JPS5822515A - Device for inserting flaw detecting cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for inserting a cable for flaw detection of a tube body, and in particular a cable insertion device suitable for detecting multilayer helical coils used in heat exchangers of nuclear reactors ('II). Regarding equipment.

Heat exchangers used in nuclear reactors often have heat exchanger tubes bent into complex shapes to improve heat transfer efficiency, especially multilayer helical coils.

In this case, if the heat transfer tube is damaged and the internal fluid comes into contact with the heat transfer medium, a serious accident may occur. In particular, if the fluid in the heat transfer tube is water and the heat transfer medium is IJ, there is a risk that if the two come into contact for a period of time, they will react explosively and cause a catastrophic accident such as destruction of the heat exchanger. . For this reason, it is necessary to periodically perform flaw detection on the heat exchanger tube, but flaw detection from the outside of the heat exchanger tube is not necessarily sufficient, and there is a demand for flaw detection from the inside of the heat exchanger tube. The inventors have developed and put into practical use a flaw detection cable in which a flaw detection device is attached to the tip of the cable and floats are attached at equal intervals for flaw detection from inside the heat transfer tube.

FIG. 1 shows this temporary cable insertion device.

In the figure, water W is injected and filled into the device main body 26.
The flaw detection cable 25 wound around the drum 22 is sent out by rotating the handle 23. The sent-out cable 25 enters the heat exchanger tube 27 to be inspected from the nozzle 28 along the flow of water inside the device, moves forward with the flow of water, and is inspected inside the tube by a flaw detection device (not shown) attached to the tip. Perform flaw detection from the surface. In the case of this device, if the rotation speed of the handle 23 is too fast, the cable 25 becomes slack, and the cable floats inside the device due to the buoyant force of the float 29, and in severe cases, it gets tangled in the device and becomes impossible to send out. Put it away. In this case, remove bolt 38.
Repairs had to be made by removing the two lids 21 and draining the water inside the device, which was inconvenient to handle. In addition, in the case of this type of device, there is a problem in that since it is impossible to observe the state of the cable being extended from the outside, there is no possibility of an accident until the device becomes inoperable.

In addition, the length of the tube to be tested for flaws reaches approximately 100 mm in the case of multilayer helical coils, but when a cable is inserted into such a long tube, the resistance inside the tube increases as the cable moves forward. Water flow becomes poor. If the water pressure is increased to advance the cable further, the water tends to flow backwards, eventually making it impossible to advance the cable.

An object of the present invention is to provide an apparatus which eliminates the above-mentioned problems, allows checking the cable's unwinding state, and allows the cable to be freely advanced even if it is a long tube.

In short, the present invention is a device that consists of a sprocket for sending out a flaw detection cable, and a cable feed tube that advances the flaw detection cable using pressurized water, and has a mechanism for preventing water from flowing back into the cable feed tube.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, 1 is the main body of the insertion device, and this main body 1
At the top of the main subblock (5a) supported by a spring 6,
Similarly, a sub sprocket 5b is supported by a spring (not shown) and is positioned opposite the main sprocket 5a. Recesses 5a' and 5b' are formed in the sprockets 5a and 5b, respectively, and the table 2 to be fed
Each of the floats 29 of 5 engages with this recess and prevents the cable 25 from advancing freely due to water pressure. Reference numeral 2 denotes a cable feed pipe arranged within the main body 1 of the apparatus. A water supply injection part 7 is formed at the lower part of the cable feed pipe 2.

An annular water supply distribution passage 7a is formed in this cable injection part 7, and a plurality of water supply injection passages 7b branch from this water supply distribution passage 7a, and the cable passage 2a opens in the traveling direction of the cable 25. It is open to

Next, reference numeral A indicates a water supply backflow prevention part formed at the upper part of the cable feed pipe 2. FIG. 3 shows the details of the water supply backflow prevention part, and 30 is a backflow prevention body, and a plurality (for example, four pieces) of backflow prevention bodies are arranged in the circumferential direction of the cable passage 2a, forming a - set of backflow prevention parts.

