JP4817953B2 - Double pipe connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double tube connection structure for holding an inner tube and an outer tube in a concentric form while reducing stress concentration, preventing the breakage of the tubes and ensuring piping connection. <P>SOLUTION: The outer tube 5 is connected with an external joint 1, and the inner tube 6 is connected inside with an internal joint 3. A first holding member 7 is arranged between the end face of the external joint and the end face of the internal joint, and a second holding member 8 is arranged 1.4D-3.6D apart from the first holding member, where D is the outer diameter of the inner tube. The outer diameters of both holding members are each smaller than the inner diameter of the outer tube. Preferably, a communication means is provided on the holding member for communicating one side with the other side thereof. Preferably, the external joint and the outer tube or the holding member in addition thereto are formed to be transparent or translucent for inside observation. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a connection structure of a double pipe that mainly transports chemical solution or processing waste liquid in a chemical factory. More specifically, the inner pipe and the outer pipe can be held concentrically, and stress is applied to the joint portion. Even if it is applied, the stress concentration is alleviated, and even if a sudden force such as a water hammer is applied to the pipe of the double pipe, the pipe is connected and the pipe is connected without fail.

  In the connection structure of the joint portion of the double pipe, there are a method of integrally molding the joint of the double pipe structure and a method of forming a double pipe structure by combining existing joints. As a method for combining existing joints, there has conventionally been a double pipe elbow structure as shown in FIG. 6 (see, for example, Patent Document 1). The structure is composed of an elbow pipe 101, an elbow pipe 102 that can insert and remove the elbow pipe 101, and two spacers 103, and has a protruding edge 105 on the inner wall of the straight portion 104 of the elbow pipe 102. In addition, each spacer 103 is fitted to the inner wall of the straight portion 104 of the elbow sheath 102 so that the peripheral end surface is slidable, and the peripheral end abuts against the protruding edge 105, while the through hole provided in the central portion of the spacer 103 106, both ends of the elbow actual tube 101 are fitted to each other, and the elbow actual tube 101 is housed and fixed in the elbow sheath tube 102. The effect is that the assembly of the double pipe of the elbow part can be easily performed at the construction site, and the safety and functionality of the double structure are improved.

JP 2001-200980 A

  However, in the structure of the elbow portion of the conventional double pipe, when stress is applied to the double pipe, for example, when a high-temperature fluid is flowed, the real pipe 107 connected to the elbow real pipe 101 expands, but the elbow Since the sheath tube 108 connected to the tube 102 is separated from the actual tube 107, the sheath tube 108 does not expand so much, and stress is generated because the degrees of expansion of the actual tube 107 and the sheath tube 108 are different. Since the stress tends to concentrate on the joint part with limited movement in the pipe such as the elbow part, the elbow actual pipe 101 is housed and fixed without being moved by the spacer 103 in the elbow sheath pipe 102 as in the prior art. If there is, there is a problem that any part of the spacer 103, the elbow sheath tube 102, or the elbow actual tube 101 may be damaged without being able to relieve stress concentration at the elbow portion.In addition, when the elbow Saya tube 102 or the Elbow actual tube 101 is inserted and connected to the long straight tube 107 or Saya tube 108, the Elbow actual tube 101 does not move in the Elbow Saya tube 102. There has been a problem that it is not possible to finely adjust the axis alignment by slightly shifting 102 and the connection work becomes difficult or the connection may be insufficient.

  The present invention has been made in view of the above-mentioned problems of the prior art. The inner tube and the outer tube can be held concentrically, and even if stress is applied to the joint portion, the concentration of stress is reduced. An object of the present invention is to provide a double pipe connection structure capable of reliably connecting pipes without damaging the pipe even when a sudden force is applied to the pipe of the double pipe.

In order to solve the above-mentioned problem, according to the invention of claim 1, a double pipe connection structure in which an inner pipe connected by an inner joint is covered with an outer pipe connected by an outer joint,
The end face of the outer joint is formed to protrude outward in the axial direction from the end face of the inner joint,
The outer circumference of the inner pipe at a first position between the end face of the outer joint and the end face of the inner joint and a second position outside the end face of the outer joint and separated from the first position by a predetermined distance. A holding member for separating the outer tube from the inner tube is attached on the top ,
The holding member is provided with a through hole whose inner periphery is substantially the same as the outer diameter of the inner tube, and the outer periphery is provided with a smaller diameter than the inner diameter of the outer tube so that there is a gap with the inner peripheral surface of the outer tube. And
The holding member is fixed to the outer periphery of the inner pipe by welding, welding, or adhesion,
At least a part of the outer periphery of the holding member is installed so as to be able to contact the outer tube,
A double pipe connection structure is provided, in which a notch is provided in the outer periphery of the holding member, or a through hole is provided in the vicinity of the outer periphery .
According to the invention of claim 2, the first position is set between an end face of the internal joint, an intermediate position of the end face of the external joint, and an end face of the internal joint.
According to the invention of claim 3, the second position is set between 1.4D and 3.6D from the first position, where D is the outer diameter of the inner tube.
According to invention of Claim 4, the drain is attached to the said outer tube | pipe.
According to the invention of claim 5, the outer joint and the outer tube, or further, the holding member is formed to be transparent or translucent.
According to the invention of claim 6, the inner joint and the outer joint are bent joints.

