JPS612993A - Expansion pipe 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 [Technical Field of the Invention] The present invention relates to an expansion pipe joint, and more particularly to an expansion pipe joint suitable for use in a piping system in which a lagoon fluid flows.

[Technical background of the invention and its issues]

Generally, in a lagoon where wet fluid flows, large temperature differences occur in the plant piping system as the plant starts and stops, resulting in significant expansion and contraction of the piping.

Therefore, in order to absorb this expansion and contraction of the piping, bent pipe joints and expansion pipe joints are provided in the piping system. Bent pipe joints are used in pairs, and the rigidity of the entire piping system is used to cope with expansion and contraction of the piping. On the other hand, an extensible pipe joint uses an extensible member such as an extensible bellows, and the expansion and contraction of the piping system is absorbed by this extensible member.

Figure 7: Piping connection part 1Δ of the 1U expansion pipe joint.

This figure shows a double expansion pipe joint in which two layers of expansion and contraction bellows are arranged between 1B and 1B. In this double expansion pipe joint, the inner expansion bellows constitutes the boundary bellows 3A, and the outer expansion bellows constitutes the backup bellows 3B.

Backup bellows 3B is boundary bellows 3
This is expected to have a function to prevent internal fluid from leaking if A is damaged.

Now, in such an expansion pipe joint, the boundary bellows 3A and the backup bellows 3B are expanded and compressed in proportion to fluctuations in the pressure of the working fluid in the piping. Due to this repeated deformation, both bellows 3A, 3B
Repeated stress is generated in the case, and both of these bells 3A and 3B become fatigued. This fatigue is particularly significant in double expansion pipe joints used in the primary system piping of fast breeder reactors. and,
This fatigue causes damage to the expandable bellows 3Δ, 3B, and is a factor in reducing the life of the expandable pipe joint.

Generally, in double expansion joints, the boundary bellows 3
Since A and the backup bellows 3B are formed in substantially the same shape, it is unclear which bellows 3A or 3B will break first due to the above-mentioned repeated fatigue. If the backup bellows 313 is damaged first, the fluid inside the R pipe may leak directly to the outside due to subsequent damage to the boundary bellows 3A. In order to avoid this leakage, the expansion pipe joint must be replaced while the life of the expansion joint is sufficiently secured, and this early replacement results in an increase in cost.

[Purpose of the invention]

This invention was made in consideration of the above facts,
Highly reliable expansion and contraction 1 that can prevent the leakage of fluid inside the piping and improve the safety of the piping system! The purpose is to provide fittings.

[Summary of the invention]

In order to achieve the above object, an expansion pipe joint according to the present invention has a multilayer expansion and contraction bellows interposed between piping connections, and the strength against forced displacement force acting on the piping is higher than that of the inner expansion and contraction bellows. The outer expandable bellows is set larger to prevent the outer expandable bellows from breaking before the inner expandable bellows, and to ensure that the fluid inside the pipe is dammed up by this outer bellows. This is what I did.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a half-sectional view showing a first embodiment of the expansion pipe joint according to the present invention. This expansion pipe joint 10 is a straight pipe type expansion pipe joint, and is applied to fast breeder reactors in which liquid metal sodium circulates and other chemical plants.

The opposing ends of the pair of piping connections 11A and 11B are expanded in diameter to form mounting bases 13A and 13B.

The mounting base 13A is provided with one-phase bellows fixing parts 15A and 16Δ formed in a concentric circular shape. On the other hand, similar bellows fixing parts 15B and 16B are formed on the mounting base 13B, and the bellows fixing part 15B is similar to the bellows fixing part 15B.
At A, bellows fixing parts 16B are provided corresponding to the bellows fixing parts 16A, respectively.

An inner bellows 17 is interposed between the corresponding bellows fixing parts 15A and 15B, and an outer bellows 19 is interposed between the corresponding bellows fixing parts 16A and 16B.

Among these, the outer layer bellows 19 prevents the fluid inside the pipe from leaking to the outside when the inner layer bellows 17 is damaged. In this sense, the inner bellows 17 is called a boundary bellows, while the outer bellows 19 is called a backup bellows.

