JPH08101168A - Running monitoring system for conduit pipe inspection pig - Google Patents

Abstract

PURPOSE: To grasp the position of a pig by sensing a welding line in a conduit pipe using the leakage flux method. CONSTITUTION: A leakage flux sensing device for inspection of defect in a conduit pipe 11 such as corrision, decreased wall thickness, etc., is mounted on a conduit inspecting pig 10. If the signal of a leakage flux sensed by a magnetism sensor of a leakage flux sensing device includes a specified level or more variation (level down) over the whole circumference of the conduit pipe 11, an appropriate signal is outputted which shows that the place with level veriation is the position of the welding line M, and the given signal is transmitted to an externally provided receiver 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
For inspection pigs to detect defects such as corrosion thinning of pipes, the position of the pigs can be grasped by detecting the welding line in the pipes by using the leakage flux method. The present invention relates to the traveling monitoring system.

[0002]

2. Description of the Related Art Conventionally, as a method for inspecting defects such as corrosion thinning of pipes laid underground, a magnetic flux leakage detection device for detecting defects such as corrosion thinning of pipes is installed in the pipe. There is known a means for running an operating pig by gas pressure. In the leakage magnetic flux detection device, when the tube wall of the conduit (steel tube) is magnetized by the permanent magnet, if there is a change in the wall thickness of the outer surface and the inner surface of the tube wall, the magnetic flux leaks to the inner and outer surfaces of the tube at the change location. The magnetic sensor is used to detect the coming. For example, when there is a thinned portion in the conduit, as shown in FIG. 2, the thinned wall has a thin wall as compared with other portions, so that the leakage magnetic flux becomes large and a steep rise occurs. On the other hand, at the weld line,
On the contrary, the weld metal is melted and becomes thick, the leakage magnetic flux is reduced from other places, the detection signal by the magnetic sensor becomes small, and the signal level drops. In addition, the said welding line is formed by welding a predetermined part at the time of construction according to a finished drawing. Prior to the inspection by such an inspection pig, a cleaning pig for cleaning the inside of the pipe is run in order to perform an accurate inspection, and whether the inspection pig can pass through the pipe or not. A caliper pig is run to inspect the shape of the inner surface.

By the way, when the inspection pig is traveling in the conduit, the position of the conduit in which the pig is traveling,
It is convenient for the work progress to keep track of it. At present, as described above, since the conduit (made of steel pipe) is joined by welding in accordance with the finished drawing, the sound generated when the inspection pig 1 passes through the welding line M is captured, and the finished pipe is manufactured. The position of the inspection pig 1 is grasped while comparing the drawing with the sound. The sound generated when the inspection pig 1 passes through the welding line M is a hitting sound generated when the inspection pig 1 passes through a welded portion whose inner diameter is narrower over the entire circumference of the pipe wall than other portions. Is. The passing sound of the inspection pig 1 is generated by the buried conduit 2
A sounding device R can be attached to the sinking rod 3 provided at a proper position so that the sounding device can be picked up by the sounding device R (see FIG. 3).

[0004]

However, in the method as described above, it is necessary to measure at many places, and the measurer picks up the passing sound of the inspection pig 1 with the sound detector R. There are inconveniences in that it is difficult to specify the accurate position, the measurer must move in accordance with the passage of the inspection pig 1, or a plurality of measurers are required. The present invention has been made in order to improve such inconvenience, and an inspection pig for inspecting for defects such as corrosion thinning in a conduit by traveling in the conduit is provided with a welding in the conduit. An object of the present invention is to provide a travel monitoring system for a pipe inspection pig by detecting a welding position, which enables the position of the inspection pig to be grasped by detecting the position.

[0005]

In order to solve the above-mentioned problems, the present invention provides an inspection pig for traveling in a conduit buried in the ground and inspecting for defects such as corrosion thinning of the conduit. , A receiver for receiving a signal from the oscillator at a location distant from the inspection pig, while mounting a leakage magnetic flux detection device having a magnetizing unit for magnetizing the tube wall and a magnetic sensor for detecting the leakage magnetic flux and an oscillator The leakage magnetic flux detection device detects a leakage magnetic flux with a magnetic sensor to detect a defect such as corrosion wall thinning of a conduit, and when there is a certain drop in the detection signal from the magnetic sensor, the detection portion is welded. A signal is output as the location of a line, the oscillator transmits the signal to a receiver, and the measuring device main body is provided for signal processing and displaying or notifying a signal received by the receiver. That.

