JPS61105400A - Pipe leak detector - Google Patents

Abstract

PURPOSE:To obtain early and automatic detection of leak in a pipe by providing in a heat insulator between the pipe and a sheath plate a pipe leak detecting sensor actuated by current flow through two lead wires. CONSTITUTION:Spacing tubes 6 and insulating blocks 5 which rapidly becomes electrically conductive through penetration of water are alternately disposed, two lead wires 7, 8 extending separately through respective holes in blocks 5, and a permeable coating cylinder 9 is provided to cover the outside. This structure is disposed in a heat insulator 2 provided between a pipe 1 and a sheath plate 3. This construction effects early and automatic detection of leak in the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention relates to a pipe leak detection device, and more specifically, it is a system for detecting leaks in pipes in chemical plants, nuclear power generation facilities, etc. when high temperature and high pressure water leaks to the outside. It is used as a device for detecting

Conventional technology Currently, the basic concept in the structural design of power reactor piping is the assumption of instantaneous rupture of secondary cooling system piping, and sufficient safety protection equipment is required to ensure the structural integrity of the facility. The piping is not equipped with a device to detect leakage of internal high-temperature, high-pressure water.

Problems to be Solved by the Invention As mentioned above, conventional power reactor piping is not equipped with a device to detect leaks of high-temperature, high-pressure water. In addition, there is a problem that remote detection cannot be performed reliably. The present invention
This is an attempt to solve these problems. That is, the present invention promptly and reliably prevents leakage of high-temperature, high-pressure water inside piping to the outside.

The object of the present invention is to provide a pipe leak detection device that can detect automatically and remotely.

The solution to the problem is to alternately line up the spacing tubes and insulating pieces that become electrically conductive through the penetration of water, and pass two conductive wires through the diameter holes of the pieces, respectively. A pipe leak detection sensor whose outside and sides are covered with a water-permeable covering tube was installed inside the heat insulating material between the pipe and the exterior plate. That is, the configuration of the present invention includes a pipe leak detection sensor installed in a heat insulating material between the pipe and the exterior plate, and the pipe leak detection sensor is electrically connected to the spacer by water penetration into the spacing pipe. It is characterized by consisting of two conductive wires that are arranged alternately with pieces whose insulation properties deteriorate rapidly and are passed through the diameter holes of the pieces separately, and a water-permeable covering tube that covers the outside of the spacer and the piece. It is said that

Function Even if voltage is applied between the two conductors of the pipe leak detection sensor, if water does not penetrate into the piece due to pipe leakage, the piece maintains electrical insulation, so the two conductors No current flows through the conductor. However, if there is a leak in the piping, the water from the leak will penetrate the piece through the insulation material and the covering tube, and the piece will rapidly lose its insulation and become a conductor.
The conductor of the book appears to be electrically shorted by the piece,
Therefore, current flows through the two conductors. By detecting this current with a suitable remote monitoring system, pipe leaks can be detected.

Embodiment FIGS. 1 to 5 show a first embodiment of the present invention, and a sixth embodiment of the present invention is shown in FIGS.
The figure shows a second embodiment of the invention.

In FIGS. 1 and 2, 1 is a pipe for passing high-temperature, high-pressure water in a nuclear power plant, and in this embodiment, it is installed horizontally. 2 is a heat insulating material attached to the outer periphery of the pipe 1, and 5 is an exterior plate covering the outermost surface of the heat insulating material 2. Reference numeral 4 denotes a pipe leak detection sensor, which will be described later, and is located below the pipe 1 and installed in the heat insulating material 2 along the longitudinal direction of the pipe 1.

The pipe leak detection sensor 4 includes a piece 5, a spacing tube 6, two conductive wires 7 and 8, and a covering tube 9, as shown enlarged in FIGS. 6 to 5. And piece 5
A through hole is provided in which the conductive wires 7 and 8 are passed through separately. The conductive wires 7 and 8 are good electrical conductors and are made of copper. The piece 5 is made of an insulating material that allows water to easily penetrate through capillary action, and in this embodiment, it is made of unglazed porcelain. The covering tube 9 is made of a fibrous material that has insulation properties and is easily penetrated by water, and is made of glass wool in this embodiment. Further, as shown in FIG. 3, the configuration of the pipe leak detection sensor 4 is
With a large number of spacer tubes 6 interposed between the pieces 5 and the pieces 5,
The structure is such that conductive wires 7 and 8 are passed through the holes of each piece 5 and the spacing tube 6 separately to connect them, and the outside of these is covered with a covering tube 9. Further, the total length of the detection sensor 4 is made to match the length of the pipe 1, one end of each of the two conductive wires 7 and 8 is covered with an insulating material to prevent an electrical short circuit, and the other end is connected to a respective lead wire. and is connected to a leak detection monitoring system circuit, not shown. Note that the pipe leak detection sensor 4 can be attached by tying it into the heat insulating material 2 between the pipe 1 and the exterior plate 30 with a wire or the like. The above pipe leak detection sensor 4 is attached to each pipe 1 to be detected.

