JPH0326389Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a leakage fluid diffusion prevention structure in a fluid transport pipe in which the periphery of a joint portion of the fluid transport pipe is sealed with a cover member.

[Conventional technology]

In the leakage fluid diffusion prevention structure in the fluid transport pipe described above, the cover member has conventionally been generally made of the same material as the fluid transport pipe. In order to enhance the diffusion prevention function of this cover member against leakage fluid, for example, when fixing the cover member divided into two parts in the circumferential direction with bolts, etc., the cover member is tightened strongly. It can be crimped onto the outer circumferential surface of the fluid transport pipe, or
Alternatively, a gasket or the like interposed between the cover member and the fluid transport pipe is elastically deformed to bring them into close contact with each other, thereby increasing the airtightness inside the cover member.

[Problem that the invention attempts to solve]

However, in the conventional configuration described above, in order to enhance the diffusion prevention function, it is necessary to strongly tighten bolts, etc., which tends to be time-consuming and requires a great deal of labor and special tools. Ta. In addition, the bolts that tighten the cover members that are divided into two in the pipe circumferential direction are relatively short, just enough to fasten the flange parts of the semicircular divided cover parts, so that The amount of expansion and contraction is small compared to the amount of expansion and contraction due to the thermal effect of the transportation fluid. Therefore, when piping construction is completed, no matter how strongly the bolts are tightened at room temperature, as the transportation fluid flows out, the above-mentioned Problems such as fluid transport pipes and cover members expanding and contracting caused bolts to loosen.

The purpose of the present invention is to create an extremely simple structure by devising the relative configuration of the cover member to the fluid transport pipe, and to prevent fluid leaking from the joint part of the fluid transport pipe from flowing outside the cover member. An object of the present invention is to provide a leakage fluid diffusion prevention structure in a fluid transport pipe that provides a diffusion prevention function.

[Means for solving problems]

A characteristic configuration of the present invention for achieving the above object is that a cover member for preventing the dissipation of leakage fluid from a joint portion of a fluid transport pipe surrounds the outer circumferential surface of the fluid transport pipe at a position near the joint portion. In the leakage fluid diffusion prevention structure in a fluid transport pipe provided in a state in which the fluid transport pipe and the cover member expand and contract in the circumferential direction from room temperature based on heat transfer between the fluid transport pipe and the transport fluid flowing within the fluid transport pipe. The coefficient of linear expansion of the cover member is set between the amount of expansion and contraction of the fluid transport pipe and the amount of expansion and contraction of the fluid transport pipe so that The reason is that the value is set to a value that causes a difference in .

In addition, [normal temperature] as used herein generally means the temperature of the environment where piping etc. are constructed.
It varies depending on the conditions, but it is generally between [0℃] and [40℃].
℃].

[Effect]

For example, when the fluid has a temperature lower than room temperature, such as liquefied natural gas (LNG), the cover member is made of a material with a higher coefficient of linear expansion than the fluid transport pipe. As a result, even if the cover member is installed to the extent that the inner circumferential surface of the cover member contacts the outer circumferential surface of the fluid transport pipe at room temperature, the fluid transport pipe and the cover member are cooled down as fluid is subsequently supplied into the fluid transport pipe. Then, since the cover member has a higher coefficient of linear expansion than the fluid transport pipe, it contracts more, and the inner peripheral surface of the cover member is strongly pressed against the outer peripheral surface of the fluid transport pipe.

Further, for example, when the fluid has a temperature higher than normal temperature, such as steam, the cover member is made of a material having a lower coefficient of linear expansion than the fluid transport pipe. As a result, as the temperature rises due to the passage of the fluid, the fluid transport pipe expands more than the cover member, contrary to the previous case, and similarly, the outer peripheral surface of the fluid transport pipe is strongly attached to the inner peripheral surface of the cover member. It is crimped.

