JP2011127638A - Joint structure of fluid transport pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a fluid transport pipe, maintaining the sealability for a very low temperature fluid. <P>SOLUTION: A joint 30 connecting transport pipes 20, 10 to each other, which transport liquefied gas fuel (fluid), includes: flanges 21, 11 respectively coupled to the ends of the transport pipes 20, 10; and bolts 31 fastening the flanges 21, 11 to each other. The bolt 31 is formed of material with a larger coefficient of linear expansion than the flanges 21, 11, and as the temperature of the joint 30 drops, the fastening force of the bolt 31 is increased. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a joint structure that connects fluid transport pipes that transport a cryogenic fluid.

  When supplying liquefied natural gas (LNG) from a tank truck or the like to a liquefied gas fuel vehicle, a joint for connecting transport pipes is used.

  Conventionally, this type of joint includes a flange that is coupled to each end of the transport pipe, and a bolt that fastens the flanges together via a gasket. By tightening the bolt, the gasket is compressed between the flanges and the connection of the transport pipe is sealed.

  Moreover, the joint structure of the fluid transport pipe disclosed in Patent Document 1 includes a cover member that covers the joint, and prevents fluid leaking from the joint from diffusing.

JP-A-3-26389

  However, in such a conventional fluid transport pipe joint structure, for example, when supplying fuel to a liquefied gas fuel vehicle, the liquefied gas fuel is in an extremely low temperature exceeding −100 ° C. As the temperature decreased and contracted, a gap was formed between the flange and the gasket, and high-pressure liquefied gas fuel could leak out of the gap. For this reason, it has been necessary for an operator to perform an operation of retightening a plurality of bolts for fastening the flange when supplying fuel.

  Moreover, since the joint structure of the fluid transport pipe disclosed in Patent Document 1 includes a cover member that covers the joint, it takes time to attach and detach the joint, and as a connection section (fuel supply section) of the transport pipe of the liquefied gas fuel vehicle. It is difficult to use.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a joint structure for a fluid transport pipe that can maintain hermeticity against a cryogenic fluid.

  The present invention is a fluid transport pipe joint structure for connecting a transport pipe for transporting a fluid, and includes a flange coupled to an end of the transport pipe and a bolt for fastening the flanges together. The linear expansion coefficient is formed of a material larger than the flange.

  According to the present invention, in the process of transporting a cryogenic liquefied gas fuel as a fluid through a transport pipe, the temperature of the joint gradually decreases due to heat transfer from the liquefied gas fuel, and the flange and the bolt contract, respectively. As the temperature of the joint decreases, the bolt contracts more than the flange due to the difference in linear expansion coefficient with respect to the flange, and the fastening force of the bolt gradually increases.

  Thus, the joint is prevented from generating a gap between the flanges, and fluid is prevented from leaking between the flanges.

  For this reason, the operator can abolish the work of tightening the bolts when supplying the liquefied gas fuel.

The perspective view of the joint structure of the fluid transport pipe | tube which shows embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a joint structure of a fluid transport pipe for supplying liquefied natural gas (LNG) to a liquefied gas fuel vehicle.

  The liquefied gas fuel vehicle includes an LNG container (not shown) for storing liquefied natural gas, and a transport pipe 10 connected to the LNG container.

  In the figure, reference numeral 20 denotes a transport pipe extending from, for example, a tank truck as a liquefied natural gas supply source. For example, a metal flexible hose is used for the transport pipe 20.

  At the time of fuel supply to the liquefied gas fuel vehicle, the transport pipe 20 of the tank truck is connected to the transport pipe 10 of the liquefied gas fuel vehicle via the joint 30.

  The joint 30 is interposed between the flange 21 and the flange 11, the disc-shaped flange 21 coupled to the end of the transport pipe 20, the disc-shaped flange 11 coupled to the end of the transport pipe 10. A gasket 29 and a plurality of (for example, four) bolts 31 for fastening the flange 21 and the flange 11 are provided.

