JP7039630B2 - Flexible pipe connection structure - Google Patents

Description

The present invention relates to a flexible pipe connection structure in which fixed pipes for supplying a fluid such as liquid or gas are connected to each other via a metal flexible pipe.

When connecting an industrial pipe, for example, a metal flexible pipe (hereinafter, simply referred to as a flexible pipe) as disclosed in Patent Document 1 may be used at the connecting portion. Since the flexible pipe has flexibility, by connecting the pipes to each other via the flexible pipe, for example, even if the core of each pipe is misaligned, the connection can be easily performed. Further, when one or both of the pipes are to be connected in a swingable state, a flexible flexible pipe is used for the connection portion.
In addition, the flexible pipe absorbs the vibration generated by devices such as rotating machines and pumps to reduce the propagation of vibration, and the thermal expansion and contraction of the pipe caused by the temperature of the fluid flowing through the pipe. It may be used for the purpose of absorbing by a flexible pipe and preventing damage to the connection part.

Flexible pipes are parts that are prone to fatigue fracture due to their repeated expansion and contraction and fluctuations. Therefore, the installation work is done carefully so that the distance between the connected pipes is adjusted accurately and there is no deviation or inclination so that the durability performance can be maximized.
Further, for example, when a flexible tube is used for an application in which a liquefied gas flows intermittently, large heat shrinkage and expansion are repeated, so that fatigue fracture is particularly likely to occur. Therefore, more accurate mounting work is required. Furthermore, flexible tubes made of austenitic stainless steel with a large coefficient of thermal expansion also have a large thermal deformation, so great care must be taken to prevent fatigue. Further, when it is mounted on a vehicle such as a lorry that constantly vibrates during traveling, high mounting accuracy is also required.

An example of a pipe connection structure using a flexible pipe as described above will be described with reference to FIG. FIG. 11 is a side view showing a state in which a pair of fixed pipes (fixed pipes 3) are connected via a flexible pipe 5, and only the pipe portion is shown in a cross-sectional view.

In the conventional flexible pipe connection structure 51 shown in FIG. 11, the flexible pipe 5 is arranged between a pair of fixed pipes 3 arranged at predetermined intervals, and a flange provided at the end of each fixed pipe 3 is provided. The fixed pipes 3 are connected to each other by fixing the (fixed side flange 9) and the flanges (flexible side flanges 21) provided at both ends of the flexible pipe 5 with a plurality of connecting bolts 11 and connecting them.

In the flexible pipe connection structure 51 as described above, an annular sealing material such as an O-ring 33 or a gasket 35 is provided at the connecting portion 7 of the flexible side flange 21 and the fixed side flange 9 so as to surround the flow portion. The airtightness is ensured so that the fluid flowing in the pipe does not leak from the connecting portion 7.

Japanese Patent No. 5937345

The above-mentioned O-ring 33, gasket 35, etc. need to be inspected, replaced, repaired, etc. on a regular basis in order to ensure their airtightness. Some metal flexible pipes 5 have a certain degree of rigidity, and it may be difficult for the operator to shrink the flexible pipes 5. In such a case, the fixed pipe 3 connected to the flexible pipe 5 or the device itself is displaced from a predetermined position to create a gap between the flexible side flange 21 and the fixed side flange 9, and the O-ring 33 or the gasket is formed. The 35 etc. are removed and installed.

However, when the flexible tube 5 is reattached to the fixed tube 3, it is necessary to carefully attach the flexible tube 5 with high accuracy as described above, and there is a problem that it takes a lot of time to attach the flexible tube 5.
Further, if the position of the fixed tube 3 deviates from the initial position when the fixed tube 3 and the flexible tube 5 are reconnected, the predetermined durability performance of the flexible tube 5 cannot be obtained, which causes an economic problem. Occurs. Further, when the internal fluid is dangerous, it is not preferable in terms of safety.

The present invention has been made to solve such a problem, and the removal and attachment of the O-ring or the gasket provided at the connecting portion between the fixed pipe and the flexible pipe can be performed without moving the fixed pipe from a predetermined position. It is an object of the present invention to provide a flexible tube connection structure that can be performed.

