JPH0427315B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for detecting the insulation position of a pipe, and more specifically, connects a series circuit of a power source and a continuity detection means on both sides of the insulation position of a metal pipe whose inner circumferential surface is exposed at least, The present invention relates to a method of detecting the insulation position of a metal tube by inserting a tube wire threading tool having an exposed outer periphery made of a conductive material into the metal tube. Such a method of detecting the insulation position of a pipe is necessary in order to ensure corrosion protection by flowing an anticorrosive current to a metal pipe buried underground and having an electrically insulating coating layer. When connecting metal pipes using, for example, a pipe joint, electrical continuity between the metal pipes may be cut off by a sealing material to prevent leakage. Therefore, the anti-corrosion current does not flow through all the tubes, and therefore the tubes to which the anti-corrosion current is not flowing will corrode. In order to detect the insulation position of such metal pipes, it is necessary to drill vertical holes at multiple locations along the pipe axis of the coated metal pipe to expose the coated metal pipe and detect the current flowing through the metal pipe. . Such prior art requires a great deal of manpower, time, and money for vertical hole excavation, and is inferior in workability. An object of the present invention is to provide a method that can easily detect the insulation position of a coated metal tube with simple operations. The present invention connects a series circuit of a power source and a continuity detection means on both sides of an insulated position to be detected in a metal tube whose inner peripheral surface is exposed at least, and connects a spiral circuit made of a conductive material inside the metal tube. A second wire rod made of a conductive material is wound spirally and has smaller bending stiffness and torsional stiffness than the third wire rod at the end of the third wire rod which is wound and has relatively high bending stiffness and torsional stiffness. One end of a first wire having one end connected and fixed, the other end of the second wire being helically wound with a conductive material, and having bending stiffness and torsional stiffness smaller than the second wire. is connected and fixed, a guide member made of a conductive material is connected to the other end of the first wire, and an intra-tube wire passing tool is inserted into the guide member so that the first wire can be bent by the weight of the guide member. This is a method for detecting the insulation position of a pipe. The present invention also provides a metal tube having at least an exposed inner circumferential surface, and an intra-pipe wire passing tool inserted into the metal tube, comprising:
At the end of the third wire material, which is spirally wound and has relatively high bending and torsional rigidity, the outer periphery is made of a conductive material having an electrically insulating coating. One end of a second wire rod which is spirally wound and has bending stiffness and torsional stiffness smaller than that of the third wire rod is connected and fixed, and the other end of the second wire rod has an electrically insulating coating on the outer periphery. One end of a first wire made of a conductive material, spirally wound and having lower bending and torsional rigidity than the second wire is connected and fixed, and the other end of the first wire has an exposed conductive wire. A guide member made of material is connected, and the guide member inserts into the metal tube an in-tube wire threading tool that allows the first wire to bend under the weight of the guide member, and connects the guide member with the inserted pipe wire threader. A method for detecting the insulation position of a pipe is characterized in that a series circuit comprising a power source and a continuity detection means is connected. FIG. 1 is a sectional view of an embodiment of the present invention. A covered metal pipe 61 for transporting fuel fluid such as city gas is buried in the ground 60. The coated metal tube 61 is constructed by covering the outer periphery of a steel tube made of a conductive material with a coating layer made of an electrically insulating material, such as synthetic resin, and exposing the inner periphery. In order to use the gas fuel transported within the coated metal pipe 61 in each house, the coated metal pipe 61 is provided with branch pipes 62 and 63 spaced apart from each other in the tube axis direction. The branch pipes 62 and 63 are electrically connected to the coated metal pipe 61. A power source 64 and an ammeter 65 as current detection means are connected in series to each end 62a, 63a of the branch pipes 62, 63 exposed above the ground. In this way, the coated metal pipe 61, the branch pipes 62, 63, and the power supply 6
