Page 105 - GM E-BOOKLET 2022

4.2. RETROFITTING OF 37°F/B PROBE IN PLACE OF 70° F/B NGFC PROBE

Based on experience SCR recommended that all B-Scan machines
should have 37° F/B Probes, in addition to 70° F/B probes (central, GFC
and NGFC). Anyhow 0° probe is common in all USFD machines.

This item (Item no.1355) was raised in minutes of 10th Extraordinary
meeting (on-line) of Track standards committee on 22nd June 2021. The
committee recommendations are:
 In existing SRT/DRT channels for 70º Non-Gauge face probes should be
used to accommodate 37º probes for detection of bolt hole cracks in
alternate rounds of USFD testing in Zonal Railways.
 Based on the above recommendation the SC Division has already
modified 3 No B-Scan DRT m/cs, 2 No A-Scan DRT m/cs and 1 No A-Scan
SRT m/c with the provision of 37º probes in the place of 70ºNGFC probes.
 The division will do USFD Rail testing by using with 37º probes and

70ºNGFC probes in alternative rounds simultaneously.

Bolt Hole Cracks Detected By USFD B Scan Machine From 01.04.2022 To
16.11.2022 in SC Division
SrDEN/ TOTAL IMR TOTAL TOTAL IMR DUE TO BOLT HOLE
DEN IMRW IMR/IMRW CRACK
North 12 0 12 10
South 38 1 39 33
Central 10 1 11 8
West 9 3 12 6

TOTAL 69 5 74 57

Total IMR detected = 74 Nos
Total IMR of bolt hole crack = 57
Percentage of bolt hole crack = 57/74 x 100 = 77.03%

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