RU2295721C2 - Magnetic field flaw detector - Google Patents

Abstract

FIELD: methods of magnetic inspection of ferromagnetic pipelines.

SUBSTANCE: magnetic field flaw detector has removable frame composed of carrier base and two half-frames connected by hinges. Frame gets in contact with surface of pipeline by drive wheels which are connected with longitudinal movement motor-reducer, support and fit wheels and roller supports. Two magnetic modules with magnetic field detector units - one of which magnetize wall of pipeline at longitudinal direction and the other one at lateral direction - are fixed through suspensions onto toothed ring composed of two half-wheels connected by loop knot. Ring is mounted onto roller supports of frame and it is connected with motor-reducer of circular movement drive. Longitudinal movement odometer and power plant are mounted onto frame, which plant and odometer are connected electrically with units for controlling drives of longitudinal and circular movement. Circular movement odometer, data storage unit connected with magnetic field detectors and with odometers, and power supply are mounted onto toothed ring.

EFFECT: improved efficiency of inspection of longitudinal and lateral defects outside pipeline.

2 dwg

Description

The device relates to the field of non-destructive testing of ferromagnetic objects and can be used for external flaw detection of gas and oil pipelines.

A German patent is known (DE 10253123, IPC F 16 L 55/16, Bezechnung Vorrichtung und Verfahren zur Jnspektion order Reparatur von erdveriegten Rohr-feltungen). The introduction of a screw conveyor with elements covering the pipe allows you to clean it from the ground and identify defects using an inspecting device 5. This device does not describe the method and design of the flaw detector. In MNPO “Spectrum” a magnetic scanner SKN-1 is installed, with a width of the control zone of 150 mm. This scanner and the method in its basis do not allow to detect defects in large sections of pipelines in an automated mode. Known EPS scanner company Rosen (Bakaev V.V. Improvement of technology and diagnostic equipment of the company Rosen. Sat XI international business meeting "Diagnostics-2001". T.2,1. M 2001, p.52), which, moving along the outside pipe surface, reveals defects on the inner surface and in the pipe body. The company's equipment consists of three main components: a wireless self-propelled scanner installed on the pipeline, a control panel for manual or remote control, and a computer for processing and visualizing data. The survey is carried out around a 360 ° circle of surface open pipelines made of carbon steel. It can be used to inspect numerous open sections of the pipeline. For more information on this equipment, see the Ronold Tuls "External Jnspesotion" article: Higt Resolution MFL Robotic Pipe Scanner (RPS) (Not nec. June 2004, vul N006). However, the design presented is presented without a detailed description and cannot reliably identify defects around the circumference due to the one-sided vertical location of the scanner.

Known magnetic flaw detector for monitoring cylindrical objects (AS SU 1161859, IPC G 01 N 27/82) containing a magnetizing system, measuring transducers, a registration unit and a trolley made in the form of a self-propelled chassis. In this device, a flaw detector is installed on a controlled surface; Orient it along a given direction, for example along a helix; set the specified value of the gap between the pole of the magnetizing system and the controlled surface, move the flaw detector on the controlled surface of the object with a certain speed and record the magnetic flux of scattering from defects in the walls of the object using a measuring transducer.

This flaw detector improves the performance of inspection of cylindrical objects, but has an unstable position of supports, ensuring the excess of large attractive forces over the weight of the flaw detector and the absence of positioning of defects.

Known magnetic introscope is a prototype device (US Pat. RU 2185616, IPC G 01 N 27/83) for monitoring gas pipelines without removing protective insulation, containing a mobile magnetizing device on wheels, a scanning magnetic field transducer, a transducer controller, a video monitoring terminal, a time-scale converter and a scanning transducer located directly on the mobile magnetizing device on wheels, so that between the poles of the magnetizing device and the control object is made Azores, the scan converter is a magnetic field between the poles of magnetizer and entered frame made of guide associated with the end plate, disposed on the surface due to the attractive forces of the magnetizing device. This introscope has a control zone limited by the frame size and does not allow detecting defects over the entire surface of the pipeline in an automated mode.

The objective of the invention is to increase the performance of a magnetic flaw detector for monitoring the pipeline outside longitudinal and transverse defects.

New in the proposed technical solution is the installation of two magnetic field transducers on a removable frame and their movement in the axial and tangential directions from the engines through the gearbox, positioning of defects using two odometers.

The solution to this problem is ensured by the fact that a magnetic flaw detector containing mobile modules with blocks of magnetic field sensors mounted on wheel supports contains a detachable frame consisting of a bearing base and two half-frames connected by hinges and contacting the pipeline surface with drive wheels connected to the motor - a longitudinal motion reducer, supporting and clamping wheels and roller bearings, two magnetic modules with blocks of magnetic field sensors, one of which magnetizes the wall of the water supply pipe in the longitudinal direction, and the other in the transverse direction, fixed through suspensions on a toothed ring consisting of two half rings connected by a loop assembly mounted on the roller bearings of the frame and connected to the gear motor of the drive for peripheral movement, and the odometer of longitudinal movement is installed on the frame, power plant, electrically connected to the control unit for the drives of longitudinal and circumferential movement, on the toothed ring - the odometer of the circular movement, the information storage unit connected to the sensors field and odometers, and power supply.

