RU142185U1 - THERMAL DEFECTOSCOPE FOR NON-DESTRUCTIVE CONTROL OF CYLINDRICAL METAL PRODUCTS - Google Patents

Abstract

Thermal flaw detector for non-destructive testing of cylindrical metal products, containing controlled lamps for thermal stimulation of controlled products, a thermal imager, a computer located on the outside of the controlled cylindrical metal products, characterized in that the thermal flaw detector further comprises a rotation device connected to the test table and located on the test table a table with a controlled cylindrical metal product, the rotation device is connected to a computer m, connected to a thermal imager, and lamps for thermal stimulation are connected to a lamp power supply connected to a computer, software-controlled optically opaque curtains of lamps for thermal stimulation are made with the possibility of opening the light flux of heating when the lamps for thermal stimulation are turned on and shut off after switching off lamps for thermal stimulation.

Description

The utility model relates to the field of non-destructive testing, in particular, to active one-way thermal control of latent corrosion of cylindrical containers intended for storage of radioactive waste.

A device is known for determining the depth of local corrosion and monitoring its development using acoustic emission transducers. The device contains one or more acoustic emission transducers that convert the acoustic signal of the acoustic emission process that occurs in the controlled product into an electrical signal. Acoustic emission transducers installed on the controlled product are connected to an oscilloscope that registers the received signals in the form of oscillograms. The oscillogram determines the proportion of the symmetric Lamb wave in the signal and / or the proportion of the antisymmetric Lamb wave in the signal and the received fraction, or the received fractions, or the ratio of the fractions, judge the depth and development of corrosion (patent No. RU 2379675, October 15, 2011) .

The main disadvantages of this technical solution are low productivity and contact control method.

A device related to corrosion control and used to assess the degree of danger of corrosion penetration and protection of metal structures in contact with electrically conductive and low conductive environments is known. The device consists of an enclosure electrically closed to the structure made of the same material as the structure. The body part in contact with the medium has a smaller thickness than the wall of the structure. The cavity of the housing is filled with a non-conductive inert capillary-porous material into which a metal electrode is inserted with the possibility of electrical contact between the housing and the electrode. Also, a recording device is connected between the housing and the electrode. This embodiment of the device allows to simplify its design and provide remote detection of the dangerous penetration of local corrosion regardless of pressure, temperature, movement of the medium and the type of structure, the corrosion of which is controlled (patent No. RU 2143107, from 20.12.1999).

The disadvantages of this technical solution include the requirement of access inside the controlled object and the inability to apply to structures in contact with non-conductive media.

Closest to the claimed technical solution is a device for one-sided pulsed thermal control, the principle of which is based on the processing of thermal images in order to determine the thickness of the product and the depth of defects. The device is intended for non-destructive testing of plastics, ceramics, metals and other materials. Two sources of thermal stimulation - flash lamps - and a thermal imager are located on one side of the controlled product. The computer, using a special program, controls and synchronizes the start of flash lamps and the operation of the thermal imager to collect and process thermal images with the subsequent determination of the thickness of the product and the depth of the defect (patent No. US 6542849, published 1.04.2003).

The disadvantages of this technical solution are the inability to control steel products with a thickness of more than 0.5-1 mm due to the pulsed nature of heating, the presence of interference due to reflected radiation after turning off the flash lamps, the absence of a device for rotating the product with a step determined by the size of the zone of a single control.

The objective of the utility model is to automate the process of non-destructive testing, to obtain latent corrosion maps of metal cylindrical steel products 1-6 mm thick used at nuclear power plants to store low-level radioactive waste, and access to the products is possible only from the outside.

A thermal flaw detector for non-destructive testing of cylindrical metal products contains controlled lamps for thermal stimulation of controlled products, a thermal imager, a computer located on the outside of the controlled cylindrical metal products. The thermal flaw detector further comprises a rotation device connected to the test table and a controlled cylindrical metal product located on it. The rotation device is connected to a computer connected to the thermal imager. Lamps for thermal stimulation are connected to a lamp power supply connected to a computer. Software-controlled optically opaque curtains of lamps made with the possibility of opening the luminous flux of heating when the lamps are turned on and its overlap after turning off the lamps.

The essence of the utility model is illustrated by drawings.

In FIG. 1 is a top view of the device,

In FIG. 2 is a side view

In FIG. 3 - photo - the location of the controlled product and lamps for thermal stimulation.

In FIG. 4 - shows an example of processing the results of thermal non-destructive testing of metal cylindrical products, including analysis of the sequence of infrared thermograms to obtain a defect map.

In FIG. 5 shows a defect map using a neural network.

In FIG. 1 and in FIG. 2 shows a thermal flaw detector for non-destructive testing of cylindrical metal products containing a rotation device 1 connected to a test table 2 and a controlled cylindrical metal product 3 located thereon. A rotation device 1 is connected to a computer 4. Computer 4 is connected to a thermal imager 5. Software-controlled optical the opaque curtain 6 of the lamp for thermal stimulation 7 and the program-controlled optically opaque curtain 8 of the lamp for thermal stimulation 9 are configured to open ment light flux heating and overlap after turning off lamps for thermal stimulation. Lamps for thermal stimulation 7 and 9 are connected to the power supply unit of the lamps 10. The power supply unit of the lamps 10 is connected to the computer 4.

