JPH08285830A - Float for carrying cable - Google Patents

Abstract

PURPOSE: To reduce the contact friction of an object, to be inspected, with a float for a carrying cable and to enhance the insertion property of a probe by a method wherein a roller is attached to the float and the roller is brought into contact with the inside wall of a fine tube. CONSTITUTION: Floats 3 are used as pressure receiving bodies when a flaw detection probe such as an eddy-current flaw detection probe, an ultrasonic flaw detection probe or the like is inserted into a slender tube by a gas pressure or a liquid pressure such as a water pressure or the like, and they are attached to a carrying cable 2 at equal intervals. Rollers 4 which are rugby ball-shaped and which are made of superhigh polymer polyethylene are installed at four places on the circumference of every float 3. Every roller 4 shaves a part of a float wall, and it is turned while a shaft 5 composed of a stainless steel pin is used as a fulcrum. As the shape of every roller, a spherical shape, a cylindrical shape or the like may be used. When the carrier-frequency cable 2 is inserted into an object to be inspected, the outermost circumference of every roller 4 comes into contact with the inner wall of the object to be inspected, and the roller is turned so as to relax its friction with the object to be inspected. Thereby, the flaw detection probe can be inserted easily into the whole length of a spiral slender tube which is long and which has a bent tube part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current flaw detection probe, an ultrasonic flaw detection probe, a laser inner diameter measurement probe used for inspecting heat transfer tubes of various heat exchangers of nuclear power plants, various small diameter pipes of petroleum and chemical plants. Also, the present invention relates to a float for a carrier cable for inserting a small CCD camera, a fiberscope or the like used for visual inspection in a narrow tube.

[0002]

2. Description of the Related Art Conventionally, when a long (about 100 m) thin tube (heat transfer tube) having a bent tube portion (minimum bend R160) is inspected by using eddy current or ultrasonic waves, a flaw detection probe is fed into the tube. On the cable, spherical floats (pressure receiving bodies) are provided at equal intervals on the cable, and at the same time mechanically pushing this, gas pressure or water pressure is applied to the float, and the carrier cable is driven (propulsed) by the pressure difference generated at this time, A flaw detection probe is inserted. FIG. 3 is a schematic diagram of such a fluid pressure feeding system. In this example, the heat transfer tube 11 of the steam generator 10 is inspected. This system will be described as an example. A tube 22 is extended from the probe insertion device 20 and connected to the tube plate positioning device 12 to which one end of the heat transfer tube is connected, and the conveyance is performed by grasping in the cable storage tank 20a of the probe insertion device 20. The cable 2 is mechanically sent into the pipe 22 by the rotation of the motor, and at the same time, the gas supply unit 21 pressurizes and sends nitrogen gas to the storage tank 20a under pressure. The gas fed under pressure passes through the pipe 22 and the helical coil portion 11a, the vent portion 11b, and the descending pipe portion 11 of the heat transfer pipe 11.
It flows through c and is exhausted from the tube sheet positioning device 13. In the figure, the gas is expelled for the sake of convenience, but the gas is not actually exhausted but is recovered in the gas supply / distribution unit 21. The flaw detection probe 1 is attached to the front portion of the transport cable 2, and the floats 3 are attached to the transport cable 2 at equal intervals. As shown in Fig. 4, gas flows and a pressure difference is generated before and after the float. When the pressure difference exceeds a certain value, the float starts to move. As a result, the entire carrier cable moves and the flaw detection probe is inserted. To be done.

When the flaw detection probe 1 is pulled out, the delivery port of the gas distribution unit 21 is connected to the tube sheet positioning device 13
Then, the suction ports are connected to the storage tanks 20a, respectively, and gas is pressure-fed in the opposite direction to the heat transfer tube 11, and the transport cable is rewound by the motor of the probe insertion device 20.

As shown in FIG. 5, the float and the probe are attached to the carrier cable by forming a through hole in the center of the float and the probe, passing the cable 2 through the hole, and fixing them with an adhesive and a wedge 3a. ing.

[0005]

However, in the case where the subject is a long thin tube having a curved tube portion and a complex thin tube having a spiral shape, the subject is tested as the insertion distance into the thin tube increases. The number of carrier cable floats in contact with the inner wall increases, and at the same time, the friction with the inner wall of the subject increases,
There is a problem that the insertion thrust of the probe decreases and the probe stops inside the tube.

