JPS58211620A - Piping structure - Google Patents

Abstract

PURPOSE:To facilitate detection of minute leakage, by providing two types of hermetically sealed pipe structures in the vicinity of weak points of piping such as welded parts. CONSTITUTION:An outer pipe 46 is attached to annular protruded parts 44, which are attached to the outer part of a pipe 41 in the vicinity of welded part 42 by bolts and nuts 44. A rupture disk 48, which is broken when the pressure of leakage detecting fluid 47 filled in a gap formed by the pipe 41 and the outer pipe 46 becomes larger than limit pressure, is provided in the outer pipe 46. A minute leakage detecting sensor 49 is provided in the vicinity of the welded part 42. Even though cracks are generated at the weak point 42 such as welded parts of the pipes and working fluid 43 leaks, the leakage can be detected by the sensor 49 while the amount is minute because the space is hermetically sealed. When the cracks are expanded and the amount of leakage is increased, the pressure of the leakage detecting fluid 47 is increased, and the rupture disk 48 is broken. Even though the cracks are further expanded and the pipe 41 is separated therefrom, the pipe is constrained by the outer pipe 46, and damage of neighboring equipment is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piping structure, and particularly to a piping structure suitable for filling high pressure fluid.

In piping structures, welded joints are often used, such as the nozzle section 11, straight pipe section 12, and elbow section 13 shown in FIG. This joint is likely to become a weak point in terms of strength because it becomes a shape discontinuity, a metallographically altered part due to the influence of welding heat, and a high tensile stress remains. In piping through which high-temperature, high-pressure water flows, such as piping for nuclear power equipment, the corrosive effects are further superimposed, which may cause cracks near the welded portion 21, as shown in FIGS. 2 and 3. 31 is a through crack. These cracks cause leakage of harmful substances within the pipe, and when the pipe undergoes complete separation and rupture, the pipe is deformed by the force exerted by the ejection of the contents. This deformation may also cause secondary damage to adjacent equipment piping.

Nuclear equipment is required to have exceptionally high safety and reliability compared to other general equipment. For this reason, it is necessary to detect microscopic cracks and microscopic leaks early so that appropriate measures can be taken before they become serious. Furthermore, if
In the unlikely event that separation occurs, sufficient measures must be taken to ensure that adjacent equipment piping is not affected.

An object of the present invention is to provide a piping structure suitable for early detection of minute leakage of piping contents and for preventing deformation of the piping at the time of separation and rupture.

When a pipe ruptures, as mentioned above, first a fine crack is generated, then the crack grows and becomes a penetrating crack that reaches the outer surface of the pipe as shown in Figure 3, causing a small amount of leakage, and then the crack grows. This usually occurs after the mounting surface has opened to a large extent and the amount of leakage has become large. However, in nuclear power piping equipped with heat insulators, it is extremely difficult to detect minute leaks because they seep into the heat insulators.

The main point of the present invention is to make it easy to detect minute leaks by creating a sealed double pipe structure near the weak points of the piping such as welded parts, and if the amount of leakage becomes large, a love desk is installed on the double pipe in advance. In addition to controlling the amount of leakage from this area to a constant level, we decided to create a local double-pipe structure that would prevent the separated pipes from being excessively deformed even if the pipes were completely separated and destroyed. be. Hereinafter, it will be explained in detail using examples.

An embodiment of the present invention is shown in FIG. In this figure, tube 4
1 are connected by a tube connection weld 42, and the tubes are filled with a working fluid 43.

A continuous annular protrusion 44 is tightly attached to the outer periphery of the pipe 4 in the vicinity of the welded portion 42 by, for example, fillet welding 45. The annular protrusion 44 has an outer tube 46 with a split structure.
is attached by bolts and nuts 44. Outer tube 4
In order to prevent the contents 43 from leaking, the leakage detection fluid 47 filling the gap formed between the inner tube 41 and the outer tube 46 is filled with a leakage detection fluid 47 which is broken when the pressure rises and exceeds a certain limit pressure. A weak point, ie, a loveture desk 48 is provided. A sensor 49 for detecting a small amount of working fluid 43 and leakage is provided near the welding portion 42 .

