JP3090971B2 - Pipe structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe structure, and more particularly to a pipe structure excellent in high-temperature, high-pressure resistance and vibration resistance.

[0002]

2. Description of the Related Art Pipes used under high temperature and high pressure, especially pipes whose flow velocity changes and undergoes pressure and heat fluctuations, are liable to breakage due to metal fatigue and the like. Those installed in an environment where replacement work is easy can be dealt with by periodic replacement, but for example, various pipes used in nuclear power plants are not only difficult to replace themselves, but also damaged. The impact of doing so is immeasurable. The behavior of materials including pipes in a nuclear power plant is largely unknown, and double and triple safety measures are particularly desired for the pipe structure in a nuclear power plant through which high-temperature and high-pressure fluid passes.

[0003]

The object of the present invention is to provide a metal pipe having high temperature and pressure resistance.
It is an object of the present invention to obtain a pipe structure that dramatically improves vibration resistance.

[0004]

SUMMARY OF THE INVENTION The pipe structure of the present invention has been completed based on the idea that the outer periphery of a center pipe is reinforced with an outer peripheral pipe via a flowable substance. In the pipe structure of the present invention, at least one layer of a metal outer pipe is provided concentrically on the outer circumference of a metal center pipe to form a cylindrical space between both pipes. Is characterized by encapsulating a low-melting-point alloy that does not boil at the temperature of the fluid flowing through the center pipe and is solid. "Low melting point alloy" means a substance that is brought into a fluid state by the temperature of the fluid flowing through the central pipe but does not boil.

According to this pipe structure, when a high-temperature and high-pressure fluid flows through the central pipe, the low-melting alloy surrounding the central pipe is in a flowing state. The low melting point alloy in the flowing state is sealed between the center pipe and the concentric outer pipe, so that the outer pipe acts to reinforce the center pipe. In other words, if a force in the radially expanding direction is applied to the center pipe, this force is transmitted to the outer pipe through the low-melting alloy in a flowing state, so that the outer pipe also functions as a strength member. It is reduced. In other words, a uniform pressure (stress) is applied to the inner and outer pipes through the low-melting alloy in the flowing state, and therefore the high-temperature and high-pressure resistance of the center pipe is increased. At the same time, the low melting point alloy in the flowing state absorbs vibrations due to changes in the pressure, heat, and flow velocity of the central pipe, so that the vibration resistance is also improved.

In order to surely transmit the expanding force applied to the center pipe to the outer peripheral pipe through the low melting point alloy, means for adjusting the pressure in the cylindrical space when the low melting point alloy is in a flowing state is provided. Is preferred. This pressure adjusting means can be constituted, for example, by a pressurizing and supplying device which pressurizes and supplies the same substance as the low melting point alloy in the cylindrical space into the cylindrical space.

[0007] The low melting point alloy is selected according to its own solid-to-fluid phase change temperature and the temperature and pressure of the fluid flowing through the center pipe. For example, tin-based or lead-based alloys are used. it can. The center pipe and the outer pipe are preferably made of a still-based material having excellent strength.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
1 and 2 show an embodiment of a pipe structure 10 according to the present invention. The pipe structure 10 includes a concentric central pipe 11 and an outer peripheral pipe 12 made of, for example, a still-based material, and a closed cylindrical space 13 is formed between the two pipes. A bulging portion 14 as a pressure adjusting means connecting portion is formed in a part of the cylindrical space 13, and the low melting point alloy 15 is filled in the cylindrical space 13 and the bulging portion 14. Of course, when the low melting point alloy is filled, the center pipe 11, the outer peripheral pipe 12, and the low melting point alloy 15 are heated to the melting temperature of the low melting point alloy. The center pipe 11 and the outer peripheral pipe 12 can be bent in advance into a required shape in addition to a straight pipe.

