Master Semernin N.A., C.t.s. Semernin A.N.

M.Kh. Dulati Taraz state university, Kazakhstan

Perspective methods of non-destructive testing in “Kazphosphate” LLP of Zhambyl region

The study of the means and methods of nondestructive testing during operation, repair and forecasting of residual resource of the rolling stock in plants and depots showed that by a number of parameters of the controlled units, assemblies and components of rolling stock there is no reliable methods and means for complete control.

The most common method is the magnetic particle inspection, the ultrasonic testing has the second place, eddy current method goes further.

Paradoxical situation has come. Here is an example: one of the causes of fractures of parts of trucks in operation – the presence of casting defects, including internal, which were not identified at the factory. And to identify these defects in the manufacture or operation of parts of trucks is not necessary.

It is necessary to have a sufficient set of tools for the detection of internal defects and improve the detection of surface defects of parts trucks so that to improve traffic safety.

Now let us consider modern system of non-destructive testing of rolling stock:

1. As is well known the diagnostics is a system of the type "control + prediction of residual life." The first part of this system is not a big problem if the applied method of control has been well studied and validated for the specific object of control; there is a small problem with the sensors. Because as their work depends on the completeness and accuracy of the received information.

If not using the system of parts recovery or components and assemblies of rolling stock, the non-destructive testing works on the principle of "serviceable - defective."

Restoration of products is used only when they have sufficient untapped resource and it is brought to the working condition in the production, as a rule, in scheduled maintenance.

The problem is the second component of the diagnostic system – the forecast of the residual resource.

2. At present, there are many attempts to create engineering forecasting methods, the most famous of which are: analytical, statistical and probabilistic. It should be noted that the existing methods of forecasting has not been developed yet and have little practical value. This is due, above all, to the need to obtain vast information, its generalization and response to change. Therefore, all the works in the creation of residual life assessment techniques are extremely useful and relevant.

Analysis of the state of the freight wagons of LLP "Kazphosphate" Zhambyl region shows that the average age of the main types of freight rolling stock is more than 20 years at the appointed time service for 32 years (see figure 1). The order of the work to extend the life period is regulated by "Regulations to extend the service life of freight cars plying in international circulation" and "Uniform guidelines on technical diagnosis of the cargo and refrigerated wagons." The latter document proposes as the main methods of non-destructive testing the magnetic particle and ultrasonic inspection.

Figure 1. The “Kazphosphate” LLP tank wagons with yellow phosphor inside

These methods of nondestructive testing methods are active, and are based on the active cooperation of the signal of a flaw detector to a metal of construction, and the information about the state of stress of the tested object is indirect. Also, the use of these methods of nondestructive testing involves time consuming.

Application of the methods of passive control for technical diagnostics, based on the use of faulty material as the source of the recording of the physical field, allows us to estimate the actual stress-strain state of the structure. Passive method of nondestructive testing is the method of acoustic emission diagnostics.

Acoustic emission is the control of the emission of acoustic waves caused by a sudden rearrangement of the structure of the material. Register of waves and their transformation by using piezoelectric sensors allows to judge about processes occurring in the material [1,2].

The method is widespread in diagnosing of pipelines and vessels, working under pressure.

The above method is proposed to be used in the testing of tank of wagons of "Kazphosphate" LLP in Zhambyl region. The need to load the object of control by force or pressure so that to generate in it sources the acoustic emission allows to combine acoustic emission control with the hydraulic pressure test of the tank. Acoustic emission method allows you to control the entire object using a fixed transducers system that reduces the time and cost. The number of sensors can vary within wide limits (from 2 to 80) (see figure 2) [2], which allows to carry out the high-quality non-destructive testing of especially responsible railway tanks.

Figure 2. An example of the scheme of arrangement of the sensors during the acoustic emission testing of tank

1 – tank; 2 – bottom; 3 – neck; 4-14 – transducers

The only limitation of application of acoustic emission method for testing of tank wagons is the difficulty of separation of acoustic emission signals from the noise and signal interpretation, due to the fact that the acoustic emission signals are noise-like [1]. This disadvantage is likely to be eliminated by developments of catalog of reference defects that need to be compared with the actual picture of the stress-strain state of tank wagons during the acoustic emission testing.

The method of acoustic emission diagnostics of rolling stock is the most promising in terms of the possibility of determining the residual life of tank wagons of "Kazphosphate" LLP on the basis of a viewing a clear picture of the actual stress-strain state of the controlled object.

On the basis of the analysis we may advise to carry out the following integrated activities:

1. Creation on the basis of one of the contracting companies of "Kazphosphate" LLP of the experimental and testing center equipped with all existing types of testing and diagnostic equipment for fully integrated non-destructive testing and diagnosing of new and in-service rail vehicles.

2. Carrying out of the search, research, verification and certification of new most effective nondestructive inspection of railway tanks all over their volume.

3. Approval of the list of primary and backup methods (means) of nondestructive testing for the detection of all types of defects.

REFERENCES

1. Standard 20415-82. Non-destructive testing. Acoustic methods. General provisions [Text]. – 1982. – 4 p.

2. RD 03-131-97. Rules of organization and carrying out of acoustic emission testing of vessels, vehicles, boilers and process piping [Text]. – M .: NPO MBT – 2000. – 15 p.

3. Semernin, N.A. Perspectives of technology of non-destructive testing in railway transport [Text] / N.A. Semernin, A.N. Semernin, N.S. Nauryzbajev // Mechanics & Technologies, Taraz: Taraz University, – 2014, №3, P. 89-92.