4 and an ammeter 65 are electrically connected in series. Like the coated metal pipe 61, the branch pipes 62 and 63 are constructed of steel pipes made of a conductive material, the outer periphery of which is covered with a coating layer made of an electrically insulating material, and the inner periphery thereof exposed. The intraductal wire passing tool 1 inserted into the branch pipes 62 and 63 includes a longitudinal wire 1a and a guide member 5 fixed to the distal end thereof. The wire rod 1a is composed of first to third wire rods as described later, and each wire rod is formed in a coil shape and has flexibility. The pipe wire passing tool 1 is made of a conductive material, and the outer periphery of the longitudinal wire 1a is exposed. When detecting the insulation position 66 of the branch pipes 62 and 63, the tube wire passing tool 1 is inserted into the branch pipe 62 near the gas meter (not shown). This intra-pipe wire passing device 1 has a unique elastic modulus as described later, and contacts the inside of the pipe 62 elastically, thereby communicating with the power source 64 through the contact portion 62b of the pipe 62. The wire fitting 1 is maintained in electrical continuity. Furthermore, by twisting the longitudinal wire 1a of the pipe wire threading tool 1 around the axis, the elastic force with which the pipe wire threading tool 1 contacts the inner periphery of the branch pipe 62 is increased, thereby establishing electrical connection. This can be made even more reliable. During the wire threading work of the pipe wire threading tool 1 as described above, when the pipe wire threading tool 1 is inserted into the branch pipe 62, the insulation position 66 of the branch pipe 62 is
It is located on the downstream side in the insertion direction indicated by arrow 67. At this time, the branch pipe 62 is electrically cut off at the insulation position 66 at the length l1 of the in-pipe wire passing device 1, and therefore, current flows through the ammeter 65 as shown in FIG. It disappears. When the guide member 5 of the pipe wire threading device 1 passes through the insulation position 66 and reaches the downstream side in the insertion direction of the pipe wire threading device 1, it reaches the insulation position 66 at the length l2 of the pipe wire threading device 1.
The branch pipe 61 is electrically connected to the guiding member 5 of the intra-pipe wire passing device 1 that straddles the pipe and the longitudinal wire 1a,
As a result, the count value of ammeter 65 increases as indicated by reference numeral 68 in FIG. In this way, by reading the length l2 of the intra-tube wire passing device 1 inserted into the tube 62 from the current measurement result of the ammeter 65, the insulation position 66 of the tube 62 can be reliably detected. FIG. 3 is a side view of the pipe wire passing device 1 according to one embodiment of the present invention. This in-pipe wire passing device 1 has a guide member 5, a first wire 2, a second wire 3 and a guide member 5, a first wire 2, a second wire 3 and 3 wire rods 4 are formed in a row in this order. The first wire 2, the second wire 3, and the third wire 4
Each of these is made of piano wire, etc., and the piano wire is wound in a spiral shape. The third wire 4 has a relatively large bending stiffness K ₃ and torsional stiffness G ₃
and its longitudinal length l3 is in the natural state
The length is chosen to be 10 to 15 meters or longer. An end 3 a of the second wire 3 is fixed to an end 4 a of the third wire 4 . The second wire 3 has a bending stiffness K ₂ and a torsional stiffness G ₂ smaller than the third wire 4 .
The wire diameter of the second wire rod 3 is smaller than the wire diameter of the third wire rod 4, and the diameter thereof is smaller than that of the third wire rod 4. Therefore, the function of improving the wire passing rate of the pipe wire passing tool 1 is as follows. has. The length l2 of this second wire 3 is selected to be approximately 0.7 m to 1.0 m, for example. An end 2 a of the first wire 2 is fixed to the other end 3 b of the second wire 3 . The first wire rod 2 can be bent by the weight of the guiding member 5, and has a bending rigidity K ₁ and a torsional rigidity G ₁ smaller than the second wire rod 3. The wire diameter of the first wire rod 2 is smaller than the wire diameter of the second wire rod 3, and its diameter is smaller than that of the second wire rod. The length l1 of this first wire 2 is selected to be around 7 cm, for example. FIG. 4 is a perspective view of the vicinity of the guide member 5. 1st
The guiding member 5 fixed to the other end 2b of the wire 2 is
It has a square surface 6 when viewed from the free end side (left side in FIG. 4), that is, from the front, and is partially formed into a prismatic shape. The proximal end 7 of the guide member 5 has a tapered shape, and is fixed to the other end of the first wire 2 with a hexagonal screw (not shown) or the like. This guiding member 5
is made of a material such as steel, and the length l4 of one piece including the tip face 6 is selected to be around 11 mm, for example. By applying a rotational force to the third wire 4, the guiding member 5 accumulates stress against torsion in the pipe, and when the load falls below a certain level, it can rotate and vibrate due to the reaction, and can be reused. I can also bear it. Figure 5 shows the first wire 2, the second wire 3, and the third wire 4.