Further, the outer bellows 19 is formed thinner than the inner bellows 17. As a result, the outer layer bellows 19 has a flexible structure, and is set to have high strength against strong displacement forces t and lJ in the axial direction of the pipe. In other words, in general, the relationship between the stress generated in the expandable bellows and the wall thickness of the expandable bellows is as follows: σP is the stress generated based on the internal pressure of the pipe, and σ is the stress generated based on the forced displacement force in the axial direction of the pipe. , the wall thickness of the telescopic bellows is t
Then, σ ■−:σr, oc j t is shown. Therefore, if the outer layer bellows 19 is made thin, the stress σ will increase and its strength against the internal pressure of the pipe will become weaker, but in return the stress σ will decrease and the force against forced displacement in the axial direction of the pipe will become weaker. increases in strength.

The wall thickness of this outer layer bellows 19 is σ1. σ. Considering
The lower limit is set at 30 to 40% of the inner bellows 17, and the range is set to be within the wall thickness of the inner bellows 17. Therefore, the strength of the outer layer bellows 19 against forced displacement force is:
For example, when the thickness of the outer layer bellows is 40% of the thickness of the inner layer bellows 17, it increases to about 2.5 times that of the inner layer bellows 17.

Further, a bellows retainer 1@21 is formed in the pipe connection portion 11A. This bellows protection cylinder 21 is formed to extend from the inside of the mounting base 13A toward the other pipe connection part 111'3, having approximately the same diameter as the pipe connection part 11A. This bellows protection tube 21 flows inside the pipe! % Alleviates damage to the inner bellows 17 caused by liquid metal sodium in the sea.

In the other piping connection part 11B, one or more leak detectors 23 are installed between the bellows fixing parts 15B and 16B. This leak detector 23 detects the presence of liquid metal sodium that has flowed in when the inner bellows 17 is damaged and liquid metal sodium has flowed between the inner and outer bellows 17,19.

Next, the action will be explained.

Even if a forced displacement force in the axial direction is repeatedly applied to the pipe in which liquid metal sodium is flowing in the pipe in which the expansion joint 10 is installed, this forced displacement force will be applied to the inside and outside of the expansion pipe joint 10. It is absorbed by the expansion and contraction of the layer bellows 17.19. In response to this forced displacement force, the outer bellows 19 has greater strength than the inner bellows 17, so if the forced displacement force acts repeatedly, the life of the outer bellows 19 will be shorter than that of the inner bellows 17. becomes longer. Therefore, the outer bellows 19 will not be damaged before the inner bellows 17 is damaged.

If the inner bellows 17 is damaged, the fluid inside the pipe will leak into the inner and outer bellows 17.191! leak detector 23 detects this and indicates the need for replacement of expansion joint 10. On the other hand, the internal fluid such as liquid metal sodium that has flowed between the inner and outer layer bellows 17 and 19
This prevents leakage to the outside.

In this way, the strength of the outer bellows 19 is made greater than that of the inner bellows 17 with respect to forced displacement force in the axial direction of the pipe, and the outer bellows 1
Since the outer bellows 9 is prevented from being damaged, leakage of the fluid inside the pipe can be reliably prevented by the outer layer bellows 19.

As a result, the reliability of the expansion pipe joint 10 is improved, and the safety of the piping system can be increased.

In addition, since the inner layer bellows 17 is configured to be damaged first by the outer layer bellows 19, and the leak detector 23 immediately detects whether or not the inner layer bellows 17 is damaged, the expansion pipe joint 10 is The damage condition can be quickly identified and the expansion joint can be replaced.

Therefore, the safety of the piping system in which the expansion pipe joint is installed can be improved.

Furthermore, the leak detector 2 detects whether or not the inner bellows 17 is damaged.
3 is configured to detect immediately, the expansion pipe joint 10 can be used until the inner layer bellows 17 is damaged, and the period of use 11 of the expansion pipe joint 10 is extended, thereby reducing costs. I can do it.

Furthermore, since the period of use of the expansion joint 10 can be extended, the number of replacements of the expansion joint 10 can be reduced, and the operating efficiency of fast breeder reactors and other plants can also be improved.

