JPS595861B2 - Conductor drive device for tube-shaped flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead wire drive device for an intra-tube type flaw detector of an inspection device that is inserted into a tube and performs volume inspection from the inner surface.

In boilers, heat exchangers, etc., heat transfer tubes form the boundary between the fluid inside the tube and the fluid outside the tube, and are therefore important components as a pressure-resistant boundary.

For this reason, heat exchanger tubes are sometimes subjected to non-destructive testing such as eddy current testing or ultrasonic testing to confirm their integrity during regular inspections or in the event of a leakage accident. Possible inspection methods include the in-tube insertion method and the extra-tube flaw detection method, but the in-tube insertion method is generally used from the viewpoint of the structure of the boiler and heat exchanger and the supportability of the flaw detector. Fig. 1 shows a conventional conductor for an in-tube push type flaw detector, in which the flaw detector 3 is inserted into the heat exchanger tube 1 from the heat exchanger tube end 2 using air pressure, and then automatically or manually connected to the cord tube 8 and the conductor T. Pull it out.

The flaw detection of the heat exchanger tube 1 is carried out by the flaw detector 3 inside the heat exchanger tube 1 by a signal transmitted from a flaw detection signal processing device (not shown) placed at the other end of the conductor T during these insertion and withdrawal processes.
Defects in the heat exchanger tube 1 are detected by detecting changes in the signal using a flaw detection signal processing device. Flaw detector 3
The conducting wire T connected to the heat exchanger tube 1 is designed so that it does not bend in the straight pipe part and can easily bend according to the curvature in the curved pipe part, considering the ease of insertion into the straight pipe part and the curved pipe part of the heat exchanger tube 1. , an elastic tubular body consisting of a close coil spring 4 and a woven lining 5 made of steel wire. Further, in order to reduce the frictional resistance between the elastic tubular body and the inner wall of the heat transfer tube 1, a rotor 6 is fitted onto the outer surface of the elastic tubular body. Therefore, when inserting the flaw detector 3 from a straight tube section such as a U-shaped tube into a curved tube section, the conducting wire 7 is guided along the bending radius outer wall of the heat transfer tube 1 due to the appropriate flexibility of the elastic tubular body. It is then reversed.

At this time, the rotor 6 is pressed against the inner wall of the heat exchanger tube 1 due to the flexibility and rigidity of the elastic tubular body, causing an increase in frictional resistance, but this is negligible in the case of a single curved tube portion. On the other hand, when the conventional flaw detector 3 is applied to, for example, a serpentine heat exchanger tube having a large number of curved tube parts, the frictional resistance due to the elasticity of the elastic tubular body, which can be ignored in a U-shaped heat exchanger tube, is also applied to the tube wall. As the number of rotors 6 in pressure contact with the heat exchanger tube 1 increases, it becomes difficult to insert the flaw detector 3 over the entire length of the heat exchanger tube 1. Furthermore, when the conventional flaw detector 3 is inserted into the heat transfer tube 1, it is inserted by pressure feeding using air or the like. This is to drive the flaw detector 3 by the pressure difference generated before and after the flaw detector 3, but the rotor 6 is fitted into an elastic tubular body, and the elastic tubular body and the conductor 7 can move independently. Therefore, combined with the frictional force of the flaw detector 3, a large force is likely to be applied to the connection between the flaw detector 3 and the conducting wire 7, resulting in disadvantages such as poor contact and wire breakage. SUMMARY OF THE INVENTION An object of the present invention is to provide a lead wire drive device for a tube-inserted flaw detector that can reduce the contact resistance between the inner wall of the tube and the lead wire and expand the insertion range of the flaw detector.

A flaw detector that detects flaws on the pipe wall from the inside is connected to one end of the conductor,
The above-mentioned conductor is inserted into the tube and driven, and the conductor is inserted and pulled out into the tube to be flaw-detected via a plurality of guide elements fixed to the outer surface with a predetermined pitch and driven by fluid; The guide element itself is formed to have a specific gravity smaller than that of the fluid, and the guide element is pressed against a planar end face facing the flow direction of the fluid to move the conductive wire.

An embodiment of the tube-insertion type flaw detector conductor drive device of the present invention will be described below with reference to FIG.