It is a graph showing the relationship between the length direction and the bending rigidity K and torsional rigidity G of the wire rods 2, 3, and 4. The first wire rod 2, the second wire rod 3, and the third wire rod 4 of the pipe wire passing tool 1
The bending rigidity K ₁ , K 2 , K ₃ , K ₄ of the fixed end 4a with the second wire 3 and the other end 4b of the third wire ₄ has the fifth
As shown by the solid line 8 in FIG. 1, the relationship of the first equation holds true. K ₁ <K ₂ <K ₃ <K ₄ ...(1) Also, the fixed end portion 4a of the first wire rod 2, the second wire rod 3, and the third wire rod 4 to the second wire rod 3, and the other end portion of the third wire rod 4 Figure 5 (2) shows each torsional stiffness G ₁ , G ₂ , G ₃ , and G ₄ of 4b.
As shown by the solid line 9, the relationship of the second equation holds true. G ₁ <G ₂ <G ₃ <G ₄ ...(2) The third wire 4 is hardened differently in the vicinity of the end 4a fixed to the second wire 3 and in the vicinity of the other end 4b, As a result, from the end 4a to the other end 4
Bending stiffness K ₃ and torsional stiffness G ₃ as b
are configured to gradually become larger, as shown by the solid line 8 in FIG. 5(1) and the solid line 9 in FIG. 3(2). In addition, the bending rigidity of the third wire 4 is K ₃
and the torsional stiffness G ₃ is expressed by the dashed dotted line 10 in Fig. 5 (1),
The two-dot chain line 11 and the one-dot chain lines 12 and 2 in FIG. 5(2)
As shown by the dashed dotted lines 13, the size may be increased in stages. By configuring the bending rigidity K and the torsional rigidity G to gradually increase from the first wire rod 2 to the other end of the fourth wire rod 3, the wire passage rate of the in-pipe wire passing tool 1 can be increased. can be improved. Referring to FIG. 6, a chi 15 is connected to the upper part of the underground pipe 14. A ground pipe 17 is connected to this chi 15 from a service pipe 16, and a house 18
gas is supplied to the A pipe joint 19, an elbow 20, and a valve 21 are interposed between the lead-in pipe 16 and the standpipe 17. According to the in-pipe wire passing tool 1 according to the present invention, the guide member 5 can enter the underground pipe 14 from these standpipes 17 via the lead-in pipe 16. FIG. 7 shows the state in which the pipe wire passing tool 1 enters the chi 15 from the lead-in pipe 16. The first wire rod 2 is bent by the gravity of the guiding member 5, so that the guiding member 5 can easily advance from the chi 15 into the underground pipe 14. When the first wire 2 hangs down due to the gravity of the guiding member 5, the guiding member 5 is rotated and pushed in while rotating the third wire 4 around its axis. It is possible to enter the underground pipe 14 while vibrating. Further, as shown in FIG. 8, the end of the tube 23 is closed with a plug 22.
Even when a branched pipe 24 is connected near the pipe 24, the in-pipe wire passing tool 1 according to the present invention can be inserted into the pipe 23 or the pipe 24 as shown by the arrow 25, and vice versa. 23 can be entered as indicated by arrow 26. The leading end surface 6 of the guiding member 5 is square.
Therefore, the corner portion 6a of the tip surface is likely to get caught in a step at an elbow, a tee, a pipe joint, etc. When this corner portion 6a catches on a step inside the tube, it bounces due to the bending rigidity and torsional rigidity of each of the first wire rod 2, second wire rod 3, and third wire rod 4. This allows the guiding member 5 to enter the pipe while climbing over the step. Table 1 shows the experimental results of the inventor.