FIGS. 2 and 3 show a second example of the expansion pipe joint according to the present invention.
FIG. 10 is a half cross-sectional view showing each of the third embodiment and the third embodiment. In both of these embodiments, the same parts as in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

First, the second embodiment differs from the first embodiment in that the height of the extendable O-z is different. In other words, the height of the outer bellows 29 is greater than that of the inner bellows 27.

Generally, the relationship between the stress generated in the expandable bellows and the bellows height is as follows, where W is the bellows height. Therefore, if the height of the outer layer bellows 29 is made large, the stress σ generated based on the pipe internal pressure will increase and its strength will decrease against the internal pressure, but conversely, due to the forced displacement force in the pipe axial direction, the stress σ will increase. The stress σ generated by decreases, and the strength of the outer layer bellows 29 against forced displacement force increases. The height of the outer layer bellows 29 is determined by the stress σ2. σ. In consideration of this, the upper limit is about 1.6 to 1.7 times the height of the inner bellows 27, and the height is set within a range that is less than or equal to the height of the inner bellows 27. Therefore, the strength of the outer bellows 29 against forced displacement force increases to about 2.3 times that of the inner bellows 27, for example, when the height of the outer bellows 29 is 1.5 times the height of the inner bellows.

Next, the third embodiment is different from the first and second embodiments in that the number of bellows ridges of the inner layer bellows 37 and the outer layer bellows 39 are different, and the number of ridges of the outer layer bellows 39 is changed from the number of ridges of the inner layer bellows 37. This is because the number of units has been increased even more.

The relationship between the stress generated in the expandable bellows and the number of bellows ridges is as follows, where n is the number of bellows ridges. Therefore, when the number of peaks of the outer layer bellows 39 is increased, the stress σ generated based on the pipe internal pressure and the forced displacement force σ in the pipe axial direction
0 decreases, and the internal pressure and strong υ1 displacement force increase.

However, if the number of ridges in the outer layer bellows 39 is increased too much, an adverse effect such as bending of the bellows will occur.
The upper limit is 3 times, and any value below this is set within a range that is greater than or equal to the number of peaks of the inner layer bellows 37. For example, if the number of ridges of the outer bellows 39 is 2.5 times that of the inner bellows 37, the strength of the outer bellows 39 against forced displacement force will increase to about 2.5 times that of the inner bellows 37.

In this manner, also in the second and third embodiments, the strength of the outer layer bellows against forced displacement force increases, so the life of the outer layer bellows 29, 39 is longer than the life of the inner layer bellows 27.37, and the inner layer bellows 27.37 The outer bellows 29, 39 will not be damaged earlier. Therefore, as in the case of the first embodiment, the reliability of the expansion pipe joint is improved,
The safety of the piping system can be improved.

Furthermore, in both the second and third embodiments, the leak detector 23 is connected in the same way as in the first embodiment, so that the inner bellows 27, 37 can quickly replace damaged expansion joints. This embodiment has the same effects as the first embodiment, such as improving the safety of the piping system, reducing costs by using the inner bellows 27 and 37 to their serviceable limits, and improving the operating rate of the plant. can be achieved.

Figures 4 to 6 show the fourth example of the expansion pipe joint according to the present invention.
It is a half sectional view showing an example. 4, FIG. 5, and FIG. 6 correspond to FIG. 1, FIG. 2, and FIG. 3, respectively, and similar components are given the same reference numerals and explanations will be omitted.

In this fourth embodiment, reinforcing members 41, 43, 45 are attached to the outer periphery of the outer bellows 19, 29° 39. These reinforcing members 41, 43, 45 include a large number of reinforcing rings 41A,
43A and 45A are arranged in large numbers in the axial direction of the pipe, and each reinforcing ring 41A.

43A, 45A fit into one valley of the outer bellows 19.29.39.

Thus, in the fourth embodiment, the outer bellows 19.29
．． A reinforcing member 41. /13°45 is installed, so even if the outer layer bellows 19°29 is formed with a thin wall or a large bellows height and its strength against pipe internal pressure is reduced, the outer layer bellows will not be damaged by this pipe internal pressure. It can be prevented. Furthermore, even if the outer layer bellows 39 has an increased number of ridges and the bellows strength increases, the outer layer bellows can be reinforced by the reinforcing member 45.