In the illustrated example, two sets (two stages) of the backflow prevention parts are arranged. Reference numeral 33 denotes an adjustment body that is screwed into the cable feed pipe, and 31 represents a spring interposed between the adjustment body 33 and the backflow prevention body 30. This spring 3]- is connected to the backflow prevention body 30 by a method such as welding, and the adjusting body 33 side is connected to the adjusting body 33 through an engagement pin 33a connected to the adjusting body 33, independently of the rotation of the connecting body. are in contact with each other. A ring 19 is inserted into the float 29 of the cable 25 to engage with the backflow prevention body 30 to improve water sealing performance.

The operating state of the above device is shown below.

First, when inserting the cable 25 into the pipe body to be inspected, pressurized water W is supplied from the water supply nozzle 4.

The water supply W is provided through the water distribution passage 7a.

The water is violently injected into the cable passage 2a in the cable traveling direction through the water supply injection passage 7b, and the cable 25 moves forward along the flow of this water supply. In this case, each float 29 of the cable 25 is held between the main sprocket 5a and the sub sprocket 5b, so the cable does not move forward automatically due to the water flow, and by adjusting the rotation of each sprocket, the advancing speed of one cable 25 can be adjusted. can be adjusted. Further, in this case, the tensile force of the cable 25 is absorbed by the spring 6, so there is no risk of the cable breaking.

In addition, a part of the injected water supply W flows backward into the cable passage 2a.
However, most of it is blocked by the backflow prevention part formed at the upper part of the cable feed pipe 2. That is, as shown in FIG. 3, when the cable 25 moves forward and the float 29 passes, each backflow prevention body 30 retreats to allow the float 29 to pass and prevent water from flowing back. In this case, the pressing force of the spring 31 can be adjusted by rotating the adjustment body 33.

Note that since the spring 31 is arranged independently of the rotation of the adjustment body 33, the backflow prevention body 3o does not rotate via the spring 31.

Next, when pulling back the cable 25, the supply of water W is stopped, and each subrocket 5a, 5b is rotated in the opposite direction to that described above and pulled back. In this case, in the backflow prevention section, the adjustment body 33 is rotated so that the backflow prevention body 30 is not caught on the float 29. That is, by rotating the adjustment body 33 and moving it to the outside of the cable feed pipe 2, the engagement pin 33a that freely engages with the spring 31 pulls the spring 31 in the moving direction of the adjustment body 33, and the spring The backflow preventer 30 fixed to the spring 31 is drawn into the space in which the spring 31 is arranged.

By implementing this invention, there is no need to worry about the flaw detection cable being terminated, and the reliability of the device is greatly improved.Also, even when using high-pressure water supply, there is only a slight backflow of the water supply, so even long pipes can be used. The flaw detection cable can be advanced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional flaw detection cable insertion device, FIG. 2 is a sectional view of a flaw detection cable insertion device according to the present invention, and FIG.
The figure is an enlarged sectional view of the backflow prevention part. 2...Cable feed pipe 2a...Cable passage 5a...Main sprocket 5b...Sub-sprocket 5a, 5b...For float engagement Recess 6...
... Spring 7b ... Water supply injection passage 25 ... Flaw detection cable 29 ... Float 30 ... Backflow prevention body 31 ... Spring 33 ...Regulator's representative patent attorney Oka Tagobe (9) Figure 1 Figure 3

Claims (1)

[Claims] 1. A sprocket having a recess that engages with a float of a flaw detection cable, a cable feed pipe having a cable passage in the center, a backflow prevention portion formed at the top of the cable feed pipe, and A flaw detection cable insertion device consisting of a water supply injection passage that opens in the cable traveling direction with respect to the cable passage below the backflow prevention part. 2. A set of backflow prevention bodies consisting of a plurality of backflow prevention bodies arranged in the circumferential direction of the cable passage, an adjustment body screwed into the cable feed pipe, and a spring interposed between the backflow prevention bodies and the adjustment body. The flaw detection cable insertion device according to claim 1, characterized in that the prevention portion is arranged in one or more stages in the cable traveling direction. 3. The flaw detection cable insertion device according to claim 1 or 2, wherein the sprocket is supported by a spring.