The present invention has the structure as described above, and the following excellent effects can be obtained.
(1) Since the inner and outer pipes are held by the first and second holding members, the connection structure of the inner joint and the inner pipe and the outer joint and the outer pipe is always held concentrically. Can prevent the inner pipe and outer pipe from colliding, and even if the inner pipe breaks, the fluid does not flow around the pipe of the double pipe, and secondary damage is caused by the fluid that flows out. Can be prevented and damage caused by breakage of the tube can be minimized.
(2) Even if stress is applied to the joint due to expansion or contraction of the pipe, the stress concentration is eased by slightly moving or deforming the internal joint in response to the stress. Can be prevented.
(3) Even if an abrupt force is applied to the double pipe by a water hammer or the like, the applied force can be distributed almost evenly between the first holding member and the second holding member, and the outer pipe can be held so as not to break. .
(4) During the piping work, the internal joint and the external joint can be moved to finely adjust the insertion angle of the receiving port, and the pipe connection can be ensured.
(5) If the holding member is provided with at least one notch or through hole, the holding member does not stop the flow of fluid when the inner tube breaks and fluid flows into the bottom of the outer tube and flows into the drain. The fluid can safely flow out to the outside in a short time, and the fluid can flow to the drain, so that damage to the inner tube and fluid leakage can be detected at an early stage.
(6) If all or any of the outer joint, outer tube, first and second holding members are formed to be transparent or translucent, the state of the inner tube can be visually recognized from the outside, so fluid breakage or leakage Can be confirmed at an early stage, and the location where fluid breakage or leakage has occurred can be immediately identified.

  Hereinafter, although an embodiment of the present invention is described with reference to drawings, it cannot be overemphasized that the present invention is not limited to this embodiment.

In the figure, reference numeral 1 denotes an external joint which is a PVC 90 ° elbow having a diameter of 100 mm . Receiving ports 2 are provided at the openings on both sides of the external joint 1. Reference numeral 3 denotes an internal joint which is a PVC 90 ° elbow having a diameter of 50 mm and housed inside the external joint. Receiving portions 4 are provided at openings on both sides of the internal joint 3.

5 is an outer tube made of PVC having a diameter of 100 mm , and one end of the outer tube 5 is inserted and connected to each receiving port 2 of the outer joint 1. 6 is an inner tube made of PVC having a diameter of 50 mm (outer diameter D is 60 mm), and one end of the inner tube 6 is inserted and connected to each of the receiving ports 4 of the inner joint 3.

  7 and 8 are first and second holding members made of PVC. The first and second holding members 7 and 8 have a disk shape, and are provided with through holes 9 whose inner circumference is substantially the same as the outer diameter of the inner pipe 6, and whose outer circumference is smaller than the inner diameter of the outer pipe 5. 5 is provided so as to form a gap with the inner peripheral surface. The first and second holding members 7 and 8 are each fitted to the outer periphery of the inner tube 6 and fixed by welding, and at least a part of the outer periphery is installed so as to be able to contact the inner peripheral surface of the outer tube 5. . As a result, the inner tube 6 and the outer tube 5 are held concentrically. Further, the length L1 from the end face of the receiving portion 4 of the internal joint 3 to the first holding member 7 is set to 2 mm, and the length L2 from the first holding member 7 to the second holding member 8 is set to the inner pipe 6. It is installed in the position which becomes the space | interval of 100 mm used as 1.67D with respect to the outer diameter D of this. Further, four cutout portions 10 (see FIG. 3) are provided at equal intervals on the outer circumferences of the first and second holding members 7 and 8, and one of the cutout portions 10 is formed at the bottom of the outer tube 5. It is installed to be located.

  Next, the connection method of the connection structure of the double pipe of this embodiment is demonstrated based on FIG.

