Non-destructive testing of rails and welds


Monitoring and testing technology

Manual testing of rails and welded rail connections

Mechanized rail testing by means of removable trolleys

Rapid continuous rail testing by means of mobile means



The strength and reliability of rails during their operation is crucial for the railway industry, this is due to the fact that the development of defects and violations of the strength characteristics of the rail may lead to their breaking or even to railway crashes. Long-term operation of rails showed which defects were mainly developing (see UIC Code 712 R) and of course this can seriously affect the safety of the railway transportation. The scientific and industrial enterprises engaged in non-destructive rail testing during their operation improve both the methods of testing and the technology of analysis of inspection results to ensure timely detection of not only critical defects, but also defects that have started their development.
To this purpose, the research and production company OKO GROUP has developed a series of ultrasonic rail flaw detectors: double -rail ultrasonic flaw detector UDS2-73, single-rail ultrasonic flaw detector -UDS2-77 and hand-held ultrasonic flaw detector Sonocon B, which are used for rail track testing.






Monitoring and testing technology




Railway tracks are inspected by ultrasonic high frequency waves, usually the ultrasonic waves with a frequency of 2 to 5 MHz are used to inspect rails.
Since the defects in rails have different character (direction of development, manufacturing defects, operational defects), different angles of ultrasound input into the rail and various sounding schemes and testing methods are used, for example: echo method, echo-shadow method, tandem methods.
The manufacturers of ultrasonic rail testing equipment for the effective and efficient defects detection realize different types of data output to the screen, for example: A-scan, B-scan and their various combinations.
The variety of testing methods and sounding schemes, as well as various types of data visualization make it possible to effectively and with great probability detect the defects at different stages of their development.





Manual testing of rails and welded rail connections




At the moment various rail testing technologies are used in ultrasonic rail inspection, which in turn require the participation of a person to interpret the results of their test. Different regions and countries apply their own approach to ultrasonic rail testing. There are three basic approaches to rail inspection:

Manual inspection and ultrasonic testing of rails implies using a hand-held ultrasonic flaw detector (Sonocon B) plus a set of ultrasonic transducers and a special scanning device (USR-01) with the help of which it is possible to carry out a secondary testing of railroad tracks laid, according to the results of mechanized inspection by ultrasonic or combined ultrasonic rail flaw detectors and flaw monitoring and detecting railcars, as well as for the pre-weld inspection of the end sections of new and used rails before welding them at rail welding enterprises or monitoring joints welded by electrocontact or aluminothermic method.





Mechanized rail testing by means of removable trolleys




This type of testing involves the use of mechanized trolleys, which are moved by operator. There are two types of trolleys exist:

  1. Singlerail trolley;
  2. Double–rail trolley.

 

Such mechanized trolleys house the electronic equipment and transducer blocks, which in turn implement various rail inspection schemes.

Mechanized ultrasonic rail testers allow to carry out:

  1. Continuous monitoring at a speed of up to 4 km / h for defects in both rails of the railway track along the entire length and section of the rail, with the exception of the flanges of rail foot;
  2. Manual confirming testing of individual sections of rails and welds;
  3. Determine the parameters of detected defects and store the results of testing in energy independent memory.




Rapid continuous rail testing by means of mobile means




This technology lies in the fact that the ultrasonic testing of railway tracks is carried out by means of high-speed transport systems (vehicle, wagon or rail car) without stopping along the assigned route; this allows you to inspect areas exceeding 100 km per shift.

 After that, the monitoring data is sent and analyzed in a remote location. Once the data has been analyzed and potentially dangerous sections of rail are revealed, the report is sent to the operators who are conducting confirmatory checks with the help of manual or mechanized flaw detectors.