(1) The flexible pipe connection structure according to the present invention includes a fixed pipe having a fixed side flange at an end portion and a flexible pipe portion having a flexible pipe portion and having a flexible side flange on at least one end side of the flexible pipe portion. The fixed pipe and the flexible pipe are connected by connecting the flexible side flange to the fixed side flange to form a connecting portion, and the fixed side flange or the flexible side flange to be connected is connected. One of them is characterized in that a plurality of push bolt screw holes for screwing push bolts for forming a gap in the connecting portion by compressing the flexible pipe portion are provided. Is.

(2) Further, in the one described in (1) above, the plurality of push bolt screw holes are provided at positions rotationally symmetric with respect to the center of the fixed side flange or the flexible side flange. It is characterized by.

(3) Further, in the one described in (1) or (2) above, the thickness of the fixed side flange or the flexible side flange which is further provided with the push bolt and in which the screw hole for the push bolt is formed is a. When the maximum reduction length of the flexible tube is b, the length of the shaft portion of the push bolt is set to a + b or less.

(4) Further, in any one of the above (1) to (3), the connecting bolt hole for inserting the connecting bolt connecting the flexible side flange and the fixed side flange is the flexible side. A plurality of push bolt screw holes are provided on the flange and the fixed side flange, and the push bolt screw holes are provided at a position intermediate between adjacent connecting bolt holes in the circumferential direction.

In the present invention, the push bolt is screwed into the push bolt screw hole by having a plurality of push bolt screw holes for screwing the push bolt into either the fixed side flange or the flexible side flange. By doing so, the flexible tube portion can be compressed to form a gap in the connecting portion. This makes it possible to remove and attach the O-ring or gasket without moving the fixed tube from a predetermined position.

It is a figure explaining the flexible tube connection structure which concerns on one Embodiment of this invention. It is a figure explaining the screw hole provided in the flexible side flange which concerns on one Embodiment of this invention. It is a figure explaining the state at the time of inspection / replacement of the O-ring or the gasket in the flexible pipe connection structure which concerns on one Embodiment of this invention. It is a figure explaining another aspect of the flexible tube connection structure which concerns on one Embodiment of this invention. It is a figure explaining the state at the time of inspection / replacement of the O-ring or the gasket in another aspect of the flexible pipe connection structure which concerns on one Embodiment of this invention (the 1). It is a figure explaining the state at the time of inspection / replacement of the O-ring or the gasket in another aspect of the flexible pipe connection structure which concerns on one Embodiment of this invention (the 2). It is a figure explaining another aspect of the screw hole provided in the flexible side flange which concerns on one Embodiment of this invention (the 1). It is a figure explaining another aspect of the screw hole provided in the flexible side flange which concerns on one Embodiment of this invention (the 2). It is a figure explaining another aspect of the screw hole provided in the flexible side flange which concerns on one Embodiment of this invention (the 3). It is a figure explaining the application example of the flexible pipe connection structure which concerns on embodiment of this invention. It is a figure explaining the conventional flexible pipe connection structure.

As shown in FIG. 1, the flexible pipe connection structure 1 according to the embodiment of the present invention is arranged between a pair of fixed pipes 3 arranged at predetermined intervals and a pair of fixed pipes 3. A flexible pipe 5 is provided, and both ends of the flexible pipe 5 are connected to the fixed pipe 3 to form a connecting portion 7, thereby connecting the fixed pipes 3 to each other.
Hereinafter, each configuration will be described in detail. Note that FIG. 1 shows a side view of the flexible pipe connection structure 1, and only the pipe portion is shown in a cross-sectional view. Hereinafter, FIGS. 3 to 6 will be illustrated in the same manner.

<Fixed tube>
The fixed pipe 3 is a metal pipe for supplying a fluid such as a liquid or a gas to an apparatus or the like, and has a fixed side flange 9 at an end on the side connected to the flexible pipe 5. The other end is connected to a fixed device, pipe, etc. (not shown).

