RU93987U1 - MAGNET POWDER DEFECTOSCOPE FOR DIAGNOSTIC OF MAIN PIPELINES - Google Patents

Abstract

 1. Magnetic particle flaw detector for diagnosing trunk pipelines, comprising a power supply unit, a magnetizing current unit, a magnetizing device, characterized in that the magnetizing device is made in the form of parallel rectilinear conductors, covered with a transformer iron magnetic circuit located on the surface of the pipe section to be checked and connected to the magnetizing unit current, the input of which is connected to the power supply. ! 2. The flaw detector according to claim 1, characterized in that the number of parallel conductors is equal to ШЗ / 20 mm (ШЗ - width of the control zone).

Description

The utility model relates to the field of non-destructive testing of pipeline transport pipes in the field, can be effectively used to diagnose when they are re-insulated, to control the pipelines of compressor stations.

According to information obtained by means of in-line flaw detectors, it is not possible to obtain the exact location of the defect, so they dig out 2-3 pipes, release them from the ground, and also remove the insulation coating from them. Then, using magnetic particle flaw detectors, the presence of defects and their exact location on the pipe are established, which allows you to take measures to eliminate dangerous defects.

There are many types of flaw detectors used for these purposes.

A flaw detector, which is a horseshoe-shaped magnet like PM 68 (see Appendix 1). The size of the controlled area is approximately 60 × 100 mm. To check the pipe sections with a length of 20 m, only one generatrix will need to rearrange the magnet 200 times. The force of attraction of the magnet is 68 kg (680 N). To check the entire surface of the pipe will require a lot of time and effort. The use of such flaw detectors for pipe inspection is not advisable

A known permanent magnet flaw detector type yoke series YM5 (see Appendix 2). The size of the controlled area is approximately 100 × 100 mm. The force of separation of the flaw detector from the pipe is 18 kg (180 N). To control a pipe 20 meters long, it will be necessary to rearrange the magnet 200 times. The use of such flaw detectors for pipe inspection is also not advisable.

The closest technical solution to the proposed one is a portable flaw detector KN20, containing flexible cables and solenoids, consisting of parallel-connected conductors (turns) (see Appendix 3). To identify transverse defects on pipes of small diameters, cables and solenoids are used (see Appendix 3, Issue RD 13-05-06, p. 75). However, the identification of longitudinal defects by these devices, especially on pipes with a diameter of 1000-1420 mm, is very problematic. In addition, the power consumption of the KN20 flaw detector leaves more than 13 kVA, and this requires a special generator for field conditions. The use of such flaw detectors to control the pipes of gas pipeline transport is also not advisable.

A device that does not have these disadvantages, which has the following advantages:

- the force of magnetic attraction of the magnetizing device when it is rearranged on the pipe is absent, since current is passed through the device for a duration of 1.5 ms;

- the size of the magnetized area for one operation of magnetization is 500 × 150 mm; the size of which is 5 times the size of the monitored sections of devices of a similar purpose;

- control is carried out by the method of residual magnetization, therefore, it is convenient to inspect and apply a magnetic indicator (powder or suspension);

- the use of pulsed current provides a good detection of cracks and other defects.

The purpose of creating the proposed utility model is to increase the operational reliability of the main pipeline transport, the reliability and reduce the labor costs of magnetic particle inspection to detect stress-corrosion cracks, which are the main cause of the destruction of main pipelines.

The goal is achieved by the use of a magnetizing device made in the form of parallel rectilinear conductors, covered with a magnetic core made of transformer iron, located during magnetization on the surface of the tested pipe section and connected to the magnetizing pulse current unit.

In this case, the following control technology is performed. Marking the surface of the pipe to be checked on controlled sections (each section size is 500 × 150 mm), magnetizing them successively by passing a pulse current through the magnetizing device of the proposed flaw detector, applying a magnetic indicator to all magnetized sections and inspecting them to identify defects.

The figure 1 "Diagram of a magnetic particle flaw detector for diagnosing pipes of pipelines" is shown and indicated:

1 - rectilinear parallel conductors made of copper or aluminum busbars of rectangular cross section; 2 - copper or aluminum busbars connecting the conductors 1; 3 - screws; 4 - section of a section of the checked pipe; 5 - connecting wires; 7 - magnetic core from a sheet of transformer iron; 8 - power supply (batteries); 9 - button to turn on the pulse current; Q, L is the width and length of the magnetizing device.

Figure 2 "Connection diagram of blocks of a magnetic particle detector for diagnosing pipes of pipelines" is shown and indicated:

1 - rectilinear parallel conductors; 2 - tires connecting the conductors 1; 6 - pulse current block; 7 - magnetic core from a sheet of transformer iron; 8 - power supply (batteries); 9 - button to turn on the pulse current; 10 - magnetizing device.

