JPS59777B2 - Pipeline leakage defect detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for detecting pipeline leakage defects.

In order to detect leakage defects in pipelines, a method of detecting leakage by inserting a leakage monitoring device such as a pig inside the pipeline has been used.

However, although this method allows inspection to be performed while the fluid is flowing, it is difficult to inspect the fluid inside the pipeline when loading and unloading the equipment. There is a major problem in ensuring sealing performance, and even if the inspection is performed while the fluid is flowing, it is actually necessary to take measures such as reducing the pressure of the internal fluid. There are various problems in practical use, such as damage to the line caused by passing it directly into the line and the need for incidental equipment for device loading. In addition, this method has the disadvantage that it is difficult to apply to buried pipelines due to the problem of installing a leak monitoring device inside the pipe, and it is also difficult to apply it to underground pipelines, etc. In this case, there is a risk of ignition due to sparks within the pipe, so there is a drawback that it is virtually impossible to apply it to pipelines that are intended for these. Also, as another method,
A so-called acoustic transmission detection method is used.

This method attaches a high-frequency acoustic noise center to the pipeline, amplifies the signal detected by each sensor with an amplifier corresponding to each sensor, and compares this signal with a predetermined reference signal to determine whether there is any leakage. The approximate location of the leak is estimated from the amplitude ratio of the signals from the phase sensors and the damping constant of the piping. However, the monitoring range of one sensor varies greatly depending on the coating condition of the pipe diameter of the pipeline. For example, for an uncoated steel pipe with a diameter of 00 mm, one sensor can monitor approximately 200
While a plastic-lined steel pipe with a diameter of 600 mm can be monitored over a range of several meters, the range that can be monitored is within a few meters, and pipelines that use coating equipment over long distances require a large number of sensors. The disadvantage is that the equipment itself is extremely damaged due to the fact that it is difficult to maintain and inspect individual sensors, amplifiers, etc. For this reason, the inventors first
We have proposed a method that can be applied to buried pipelines, fuel pipelines, etc., and can detect leakage defects with a relatively simpler configuration than conventional methods.

As shown in FIG. 1, this method moves a traveling body 5 equipped with a detection element 4 for detecting high-frequency acoustic noise within an auxiliary pipe 3 attached to a pipeline 1 via a clamp 2,
During this movement, the detection element 4 detects high-frequency acoustic noise caused by fluid leakage from the defective portion of the pipeline via the clamp 2 and the auxiliary pipe 3. However, in the above method, high-frequency acoustic noise is detected through the clamp 2 and the sub-pipe 3, so the high-frequency noise is attenuated significantly, and the leakage signal obtained becomes an extremely small voltage, which makes accurate detection impossible. In addition, it has been found that there are problems such as the distance between the clamps 2 in the length direction of the pipeline 1 must be considerably narrowed in order to perform accurate detection. . The present invention was devised in view of the above circumstances, and is a method for detecting high-frequency acoustic noise in a sub-pipe attached to a pipeline such that part of the outer wall of the pipeline forms part of the inner wall. A traveling body equipped with a detection element is moved, and during the movement, the detection element detects high frequency noise caused by fluid leakage from a pipeline defect, and the leakage defect is detected based on the detection result. This enables accurate detection of leakage defects.

Next, embodiments of the present invention will be described based on the drawings.

FIG. 2 shows an embodiment of the leakage defect detection method according to the present invention. In carrying out the present invention, an auxiliary pipe 6 is attached to the pipeline 1; Specifically, a notch 7 having a constant width is provided along the entire length of the sub pipe 6, and both ends 61, 61 of the notch 7 are fixed to the outer wall a of the pipeline 1 by gluing, welding, etc. As a result, a part of the outer wall a of the pipeline 1 becomes a part of the inner wall of the auxiliary pipe 6. In addition to the above-mentioned welding, etc., as a means of attaching the secondary pipe 6,
A clamp 8 as shown in the figure may also be used. However,
The basic configuration of the present invention is to move a self-propelled or pressure-feeding traveling body 5 equipped with a high-frequency acoustic noise detection element 4 inside the sub-pipe 6.
If there is a defective part and fluid is leaking from this part, high-frequency acoustic noise generated by this fluid leakage is directly transmitted to the inside of the sub-pipe 6, and the traveling body 5 is equipped with The detection element 4 can detect this, and based on the detection result, leaks and defective parts can be detected.

In contrast to the above basic configuration, a more specific configuration of the defect detection method is as follows.