[0006]

[Operation] Run the inspection pig in the pipe to be inspected,
In addition to detecting defects such as corrosion thinning of the pipe by detecting the leakage magnetic flux with the magnetic sensor of the leakage magnetic flux detection device, the level of the detection signal by the magnetic sensor drops above a certain level over the entire circumference of the conduit. If there is, it is assumed that the place where the depression of that level is the weld line is,
The signal is transmitted from the oscillator to the receiver, and the measuring instrument body processes the signal and passes through the welding point.
For example, it can be displayed on an appropriate display means or can be notified by counting the number of the number, and the measurer can compare it with the number of received signals and the ready-made drawing of piping,
The current position of the inspection pig can be easily grasped.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A travel monitoring system for a pipe inspection pig according to the present invention will be described in detail below with reference to an embodiment. FIG. 1 shows a state where a conduit inspection pig 10 is run in a conduit 11 buried in the ground. This conduit inspection pig 10 is equipped with a leakage magnetic flux detection device (not shown) for traveling inside the conduit 11 and inspecting for defects such as corrosion thinning of the conduit 11 and the like. It is slidable in close contact with the inner surface. The inspection pig 10 is guided into the conduit 11 through a launcher (not shown) provided on one end side of the conduit 11 to be inspected (a launcher for guiding and running the pig in the conduit) (not shown), It is configured to travel in the conduit 11 by gas. An oscillator 12 is mounted on the inspection pig 10.

The leakage magnetic flux detecting device is, for example, a conduit 11
A magnetizing unit (not shown) for magnetizing the tube wall of No. 1 and a magnetic sensor (not shown) for detecting a leakage magnetic flux are provided. Further, although the leakage magnetic flux detection device does not show a detailed configuration, if the signal related to the leakage magnetic flux detected by the magnetic sensor has a level variation (level down) over the entire circumference of the conduit 11 of a certain value or more, It has a function of outputting a signal that the level change point is the position of the welding line M,
This signal is transmitted by the oscillator 12 to the receiver 13 provided at a remote place. In addition, at the observation point 14 provided near the receiver 13,
A measuring device main body 15 is installed which processes a signal from the oscillator 12 received by the receiver 13 and displays it on a CRT display or the like, or notifies that the welding line M has been passed by an appropriate voice notifying means or the like. .

The conduit inspection pig traveling monitoring system according to the present invention is constructed as described above, and its operation will be described below. When the inspection pig 10 is introduced into the conduit 11 from the launcher on one end side of the conduit 11 to be inspected, the inspection pig 10 can travel in the conduit 11 by the gas pressure. The inspection pig 10 detects the leakage magnetic flux by a magnetic sensor of the leakage magnetic flux detection device while traveling inside the conduit 11 to be inspected. In this case, conduit 1
If there is a defect such as corrosion thinning in part 1, a part of the magnetic flux running on the pipe wall leaks, so that the detection signal by the magnetic sensor causes a steep rise change. On the other hand, welding line M
Since the weld line M is thickly formed over the entire circumference of the pipe wall, the level of the detection signal by the magnetic sensor fluctuates in the opposite direction over the entire circumference of the pipe wall. . The leakage magnetic flux detection device outputs a signal that the location where the level drop is the location of the welding line M, and transmits the signal from the oscillator 12 to the receiver 13, and the receiver 13
A predetermined signal processing is carried out in the measuring device main body 15 installed at the observation point 14 near the position of the welding line M, and it is displayed on a suitable CRT display as if it passed through the position of the welding line M. It is possible to count and report the number of times, and the measurer, based on the information indicating the display signal or the position of the welding line M,
The current position of the inspection pig 10 can be easily grasped by comparing it with a ready-made drawing of piping.

In this way, the measurer can grasp the position of the inspection pig 10 at the observation point 14 near the receiver 13, so that the measurer moves as the inspection pig 10 passes. However, many measurers do not need to measure at multiple points. Further, since the traveling position of the inspection pig 1 can be specified by the welding line M which is known in advance, it is convenient for the work progress.

[0011]

As described above, according to the present invention, since the welded portion can be accurately grasped, the position of the inspection pig can be grasped accurately, which is convenient for the progress of work. In addition, the oscillator installed in the inspection pig sends a signal related to the welding location, so the measurer can grasp the position of the inspection pig only by being at the observation location where the measuring device body near the receiver is installed. be able to.

[0012]

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a traveling monitoring system for a conduit inspection pig according to the present invention.

FIG. 2 is a graph showing an example of fluctuations of detection signals corresponding to a thinned portion and a welded portion in a conduit, which are caused by a magnetic sensor of a leakage magnetic flux inspection device in a conduit inspection pig according to the present invention.

FIG. 3 is a schematic explanatory view showing a conventional means for monitoring traveling of a conduit inspection pig.

[Explanation of symbols]

 10 Inspection Pig 11 Conduit 12 Oscillator 13 Receiver 14 Observation Point 15 Measuring Instrument Main Body M Welding Point

Claims (1)

[Claims] 1. A magnetizing unit for magnetizing a tube wall and a magnetic sensor for detecting a leakage magnetic flux in an inspection pig that runs in a conduit buried in the ground and inspects for defects such as corrosion thinning of the conduit. While equipped with a leakage magnetic flux detection device and an oscillator equipped with, a receiver for receiving a signal from the oscillator is provided at a location distant from the inspection pig, and the leakage magnetic flux detection device detects the leakage magnetic flux with a magnetic sensor. While detecting defects such as corrosion wall thinning of the conduit, when there is a certain drop in the detection signal by the magnetic sensor, a signal is output assuming that the detection location is the location of the welding line, and this signal is generated by the oscillator. According to the present invention, there is provided a traveling monitoring system for a conduit inspection pig, which comprises a measuring device main body for transmitting to a receiver and processing or displaying or notifying a signal received by the receiver.