For example, if the inner bellows 17.27.37 breaks and the fluid inside the pipe leaks into the human body, the outer bellows 19.29.3
Even if the internal pressure of the pipe acting on the pipe 9 exceeds the pressure limit of the outer bellows, the reinforcing member 41.43.45 protects the outer bellows 19.29.39. The bundling and prevention of breakage of the outer layer bellows 19, 29, 39 are ensured, the reliability of the expansion pipe joint is further improved compared to the first to fourth embodiments, and the safety of the piping system is improved. I can do it.

Other effects similar to those of the first to third embodiments can be achieved.

In each of the above embodiments, the expansion pipe joint is of a straight pipe type, but the present invention may be applied to a hinge type, gimbal type, or conniversal type expansion pipe joint.

When this invention is applied to a straight pipe type expansion pipe joint, the outer layer benz 17.27.3
However, when applied to hinge-type and gimbal-type expansion pipe joints, it is necessary to increase the strength of the outer layer base with respect to forced bending displacement force in the axial direction of the pipe. There are things out there. Furthermore, when applied to a 2I universal type expansion pipe joint, the strength of the outer layer bellows is increased with respect to the shear strength υ1 displacement force in the axial direction of the pipe. Regardless of whether it is applied to a hinge type, gimbal type or conniversal type expansion pipe joint, the reliability of the expansion pipe joint can be improved and the safety of the piping system can be increased. The same effects as those of the fourth embodiment can be achieved.

Further, in each of the above embodiments, a case has been described in which the expandable bellows is a double expandable pipe joint consisting of two layers, an inner and outer layer, but the expandable bellows may be configured of three or more layers. In this case, the strength against forced displacement force acting on the piping (forced displacement force in the axial direction of the piping (O force; forced bending displacement force in the axial direction of the piping, forced shearing displacement force in the axial direction of the piping) is provided on the outside. Preferably, the telescopic bellows is set to a certain size. Further, the leakage detector differs depending on the location of the expansion pipe joint, but for example, it is arranged between the outer layer bellows and the middle layer bellows, between the middle layer bellows and the inner layer bellows, or both.

Even when three or more layers of extensible bellows are provided, the same effects as in each of the embodiments described above can be achieved.

(Effects of the Invention) As described above, according to the expansion pipe joint according to the present invention, among the expansion bellows interposed in the outer layer, the outer expansion bellows has a strength higher than that of the inner expansion bellows against the forced displacement force acting on the pipe. Since it is set larger than that of , it is possible to reliably prevent the leakage of the fluid inside the piping, improve the reliability of the expansion pipe joint, and increase the safety of the piping system.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view showing a first embodiment of an expansion pipe joint according to the present invention, FIG. 2 is a half-sectional view showing a second embodiment, FIG. 3 is a half-sectional view showing a third embodiment, and FIGS. FIG. 6 is a half-sectional view showing the fourth embodiment, and FIG. 7 is a half-sectional view showing a conventional expansion pipe joint. 10... Expansion pipe joint, 11△, 11B... Piping connection part, 17.27.37... Inner layer bellows, 19°29
．． 39... Outer layer bellows, 23... Leak detector, 4
1.43.45...Reinforcement member.

Claims (1)

[Claims] 1. In a telescopic pipe joint in which multiple layers of telescopic bellows are interposed between pipe connections, the outer telescopic bellows has greater strength against the corrective deformation force acting on the pipe than the inner telescopic bellows. Expansion joint set. 2. The expandable bellows is composed of two layers, an inner and outer layer, and the strength of the inner bellows against forced deformation force acting on the piping is set to be greater than the strength of the outer bellows.
Expansion pipe joints described in section. 3. The expansion pipe joint according to claim 2, wherein the outer layer bellows is formed thinner than the inner layer bellows. 4. The expansion pipe joint according to claim 2, wherein the number of ridges on the outer layer bellows is greater than the number of ridges on the inner layer bellows. 5. The expansion pipe joint according to claim 2, wherein the bellows height of the outer layer bellows is set larger than that of the inner layer bellows. 6. The telescopic pipe joint according to any one of claims 1 to 5, wherein a reinforcing member is attached to the outer periphery of the outermost telescopic bellows. 7. The telescopic pipe joint according to any one of claims 1 to 6, wherein a leak detector is provided between the outer and inner telescopic bellows.