That is, the secondary pipe 3 is provided with a charging port and a recovery port (not shown) for the traveling body 5, and the detection element 4 of the traveling body 5 is connected to a pipeline whose detection element end forms the inner wall of the secondary pipe 3. 1, or a separate hydraulic device is provided on the traveling body 5, and the end of the sensing element is pressed against the outer wall a by this hydraulic device. The driving method for the traveling body 5 is an internal power supply method in which a battery for driving the traveling body is built inside the traveling body 5, or
An external power supply system that supplies power from outside the traveling body 5, such as a rail or a wire, is used. Furthermore, as shown in FIG. 3, the traveling body 5 is equipped with a speedometer 9, an integrator 10, and an automatic recording device 11 (for example, a magnetic tape recorder) in addition to the detection element 4, so that the speed value detected by the speedometer 9 can be measured. is supplied to the integrator 10 to determine the traveling distance of the traveling body 5, and this traveling distance is recorded by the automatic recording device 11. At the same time, the high frequency acoustic noise detected by the detection element 4 is also detected and amplified. (waveform shaping in some cases) and then recorded by the automatic recording device 11. In this way, the automatic recording device 11 records the traveling distance of the traveling object 5 and the high frequency wave corresponding to this traveling distance. Acoustic noise detection results will be recorded. In reality, however, the traveling body 5 is charged into the auxiliary pipe 6 from the charging port, recovered from the collection port located at an appropriate distance from the charging port, and the records of the automatic recording device 11 are analyzed. By doing so, the leakage defect portion of the pipeline 1 can be accurately known.

In this embodiment, the traveling body 5 used in the detection method of the present invention has a detection element 4 attached to the outside, and has a built-in speedometer 9, an integrator 10, and an automatic recording device 11 as shown in FIG. The traveling body 5 consists of a main body 12, legs 13 extending in three directions from the main body 12, and wheels 14 attached to the tips of each leg 13, and the traveling body 5 drives the wheels 14 using the driving battery as a power source. It is designed to be able to run on the inner surface of the auxiliary pipe 6 by itself.

In addition, as another embodiment of the detection method, the inside of the sub-pipe 6 is filled with a suitable filling of liquid or gas, the detection element 4 is brought into a non-contact state with the outer wall a of the pipeline 1, and the sub-pipe 6 is It is also possible to adopt a configuration in which high-frequency acoustic noise is detected through the filling liquid inside.

Further, in this case, the traveling body 5 may be forced to be fed through the auxiliary pipe 6 using the filling liquid. According to the embodiments described above, the detection element 4 is brought into direct contact with the outer wall a of the pipeline 1, or is directly opposed to the outer wall a, so that it is possible to detect high-frequency acoustic noise that is not significantly attenuated. .

According to the pipeline leakage defect detection method of the present invention as described above, the pipeline
A traveling body 5 equipped with a detection element 4 for detecting high-frequency acoustic noise is moved within a sub-pipe 6 attached so that a part of the outer wall a forms a part of the inner wall, and during the movement, the detection element 4, the high-frequency acoustic noise caused by fluid leakage from pipeline defects is detected, and leakage defects are detected based on the detection results, so it is not necessary to install a detection device in the pipeline itself. Therefore, there is no need to consider the sealing performance of the fluid inside the pipeline, or any incidental equipment or equipment for that purpose, and there is no need to take measures such as reducing the fluid pressure inside the line.
The traveling body method allows for proper detection of leakage defects, and in particular, detection is performed using a traveling body that moves within the sub-pipe, so it is possible to detect leakage defects in buried pipelines or for transporting natural gas or oil, which was previously difficult to do. It can be easily and safely applied to detect leaks in pipelines, which are highly flammable fluids such as fluids.Moreover, since the detection element can detect high-frequency acoustic noise with little attenuation, it can be used to detect leak defects with extremely high accuracy. It has excellent industrial utility value, such as being able to detect parts.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an apparatus used to implement a conventional leakage defect detection method. FIG. 2 is a longitudinal cross-sectional view showing an apparatus used to carry out the method for detecting leakage defects in pipelines according to the present invention. Third
The figure is an explanatory diagram schematically showing a detection and recording mechanism included in the traveling body shown in FIG. 2. In the figure, 1 is a pipeline, 4 is a detection element, 5 is a traveling body, 6 is a sub pipe, and a is an outer wall.

Claims (1)

[Claims] 1. Moving a traveling body equipped with a detection element that detects high-frequency acoustic noise within a sub-pipe attached to a pipeline such that a part of the outer wall of the pipeline forms a part of the inner wall,
During the movement, the detection element detects high-frequency acoustic noise caused by fluid leakage from a pipeline defect, and the leakage defect is detected based on the detection result. Defect detection method.