JPS63305242A - Apparatus for inspecting corrosion in outer surface of pipe body - Google Patents

Abstract

PURPOSE:To move a capsule smoothly, by constituting the capsule by linking a drawing pig, an inspecting pig and a pushing pig, providing sealing property for the pigs, which are linked before and after the inspecting pig, and forming a pressure difference state. CONSTITUTION:After a capsule 22 is inserted into a launcher 23, a cable 31 is pushed and connected to a pig 44. A cap 25 is closed. Then, a valve 26 is opened, and a basic pressure is applied into a pipe body 21 to be inspected. The valve 26 is closed. A valve 27 is opened, and a gas is supplied. Then a pressure difference is formed with a sealing cup 44b as a boundary. The capsule 22 is moved in the pipe body 21 to be inspected. A cable feeding control device 33 sends out the cable 31 in a constant amount, and a constant speed running is realized. The magnetic flux from a magnet 43b passes through a wire brush 43c, the pipe body 21 to be inspected and a wire brush 43d, and a closed magnetic path is formed. When a corroded part is present, the magnetic flux leaks to the inner surface of the pipe body. The leaking magnetic flux is detected with a sensor 43f, which is fixed in a plate spring 43e. The detected signal is sent out through the cable 31 and connected to a data processing part 38.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus for inspecting external surface corrosion of gas piping and other various types of piping (hereinafter referred to as pipe bodies), and particularly relates to This invention relates to an apparatus for inspecting corrosion on the outer surface of a tube body for stable long-distance running of a capsule.

(Prior art) Generally, when a pipe to be inspected has a long distance, there are many joints and vents along the way. However, it is necessary to perform the necessary inspections.

Conventionally, the fourth pipe inspection method that satisfies these conditions has been
As shown in the figure, a capsule 2 has been developed which has an inspection pig that inspects corrosion on the outer surface of the tube while traveling inside the tube. Specifically, an index pig 4 having a guide head 3 and wire brushes 5a placed on both sides of a magnet 5 housed in the body.

A test pig 8 having a leakage flux detection sensor 7 provided at an intermediate position of the test pig 6b is connected via a spring 9, and the detection signal obtained by the test pig 8 is processed inside the test pig 8 or the index pig 4. Alternatively, there is a type in which the detection signal obtained by the inspection pig 8 is transmitted to the outside of the tube body 1 through the cable 10.

Therefore, the capsule described above creates a pressure difference inside the tube to be inspected between the seal cups 4a and 4b installed before and after the index pig 4, and uses this pressure difference to control the capsule 2.
to be transferred. At this time, the magnetic flux generated from the magnet 5 passes through one wire brush, for example 6a, and the tube body 1 to be inspected.
Furthermore, a closed magnetic path is formed that passes through the other wire brush 6b and returns to the original state, and if there is corrosion on the outer surface of the tube to be inspected, that part is squeezed and resistance increases, causing magnetic flux to leak into the tube. Therefore, the sensor 7 detects the leakage amount of this magnetic flux. Since the amount of leakage of magnetic flux is proportional to the magnitude of corrosion, by detecting this leakage with the sensor 7, it is possible to grasp the state of corrosion on the outer surface of the tube.

(Problems to be Solved by the Invention) However, in the capsule 1 described above, a joint part 11 is provided in the middle of the tube body 1 to be inspected, as shown in FIG. Seal cup 4a of pig 4,
4b, the capsule 2 will not be able to seal at all, making it impossible to create a pressure difference inside the tube to be inspected, and ultimately making it impossible for the capsule 2 to travel.

Furthermore, if the vent portion 12 is formed as shown in FIG. 5 while the capsule 2 is traveling, forces (a) and (b) that are opposite to each other between the index pig 4 and the inspection pig 8 on both sides of the spring 9 can be generated. moves, a large force acts on the center of curvature of the tubular body 1, making it difficult for the capsule 2 to move forward.

In addition, in the case of the capsule 2 in which two pigs 4 and 8 are connected, signal processing is performed inside the pig, but the outer diameter of the pig itself cannot be made small, and especially in the case of a medium diameter pipe, the signal processing necessary for the pig itself is There is a problem that it is difficult to store the system.

Therefore, conventionally, as a capsule traveling means to make the capsule run smoothly even at the vent part in the tube body 1 to be inspected, a cable led out from the rear of the inspection probe is connected at intervals of a predetermined distance to reduce the pressure loss of the fluid in the tube. There is a device that is equipped with a predetermined number of guide elements for easy movement even on a tube body to be inspected with a long curvature (Japanese Patent Application Laid-open No. 142456/1983).
.

