CHAPTER 3

ULTRASONIC RAIL TESTING EQUIPMENT AND ACCESSORIES

3.0  Ultrasonic testing of rails is a specialized activity and the inspectors carrying out the ultrasonic testing of rails shall be trained by RDSO, in the techniques of USFD testing.  Each zonal railway shall create adequate number of ex-cadre posts of inspectors to ensure that entire track length in their jurisdiction is ultrasonically tested at the laid down periodicity. (New para 3.0 introduced vide ACS  No. 7 of 2000)

3.1  On Indian Railways, flaw detection by ultrasonic is carried out with the help of two different types of equipments viz. single rail tester and double rail tester. The single rail tester has been utilised on Indian Railways for over 35 years and the double rail tester is of a relatively recent origin (developed seven years back). In addition  hand testers of some designs are also being used. Current list of RDSO approved sources of single and double rail testers with their respective equipment models is given below. Procurement of USFD equipments should be done only from the RDSO approved sources (as per latest list). (Para 3.1 replaced vide ACS  No.10 of 2002)

 

Manufacturer

Models approved

1

M/s ECIL, Instruments Group (Testing), Hyderabad-500 762.

6256 A Single Rail Tester

2

M/s EEC, EEC House, Plot C-7, Off New Link Road, Near Laxmi Industrial Estate, Andheri (W),                Mumbai- 400 058.

RT-22 Single Rail Tester

RT-44 Double Rail Tester

3

M/s Vibronics Pvt. Ltd., Masrani Estate, Halav Bridge, Mumbai - 400 070.

FD 301R Single Rail Tester

4

M/s Paras Electronics F-1/A, Kakateeya Nagar, Uppal Road, Hyderabad- 500 007.

RT- 101 Multi channel Single Rail Tester RT-201 Multi channel Dual Rail Tester.

3.1.1 Total life of USFD Machine is eight years.

 

3.1.2  Maintenance spares be procured along with Machine and should be as per para 4.4 pertaining to maintenance spares. (New para 3.1.1 & 3.1.2 introduced vide ACS  No. 10 of 2002.)

3.2 Single rail tester : Single rail tester is capable of testing only one of the rails at a time and is provided with five probes i.e. 0, 70 Forward (F), 70 Backward (B), 37 Forward (F) and 37 Backward (B). The normal probe (0) is utilised for the purpose of detecting horizontal defects situated in head, web or foot. The 70 probe has been specifically provided for detecting defects in the rail head, the most typical of which is the transverse fissure or kidney fracture. 37 probes have been provided to find out defects originating from the bolt hole (star cracks). The approximate coverage of the rail section with the help of the above arrangement is indicated in Fig. 2.

The signal received from the defects by any of the above probes is indicated on the cathode ray tube (CRT) screen. In order to find out the origin of detection i.e. which probe has picked up the defect, provision for eliminating the individual probe operation has been made in the equipment.

 

3.3 Double rail tester

 

3.3.1 The double rail tester is capable of testing both the rails at a time. However, for each rail, only three probes have been provided for the present i.e. 0, 70 Forward and 70 Backward. This equipment, unlike the single rail tester, has multichannel facility i.e. the signal received from each probe can be instantaneously distinguished without taking recourse to process of elimination. This equipment has also been provided with a threshold arrangement, LED display and audio alarm in addition to the CRT screen. Thus there are three modes of defect indication i.e., CRT, audio alarm and LED display.

3.3.2 The normal probe is provided for detection of horizontal defects and 70 probes have been provided for transverse defects in the head. For detection of bolt hole defects, the equipment works on the principle of backwall drop, which in the event of a bolt hole crack shows reduction in echo-amplitude of the backwall. It is also supported by separate audio alarm with distinctly different tone and LED display.

 

3.3.3 The introduction of double rail tester has been specifically made for enhancing the productivity of testing and as well as improving the quality and accuracy of flaw detection. Due to pre-calibrated arrangement, frequent setting of the equipment is not considered necessary.

 

3.3.4 Due to frequent misalignment of probes on the fish plated joints and limitations of detection of bolt  hole cracks having unfavorable orientation and size, it is desirable to deploy double rail testers on LWR/CWR sections.

 

          It is desirable to deploy only the ultrasonic Machine of the single rail tester for testing sections other than LWR/CWR, new AT Welds and flange testing of AT Welds by 700 ,1.25 MHz probe. (Para 3.3.4 replaced vide ACS No. 10 of 2002)

 

3.4 Specification of rail testers

 

3.4.1 The single and double rail testers shall be procured to RDSO specification, details of which are placed at Annexure II and III. The responsibility of inspection for these equipments rests with Director General, RDSO.

 

3.5 Types of probes : Following types of probes other than mentioned in para 3.2 and 3.3 are also in use. Details of probes and their uses are given at Fig. 35.

 

45 probe

For testing Gas Pressure and Flash Butt Welded joints

70  , 2.0 MHz probe (20 mm or 20 mm X 20 mm)
Flange testing of AT welds

(Para 3.5 replaced vide ACS No. 10 of 2002)