For example, when the working fluid 43 is high-temperature, high-pressure water, such as water temperature 290C and water pressure: 70Ky/cm, as in nuclear piping, the leak detection sensor 44 is a moisture detection sensor,
As the leak detection fluid 47, it is preferable to use COx gas, air, or the like. In this example, even if a crack that occurs in a weak point 42 such as a pipe weld penetrates the pipe wall and leaks the working fluid 43 through that route, it is sealed by the annular protrusion 44 and the outer pipe 46. Since the leakage fluid can be prevented from dissipating, the leakage detection sensor 49 can detect even a minute leakage, so that appropriate leakage countermeasures can be taken at an early stage. Furthermore, if for some reason a microleakage is not detected and the crack expands and the amount of leakage increases, the pressure of the leakage detection fluid 47 will increase. When the pressure rises to a certain set pressure, the jibuture desk 48
destroys. When this stage is reached, the amount of leakage becomes extremely large. By selecting the dimensions of the loveture desk 48 as shown in FIG. 5 to be within the detection limit of the water level monitoring sensor 51 provided in a separate tank 50, the influence of leakage on others can be reduced. For example, the detection limit f4 of the water level monitoring center 51
0t/IHB, and the flow rate of the high temperature water is 201/m1t.
If it is rt-, the diameter of the loveture desk 48 is approximately 1 cr.
It may be about n. In other words, this enables the second step of leakage detection. If the crack further expands and the pipe 41 is completely separated, in conventional piping, the pipe 41 will be greatly deformed by the impact force of the leaked fluid, which may cause damage to adjacent equipment. To this end, conventionally, the pipe is attached to a fixed wall via a restraint to prevent excessive deformation of the pipe. However, in this embodiment, the deformation of the separated tube 41 is restrained by the outer tube 46, so there is no risk of damage to adjacent equipment. The feature of this example for preventing deformation is that it is self-restricted, so there is no need for a fixing wall, which is different from the conventional one. Furthermore, when inspecting the welded portion 42 during use, the inspection can be easily done by removing the fastening bolts 44 of the outer tube 4'6.

By using a colored fluid, for example, a developer for dyed flaw detection, or a luminescent fluid such as a fluorescent flaw detection liquid, as the leakage detection fluid 47 of the embodiment described above, damage to the loveture disk can be easily detected visually. In this case, it is convenient for early detection of leakage if the love desk is set so that it will be damaged by a slight increase.

Figure 6 shows the outer tube 4 to improve the sealing performance of the leakage detection fluid.
6 is not detachable, but the outer tube 46 is attached to the annular protrusion 44 by welding, which has the effect of improving airtightness.

Moreover, FIG. 5B and FIG. 7 are examples in which the outer cylinder detachable system is applied to the elbow portion. The feature of this example is that the outer tube 46 has a divided structure as shown. The jet force when the pipe 41 separates and breaks is the jet force Fy moving in the radial direction.
The jet force Fn acting in the horizontal direction (longitudinal direction) is generated, and the effect of this is that by using the structure shown in Figure 7, the load applied to the fastening bolt can be reduced and manufacturing is easy. The point is that.

According to the present invention, it is possible to detect early leakage of fluid in a pipe due to a through crack from a weak point in the pipe, and there is an effect that even if there is a problem, the equipment will not be affected.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of piping, FIGS. 2 and 3 are explanatory diagrams showing cracks and through cracks that occur near the welded part, FIG. 4 is a diagram showing an embodiment of the present invention, and FIG. The figure is an explanatory diagram when applied to a straight pipe part and an elbow part as an example of actual piping, Figure 6 is an explanatory diagram showing a modification of the present invention, and Figure 7 is a detailed diagram when applied to an elbow part. This is an explanation. 41... Pipe, 42... Welded portion, 43... Working fluid, 44... Annular protrusion, 46... Outer tube, 47...
・Leak detection fluid, Hata / [1 No. 4 Hayabusa 5 Mouth 0 Continued from page 1 0 Author Masui Tsutomu, Hitachi Machinery Research Laboratory, 502 Kandatecho, Tsuchiura City 0 Author Shinji Sakata Kandatecho, Tsuchiura City 502, Hitachi, Ltd. Mechanical Research Laboratory Author: Ionari Higuchi 502 Kandatecho, Tsuchiura City, Hitachi, Ltd. Mechanical Research Laboratory Author: Jun Kurosawa 502 Kandatecho, Tsuchiura City, Hitachi, Ltd. Mechanical Research Center

Claims (1)

[Claims] 1. A pipe having a welded part, a partial cylindrical pipe installed surrounding the welded part, and having both ends tightly fixed to the pipe;
A space formed by the piping and the partial cylindrical pipe is filled with a leakage detection fluid, and a cylindrical pipe is provided so that the cylindrical pipe is partially destroyed when the pressure of the leakage detection fluid rises above a certain pressure. A piping structure consisting of partially destroyed means. 2. A pipe having a welded part, a partial cylindrical pipe installed surrounding the welded part, and having both ends tightly fixed to the pipe;
A leakage detection fluid filled in a space formed by the piping and the partial cylindrical tube, and a nine-part fracture provided in the cylinder 1 so that the cylindrical tube is partially destroyed by an increase in pressure of the leakage detection fluid. and a leakage detection sensor attached to the outer peripheral surface of the piping for detecting fluid leakage from inside the piping. 3. The piping structure according to claim 1 or 2, characterized in that the partial cylindrical pipe is detachably attached to the piping.