In other words, when a temperature change occurs due to passage of fluid relative to the temperature at the time of construction, the cover member expands or contracts in a manner different from that of the fluid transport pipe due to this temperature change, and the inner peripheral surface and fluid The material of the cover member is selected so that it is in strong contact with the outer circumferential surface of the transport pipe.

[Effect of idea]

As a result, even if the airtightness inside the cover member is not increased significantly during construction, when the fluid actually passes through the inside of the fluid transport pipe, the inner circumferential surface of the cover member and the outer circumferential surface of the fluid transport pipe are tightly adhered. By doing so, it is possible to improve the airtightness inside the cover member, so in order to improve the leakage fluid diffusion prevention function,
It can now be easily installed without requiring a great deal of labor or special tools, and without having to retighten bolts after fluid transport has started.

〔Example〕

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

As shown in Fig. 1, a fluid transport pipe 1 made of stainless steel for transporting low-temperature liquefied gas (LNG), which is an example of a fluid, is bolted to a joint portion via a flange 1A attached to the end face of the fluid transport pipe 1. is formed. Then, the circumference of this joint part is hermetically surrounded by a cover member 2 made of aluminum, and low-temperature liquefied gas leaked from the joint part due to deterioration of the packing (not shown) interposed between the flanges 1A. A leakage fluid diffusion prevention structure is constructed to prevent LNG from spreading into the surrounding area.

The cover member 2 is made up of a cover body 2A that is fitted onto the fluid transport pipe 1, and a pair of pressing members 2B that are disposed on both sides of the cover body 2A and bolted to the cover body 2A.

The cover main body 2A is configured to be divided into two parts in the circumferential direction, and is configured to have a cylindrical shape by being bolted together so that the fluid transport pipe 1 can be fitted onto the cover main body 2A. Both end portions of the cover body 2A are bent inward to form a pair of flanges 2a having holes with an inner diameter approximately equal to the outer diameter of the fluid transport tube 1.

Then, the innermost peripheral portion of each collar portion 2a, that is,
The edge portion of the hole is cut out in an annular shape along the outer periphery of the fluid transport pipe 1, and three annular packings 3 made of expanded graphite are interposed in each of the cutouts 2b.

On the other hand, the pair of pressing members 2B have a ring shape as shown in FIG. 2, and have an annular protrusion 2c on the inner periphery that projects in the longitudinal direction along the outer periphery of the fluid transport pipe 1. It is formed. As shown in FIG. 1, this annular protrusion 2c is inserted from the longitudinal direction of the fluid transport pipe 1 in a state in which the pressing member 2B is fitted onto the fluid transport pipe 1 and bolted to the collar 2a. It enters the notch 2b of the cover main body 2A and comes into contact with the annular packing 3, thereby elastically deforming the annular packing 3 in its radial direction, thereby causing the outer peripheral surface of the fluid transport pipe 1 and the inner periphery of the notch 2b of the cover main body 2A to The cover member 2 is configured to be in close contact with the surface of the cover member 2 to make the inside of the cover member 2 airtight.

A guide flow path 6 equipped with a control valve 5 interlocked with a pressure gauge 4 is connected to the cover member 2 . When the leakage fluid increases and the pressure inside the cover member 2 exceeds a predetermined pressure, the control valve 5 is opened and the leakage fluid is guided to the processing section 7 through the guide channel 6. ing.

As already mentioned, the fluid transport pipe 1 is made of stainless steel, and the cover member 2 is made of aluminum. The coefficient of linear expansion of the cover member 2 is larger than that of the fluid transport pipe 1. Therefore, when liquefied natural gas [LNG], which is a fluid, flows inside the fluid transport pipe 1, the fluid is transported. When tube 1 and cover member 2 are both cooled, cover member 2 contracts more than fluid transport tube 1 .

As a result, even if the airtightness inside the cover member 2 is not very high when constructing the leakage fluid diffusion prevention structure at room temperature, during actual operation, the cover member 2 will be cooled down as described above. will contract more than the fluid transport pipe 1,
The inner circumferential surface of the notch 2b of the cover main body 2A presses the annular packing 3 to bring it into close contact with the outer circumferential surface of the fluid transport pipe 1, thereby increasing the airtightness inside the cover member 2.