However, with the above-mentioned probe traveling means, if there is a joint part in the middle of the tube to be inspected, the joint part becomes a place for fluid to escape, making it difficult for the probe to travel smoothly. If the cable 10 has a small vent part, it is difficult for the cable 10 to come into contact with the vent part and move the probe smoothly forward.
A problem similar to the one shown in the figure occurs. Furthermore, the probe traveling means of the above-mentioned Bow J example does not have a means for smooth traveling in the capsule itself, so it often stops during the inspection, and the probe itself does not process the signal. When doing this, the outer diameter inevitably increases, making it difficult to apply to medium-diameter pipes.

The present invention has been made in view of the above-mentioned circumstances, and has a structure that allows the capsule to run smoothly by itself regardless of the situation inside the tube body, and is effective even when signal processing is performed inside the capsule. It is an object of the present invention to provide an apparatus for inspecting corrosion on the outer surface of a tube whose diameter can be reduced.

(Means for Solving the Problem) The apparatus for inspecting corrosion on the outer surface of a pipe body according to the present invention includes an index pig with a seal cup and a sensor that detects leakage magnetic flux caused by corrosion on the outer surface of the pipe body to be inspected using a leakage flux method. A three-carrying capsule connected by a spring between the inspection pig and the push pig with a seal cup, a capsule pressure feeding means for inserting and pressurizing the capsule into the tube to be inspected, and a tube to be inspected from the capsule. The device is equipped with a cable delivery control device that sends out the cable led out of the body at a predetermined speed.

(Function) Therefore, the present application uses the above-mentioned means to provide an index pig with a seal cup, and a sensor that detects leakage magnetic flux caused by corrosion on the outer surface of the pipe to be inspected using the il leakage flux method. A capsule is constructed by connecting the inspection pig and the push pig with a seal cup, and the pigs connected to the front and rear of the inspection pig each have sealing properties to form an appropriate differential pressure state at the joint. To enable the capsule to run smoothly, and to easily overcome even when the capsule approaches a vent part by providing a push pig at the rear of the inspection pig via a spring.

In addition, improved sealing properties enable long-distance travel.
Smooth running is achieved by using a signal cable with low friction resistance. Further, even when three pigs are connected and internal processing is performed in the capsule itself, the signal processing system can be distributed to cope with downsizing.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a diagram showing a capsule transfer system, FIG. 2 is a configuration diagram of the capsule, and FIG. 3 is a sectional view of a signal cable.

First, in the capsule transfer system, as shown in FIG. 1, a launcher 23 having an inner diameter larger than that of the tube body 21 has seven flange 24 in order to facilitate the insertion of the capsule 22 into the end of the tube body 21 to be inspected. connected via. This launcher 2
3 has an openable and closable lid 25 attached to its inlet side, and an air supply pipe 28 for applying basic pressure and a capsule transfer pipe having air-operated valves 26 and 27 in close proximity to the flange 24 and the launcher inlet side, respectively. An air supply pipe 29 is connected thereto. Reference numeral 30 denotes a guide roller which has the function of preventing damage to the cable 31 introduced into the capsule 22 and holding the center of the cable to the tube body 21 to be inspected. Reference numeral 32 denotes an air seal that prevents air flow between the inside of the launcher and the outside of the launcher. In the figure, 33 is a cable constant speed control device that sends out the cable 31 at a constant rate, and this is a device that controls the drive motor 3.
4. Cable drum 35, cable 31? ! Cable traverse mechanism 36 with constant speed rotation function by winding several times
and a rotation distance meter 37, etc.

Next, FIG. 2 is a diagram showing the structure of the capsule. That is, this capsule 22 has an indexing pig 42 . with a guide head 41 . The inspection pig 43, the push pig 44, etc. are arranged in this order, and an index lll1i is used between them.
They are connected via functional springs 45,46. The guide head 41 includes guides 41b and 41b arranged at predetermined intervals on the outer periphery of the mirror-shaped head main body 41a.
... is partially buried and rotatably attached. With this structure, the guide roller 41b has the function of rotating when it comes into contact with the inner surface of the tube body 21 to smoothly guide and advance the capsule 22.

The index pig 42 has a function of indexing the entire capsule, and has a body part 42a that houses a signal processing system for the inspection pig including an amplifier, a sensor switching circuit, etc., and
Seal cups 42b are provided at the front and rear portions of the body portion 42a to improve sealing performance, respectively.