In a pipe leak detection device configured as shown in Figures 1 to 5, the inside of the pipe 1 is usually filled with high-temperature, high-pressure water. , temperature is 543°C, pressure is 175~2G) is flowing. If this water leaks due to damage to pipe 1 (initially a pinhole or small opening, etc.), first
It ejects in the form of steam from pinholes or tiny openings. Then, the steam is absorbed by the heat insulating material 2 and immediately changes to water. While this water is still permeating into the heat insulating material 2, it gradually flows downward as the amount increases, and eventually the insulating material 2 also permeates into the covering tube 9, and then into the piece 5. When water penetrates into the piece 5, the insulation deteriorates and it becomes a conductor, so the electrical resistance between the conductive wires 7 and 8 immediately decreases, and current flows through both the conductive wires 7 and 8. The existence of a leak can be detected by an alarm from a leak detection monitor system circuit that operates using this current as an input signal.

Note that the voltage applied between both conductors 7 and 8 is between 20 and 3
A low voltage of about 0 volts may be used. Since the leak water still collects on the lower inner surface of the exterior plate 3, the installation position of the pipe leak detection sensor 4 is set to the place where the leak water collects, that is, the heat insulating material 2.
It may be placed at the bottom of the .

The embodiment shown in Fig. 6 is a case where the pipe 1 is installed vertically.
Since the water flows in the direction of gravity), from what position on the circumference of the pipe 1 does it flow down?

I don't know in advance. Therefore, the pipe leak detection sensor 4
is arranged in a spiral in the heat insulating material 2, so that it always crosses the detection sensor 4 no matter where it flows down.

The above embodiments relate to typical piping, and for elbow pipes, a piping leak detection sensor is installed at a place where leak water is most likely to flow, that is, in principle, on the lower side along an arc. Furthermore, the horizontal, vertical (
Since most damage occurs near the welded joints of vertical pipes and elbow pipes, it is best to place pipe leak detection sensors primarily along these areas.

Effects of the Invention The present invention includes a pipe leak detection sensor that is activated by current flowing through two conductive wires when leak water from the pipe penetrates into the piece, in a heat insulating material between the pipe and the exterior plate. With this installed, leaks from piping can be detected early and automatically without the need for periodic inspections.
It can also enable remote detection.

Moreover, since the pipe leak detection sensor is activated by the action of leak water, it will not activate even when the humidity in the air is quite high unless there is condensation on the inner surface of the exterior plate, and there will be no false alarms. Even if the amount is relatively small, it can be detected by converting into water and has good sensitivity. In addition, the detection sensor consists of the pieces and the spacing tubes arranged alternately, two conductive wires passed through the holes of the pieces separately, and the outside covered with a covering tube, so that it can be used as a single long object. It is easy to handle and attach to heat insulating material, and after installation, there is no malfunction due to contact between two conductors, and the electrical insulation properties of the bridge rapidly deteriorate due to water penetration. Since the covering tube is water-permeable, leakage water quickly penetrates into the tube, and the reliability of the IJ detection operation is therefore guaranteed.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG.
2 is a sectional view taken along cutting line A-A in FIG. 1, FIG. 3 is an enlarged sectional front view of the piping leak detection system in FIG. 1, and FIG. 4 is a sectional front view of the embodiment. 5 is a cross-sectional view taken along cutting line B--B in FIG. 5, FIG. 5 is a cross-sectional view also taken along cutting line a-C, and FIG. 6 is a cross-sectional front view of the second embodiment. 1... Piping, 2... Heat insulation material, 3... Exterior board, 4...
... Piping leak detection sensor, 5... Piece, 6... Spacing tube, 7, 8... Conductor, 911. Covered tube. Hayabusa 1 Tomoe 2nd figure $3 @ figure v-6

Claims (1)

[Claims] 1. Equipped with a pipe leak detection sensor installed in the heat insulating material between the pipe and the exterior plate, and this pipe leak detection sensor is equipped with a pipe leak detection sensor whose electrical insulation property is suddenly deteriorated due to the penetration of water into the spacing pipe. Piping leak detection characterized by comprising two conductive wires that are alternately arranged with deteriorating pieces and individually passed through each hole of the piece, and a water-permeable covering tube that covers the spacer tube and the outside of the piece. Device.