reliable external pressure multiple bellows joint by making all the welded parts that form the boundaries of the parts have a structure that can be inspected by radiation.

[Means to solve the problem]

The structure of the external pressure type multiple bellows joint of the present invention is that in the external pressure type multiple bellows joint in which backup bellows are arranged concentrically inside the boundary bellows, a skirt with a J-shaped cross section is provided at one end of the boundary bellows. and connect a short pipe to one end of the back-up bellows, and connect the other end of the short pipe to the inner bent end of the skirt having a J-shaped cross section,
The other end of the skirt having a J-shaped cross section is connected to the other end of an outer cylindrical tube arranged concentrically outside the boundary bellows via a ring-shaped joint member having a horizontally U-shaped cross section, and a shell is connected to one end of the outer cylindrical tube. , the shell is connected to the skirt, the outer bent end of the skirt having an inverted J-shaped cross section is connected to the other end of the boundary bellows, and one end of the skirt having an inverted J-shaped cross section is connected to an inner cylindrical pipe, One end of a short tube is connected to the other end of the boundary bellows, and the other end of the short tube is connected to the other end of the skirt having an inverted J-shaped cross section via a ring-shaped joint member having a horizontally U-shaped cross section. It is characterized by this.

[Effect]

The structure of the external pressure type multiple bellows joint configured as described above is such that the members to which both ends of the boundary bellows and both ends of the back-up bellows are connected can be individually displaced in the axial direction.
The expansion-contraction of the boundary bellows and the expansion-contraction of the backup bellows are not constrained by each other,
They can be individually deformed freely and can sufficiently absorb the thermal expansion of piping. Furthermore, the welded portions of the members sequentially connected to both ends of the boundary bellows and the members sequentially connected to both ends of the backup bellows have a circular tube shape that can be inspected by radiation. Therefore, an external pressure type multiple bellows with excellent reliability and soundness can be realized.

〔Example〕

One embodiment of the structure of the external pressure type multiple bellows joint of the present invention is explained in the case of a gimbal type bellows joint with reference to FIGS. Backup bellows arranged in concentric circles. A skirt 4 having a J-shaped cross section is connected to one end of the boundary bellows 1, and a back up bellows 2 is connected.
A short pipe 4' is connected to one end, the other end of the short pipe 4' is connected to the inner bent end of the skirt 4 having a J-shaped cross section, and the other end of the skirt 7 having a J-shaped cross section is connected to the boundary bellows 1. It is connected to the other end of an outer cylindrical pipe 7 arranged concentrically outside of the outer cylindrical pipe through a ring-shaped joint member 6 having a horizontally U-shaped cross section, and a shell 9 is connected to the other end of the outer cylindrical pipe 7. Skirt 10 is connected to 9.

On the other hand, the outer bent end of the skirt 3 having an inverted J-shaped cross section is connected to the other end of the back-up bellows 2.
One end of the skirt 3 is connected to the inner cylindrical pipe 7', one end of the short pipe 5' is connected to the other end of the boundary bellows 1, and the other end of the short pipe 5' has a transverse U-shaped cross section. It is connected to the other end of the skirt 3 having an inverted J-shaped cross section via a ring-shaped joint member 5, thereby forming a boundary between the boundary bellows 1 and the back-up bellows 2. The inner tube 7' is connected to the skirt 11. 12 is boundary bellows 1 and backup bellows 2
This is a gas pipe connection nozzle that supplies inert gas at a constant pressure to the space between the Reference numerals 13 and 13' designate flow sleeves, which are integrally connected to the skirts 10 and 11 by welding, respectively, and whose other ends are in sliding contact with each other to reduce the flow resistance of the fluid within the bellows joint. play a role. The two opposing shells 14, 14' are the skirts 10, 1
1, and is further rotatably joined by a pin 16 via connecting rings 15, 15'.

In the external pressure type multiple bellows joint of the embodiment configured as described above, one end of the boundary bellows 1 is connected to the skirt 4 having a J-shaped cross section, and the other end is connected to the short pipe 5. 5' are ring-shaped joint members 6, 5 each having a horizontally U-shaped cross section.
Since the boundary bellows 1 is connected to the outer cylindrical pipe 7 and the inner cylindrical pipe 7' through the Thermal expansion of the piping can be fully absorbed. Also, one end of the backup bellows 2 is connected to the short pipe 4',
The other end is connected to the outer bent end of the skirt 3, which has an inverted J-shaped cross section, and these short tubes 4' and the skirt 3 have a cross section of J.
Since it is connected between the inner bent end of the shaped skirt 4, the ring-shaped joint member 5 having a horizontally U-shaped cross section, and the inner cylindrical pipe 7', the members connected to both ends of the back-up bellows 2 are axially It can be freely displaced, the expansion and contraction of the back-up bellows 1 is not restricted, and it can sufficiently follow the thermal expansion of the piping.