The inspection pig 43 uses the magnetic flux leakage method to inspect the tube body 2 to be inspected.
A strong stone 43b is housed inside a casing member 43a forming a part of the body, and wire brushes 43G and 43d are used to form a magnetic path at the front and rear of the casing member 43a. has been planted. This magnet 43
Loop-shaped handling springs 43e are provided at predetermined intervals on the front and rear outer peripheries of the fuselage portion on which b is mounted. The detecting sensor 43f is fixed. This leaf spring 43e is made of a non-magnetic material that is wear-resistant and has strong spring properties, such as polyimide, but leaf springs with various structures and shapes are selected in consideration of fluctuations in the tube axis direction, frictional force, etc. shall be used. In addition, the sensor 43f,...
* is not limited to the leaf spring 43e, but may be attached to a conventional lever set or other members.

Next, the push pig 44 has a function of pushing out the test pig 43 by using the spring force of a spring 46, and specifically, in addition to the cable removal II mechanism, each pig 42,
A fuselage section 44a in which the signal processing system is shared and internalized with 43 etc.
Seal cups 44b, 44b are provided at the front and rear of the body portion 44a to improve sealing performance.

One end side of the signal cable 31 is connected to each pig 42 to
44 and springs 45, 46, etc.,
The other end of the cable is attached to the cable drum 3 as shown in Figure 1.
5 and is connected to the signal processing section 38. This signal processing section 38 has a function of transmitting and receiving signals to and from the capsule 22 and converting them into required signals, particularly a function of converting them into output signals of terminal devices such as a recorder 39a and three plotters b. There is. At this time, data processing is performed while taking in distance data from the rotating distance meter 37. Further, the signal cable 31 has a structure as shown in FIG. In other words, the tension member 31, such as aviation wire or Kevlar, receives the indexing force in the center.
a is arranged, and transmission/reception signal lines and power feed lines 31b, . . . to the capsule 22 are arranged outside the tension member 31a. In addition, the cable sheath 31C is made of a material with low resistance (for example, fluorocarbon resin).
It is made up of.

Next, the operation of IT configured as above will be explained.

First, open the lid 25 and insert the capsule 22 into the launcher 23.
After inserting the cable 31, one end of the cable 31 is connected to the push pig 44, and then the lid 25 of the launcher 23 is locked. In this state, the motor 34 is reversed to take up the slack in the cable 31. After that, the air-operated valve 26 is opened to apply a base pressure to the pipe body 21 to be inspected, and then the air-operated valve 36 is closed and the other air-operated valve 27 is opened to supply gas at a pressure higher than the base pressure. Then, the seal cup 4 of the push pig 44
A pressure difference is created across 4b, which causes capsule 2 to
2 transports the inside of the tube 21 to be inspected. After the capsule '22 passes through the launch t23 and completely enters the inside of the tube body 21 to be inspected by this transfer, when a pressure difference is applied to both ends of the tube body 21 to be inspected, the cup of the index pig 42 or the push pig 44 is A pressure difference is generated across the seal, and the capsule 22 is transported in a predetermined direction.

When transferring the capsule 22, the cable delivery control device 33
From the viewpoint of improving the measurement yi degree, constant speed running can be realized by sending out the cable 31 at a constant rate while suppressing the running of the capsule 22. In other words, the motor 34
For example, the cable 31 is fed out in a fixed amount using a servo motor, hydraulic motor, etc., and a cable traverse mechanism 36 that winds the cable 31 multiple times to obtain a constant speed rotation function, and the cable feeding distance data at this time is calculated. The data is input from the rotary distance meter 37 to the data processing unit 38 to obtain data on the transfer distance of the capsule 22 and the inspection position of the inspection pig 43.

When the capsule 22 is transferred, the strong magnetic flux generated from the magnet 43b forms a closed magnetic path that returns through the wire brush 43C, the tube body 21 to be inspected, and the wire brush 43d, causing corrosion on a part of the outer surface of the tube 21 to be inspected. If there is a portion, magnetic flux leaks out to the inner surface of the tube at the corresponding portion, and this leakage magnetic flux is detected by a sensor 43f fixed to the inside of the leaf spring 43e. At this time, since a sensor 43f is fixed to each plate spring 43e, the signal processing system in the body 42a, which constitutes a part of the index pig 42, sequentially takes in the sensor output and outputs an appropriate signal. After the treatment, it is sent to the outside of the tube 21 to be inspected through the cable 31.

The data processing section 38 is connected to the end of this cable 31 as described above, and here the cable 3 is connected to the capsule 22.
1 and the signal from the aforementioned rotary distance meter 27, the corrosion state of a specific portion of the tube body 21 to be inspected is inspected. Note that a defect between two sensors can be inspected by adding the signals detected by the two sensors 43f and 43f and performing interpolation processing or the like.