≪Flanged side flange≫
The fixed side flange 9 is for connecting the fixed pipe 3 to the flexible pipe 5, and has a plurality of connecting bolt holes 13r for inserting the connecting bolt 11. An opening 15r for allowing fluid to flow is provided in the center of the fixed-side flange 9, and a groove 17r for arranging an O-ring or a gasket so as to surround the opening 15r (see FIG. 3). Is provided.

<Flexible tube>
The flexible pipe 5 is a flexible metal pipe, and has a flexible pipe portion 19 and flexible side flanges 21 provided at both ends of the flexible pipe portion 19.

≪Flexible pipe part≫
The flexible tube portion 19 is composed of a tubular bellows tube 23 having a bellows shape and a cover 25 that covers the outside of the bellows tube 23. The cover 25 is formed by knitting a strip of stainless steel, and protects the thin-walled and easily damaged bellows tube 23.

≪Flexible side flange≫
The flexible side flange 21 is for connecting the flexible pipe 5 to the fixed pipe 3, and has a connecting bolt hole 13f at a position corresponding to the connecting bolt hole 13r of the fixed side flange 9. An opening 15f for allowing fluid to flow is provided in the center of the flexible side flange 21, and a groove 17f for arranging an O-ring or a gasket so as to surround the opening 15f (see FIG. 3). Is provided.

Further, the flexible side flange 21 has four push bolt screw holes 29 for screwing the push bolt 27 used for compressing the flexible pipe portion 19. As shown in FIG. 2, the four push bolt screw holes 29 are arranged so as to be inside the flexible side flange 21 in the radial direction from the connecting bolt hole 13f and to be rotationally symmetric with respect to the center.

The method of compressing the flexible pipe portion 19 by using the push bolt 27 will be described later, but the reason why the push bolt screw hole 29 is located radially inside the connecting bolt hole 13f and close to the center of the flexible side flange 21. This is because the flexible side flange 21 is less likely to tilt when the flexible pipe portion 19 is compressed by the push bolt 27.
Further, the reason why the four push bolt screw holes 29 are arranged so as to be rotationally symmetric is that the push bolt 27 is arranged by minimizing the tilt of the flexible side flange 21 when the flexible pipe portion 19 is compressed by the push bolt 27. This is so that it can be screwed in.
That is, such an arrangement is suitable without impairing workability even when applied to a flexible tube having low flexibility (hard to be deformed).

Note that rotational symmetry is a property that when an n-degree figure is rotated around a certain point, it overlaps with the figure before rotation (also referred to as n-degree symmetry), and point symmetry (180-degree symmetry) is also included.

<Connecting part>
The connecting portion 7 is a portion where the fixed side flange 9 and the flexible side flange 21 are connected. The connecting bolt 11 is inserted into the connecting bolt holes 13r and 13f, and the fixed side flange 9 and the flexible side flange 21 are fastened by screwing the nut 31 into the connecting bolt 11.

Grooves 17r and 17f provided on both flanges are arranged to face each other on the contact surface between the fixed side flange 9 and the flexible side flange 21 in the connecting portion 7, and an O-ring 33 or a gasket 35 is installed in the groove portions 17r and 17f. ing. The O-ring 33 and the gasket 35 are ring-shaped sealing materials, and are for preventing the fluid flowing in the pipe from leaking from the connecting portion 7.

In the present embodiment, an example in which the O-ring 33 is arranged on one connecting portion 7 and the gasket 35 is arranged on the other connecting portion 7 of the flexible tube 5 is shown, but the present invention is not limited to this, and the present invention is not limited to this, for example. O-rings 33 or gaskets 35 may be placed on both.

The method of replacing the O-ring 33 in the flexible pipe connection structure 1 according to the present embodiment described above will be described below with reference to FIG.

When removing or attaching the O-ring 33, first loosen or remove all the nuts 31 screwed to the connecting bolt 11 at the connecting portion 7 on one side (right side in the figure) to compress the flexible pipe 5. Make it possible. At this time, since the connecting bolt 11 is still inserted into the connecting bolt holes 13r and 13f, the axes of the flexible pipe 5 and the fixed pipe 3 are maintained in a state in which they are not easily displaced.