[Table] When the first wire rod 2, the second wire rod 3, and the third wire rod 4 made of the materials shown in Table 1 were used to wire the gas pipe shown in FIG. The wire 1 was able to enter from the ground pipe 28 through the elbows 29 to 39, into the service pipes 40 to 50 connected in a zigzag manner, and reach the inside of the main pipe 42 from the chi 41. In this way, when I ran wires inside various gas pipes using the subject pipe wiring tool 1, I found that it was approximately 92~
It was confirmed that the wire can be connected with 100% probability, the success rate is extremely high, and the time required to connect the wire is relatively short. The in-pipe conduit according to the present invention is capable of passing not only underground gas pipes, but also other pipes installed in building walls or other hidden parts, or even exposed pipes. good. Alternatively, the end portion 4b of the third wire 4 of the intra-tube wire threading tool may be rotated around the axis using, for example, a pistol-shaped tool to feed the intra-tube wire threading tool into the pipe. As another embodiment of the present invention, the first wire 2, the second
The wire rod 3 and the third wire rod 4 are wound inside and outside 2 in opposite directions.
It may be configured by a coil spring having a heavy structure, and the first wire 2, the second wire 3, and the third wire 4
may be made of different materials. FIG. 10 is a sectional view of still another embodiment of the present invention. FIG. 10 is similar to the configuration of FIG. 1, and corresponding parts are given the same reference numerals. What should be noted is the coated metal tube 62 whose inner peripheral surface is exposed at least.
A series circuit consisting of a power source 64 and an ammeter 65 is connected between the pipe and the pipe wire passing device 1 inserted into the coated metal pipe 62. The guiding member 5 of this in-pipe wire passing tool 1 is made of a conductive material with an exposed outer periphery, and the longitudinal wire 1 is electrically connected to the guiding member 5.
A is made of a conductive material having an electrically insulating coating layer 100 on its outer periphery, as shown in FIGS. 12 and 13. Therefore, before the guiding member 5 of the pipe wire passing device 1 reaches the insulating position 66, the guiding member 5 and the ammeter 65 are electrically connected via the terminal portion 62b of the pipe 62. Therefore, a current indicated by reference numeral 69 in FIG. 11 flows through the ammeter 65. When the induction member 5 passes the insulation position 66, the induction member 5 and the ammeter 65 are connected to the tube 62.
is electrically interrupted by the insulating position 66, and no current flows through the ammeter 65 as shown in FIG. In this manner, the insulation position 66 can be reliably detected by measuring the length l1 of the intra-pipe wire passing device 1 inserted into the pipe 62 according to the measurement result of the ammeter 65. Furthermore, since the insulation position can be detected for each branch pipe, the practicality is further improved. Further, even if the structure is such that the end portion of the longitudinal wire 1a covered with the electrical insulating layer 100 on the guiding member 5 side is partially exposed and electrically connected to the inner surface of the tube 62 together with the guiding member 5, good. FIG. 14 is a perspective view of another embodiment of the invention. FIG. 14 is similar to the configuration of FIG. 4, and corresponding parts are given the same reference numerals. In this embodiment, a flexible supply pipe 70 is inserted into the longitudinal wire 1a of the pipe wire passing tool 1, and the supply pipe 70 is inserted into the peripheral wall of the guiding member 5.
A plurality of nozzle holes 71 are formed to communicate with the supply pipe 70, and the other end of the supply pipe 70 is connected to a supply source (not shown) that is installed on the ground and supplies synthetic resin made of a conductive material under pressure. It is. When the guiding member 5 of the in-pipe wire passing device 1 reaches the insulation position 66 of the pipe 62 according to the measurement result of the ammeter 65 installed on the ground, a synthetic resin made of a conductive material is released from the nozzle hole 71 of the guiding member 5. By spraying the insulating position 66 toward the insulating position 66, the insulating position 66 can be detected, and electrical continuity can be achieved at the insulating position 66, so that workability is significantly improved. . FIG. 15 is a sectional view of another embodiment of the present invention. FIG. 15 is similar to the configuration of FIG. 14, and corresponding parts are given the same reference numerals. In this embodiment, the guiding member 5 is constructed of an insulating part 80 made of an electrically insulating material, for example, synthetic resin, and a conductive part 81 made of a conductive material covering the outer peripheral surface of the insulating part 80. The distal end 2b of the first wire 2 is buried and fixed in the insulating part 80, and the electric wire 83 in the flexible electrically insulating cladding tube 82 inserted into the longitudinal wire 1a is inserted into the conductive part 81. One end portion 83a of is connected. The other end 83b of the electric wire 83 is connected to the power source 6
4. Connected to the tube 62 via an ammeter 65. Therefore, the insulation position of the pipe 62 can be reliably detected, and the conduction state is not prevented by deposits on the outer peripheral surface of the longitudinal wire 1a, and the reliability of the in-pipe wire passing tool 1 is significantly improved. Improved. Although the ammeter 65 was connected in series to the power source 64 in the above embodiment, a configuration in which a resistor was connected in parallel to the power source 64 is also included in the spirit of the present invention.
