Railways got off to a flying start and were cruising at 200 for two at one stage before they were checked by an inspired spell from Vineet Sharma who took 3 for 75.
Raja Ali (50 not out) and Shreyas Khanolkar (9 not out) were at the crease at stumps.
Put into bat, Railways began on a promising note with Bangar and Amit Pagnis (40) but lost the latter as well as the wicket of Tejinder Pal Singh (11) in quick succession to be reduced to 77 for 2.
Pagnis was dismissed leg before wicket off Sharma while T P Singh was caught by wicketkeeper and stand-in skipper Pankaj Dharmani off Reetinder Singh Sodhi.
However, Yadav and Bangar ensured that there were no more hiccups as they milked the Punjab attack for over two hours.
Yadav, who was given a life by Dharmani when on 46 off the bowling of V R V Singh, was first to depart when he was bowled by Sharma and Bangar followed immediately, holding out to Sandeep Sanwal off the same bowler.
Yere Goud (15) added 56 runs for the fifth wicket with Ali, but Navdeep Singh claimed the wicket of the former seven overs before close.
Sharma also completed a century of wickets in the Ranji Trophy tournament when he took the wicket of Pagnis.
Punjab has gone into the match without three of their key players - Yuvraj Singh, Dinesh Mongia and Harbhajan Singh - who are on national duty while Railways are missing the services of left-arm spinner Murali Kartik.
Both have met 11 times, with Railways winning on two occasions, Punjab once and eight matches have ended in draw.
The two had met in Mohali last time in 2000-01 in the Ranji Trophy semi-final in which Railways beat Punjab by five wickets.
The hosts have played two finals so far, but won only once in 1992-93, while the visitors have played in three finals having won once in 2001-02.