Therefore, when the capsule 22 approaches the joint part 11 as shown in FIG.
4 and a seal cup 42b, respectively.

441), for example, even if the seal cup 42b on the index pig side loses its sealing function due to the joint part 11, the seal cup 44b on the push pig side will perform its sealing function and the capsule 22 will be reliably and stably maintained. It can be run.

In addition, the capsule 22 is connected to the vent portion 12 as shown in FIG.
When the index pig 42 and the inspection pig 43 reach the same position as before, opposite forces are applied to the index pig 42 and the inspection pig 43 via the spring 45, but a push pig 44 is connected to the rear of the inspection pig 43, and the seal It functions and can be easily pulled out from the bend portion 12 in order to press the test pig 43 by the expansion action of the spring 46.

When the inspection of the tube body 21 to be inspected is completed as described above, the inside of the tube body 21 to be inspected is evacuated, the cable 31 is removed from the capsule 22, and the tube body 21 to be inspected is further removed from the capsule 22.
After taking out the capsule 22 from the capsule 1, the cable delivery control device 33 is reversely operated to wind up the cable 31.

Therefore, according to the embodiment described above, three pigs 42
~ 44 are connected by springs 45, 46, and the front and rear pigs 42, 44 have a sealing function. Since the sealing function is activated by this, the capsule 22 can run smoothly in the joint portion 11. In addition, when there is a bend part 12 in the middle of the tube body 21 to be inspected, the capsule 2
2 can easily pull out the bend portion 12. In addition, since the three pigs 42 to 44 are connected, the sensor 43 can appropriately share and store the output signal processing.
Therefore, each of the pigs 42 to 44 can be miniaturized 19, and even medium diameter pipes can be easily inspected. Also, signal cable 3
1 is made of a material with a small friction coefficient, so even if it comes into contact with, for example, the bend portion 12, it will not interfere with the running of the capsule 22. Furthermore, since the cable 31 is connected to the capsule 22, the data of the detection results can be transmitted and processed in real time. Furthermore, since the cable delivery control device 33 has a function of quantitatively paying out the cable 31, the capsule 22 can be run at a constant speed, which greatly contributes to stabilizing the run.

Note that the present invention can be implemented with various modifications without departing from the gist thereof.

(Effects of the Invention) As detailed above, according to the present invention, the capsule itself can run smoothly regardless of the situation inside the tube body, and it is also effective when performing signal processing inside the capsule.
Furthermore, it is possible to provide an apparatus for inspecting corrosion on the outer surface of a tube body, which can realize a smaller outer diameter and stable running of the capsule.

[Brief explanation of drawings]

Figures 1 to 3 are shown to explain one embodiment of the apparatus for inspecting the outer surface of a pipe according to the present invention.
The figure is a configuration diagram explaining the capsule transfer system, Figure 2 is a configuration diagram of a three-car connected capsule with an inspection pig, and Figure 3 is a cross-sectional view of a cable that exchanges signals between the capsule and the outside of the tube to be inspected. , Fig. 4 and Fig. 5 are shown to explain the conventional example, Fig. 4 is an explanatory diagram of the state when the capsule passes through the joint, and Fig. 5 is an explanatory diagram of the state when the capsule passes through the bend part. be. DESCRIPTION OF SYMBOLS 11... Joint part, 12... Bend part, 21... Tube body to be inspected, 22... Capsule, 23... Launcher,
31... Cable, 33... Cable sending control device, 34... Motor, 35... Cable drum, 36
... Cable traverse mechanism, 37 ... Rotating distance meter, 38 ... Data processing section, 42 ... Index pig, 43
...Inspection pig, 44...Push pig, 45.46...
・Spring, 42, b, 44b...cup seal,
431'...Sensor. Applicant's agent Patent attorney Takehiko Suzue Figure 4 Figure 5

Claims (1)

[Claims] A device that inspects corrosion on the outer surface of a tube while traveling long distances inside the tube to be inspected, uses an index pig with a seal cup and the leakage flux method to detect leakage magnetic flux caused by corrosion on the outer surface of the tube to be inspected. A three-coupled capsule in which a test pig with a sensor and a push pig with a seal cup are connected to each other by springs, a capsule pressure feeding means for inserting and pressure-feeding the capsule into the tube to be inspected, and a capsule to be removed from the capsule. 1. An apparatus for inspecting corrosion on the outer surface of a pipe body, comprising: a cable delivery control device that sends out a cable led out of the test pipe body at a predetermined speed.