Further, the continuity detection means may be configured to detect not only current but also resistance in order to detect the continuity state. As described above, according to the present invention, the insulation position of the metal pipe can be reliably detected by the continuity detection means, so that the working time and labor can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a graph showing the relationship between the length l of the wire-through device 1 and the current, and FIG. 3 is a side view of the wire-through device 1 according to the present invention. 4 is an enlarged perspective view of the vicinity of the guide member 5, and FIG.
The figure is a graph showing the relationship between the length direction l of the in-pipe wire threading tool 1, the bending rigidity K, and the torsional stiffness G. Figure 6 is a piping diagram for explaining the wire threading work, and Figure 7 is a graph showing the relationship between the length direction l of the pipe wiring tool 1, the bending rigidity K, and the torsional rigidity G. A sectional view showing the wiring state, FIG. 8 shows the pipes 23, 2.
9 is a piping diagram of one embodiment of the present invention, FIG. 10 is a sectional view of another embodiment of the present invention, and FIG. 11 is a sectional view of another embodiment of the present invention. 12 is a side view of the pipe wire passing device 1 shown in FIG. 10, and FIG.
14 is a perspective view of still another embodiment of the present invention, and FIG. 15 is a sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Wire passing through pipe, 1a... Longitudinal wire rod, 2... First wire rod, 3... Second wire rod, 4... Third wire rod, 5... Induction member, 62, 63... Metal tube, 64... Power supply, 65... Ammeter .

Claims (1)

[Claims] 1. A series circuit of a power source and a continuity detection means is connected on both sides of an insulated position to be detected of a metal tube whose inner peripheral surface is exposed at least, and the metal tube is made of a conductive material. At the end of the third wire material, which is spirally wound and has relatively high bending and torsional stiffness, is a third wire material which is spirally wound and has a smaller bending and torsional stiffness than the third wire. One end of the two wires is connected and fixed, and one of the first wires is spirally wound around the other end of the second wire and is made of a conductive material and has lower bending rigidity and torsional rigidity than the second wire. The end of the first wire is connected and fixed, the other end of the first wire is connected to a guiding member made of a conductive material, and the guiding member is capable of bending the first wire due to the weight of the guiding member. A method for detecting the insulation position of a pipe, the method comprising: inserting a pipe. 2 A metal tube whose inner peripheral surface is exposed at least;
An in-tube wire passing tool inserted into the metal tube, the end of the third wire being spirally wound and made of a conductive material having an electrically insulating coating on the outer periphery and having relatively high bending rigidity and torsional rigidity. One end of a second wire rod, which is spirally wound and made of a conductive material having an electrically insulating coating and has lower bending rigidity and torsional rigidity than the third wire rod, is connected and fixed to the second wire rod. One end of a first wire is connected and fixed to the other end of the wire, the outer periphery of which is made of a conductive material having an electrically insulating coating and is spirally wound and has lower bending and torsional rigidity than the second wire. A guide member made of an exposed conductive material is connected to the other end of the first wire, and the guide member is connected to the metal tube by an in-tube wire passing tool that allows the first wire to bend under the weight of the guide member. A method for detecting the insulation position of a pipe, the method comprising: inserting the wire into the pipe, and connecting a series circuit consisting of a power source and a continuity detection means between the inserted wire passing through the pipe.