  First, the first and second holding members 7 and 8 are fitted on the outer periphery of the inner tube 6 and fixed by welding. At this time, the first holding member 8 is fixed at a position obtained by adding 2 mm of L1 to the insertion amount of the receiving port 4 from the end face of the inner tube 6, and the second holding member 8 is 100 mm of L2 from the first holding member 7. Fix in position. Next, one end of the inner tube 6 is inserted into the receiving port 4 of the inner joint 3 and connected. At this time, since the inner joint 3 is not fixed inside the outer joint 1, when the inner pipe 6 is inserted into the receiving portion 4, the receiving portion 4 is moved to finely adjust the insertion angle, thereby easily. The receiving port 4 of the internal joint 3 and the axis of the inner pipe 6 can be aligned, and can be reliably connected. Next, one end of the outer tube 5 is inserted into the receiving port 2 of the external joint 1 and connected. At this time, the outer tube 5 can be prevented from being misaligned with the first and second holding members 7 and 8 as guides, and the outer tube 5 is inserted into the receiving port 2 by moving the receiving port 2. A fine connection can be made by adjusting the angle and aligning the axes.

  The number of holding members 7 and 8 fitted to the inner tube 6 is not particularly limited, and more holding members may be provided. The first and second holding members 7 and 8 are disc-shaped, cylindrical, polygonal (triangular, quadrangular, hexagonal, etc.) or radial ribs as long as the inner tube 6 and the outer tube 5 can be held concentrically. There is no particular limitation on the shape of the elongated shape. Here, the term “concentric” means that the axis of the inner tube 6 and the outer tube 5 is not so strict that the axes are aligned with each other. Is the right thing. In addition, if the outer periphery of the first and second holding members 7 and 8 can contact at least a part of the inner peripheral surface of the outer tube 5 so that the inner tube 6 and the outer tube 5 do not directly contact each other, The outer circumferences of the first and second holding members 7 and 8 are provided to be substantially the same diameter as the inner diameter of the outer tube 5, or a gap is formed between the outer circumferences of the first and second holding members 7 and 8 and the inner circumference of the outer tube 5. It may be provided as follows. In particular, if a slight gap is formed between the outer circumference of the first and second holding members 7 and 8 and the inner circumference of the outer tube 5, even if stress is concentrated on the joint portion, the gap is provided. Since the inner joint 3 and the inner pipe 6 are slightly deformed or moved, the stress concentration can be reduced and damage to the pipe of the double pipe can be prevented. Further, the contact portion between the inner peripheral surface of the outer tube 5 and the outer periphery of the first and second holding members 7 and 8 may be in contact with each other directly, or the contact portion may be in a sealed state, The structure which contact | abuts via a cushion material may be sufficient.

  In the present invention, the first holding member 7 is preferably fitted on the outer periphery of the inner pipe 6 in the range from the opening end face of the inner joint 3 to the opening end face of the outer joint 1. It is more desirable to be between a slight position (about 1 mm) from the position of the end face to an intermediate position between the end face of the inner joint 3 and the end face of the outer joint 1. This is because when the first holding member 7 is provided at a position slightly away from the opening end face of the internal joint 3, the internal joint 3 has a margin to move within the pipe of the double pipe, thereby relieving stress concentration at the joint portion. This is preferable. Since the inner joint 3 is not fixed even at the positions where they are in contact with each other, a slight movement is possible, so the range of L1 needs to be from the position where they contact. Further, in order to keep the inner joint 3 concentrically so as not to come out of the outer joint 1, the range of L <b> 1 needs to reach the position of the end face of the opening of the outer joint 1.

  A length L2 from the first holding member 7 to the second holding member 8 is fitted to the outer periphery of the inner tube 6 at an interval of 1.4D to 3.6D with respect to the outer diameter D of the inner tube 6. When the inner tube 6 has a diameter of less than 40A, it is 2.8D to 3.6D, and when the inner tube 6 has a diameter of 40A or more, it is preferably 1.4D to 3.0D. desirable. L2 is a range for reducing the force applied to the inner peripheral surface of the outer tube 5, and a suitable range is determined by the outer diameter D of the inner tube 6 to which the first and second holding members 7 and 8 are fitted. By keeping the first and second holding members 7 and 8 at a certain distance from each other, the inner joint 3 is prevented from rattling more than necessary, and the inner joint 3 and the inner pipe 6, and the outer joint 1 and the outer pipe. In order to keep 5 concentrically, L2 is preferably 1.4D or more. Further, when a force in the direction of the arrow in FIG. 1 is applied by a water hammer or the like, for example, the first and second holding members 7 and 8 that hold the inner tube 6 with the force in the arrow direction transmitted from the inner joint 3 to the inner tube 6 are provided. L2 is set to 3.6D or less so that the force in the direction of the arrow is not concentrated on the abutting portions 12 and 13 that abut on the outer tube 5 by being distributed almost uniformly by being arranged at a certain distance. Is preferred.