The present invention has been made in view of the above circumstances, and it is possible to improve the insertability of the probe by minimizing the contact friction between the subject and the transport cable float and obtaining a smooth insertion thrust force over the entire tube length. It is an object of the present invention to provide a float for a carrier cable that can be used.

[0007]

SUMMARY OF THE INVENTION The present invention provides an apparatus for mounting a flaw detection probe on a cable provided with a plurality of floats and inserting the cable into a long thin tube by fluid pressure to detect flaws in the thin tube. Attach the roller to the float,
The roller is brought into contact with the inner wall of the thin tube to reduce the frictional resistance between the inner wall of the thin tube and the float.
Further, the present invention is characterized in that the roller has a spheroidal shape, a spherical shape, or a cylindrical shape.

[0008]

The present invention is an apparatus for inspecting by inserting a carrier cable having a flaw detection probe and a spherical float into a pipe by fluid pressure, in which a spherical float, a rugby ball shape,
A spherical or cylindrical roller is attached, and the contact resistance is relaxed by contacting this roller with the inner wall of the pipe, which makes it relatively long and has a curved pipe portion. The flaw detection probe can be easily inserted into the entire length of the spiral thin tube.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall view of a carrier cable of the present invention, and FIG. 2 is an explanatory view of a carrier cable float of the present invention. In the figure,
1 is a flaw detection probe, 2 is a carrier cable, 3 is a float,
Reference numeral 4 indicates a rugby ball type roller, and 5 indicates a roller rotation axis. In FIG. 1, the float 3 for the carrier cable
Is a pressure receiving body when the flaw detection probe 1 for eddy current flaw detection, ultrasonic flaw detection or the like is inserted into the thin tube by fluid pressure such as gas pressure or water pressure, and is a carrier cable 2 connected to the flaw detection probe 1. They are attached at equal intervals (about 100 mm pitch).

As shown in FIG. 2 (a) (longitudinal section) and FIG. 2 (b) (horizontal section), spherical float 3 has a rugby ball shape on four circumferences and is made of ultra-high molecular polyethylene. A roller 4 is provided. Each roller 4 is formed by scraping off a part of the float wall and fixing a rotating shaft 5 made of a stainless steel pin through the center of the roller, and rotating around this shaft as a fulcrum. At this time, the pin also functions as a bearing. By forming the roller 4 in a rugby ball shape and arranging the roller 4 at four locations in the circumferential direction, the contact area with the subject can be widened. Of course, the roller shape is not limited to the rugby ball shape, but may be a spherical shape, a cylindrical shape, or the like.

When a transport cable with such a float attached is inserted into a subject, the outermost circumference of the rugby ball type roller 4 contacts the inner wall of the subject and rotates, so that the friction with the subject can be alleviated. it can.

In this way, the problem of a decrease in insertion thrust due to friction with the inner wall of the subject is solved, and it has become relatively difficult until now to provide a full length in a spiral thin tube having a curved tube portion.
It has become possible to easily insert a flaw detection probe.

[0013]

As described above, according to the present invention, the following effects can be obtained. It has become possible to reduce the contact friction between the carrier cable float and the inner wall of the subject, which occurs when the flaw detection probe is inserted into the subject (capillary tube). Long (about 100 m) and curved pipe (minimum bending R160)
It has become possible to smoothly and easily insert the flaw detection probe into the entire length of the inside of the spiral-shaped object (capillary tube) having the.

[Brief description of drawings]

FIG. 1 is an overall view of a carrier cable of the present invention.

FIG. 2 is an explanatory diagram of a carrier cable float of the present invention.

FIG. 3 is a schematic diagram of a fluid pumping system.

FIG. 4 is a diagram for explaining the action of the float.

FIG. 5 illustrates attachment of a float probe to a cable.

[Explanation of symbols]

1 ... flaw detection probe, 2 ... carrier cable, 3 ... float,
4 ... Rugby ball type roller, 5 ... Roller rotation axis.

Claims (2)

[Claims] 1. In a device for attaching a flaw detection probe to a cable provided with a plurality of floats, and inserting the cable into a long thin tube by fluid pressure to detect flaws in the thin tube, a roller is attached to the float and the roller is attached. A float for a carrier cable, characterized in that the frictional resistance between the inner wall of the thin tube and the float is reduced by contacting the inner wall of the thin tube. 2. The float according to claim 1, wherein the roller has a spheroidal shape, a spherical shape, or a cylindrical shape.