In figure 3 "Scheme of the distribution of magnetic flux in the elements of the magnetizing device and the pipe."

1 - section of rectilinear conductors; 4 - section of a section of the checked pipe; 7 - magnetic circuit; Ф - magnetic flux. "+" - the direction of the current in the plane of the drawing.

The figure 4 shows a view of the cracks identified on the pipe using the current sample of the proposed flaw detector.

Description of the design of the Magnetic particle flaw detector for diagnosing trunk pipelines.

The proposed flaw detector contains:

1. Rectilinear parallel conductors 1 made of copper or aluminum busbars of rectangular cross section. When monitoring pipes, the distance L between conductors 1 leaves 20 mm. When monitoring other objects, it can be set from 10 to 50 mm. The beginning and ends of the conductors 1 are connected by busbars 2 using screws 3, which ensures their electrically parallel connection. Conductors 1 and busbars 2 are insulated.

2. Tires 2 connecting the conductors 1. Tires 2 are bent along the radius of the tested pipe, which ensures the direct location of the conductors 1 on the tested surface of the pipe 4.

3. Dealers 5 connecting the bus 2 with the block 6 of the pulse current.

4. The magnetic circuit 7 of a sheet of transformer iron, mounted on conductors 1, is electrically isolated from them.

5. Block 6 of the pulse current with the button 9 of the current, allowing you to skip the current pulse up to 5000 A with a duration of 1.5 ... 1.8 ms

6. The power supply is batteries.

The physical picture of the identification of defects by the proposed device is as follows (figure 2). Due to the skin effect, a pulsed current lasting 1.5 ... 1.8 ms creates a magnetic field that penetrates the pipe material to a shallow depth; therefore, the magnetic flux Ф and the demagnetizing field (demagnetizing factor) turn out to be much smaller than the value of these factors for magnetization by a constant field. In this regard, the detection of stress-corrosion cracks by the magnetic particle method under these conditions is high.

The work of the flaw detector in detecting stress-corrosion cracks is as follows:

- Conduct marking of the tested part of the pipe into sections. The length of each section is 500 mm.

- Install the magnetizing device in the first controlled area so that the conductors 1 (figure 1) were directed along the axis of the pipe. In this case, all conductors 1 will be located on the surface of the pipe.

- pass current through a magnetizing device (through conductors 1) by pressing button 9, magnetizing the first section,

- similarly magnetize all other controlled areas,

- apply a magnetic indicator to all magnetized areas,

- conduct inspection of all areas in order to detect stress corrosion cracks.

Identification of cracks can be carried out using packages of transparent plastic film, in which a magnetic suspension is placed. The package is applied to the magnetized area. Suspension particles are attracted by magnetic fields over defects, forming an indicator pattern (accumulation of powder over defects), which is used to judge the presence of defects. Then the package is removed from the pipe, the suspension is agitated and applied to the next section to detect cracks. Such packages are designed for long-term multiple use.

A flaw detector with the following characteristics was manufactured and tested:

The conductors 1 (Fig. 1) are made of an aluminum bus bar with a cross section of 11 × 6.2 mm, the length of the conductors is L = 500 mm. The distance between the conductors is 20 mm. If the width of the zone (SHZ) control is set, then the number of conductors is determined as the quotient of the division SHZ / 20.

For the manufacture of the magnetic circuit 7 (Fig. 1, Fig. 3), transformer iron 0.35 mm thick was used, which is mounted on conductors 1 using insulating materials.

As block 6 (FIG. 1 and FIG. 2), an MD-I pulse current block is used, which makes it possible to obtain a current in a magnetizing device of up to 5000 A.

Block 8 used two batteries EP 1212 "EUROPAUER", the mass of one battery is 4.1 kg.

It was experimentally established that even 4000 A is sufficient for detecting stress-corrosion cracks in pipes using the developed magnetizing device. The type of stress-corrosion cracks detected using the proposed and manufactured existing flaw detector is shown in Fig. 4.

By continuous scanning of the pipe, that is, by sequentially monitoring the sections using the proposed flaw detector, reliable detection of dangerous defects in the pipes of the gas pipeline is achieved.

Thus, the above and justified set of features of the proposed device is necessary and sufficient to increase the reliability of the main pipeline in connection with the creation and use of a magnetic particle flaw detector for diagnosing main pipelines.

Claims (2)

1. Magnetic particle flaw detector for diagnosing trunk pipelines, comprising a power supply unit, a magnetizing current unit, a magnetizing device, characterized in that the magnetizing device is made in the form of parallel rectilinear conductors, covered with a transformer iron magnetic circuit located on the surface of the pipe section to be checked and connected to the magnetizing unit current, the input of which is connected to the power supply. 2. The flaw detector according to claim 1, characterized in that the number of parallel conductors is equal to ШЗ / 20 mm (ШЗ - width of the control zone).