While in operation railway tracks must meet many different requirements. Passengers expect safe, quiet, comfortable and reasonably priced transportation. To keep the costs low, the operating company is dependent on a long life cycle and long laydays of rails in the track. In addition, repairs and maintenance expenses of the track system should be as low as possible. However, the rail life cycle is significantly shortened by the formation of cracks, wear or single defects. Since the introduction of the new directive Ril. 821.2007 at the beginning of 2007 eddy current testing for the detection of critical surface defects (Head Checks, Squats etc) has become compulsory.
Eddy current testing is a useful enhancement of the proven ultrasonic test. It is able to test those areas of the rail, in which test systems based on ultrasonic are unsuitable due to physical laws. Precisely speaking, it is the surface area up to a depth of approx. 2.7 mm on the upper surface of the rail as well as on the guiding surface that is considered as “Dead Zone” in the ultrasonic field and considered as very critical for surface defects, such as Head Checks, Squats and Belgrospis.
Inspection Technique Applied
With our own measuring draisines (track motor cars) of the PLR company (WPG II = Eddy current test equipment) Delta Test is able to detect and report these near-surface defects in critical areas on main tracks and in switches. Head Checks are displayed graphically via mileage and/or tachometer indications sectioned by number and depths in 1 m areas in evaluation tracks of 100 m length. A GPS receiver enables the allocation to exact locations. The evaluation software makes it possible to assess the data on or offline.
By wear and zero line adjustment the most different rail types can be safely evaluated, no matter if they are new or already worn. Battery operation guarantees utmost mobility combined with an easy assembly of the “draisine” made out of light aluminium and CFRP.