The invention is illustrated by drawings of a magnetic system for implementing the proposed method in the form of a diagram of the device in figure 1 and in the form of a magnetic node and a block of sensors in figure 2.

A magnetic flaw detector for the inspected pipe 1 consists of two mobile magnetic modules with blocks of magnetic field sensors 2 mounted on wheel bearings 3 and mounted through suspensions 4 on a gear ring 5, consisting of two half rings connected by a loop assembly 6. A gear ring 5 is mounted on roller supports 7 of the frame 8, consisting of a bearing base and two half-frames connected by hinges 9. The split frame has drive 10, support 11 and pressure wheels 12, with the help of which it moves along the pipe 1. CA 10 are connected by a chain gear 13 to each other and to the gear motor of the longitudinal movement 14. The ring gear 5 is connected through the drive gear 15 and the chain gear 16 to the gear motor of the drive of the circular motion 17. An odometer of longitudinal motion 18 is fixed on the frame 8, and on the gear ring 5 - odometer of circular motion 19. On frame 8 there is also a power plant in the form of a diesel generator 20, which is electrically connected to the drive control unit 21, connected to gear motors 14 and 17, the longitudinal motion odometer 18 and remote wire control panel 22. On the toothed ring 5 also has an electronic unit for processing data storage and transmission 23 and a power supply 24. The magnetic module with the sensor unit (Fig. 2) consists of yoke 25, magnets 26, plates 27, pole pieces 28, sensors Hall 29 and the ADC unit 30. One module magnetizes the wall of the pipeline in the longitudinal direction, and the other in the transverse.

, где l - ширина зоны, контролируемой датчиками одного магнитного модуля; k_n,=1,1...1,2 - коэффициент перекрытия.Magnetic flaw detector operates as follows. A detachable frame 8 is assembled on the examined pipeline 1, securing it with hinges 9, which contacts the surface of the pipeline with drive 10, support 11 and clamping wheels 12. A gear ring 5 is installed on the roller supports 7, with a loop assembly 6 on which magnetic are hung through suspensions 4 modules with sensor blocks 2. When the corresponding buttons on the control panel 22 are pressed, the supply voltage from the power plant 20 is supplied through the control unit 21 to the drive of the peripheral movement (from the gear motor 17 connected by a chain gear whose 16 with pinion gear 15) and a longitudinal motion drive (consisting of a gear motor 14 connected by a chain gear 13 with drive wheels 10), the magnetic modules with sensor blocks 2 begin to roll on wheels 3 along a helical path (translational and rotational movements add up) . The helix pitch is selected from the condition of scanning the entire pipe surface with each magnetic module and is determined by the formula

where l is the width of the zone controlled by the sensors of one magnetic module; k _n , = 1,1 ... 1,2 is the overlap coefficient.

Odometers 18 and 19 allow you to determine the coordinates of defects along the length of the pipeline and their orientation relative to the “top of the pipe”, and the signal from the odometer 18 is transmitted to the electronic information storage unit 23 in a non-contact manner.

.In the process of moving the projectile along the pipeline, the magnetic modules 2 sequentially magnetize (from the magnets 26, through the yoke 25, the linings 27 and the pole pieces 28) sections of the walls of the pipeline to a state of saturation. If there is a defect in the magnetized section of the pipe wall, a crack forms a magnetic flux, the intensity of which depends on the configuration and size of the defect recorded by the Hall sensor 29, the signal is converted by the ADC unit 30 and transmitted to the electronic data processing and storage unit 23, which is fed from power supply 24. To achieve maximum detection sensitivity of both longitudinal and transverse cracks, the first magnetic module magnetizes the pipe wall in the longitudinal direction and, and the second - in the transverse. The design of the magnetic modules provides a constant air gap between the pole pieces and the wall of the pipe being monitored and a uniform magnetic field in the pole gap. As magnetically sensitive converters, thermostabilized Hall sensors with active elements SS495A are used, with field detection limits of ± 65 mT and a steepness of conversion

.

Thus, it is possible to achieve maximum performance in the control of defects outside the pipe, without violating the thin Teflon coating inside modern gas pipelines.

Claims (1)

A magnetic flaw detector containing movable modules with blocks of magnetic field sensors mounted on wheel bearings, characterized in that it contains a detachable frame consisting of a bearing base and two half-frames connected by hinges and contacting the pipeline surface with drive wheels connected to a gear motor longitudinal movement, support and clamping wheels and roller bearings, two magnetic modules with blocks of magnetic field sensors, one of which magnetizes the wall of the pipeline in the longitudinal , and the other in the transverse, is fixed through suspensions on a toothed ring consisting of two half rings connected by a loop assembly mounted on the roller bearings of the frame and connected to the gear motor of the drive for circular motion, and the odometer of longitudinal motion, power plant, are installed on the frame, electrically connected to the control unit for drives of longitudinal and circumferential movement, on the toothed ring is an odometer of circular movement, an information storage unit connected to magnetic field sensors and odometers, and Power Supply.

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