After that, when the push bolt 27 is screwed into the push bolt screw hole 29 from the flexible pipe 5 side, the tip of the push bolt 27 reaches the end surface of the fixed side flange 9. Further, when the push bolt 27 is screwed in, the flexible side flange 21 moves in the direction of the flexible pipe portion 19 by the length of the shaft portion of the push bolt 27 protruding from the push bolt screw hole 29, so that the flexible pipe portion 19 is compressed. , As shown in FIG. 3, a gap 37 can be formed between the fixed side flange 9 and the flexible side flange 21. By forming the gap 37, the O-ring 33 provided in the connecting portion 7 can be easily taken out or attached from the gap 37.

At this time, since the push bolt screw holes 29 are arranged rotationally symmetrically with respect to the center of the flexible side flange 21, both flange surfaces can be maintained in parallel, and the connecting bolt 11 is parallel to the pipe axis. Since it supports directional movement, work can be done easily.

After attaching the O-ring 33, by turning the push bolt 27 in the direction opposite to the screwed direction, the compressed flexible pipe portion 19 is returned to the original state, and all the nuts 31 are screwed into the connecting bolt 11 again. Then, the replacement work of the O-ring 33 is completed.
FIG. 3 illustrates a state in which the push bolt 27 is screwed into one connecting portion 7 of the flexible pipe 5, but similarly, the gap 37 is formed in the other connecting portion 7 by the above-mentioned method to form the gasket 35. Can be exchanged.

Since these series of operations can be performed without moving the fixed pipe 3 from a predetermined position, the work time can be shortened as compared with the conventional method in which the position of the fixed pipe 3 is shifted. Furthermore, by proceeding with the work without removing the connecting bolt 11, the central axes of the flexible pipe 5 and the fixed pipe 3 do not deviate significantly, and a series of work is completed while maintaining the adjusted state when the equipment is installed. can do.

If the gap 37 is made too large, the compression limit of the flexible pipe 5 may be exceeded and the flexible pipe portion 19 may be damaged. Therefore, the screwing amount of the push bolt 27 is the maximum reduction value of the flexible pipe 5. It is preferable to take this into consideration.
In this respect, when the thickness of the flexible side flange 21 on which the screw hole 29 for the push bolt is formed is a and the maximum reduction length of the flexible pipe 5 is b, the length of the shaft portion of the push bolt 27 is set to a + b or less. It is preferable to set it. By doing so, for example, as shown in FIG. 3, even if the push bolt 27 is screwed in as much as possible, the length of the shaft portion protruding from the flexible side flange 21 does not exceed b, so that the flexible pipe 5 is compressed. It is possible to prevent the flexible tube 5 from being damaged due to exceeding the compression limit without shrinking beyond the limit.

Further, as another method for preventing the flexible pipe 5 from being compressed more than a predetermined amount, the push bolt 27 itself is marked with a screwing limit, or when the push bolt 27 is screwed in more than a predetermined amount, the push bolt 27 spins idle and is screwed in further. A known technique such as a mechanism for preventing the bolt may be applied.

In the above, the example in which the flexible side flange 21 is provided with the push bolt screw hole 29 has been described, but as shown in FIG. 4, the fixed side flange 9 may be provided with the push bolt screw hole 29. Similarly, in such a case, when the push bolt 27 is screwed into the push bolt screw hole 29, as shown in FIG. 5, the tip of the push bolt 27 protruding from the fixed side flange 9 pushes the flexible side flange 21 and is flexible. The side flange 21 moves in the direction of the flexible pipe portion 19, and the flexible pipe portion 19 is compressed. As a result, a gap 37 can be formed between the fixed side flange 9 and the flexible side flange 21.

Further, in the above example in which the push bolt screw hole 29 is provided on the fixed side flange 9, the thickness of the fixed side flange 9 is a, the maximum reduction length of the flexible pipe 5 is b, and the shaft portion of the push bolt 27. It is more preferable to set the length of the flexible tube 5 to a + b or less because the flexible tube 5 does not shrink beyond the compression limit.