The bulging portion 14 is connected to a low melting point alloy pressurizing and supplying means 16 as pressure adjusting means. The low-melting-point alloy pressurizing / supplying means 16 is composed of a cylinder 17 and a piston 18 fitted therein. The low-melting-point alloy 15 is similarly sealed in the cylinder 17.

Therefore, this pipe structure has a central pipe 11
When a high-temperature and high-pressure fluid flows through the inside, the low melting point alloy 15 is melted. The pressure of the molten low melting point alloy 15 can be adjusted by the low melting point alloy pressurizing supply unit 16. That is, when the piston 18 is advanced, the low melting point alloy 15 in the cylinder 17 is fed into the cylindrical space 13 through the bulging portion 14, so that the low melting point alloy 15
Can be made to oppose the pressure of the fluid flowing in the center pipe 11.

In this state, when the diameter of the central pipe 11 is to be increased by the pressure of the fluid flowing in the central pipe 11, the low melting point alloy 15 and the outer peripheral pipe 12 oppose this pressure. That is, when the diameter of the central pipe 11 is to be increased, the force is transmitted to the outer peripheral pipe 12 via the low melting point alloy 15 which is a fluid. In other words, a uniform pressure (stress) is applied to the inner and outer pipes 11 and 12 via the flowing low-melting point alloy 15, so that the high-temperature and high-pressure resistance of the center pipe 11 is increased. In addition, the low melting point alloy 15 in a flowing state has a function of absorbing vibration due to a change in pressure, a change in heat, and a change in flow velocity of the central pipe, and therefore, the vibration resistance is also improved.

Further, in the pipe structure of the present invention, even if the center pipe 11 or the outer pipe 12 is broken, the outer pipe 12 or the center pipe 11 functions as a pipe for at least a short time. Therefore, the central pipe 1
If the breakage of the first or outer pipe 12 is detected by the loss of the low-melting-point alloy 15 and the operation of the source of the high-temperature and high-pressure fluid is immediately stopped, it is possible to prevent the high-temperature and high-pressure fluid from flowing out and scattering. The run-off of the low melting point alloy 15 is, for example,
It can be detected by a pressure sensor or a dimensional change of the outer diameter.

The pipe structure according to the present invention is a triple or more concentric pipe structure, and a low melting point alloy can be sealed between the pipes. The low-melting-point alloy pressure supply means 16 is
Although the cylinder device is illustrated as the simplest example, another pump device or the like may be used. Conversely, it may be omitted depending on the properties of the low melting point alloy, particularly the coefficient of thermal expansion.

[0014]

As described above, according to the pipe structure of the present invention, a high-temperature and high-pressure fluid pressure can be simultaneously supported by a plurality of concentric pipes via a flowing low-melting-point alloy. For this reason, a pipe structure with significantly improved high-temperature high-pressure resistance and vibration resistance can be obtained. In particular, low-melting alloys do not boil even at high temperatures, so that stable strength can be obtained. In addition, the breakage of the inner or outer pipe can be detected by the loss of the low-melting-point alloy. Based on this detection, if the supply of the high-temperature and high-pressure fluid is stopped, the fluid is prevented from flowing around and scattering around. can do.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a pipe structure according to the present invention.

FIG. 2 is a sectional view taken along line BB of FIG.

[Description of Signs] 10 Pipe structure 11 Center pipe 12 Outer pipe 13 Cylindrical space 14 Swelling part 15 Low melting point alloy 16 Low melting point alloy pressurized supply means 17 Cylinder 18 Piston

Claims (2)

(57) [Claims] At least one outer peripheral pipe made of metal is provided concentrically around the outer periphery of a central pipe made of metal to form a cylindrical space between the two pipes. A pipe structure characterized in that a low-melting-point alloy which does not boil at the temperature of the fluid flowing through the center pipe and is in a fluidized state is sealed. 2. The pipe structure according to claim 1, wherein the outer peripheral pipe is provided with a means for adjusting a pressure in the cylindrical space when the low melting point alloy is in a flowing state.