  The first and second holding members 7 and 8 of the present invention preferably have a configuration in which at least one notch 10 is provided on the outer periphery or at least one through hole 11 is provided on the side surface. The number and position of the notch 10 or the through hole 11 are not particularly limited, but if four or more locations are provided at equal intervals on the outer periphery of the first and second holding members 7 and 8 (in the vicinity of the outer periphery in the case of the through hole 11). No matter how the holding members 7 and 8 are installed, the inner tube 6 is broken and the fluid flows out to the outer tube 5 (the space 15 formed between the outer periphery of the inner tube 6 and the inner periphery of the outer tube 5). In this case, the fluid can flow through the notch 10 or the through-hole 11 to the drain 14 (see FIG. 2) provided at an arbitrary position of the double tube. This is preferable because breakage of the tube 6 and fluid leakage can be detected. Further, the shape of the notch 10 and the through-hole 11 is not particularly limited as long as fluid can pass through, but a linear shape is formed on the outer periphery of the disk-shaped first and second holding members 7 and 8 as shown in FIG. Examples include a configuration in which the notch portion 10 is provided, and a configuration in which the through hole 11 is provided in the vicinity of the outer periphery of the first and second holding members 7 and 8 as illustrated in FIG. 4. In addition, it is desirable that any one of the notch 10 and the through-hole 11 is always located at the bottom of the outer tube.

  The first and second holding members 7 and 8 are preferably fixed to the outer periphery of the inner tube 6 by any method of welding, welding, or adhesion. This is because, for example, even when the double pipe expands or contracts due to fluid temperature or air temperature, the first and second holding members 7 and 8 can be reliably held concentrically without being displaced. This is preferable because it is possible.

  Further, it is desirable that all or any of the outer joint 1, the outer tube 5, the first and second holding members 7 and 8 be formed to be transparent or translucent. This is suitable because the state of the inner pipe 6 can be visually recognized from the outside, so that the breakage or leakage of the fluid can be confirmed at an early stage, and the location where the breakage or leakage of the fluid has occurred can be identified immediately.

  The double pipe connection structure of the present invention can be applied to an elbow shape shown in FIG. 1 or a cheese shape shown in FIG. The elbow-shaped or bend-shaped bending angle is mainly 90 °, but may be 45 ° or 12.5 °.

  The materials of the inner joint 3, the outer joint 1, the inner pipe 6, the outer pipe 5, the first and second holding members 7 and 8 of the present invention are polyvinyl chloride (hereinafter referred to as PVC), polypropylene, polyethylene, Polyvinylidene fluoride, polystyrene, ABS resin, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene resin, iron, copper, copper alloy, brass, aluminum, stainless steel, etc. Either metal or the like may be used, and the internal double pipe and the external pipe may be provided with different materials depending on the application.

Next, the effect | action of the connection structure of the double pipe of this embodiment is demonstrated based on FIG. 1, FIG.
In FIG. 1, hydrochloric acid is supplied as a fluid only to the inner tube 6. When the inner pipe 6 is damaged, hydrochloric acid flows out into the outer pipe 5 (the space 15 formed between the outer circumference of the inner pipe 6 and the inner circumference of the outer pipe 5). Since it does not flow out around the pipe, it is possible to prevent hydrochloric acid from flowing out around the pipe of the double pipe and cause secondary damage due to hydrochloric acid, and damage due to breakage of the inner pipe 6 can be minimized. The fluid stored in the outer tube 5 can be safely discharged to the outside by providing the drain 14 of FIG. The fluid flowing through the double pipe of the present invention is not particularly limited as long as there is no problem in chemical resistance of the material of the pipe and the joint such as a chemical solution and a processing waste liquid. The connection structure of the inner joint 3 and the inner pipe 6 and the outer joint 1 and the outer pipe 5 is always held concentrically by the first and second holding members 7 and 8, and the inner joint 3 and the outer joint 1 collide. Or the inner pipe 6 and the outer pipe 5 are prevented from colliding with each other.

  When a high-temperature fluid is passed through the inner pipe 6, the inner pipe 6 connected to the inner joint 3 expands, but the outer pipe 5 connected to the outer joint 1 does not expand so much, and the inner pipe 6 and the outer pipe 5 Since the degree of expansion is different, stress is generated and the stress tends to concentrate on the internal joint 3 due to the structure of the double pipe, but the internal joint 3 is not held inside the external joint 1, so If the stress is concentrated on the inner joint 3, the stress concentration is alleviated by slightly moving or deforming the inner joint 3 according to the stress. Can be prevented. Further, the same effect can be obtained when the degree of expansion or contraction is different between the inner tube 6 and the outer tube 5 when the outside air temperature is high or low.