In the examples described with reference to FIGS. 1 and 3 to 5, both ends of the flexible pipe 5 are connected to the fixed pipe 3 by connecting bolts 11, but the present invention is not limited thereto. For example, the flexible pipe connection structure 39 shown in FIG. 6 is an example in which only one end side of the flexible pipe 41 is connected to the fixed pipe 3 by a connecting bolt 11, and the other end side is connected to the fixed pipe 3 by welding or the like. The flexible pipe 41 shown in FIG. 6 has a flexible pipe flange 21 at one end and a pipe joint 41 at the other end, and the pipe joint 43 and the fixed pipe 3 are welded and connected. Even in the above example, the present invention is effective when replacing the O-ring 33 on one end side.

Further, regarding the arrangement of the push bolt screw holes 29, in the above example, four push bolt screw holes 29 are provided rotationally symmetrically with respect to the center of the flexible side flange 21. Is not limited to this, and the number of screw holes 29 for push bolts may be a plurality, and in the case of three, for example, they are arranged as shown in FIG.
Further, when the flexibility of the flexible tube is large (prone to deformation), the arrangement of the push bolt screw holes 29 does not necessarily have to be rotationally symmetric, and even if the arrangement is as shown in FIG. 8, for example. good. The three push bolt screw holes 29 shown in FIG. 8 have the center of gravity of the triangle formed by the broken line in the figure deviated from the center of the flexible side flange 21, and are rotationally symmetric with respect to the center of gravity of the triangle. This is an example that is not rotationally symmetric with respect to the center of the flexible side flange 21.
When the flexibility of the flexible tube is large, the resistance of the flexible tube is small even if the flexible side flange 21 is slightly tilted when the push bolt 27 is screwed in, so that the push bolt 27 can be screwed in and the flexible side flange. Even if the 21 is slightly tilted and bending stress acts on the flexible tube, there is little risk of damaging the flexible tube, so the arrangement shown in FIG. 8 is also allowed.

Further, regarding the relative positional relationship between the connecting bolt hole 13f and the push bolt screw hole 29, the example shown in FIG. 2 is an example in which the push bolt screw hole 29 is radially inside the connecting bolt hole 13f. However, the present invention is not limited to this, and the position of the push bolt screw hole 29 in the radial direction is outside the connecting bolt hole 13f or the same (on the broken circle connecting the connecting bolt holes 13f). You may.

Further, in the example shown in FIG. 2, the connecting bolt hole 13f and the push bolt screw hole 29 are arranged on the same linear line in the radial direction of the flexible side flange 21, but in this case, the connecting bolt located on the outer side in the radial direction. The connecting bolt 11 inserted into the hole 13f makes it difficult to see the push bolt screw hole 29 inside in the radial direction, and when the diameter of the flexible side flange 21 is small, the connecting bolt hole 13f and the push bolt screw The position with the hole 29 becomes close, and it may take time to work in a narrow site or the like.
Therefore, as shown in FIG. 9, by arranging the push bolt screw holes 29 so as to be located in the middle of the circumferential direction of the connecting bolt holes 13f adjacent to each other in the circumferential direction, the connecting bolt holes 13f and the push bolt screws are arranged. It is preferable because it can be separated from the hole 29 and does not hinder workability.

The action and effect of the flexible pipe connection structure 1 of the present invention will be described based on specific examples.
In this embodiment, the O-ring replacement work was carried out in the flexible pipe connection structure installed in the liquid nitrogen lorry 45 as shown in FIG. In the liquid nitrogen lorry 45, the liquid nitrogen in the storage tank 47 on the vehicle is introduced into the pump 49 through the fixed pipe 3 and the flexible pipe 5, pressurized by the pump 49, and supplied to the customer's liquid nitrogen storage tank or the like. .. The fixed pipe 3 and the pump 49 are connected by a flexible pipe 5 in order to prevent metal fatigue from occurring in the storage tank 47 and the fixed pipe 3 due to vibration during operation of the pump 49.

First, as a conventional example, the O-ring 33 was replaced in the flexible pipe connection structure 51 (see FIG. 11) not provided with the push bolt screw hole 29. As a method, the bolt fixing the pump 49 was loosened, the pump 49 having a weight of about 80 kg was moved, and then the O-ring 33 was replaced. After that, the position of the pump 49 was adjusted with an accuracy of ± 1 mm or less so that the flexible tube 5 was not subjected to extra displacement or residual stress. This work took an hour.