A plurality of guide elements 9 are directly fixed to the conductive wire 7 that connects the flaw detector 3 to one end with a pitch that is 3 to 30 times the outer diameter of the serpentine heat exchanger tube 10 to be flaw detected. The conductor 7 inserted from the upper end or lower end of the heat tube 10 is connected to the drive device 11.
The guide element 9 is driven by receiving a fluid such as water pumped from a pump (not shown) or the like by the end face of each guide element 9 which faces the direction of fluid flow and is formed into a flat shape as shown in the figure. Because of its curved shape, it can be smoothly and deeply inserted into the coiled tube or spiral-shaped curved tube portion of the heat tube 10 with little resistance.
The conductor 7 and the flaw detector 3 are pulled out by applying pressure and pushing them out from the tube end opposite to the insertion end via the drive device 11.
Flaw detection of the heat exchanger tubes 10 is performed during these insertion and withdrawal processes. The guide 9 is desirably made of a material that has low frictional resistance with the inner wall of the serpentine heat exchanger tube 10 and is highly wear resistant, and is preferably made of a synthetic resin, for example.

Further, it is desirable that the guide element 9 is lightweight relative to the pumped fluid, and is configured to have a specific gravity smaller than that of the pumped fluid. As a means for making the guide element 9 lighter, a gas space 13 may be provided as shown in FIG. 3 and gas may be filled inside the guide element 9 to make it lighter. Furthermore, the guide 9 has the function of receiving driving force from the fluid and directly transmitting it to the conductor 7, and in order to obtain a larger driving force, it is effective to increase the axial length of the guide 9 (guide Although the driving force of the guide element 9 is based on the pressure difference between the front and rear end surfaces, the axial length of the guide element 9 that can be passed through is limited by the minimum bending radius of the serpentine heat exchanger tube 10. Note that the insertability is different depending on the outer diameter of the conductor 7, compared to that of the outer diameter of the conductor 7 of 1 and 2.
The results of testing two conductors 7 with an outer diameter of 2 times the same pitch showed that the thicker conductor 7 with an outer diameter of 2 was difficult to insert, and the degree of difficulty was 1/3 the length of the conductor 7 with an outer diameter of 1. The rigidity of the conducting wire 7 has a great influence on the insertion.
Further, the driving fluid differs depending on the type of flaw detection test, and gas is normally used in eddy current flaw detection, while liquid is normally used in ultrasonic flaw detection.

FIG. 4 shows another embodiment, in which the heat exchanger tube 10 is of a helical coil type, and has the same effect as the above-described embodiment of the coiled tube type.

As mentioned above, this tube-insertion type flaw detector lead wire drive device can directly fix and drive a large number of guide elements pressed by fluid to the conductor wire, and can also reduce the contact resistance of the guide elements against the inner wall of the tube. With this structure, the flaw detector can be smoothly inserted deep into the heat insulating tube having a large number of curved tube sections.

By eliminating the conventional elastic tubular body, there is an advantage that the pressure receiving area for applying driving force to the guide can be increased, and the conductor part is lighter and less rigid, allowing the conductor winding device to be made smaller. . When a liquid is used as the driving fluid, contact resistance can be reduced by the lubricating action of the liquid between the guide element and the inner wall of the tube. In addition, since the driving force is evenly distributed by the guide, the tension between the flaw detector and the conducting wire is small, and poor contact and disconnection of the conducting wire are less likely to occur. As described above, the tube-insertion type flaw detector conductor drive device of the present invention reduces the contact resistance between the inner wall of the tube and the conductor, and allows the flaw detector to be smoothly inserted deep into the heat exchanger tube having a large number of curved tube parts. It has the effect that it can.

[Brief explanation of the drawing]

FIG. 1 is a plan view partially showing a cross section of a conventional lead wire for a tube-inserted flaw detector when it is inserted into a tube, and FIG. FIG. 3 is a cross-sectional view of another embodiment of the guide of the conductor drive device for the tube-inserted flaw detector of the present invention, and FIG. It is a front view showing a part of another example of a conducting wire drive device in section. 1, 10... Heat tube, 3... Flaw detector,
7... Conductor, 9... Guide.

Claims (1)

[Scope of Claims] 1. A conductor drive device for an intra-tube type flaw detector, in which a flaw detector for testing a tube wall from the inner surface is connected to one end of a conductor, and the conductor is inserted into the tube and driven. The conductive wire is inserted into and pulled out of the tube to be tested through a plurality of fixed guide elements driven by fluid, and the guide element itself is formed to have a specific gravity smaller than the fluid and is opposed to the flow direction of the fluid. 1. A conductor wire drive device for a tube-inserted flaw detector, characterized in that said guide element moves said conductor wire by being pressed against a flat end face thereof. 2. The conductor drive device for in-pipe press-type flaw detection according to claim 1, wherein a gas is sealed inside the guide as a means for reducing the specific gravity of the guide.