  When a force in the direction of the arrow in FIG. 1 is applied by a water hammer or the like, the force in the direction of the arrow transmitted from the inner joint 3 to the inner tube 6 is transmitted to the first and second holding members 7 and 8 that hold the inner tube 6. The force in the direction of the arrow is applied to the contact portions 12 and 13 where the first and second holding members 7 and 8 contact the inner peripheral surface of the outer tube 5. The force in the direction of the arrow tends to concentrate on the contact portion 12 of the first holding member 7 closest to the internal joint 3, but the length L2 from the first holding member 7 to the second holding member 8 is outside the inner tube 6. By being provided at 1.4D to 3.6D with respect to the diameter D, the force in the direction of the arrow is not concentrated and can be distributed almost evenly between the first holding member 7 and the second holding member 8, and contact The force applied to the portions 12 and 13 can be suppressed to about ½ compared to the case where the force in the arrow direction is concentrated, and the outer tube 5 can be held so as not to be damaged by the force applied in the arrow direction.

  In FIG. 2, when the inner tube 6 is broken and the fluid flows into the outer tube 5 (the space 15 formed between the outer periphery of the inner tube 6 and the inner periphery of the outer tube 5), the fluid flowing out from the inner tube 6 It flows through the bottom of the pipe 5 and flows into the drain 14 installed at an arbitrary position of the double pipe, and the fluid flows into the drain 14, so that it is possible to detect breakage of the inner pipe 6 and fluid leakage. At this time, the first and second holding members 7 and 8 and the inner peripheral surface of the outer tube 5 are not connected to each other, and a gap is provided. Further, by providing the notch 10, the fluid passes through the notch 10. Therefore, the fluid flowing out from the inner tube 6 can be flowed to the drain 14 in a short time without stopping by the first and second holding members 7 and 8, and leakage of the fluid can be detected.

It is a longitudinal cross-sectional view which shows embodiment of this invention whose joint is an elbow. It is a schematic diagram which shows the case where an inner pipe is damaged in embodiment of this invention which provided the drain in piping of the double pipe. It is a perspective view which shows the holding member which has a notch part. It is a perspective view which shows the holding member which has a through-hole. It is a longitudinal cross-sectional view which shows other embodiment of this invention whose joint is cheese. It is a longitudinal cross-sectional view which shows the structure of the elbow part of the conventional double piping.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External joint 2 Receiving part 3 Internal joint 4 Receiving part 5 Outer pipe 6 Inner pipe 7 1st holding member 8 2nd holding member 9 Through-hole 10 Notch part 11 Through-hole 12 Contact part 13 Contact part 14 Drain 15 space

Claims (6)

A double pipe connection structure in which an inner pipe connected by an inner joint is covered with an outer pipe connected by an outer joint,
The end face of the outer joint is formed to protrude outward in the axial direction from the end face of the inner joint,
The first position between the end face of the outer joint and the end face of the inner joint, and the second position outside the end face of the outer joint and separated from the first position by a predetermined distance, holding member for allowing spaced from the inner tube said outer tube is attached on the outer circumference,
The holding member is provided with a through hole whose inner periphery is substantially the same as the outer diameter of the inner tube, and the outer periphery is provided with a smaller diameter than the inner diameter of the outer tube so that there is a gap with the inner peripheral surface of the outer tube. And
The holding member is fixed to the outer periphery of the inner pipe by welding, welding, or adhesion,
At least a part of the outer periphery of the holding member is installed so as to be able to contact the outer tube,
A notch is provided on the outer periphery of the holding member, or a through hole is provided in the vicinity of the outer periphery.
A double pipe connection structure characterized by that.   2. The double pipe according to claim 1, wherein the first position is set between an end face of the inner joint, an intermediate position between end faces of the outer joint, and an end face of the inner joint. Connection structure.   2. The second position according to claim 1, wherein the second position is set between 1.4D and 3.6D from the first position, where D is an outer diameter of the inner tube. Heavy pipe connection structure. The double pipe connection structure according to any one of claims 1 to 3, wherein a drain is attached to the outer pipe. The double pipe connection structure according to any one of claims 1 to 4, wherein the outer joint and the outer pipe, or further, the holding member is formed to be transparent or translucent. . The double pipe connection structure according to any one of claims 1 to 5, wherein the inner joint and the outer joint are bent joints.

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