Further, as another method using the conventional example, the O-ring 33 was replaced by securing a gap 37 between the flange surfaces with a commercially available wedge, crowbar, or the like without moving the pump 49. This method requires a person for securing a gap 37 between flange surfaces, a person for inserting an O-ring 33, two workers, and a plurality of tools. In addition, there was a high risk because two workers work in a narrow space. This work took 30 minutes.

Subsequently, the O-ring 33 was replaced in the flexible pipe connection structure 1 (see FIG. 1) provided with the push bolt screw hole 29 described in the embodiment of the present invention. In the method shown in FIG. 3, the only tool required to create the gap 37 for O-ring replacement is the tool for turning the push bolt 27, and the work by one worker takes 3 minutes. Met.
In the example of the present invention, the working time can be significantly reduced without increasing the number of personnel. In addition, the work can be done safely, and no specialized knowledge or advanced skill is required.

Although the material of the flexible tube 5 is not limited in the above embodiment, the flexible tube 5 through which liquefied gas (liquid nitrogen, liquid oxygen, liquid air, etc.) flows like the liquid nitrogen lorry 45 of the present embodiment. As the material of the bellows tube 23, austenite-based stainless steel typified by SUS304 is often used. Austenitic stainless steels are generally rich in ductility and toughness, have good cold workability such as deep drawing and bending, and have excellent weldability, and also have excellent corrosion resistance and excellent properties at low and high temperatures.
On the other hand, the coefficient of thermal expansion of austenitic stainless steel is large among stainless steels, and the thermal deformation is large. In the case of this embodiment in which the temperature difference between the use state and the maintenance state is large, it is difficult to secure the gap 37 required for O-ring replacement because the bellows tube 23 is thermally expanded during maintenance. Met.
Therefore, when the bellows tube 23 of the flexible tube 5 is made of austenitic stainless steel, the application effect of the present invention can be further obtained.

1 Flexible pipe connection structure 3 Fixed pipe 5 Flexible pipe 7 Connecting part 9 Fixed side flange 11 Connecting bolt 13r Connecting bolt hole (fixed side flange)
13f Connecting bolt hole (flexible side flange)
15r opening (fixed side flange)
15f opening (flexible side flange)
17r groove (fixed side flange)
17f groove (flexible side flange)
19 Flexible pipe part 21 Flexible side flange 23 Bellows pipe 25 Cover 27 Push bolt 29 Screw hole for push bolt 31 Nut 33 O-ring 35 Gasket 37 Gap 39 Flexible pipe connection structure (other aspects)
41 Flexible tube (other aspect)
43 Pipe fitting 45 Lori for liquid nitrogen 47 Storage tank 49 Pump 51 Flexible pipe connection structure (conventional example)

Claims (3)

A fixed pipe having a fixed side flange at an end and a flexible pipe having a flexible pipe portion and having a flexible side flange on at least one end side of the flexible pipe portion are provided, and the flexible side flange is connected to the fixed side flange. It is a flexible pipe connection structure that connects the fixed pipe and the flexible pipe by forming a connecting portion.
A push bolt for forming a gap in the connecting portion by compressing the flexible pipe portion, and
It is provided on either the fixed side flange or the flexible side flange to be connected, and is provided with a plurality of push bolt screw holes for screwing the push bolt .
When the thickness of the fixed side flange or the flexible side flange on which the screw hole for the push bolt is formed is a and the maximum reduction length of the flexible pipe is b, the length of the shaft portion of the push bolt is a + b. Flexible pipe connection structure characterized by being set as follows . The flexible pipe connection structure according to claim 1, wherein the plurality of push bolt screw holes are provided at positions rotationally symmetric with respect to the center of the fixed side flange or the flexible side flange. A plurality of connecting bolt holes for inserting connecting bolts connecting the flexible side flange and the fixed side flange are provided in the flexible side flange and the fixed side flange, and the push bolt screw holes are provided in the circumferential direction. The flexible pipe connection structure according to claim 1 or 2, wherein the flexible pipe connection structure is provided at an intermediate position between adjacent connecting bolt holes.

Images