In FIG. 3 shows a thermal flaw detector for non-destructive testing of cylindrical metal products. In the center is a rotation device 1 connected to the test table 2 and a controlled cylindrical metal product of 3 to 200 liter capacity mounted on it. There are lamps for thermal stimulation 7 and 9 on both sides of the controlled product - capacity.

In FIG. 4. An example of processing the results of thermal non-destructive testing of metal cylindrical products, including an analysis of the sequence of infrared thermograms with obtaining a defect map, is shown. The result of the control is a panoramic infrared thermogram "sewn" from individual thermograms, on which the color corresponds to a certain temperature according to the color scale shown on the right. The panoramic thermogram clearly shows two bright areas in zone 11, which correspond to defects in the corrosion entrainment of the material. Other temperature field anomalies reflect the surface structure of the test object. For example, in area 12, bright areas are visible that correspond to the air cavities under the paper labels pasted on the surface of the controlled product with the labeling of the substance in the product. These areas have sharp boundaries, in contrast to smoothed temperature imprints of latent defects in the form of corrosion in zone 11. Zone 13 has a uniform temperature distribution over the surface of the control product, which indicates the absence of defects.

In FIG. 5 shows a binary defect map obtained using a neural network. On the defectiveness map, defects are presented as white spots on a black defect-free background in zone 14. The device operates as follows.

- A controlled cylindrical metal product 3 is installed on the test table 2.

- The operator starts the program to set the parameters of the non-destructive testing, control and synchronization of the operation of the computer 4, the thermal imager 5, the power supply unit of the lamps 10, the lamps for thermal stimulation 7, 9, the analysis of the recorded thermal images and the creation of a defective product card.

- After starting the program, the thermal imager 5 starts sequential recording of a given number of infrared thermograms with a given time interval. The interval for recording thermograms is determined by the frequency of the change of images in the thermal imager 5 and usually ranges from 1/100 second to 1 s, and the total number of recorded thermograms is from 10 to 200.

- Taking into account the delay time set by the operator, the program-controlled optically opaque curtain 6 of the lamp for thermal stimulation 7 and the program-controlled optically opaque curtain 8 of the lamp for thermal stimulation 9 open the light flux by performing thermal stimulation of a certain area of the cylindrical metal control product 3. By after a predetermined time of thermal stimulation, program-controlled optically opaque curtains 6, 8 are automatically closed.

- After holding the programmable time interval necessary for cooling the controlled area, the test table 2 rotates the cylindrical metal product 3 until the next control zone enters the field of view of the thermal imager 5. Moreover, as a rule, two consecutive control zones are overlapped by 10-30% for better “stitching” of thermograms after the end of the control process.

- The cycle is repeated until the cylindrical metal product 3 makes a 360 ° revolution, after which the recording of infrared thermograms ends.

- To control the entire surface of the cylindrical metal product 3, the operator moves the test table 2 with the rotation device 1 in the vertical direction up or down together with the cylindrical metal product 3, thereby shifting the field of view of the thermal imager 5. The operation is repeated until the entire side surface of a cylindrical metal product 3.

- The result of the control procedure is a set of N sequences of infrared thermograms, where N is the number of individual control zones on the surface of a cylindrical metal product 3. In practice, for example, at nuclear power plants, both bottoms of a cylindrical product are also controlled, for which additional mechanical devices are used, for example, a robot.

- The overall result of the control is a defect map of the side surface of a cylindrical metal product 3, consisting of N images, each of which is obtained by processing the corresponding sequence of infrared thermograms according to the algorithm used, for example, polynomial approximation and determination of the second time derivative of temperature, as well as Fourier transform and wavelet analysis, the use of a neural network, the method of analysis of the main components, etc.

The control of latent corrosion in containers with radioactive waste is the main condition for their safe operation. Thermal flaw detector for non-destructive testing provides one-sided access to metal cylindrical products - containers, high reliability of corrosion detection, express character associated with relatively large inspection areas and a large number of containers to be tested at nuclear power plants, as well as a short time for operators to stay near containers, distance test procedures and the ability to quantify the degree of material entrainment.

The use of controlled lamps in the proposed utility model for thermal stimulation with a heating duration of 1-10 seconds allows us to expand the range of controlled thicknesses in steel to 1-6 mm by increasing the amount of absorbed heating energy compared to flash lamps. The presence of software-controlled optically opaque curtains eliminates the interference caused by the reflection of the thermal radiation of the lamps for thermal stimulation after they are turned off. The introduction of the rotation device allows you to control the entire surface of the product by sequential control with a step determined by the size of the zone of a single control.

Claims (1)

Thermal flaw detector for non-destructive testing of cylindrical metal products, containing controlled lamps for thermal stimulation of controlled products, a thermal imager, a computer located on the outside of the controlled cylindrical metal products, characterized in that the thermal flaw detector further comprises a rotation device connected to the test table and located on the test table a table with a controlled cylindrical metal product, a rotation device connected to a computer m, connected to a thermal imager, and lamps for thermal stimulation are connected to a lamp power supply connected to a computer, software-controlled optically opaque curtains of lamps for thermal stimulation are made with the possibility of opening the light flux of heating when the lamps for thermal stimulation are turned on and shut off after switching off lamps for thermal stimulation.

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