Further, according to the structure of the external pressure type multiple bellows joint of the embodiment, the boundary portion composed of the boundary bellows 1 and the backup bellows 2 can be manufactured as follows. That is, as shown in FIG. 1, first, the outer bent end of the skirt 3 having an inverted J-shaped cross section is connected to the other end of the back-up bellows 2 by butt welding a short pipe 4' to one end, and then the short pipe 4' is connected to the other end of the back-up bellows 2. The inner bent end of the skirt 4 having a J-shaped cross section is butt-welded and connected to 1, and necessary predetermined tests and inspections are performed. Next, the back-up bellows 2 is inserted into the boundary bellows 1 with the short pipe 5' welded to the other end and set concentrically, and one end of the skirt 4 is butt-welded to one end of the boundary bellows 1 and connected. , carry out the necessary prescribed tests and inspections. After passing the test, the grooves of the ring-shaped joint member 5 having a horizontally U-shaped cross section are aligned with the skirt 3 and the short pipe 5' welded to the other end of the boundary bellows, and then butt welded, and necessary predetermined tests and inspections are carried out. . Next, one end of a ring-shaped joint member 6 having a horizontally U-shaped cross section is welded to the other end of the skirt 4 having a J-shaped cross section.
The other end and the outer tube 7, the outer tube 7 and the shell 9, and the shell 9 and the skirt 10 are sequentially butt-welded, and necessary predetermined tests and inspections are performed. On the other hand, the inner cylindrical pipe 7' is inserted into the inside of the back-up bellows 2 from the skirt 4 side, aligned with the skirt 3, and butt-welded.
Next, after the skirt 11 is butt welded to the inner tube 7', necessary predetermined tests and inspections are carried out. In this way, in the manufacturing procedure of the most important boundary part of the bellows joint, all weld lines are butt welded, which makes it possible to carry out all the required tests and inspections. Radiological examinations, which were previously impossible in the department, will now be possible.

[Effects of the Invention] As detailed above, the structure of the external pressure type multiple bellows joint of the present invention allows the members to which both ends of the boundary bellows and both ends of the back-up bellows are connected to be individually displaced in the axial direction. Therefore, the expansion-contraction of the boundary bellows and the expansion-contraction of the back-up bellows are not restricted to each other, and can be freely deformed individually, so that the thermal expansion of the piping can be sufficiently absorbed. In addition, the welded parts of the members sequentially connected to both ends of the boundary bellows and the members sequentially connected to both ends of the back-up bellows are all circular pipe shapes that can be butt welded, making it possible to perform radiographic inspection of the welded parts. It is. Therefore, a bellows joint with excellent reliability and soundness can be realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of an external pressure type multiple bellows joint according to the present invention, FIG. 2 is an enlarged sectional view of the main part thereof, and FIG. 3 is a sectional view of a conventional external pressure type double bellows joint. 1...Boundary bellows, 2...Back up bellows, 3, 4...Skirt, 5, 6...
Ring-shaped joint member, 9... shell, 10, 11...
…skirt.

Claims (1)

[Claims] 1 In an external pressure type multiple bellows joint in which back-up bellows are arranged concentrically inside a boundary bellows, a skirt with a J-shaped cross section is connected to one end of the boundary bellows, and a short skirt is connected to one end of the back-up bellows. After connecting the tube, the other end of the short tube is connected to the inner bent end of the skirt having a J-shaped cross section, and the other end of the skirt having a J-shaped cross section is connected to a boundary bellows through a ring-shaped joint member having a horizontally U-shaped cross section. A shell is connected to one end of the outer cylindrical tube, the shell is connected to a skirt, and the other end of the back-up bellows has an inverted J-shaped cross section. one end of the skirt having an inverted J-shaped cross section is connected to the inner cylindrical pipe, one end of a short pipe is connected to the other end of the boundary bellows, and the other end of the short pipe is connected to the outer bent end of the skirt of the boundary bellows. A structure of an external pressure type multiple bellows joint, characterized in that it is connected to the other end of the skirt having an inverted J-shape cross section via a ring-shaped joint member having a horizontal U-shape cross section.