MOBILE BETATRON LABORATORY

V. A. VOROBYOV, Yu. D. GAVKALOV, G. A. KUNITSYN,
V. F. SHUMIKHIN, V. D. YAROSLAVTSEV

(Presented by the scientific seminar of the Research Institute of Electron Introscopy)

The widespread use of radiation flaw-detection methods brings to the fore the question of creating mobile flaw-detection laboratories, with whose help it would be possible to inspect large-sized parts, units, and products under field conditions, in a shop, or at an assembly site. This is especially true of mobile betatron laboratories, the experience of whose creation at the Research Institute of Electron Introscopy shows the promise of their application and further improvement.

The implementation of a betatron laboratory in a mobile version, in addition to the possibility of inspecting large-sized products under nonstationary conditions, also has the advantage that it becomes possible for a single installation to serve not one but several enterprises, which increases the utilization factor of the laboratory equipment and reduces the expenses of each individual enterprise for the acquisition and maintenance of a betatron installation.

The requirements for such a laboratory may vary depending on the specific inspection conditions, the set of objects to be inspected, the nature of the defects to be detected, and the requirements for detectability of defects and inspection productivity. In addition to these requirements, which are specific to various branches of the national economy and even to individual inspection objects, there exists a system of technical conditions common to most tasks whose solution is expedient with the aid of a laboratory of this type. Such general technical conditions include, first of all, the following:

The equipment of a mobile flaw-detection laboratory must be manufactured in a form permitting its movement over the territory of a construction-and-installation site, an engineering structure, or a shop of an industrial enterprise by means of the simplest lifting-and-transport devices or manually.

Installation of the equipment at the workplace must be carried out quickly and require a minimum of subsequent tuning and adjustment. During transportation and preparatory work, all equipment elements must be completely safe. The servicing of the equipment of mobile flaw-detection laboratories must be accessible to persons having a secondary technical education.

Transportation of the equipment of mobile flaw-detection laboratories must be carried out on motor vehicles of increased cross-country capa-

cost, and the travel of the vehicle over off-road terrain must not cause any violations of the laboratory’s operating parameters.

As our experience has shown, these basic requirements for the equipment of mobile flaw-detection laboratories are fully met by laboratories created on the basis of mobile and transportable betatrons of the PMB-6 and B-18 types. In this case the betatron has the advantageous difference from isotope radiation sources that, when switched off, it is completely safe, which substantially facilitates its transportation.

At the Research Institute of Electrical Engineering, mobile betatron laboratories have been developed, with the aid of which it is possible to inspect products under nonstationary conditions. The laboratory equipment is mounted in the enclosed body of a motor vehicle. Installed there are the betatron electromagnet, the power-supply circuit and control panel, as well as the photographic-laboratory equipment.

At present three versions of laboratories have been developed—PBL-1, PBL-2, and PBL2A—which differ from one another in the type of betatrons used, the set of equipment for processing film and, accordingly, in their inspection capabilities in terms of thickness and detectability, and in film-processing speed. The betatrons included in the set of mobile laboratories are made in the form of three units: the emitter unit, the power-supply unit, and the control panel, which in operating position are connected by cables up to 25 m long.

The set of equipment of the PBL-1 laboratory, housed in the enclosed body of a UAZ-450 truck, includes a PMB-6 betatron, a developing box intended for loading and unloading cassettes and for manual development of films, a drying cabinet, and a film viewer. The laboratory is intended for inspection, under factory conditions, of products up to 250 mm thick in steel or 2.5 t/m² for reinforced concrete.

The PBL-2 laboratory is housed on a ZIL-151 vehicle. The vehicle is equipped with an insulated booth fitted with a ventilation and heating system. The photographic laboratory includes an automatic developing machine, which makes it possible to substantially accelerate the film-processing operation, a washing tank and a drying cabinet, a film viewer, and various auxiliary equipment.

The PMB-6M betatron, produced serially under factory conditions, ensures operation of the betatron flaw detector with much greater reliability than the PMB-6 betatron. The greater intensity provided by the PMB-6M betatron, as compared with the PMB-6 betatron, makes it possible to increase the productivity of flaw-detector inspection.