  The bolt 31 includes a cylindrical shaft portion 33, a head portion 32 formed at the base end portion of the shaft portion 33, and a screw portion 34 formed at the distal end portion of the shaft portion 33.

  When the joint 30 connects the transport pipe 20 to the transport pipe 10, the bolt 31 passes the shaft part 33 through the holes formed in the flange 11, the gasket 29 and the flange 21, and the head part 32 contacts the flange 11. The nut 36 that is brought into contact with and screwed into the threaded portion 31 is brought into contact with the flange 21 through the washer 35. By tightening the nut 36, the gasket 29 is compressed between the flange 21 and the flange 11, and the connection portion between the transport pipe 20 and the transport pipe 10 is sealed.

  The joint 30 is not limited to this, and a configuration may be adopted in which a female screw portion is formed in the flange 21 and the screw portion 34 of the bolt 31 is screwed into the female screw portion. Thereby, the nut 36 can be abolished.

  By the way, when the fuel is supplied to the liquefied gas fuel vehicle, the liquefied gas fuel is in an extremely low temperature exceeding −100 ° C. Therefore, in the conventional fluid transport pipe joint structure, the temperature of the flange, gasket, etc. is lowered. A gap was generated between the flange and the gasket along with the contraction, and high-pressure liquefied gas fuel could leak out of the gap. For this reason, it has been necessary for an operator to perform an operation of retightening a plurality of bolts for fastening the flange when supplying fuel.

  In response to this, in the present invention, the bolt 31 is formed of a material whose linear expansion coefficient (thermal expansion coefficient) is larger than that of the flange 21 and the flange 11.

  For example, the flange 21, the flange 11, the nut 36, and the washer 35 are formed of SUS430 (stainless steel) having a linear expansion coefficient of 10.4. On the other hand, the bolt 31 is formed of SUS304 (stainless steel) having a linear expansion coefficient of 17.3.

  As described above, in the present embodiment, the fluid transport pipe joint structure includes the transport pipe 20 that transports the liquefied gas fuel (fluid) and the joint 30 that connects the two, and the joint 30 includes the transport pipe 20, 10, and flanges 21 and 11 respectively coupled to the end portions of bolts 10 and bolts 31 for fastening the flanges 21 and 11, and the bolts 31 are formed of a material whose linear expansion coefficient is larger than that of the flanges 21 and 11. The fastening force of the bolt 31 increases as the temperature of the joint 30 decreases.

  Based on the above configuration, during the process of supplying the liquefied gas fuel vehicle to the liquefied gas fuel vehicle, the cryogenic (for example, −162 ° C.) liquefied gas fuel is transported through the transport pipe 20, the joint 30 and the transport pipe 10. The temperature of the joint 30 gradually decreases due to heat transfer, and the flange 21, the flange 11, and the bolt 31 contract. As the temperature of the joint 30 decreases, the bolt 31 contracts more greatly than the flange 21 and the flange 11 due to the difference in linear expansion coefficient, and the fastening force of the bolt 31 gradually increases. As a result, the joint 30 is prevented from generating a gap between the flange 21, the gasket 29, and the flange 11, and the high-pressure liquefied gas fuel is prevented from leaking. For this reason, an operator can abolish the operation of retightening the plurality of bolts 31 at the time of fuel supply.

  Further, since the sealability of the joint 30 is ensured in this way, it is not necessary to provide a leakage fluid diffusion preventing structure such as a cover member that covers the joint 30, and the structure can be simplified.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  In addition, the joint structure of the fluid transport pipe of the present invention is not limited to transporting liquefied natural gas to a liquefied gas fuel vehicle, and may be provided in other devices, equipment, etc. for transporting low-temperature fluid.

10 Transport pipe
11 Flange 20 Transport pipe 21 Flange 29 Gasket 30 Joint 31 Bolt 36 Nut

Claims (1)

A fluid transport pipe joint structure for connecting a transport pipe for transporting fluid,
A flange coupled to an end of the transport pipe;
A bolt for fastening the flange,
A joint structure for a fluid transport pipe, wherein the bolt is made of a material whose linear expansion coefficient is larger than that of the flange.