Therefore, the leakage fluid diffusion prevention structure in the fluid transport pipe can be easily constructed without requiring much labor or special tools, so that the leakage fluid diffusion prevention function can be enhanced.

[Another example]

The leakage fluid diffusion prevention structure in a fluid transport pipe according to the present invention can be implemented for various fluids in addition to the liquefied natural gas (LNG) described in the previous embodiment. In that case, the material of the cover member 2 is determined based on the height relationship between the temperature of the fluid and room temperature.

If the fluid is transported at a low temperature, such as liquefied natural gas [LNG] or [LPG], the cover member 2 should be made of a material whose coefficient of linear expansion is larger than that of the fluid transport pipe 1. Bye. For example, if the fluid transport pipe 1 is made of stainless steel as in the previous embodiment, the cover member 2 can be replaced with aluminum.
It may be FRP.

On the other hand, if the fluid is transported at a high temperature, such as steam or thermal oil, the cover member 2 may be made of a material whose linear expansion coefficient is smaller than that of the fluid transport pipe 1. An example is the fluid transport pipe 1
is made of carbon steel, and the cover member 2 is made of cast iron.

In this way, the linear expansion coefficient of the cover member 2 is determined by the magnitude relationship between the value obtained by dividing the linear expansion coefficient of the fluid transport pipe 1 by the linear expansion coefficient of the cover member 2, and 1, so that the temperature of the transport fluid is at room temperature. It may be made of a material that matches the magnitude relationship between the value divided by 1 and 1.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

The drawings show an embodiment of the leakage fluid diffusion prevention structure in a fluid transport pipe according to the present invention, and FIG. 1 is a sectional view of the main part, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 3 is an overall view. It is a schematic sectional view. 1...Fluid transport pipe, 2...Cover member, 2A...
...Cover body, 2B...Press member, 3...Putskin.

Claims (1)

[Claims for Utility Model Registration] 1. A cover member 2 for preventing the dissipation of leakage fluid from a joint portion of a fluid transport pipe 1 in a state that surrounds the outer circumferential surface of the fluid transport pipe 1 at a position near the joint portion. In the leakage fluid diffusion prevention structure in the fluid transport pipe provided, the fluid transport pipe 1
The expansion and contraction action of the fluid transport pipe 1 and the cover member 2 in the circumferential direction from normal temperature based on heat transfer between the fluid transport pipe 1 and the transport fluid flowing therein causes the fluid transport pipe 1 to expand and contract from room temperature.
The coefficient of linear expansion of the cover member 2 is determined by the difference in the amount of expansion and contraction between the amount of expansion and contraction of the fluid transport pipe 1 so that the outer peripheral surface of the cover member 2 acts as an acting force in the direction of bringing the inner peripheral surface of the cover member 2 closer to each other. A leakage fluid diffusion prevention structure in a fluid transport pipe that is set to a value that causes 2. The cover member 2 includes a cover body 2A that fits onto the fluid transport pipe 1, and a cover body 2A that fits onto the fluid transport pipe 1.
The annular packing 3 interposed between the cover body 2A and the fluid transport pipe 1 is elastically deformed in the radial direction by contacting the fluid transport pipe 1 from the longitudinal direction. Pressing member 2B brought into close contact with the outer peripheral surface and the inner peripheral surface of the cover body 2A
A leakage fluid diffusion prevention structure in a fluid transport pipe according to claim 1 of the utility model registration claim, which comprises: 3 Utility model registration claim 2, in which the cover main body 2A is divided into two in the circumferential direction.
A structure for preventing leakage fluid diffusion in a fluid transport pipe as described in 2. 4. A structure for preventing leakage fluid diffusion in a fluid transport pipe according to any one of claims 1 to 3, wherein the fluid is a low-temperature liquefied gas.