The PBL-2A laboratory is intended for inspecting thick-walled and large-size products by organizing periodic inspection stations with operating times from several days to several months. The equipment set of the PBL-2A laboratory additionally includes a B-18 betatron. The betatron parameters provide a combination of optimum sensitivity in the thickness range up to 250 mm for steel and 0.5–2.5 t/m² for reinforced concrete with an optimum ratio of inspection productivity to cost. The increase in the energy and intensity of bremsstrahlung radiation in comparison with PMB-type betatrons makes it possible to increase the maximum thickness of transilluminated products to 300 mm in steel and 3.5 t/m² for reinforced concrete.

The technical data of all laboratories are given in Table 1.

When the laboratory is used, the emitter (betatron) can be removed from the vehicle and taken away from it to a distance of up to 50 m. In the case of using PMB-6 and PMB-6M betatrons, the emitter can be carried by hand. In the case of using the B-18 betatron, the emitter is rolled on a cart on which the electromagnet is mounted—

also manually or with the aid of any towing vehicle or hoisting-and-transport device. In any case, the control console can be used both inside the vehicle and at a distance from the vehicle of up to 25 m.

Table 1

In the case of prolonged use of the betatron, for example on a production line or in an inspection area before products are sent to the finished-goods warehouse, all betatron units can be removed from the vehicle and placed at the work stations. During this period the vehicle can be used for other purposes.

The laboratory is powered from a three-phase 50 Hz alternating-current network. Power consumption is up to 1.5 kW when using the PMB-6 and PMB-6M betatrons and up to 5 kW when using the B-18 betatron.

The installation can be powered both from a stationary network and from mobile gasoline-electric units capable of providing the required power. The laboratory is serviced by two operators of average technical qualification, trained in handling the betatron, in radiographic inspection methods, and in processing and interpreting X-ray films.

At present, more than three years of experience has been accumulated in the use of mobile betatron flaw-detection laboratories. Thus, the equipment of the PBL-1 type mobile betatron flaw-detection laboratory, used for inspecting reinforced-concrete building structures, was manufactured in 1967 and in the same year was transferred to the Tomsk Construction Administration.

Over the past three years the laboratory has carried out work in the course of which various building structures were inspected at construction sites and enterprises in the Tomsk and Kemerovo regions; some work was also performed in Moscow and the Moscow region.

The laboratory equipment was transported by various motor vehicles, including unequipped ones, as well as by train, airplane, and helicopter. All expenses for the creation of the PBL-1 mobile betatron laboratory of the Tomsk Construction Administration were recouped during the first half-year of its operation.

Thus, a single inspection of the building of one of the plants, carried out in 1968, as a result of which work on strengthening columns and beams when replacing five-ton crane equipment with ten-ton equipment was canceled as unnecessary, yielded direct savings of more than 31 thousand rubles—that is, more than the cost of all the laboratory equipment. The inspection of the building, during which it was necessary to take more than 150 images, required no more than two weeks. In order not to disrupt work in the shops, radiographic examination of the columns and beams was carried out only at night.

The experience of operating mobile betatron defectoscopic laboratories has shown that they are an effective means of radiographic nondestructive testing and, in operation, pay for themselves in less than a year.

REFERENCES

1. Anan’ev L. M., Vorob’ev A. A., Vorob’ev V. A., Gavkalov Yu. D., Murav’ev G. F., Ermolin N. Ya., Yaroslavtsev V. D. Technical and production principles and organization of the betatron defectoscopy service for structures and facilities made of concrete and reinforced concrete. Proceedings of the All-Union Symposium “Experimental Studies of Engineering Structures.” Collection of the Novosibirsk Institute of Railway Engineers, No. 10, Novosibirsk, 1969.

2. Anan’ev L. M., Vorob’ev V. A., Gavkalov Yu. D., Yaroslavtsev V. D. Equipment for radiographic defectoscopy. Journal “Assembly and Special Works in Construction,” No. 2, 1969.