I am saying that can I crack BHEL exam after doing b teach from a simple engineering college or I need to be graduate from NIT or IIT's.

Hello Kshitij, it does not matter as to from where you did your graduation. What matters is your intelligence and resourcefulness. In any case, many of the PSU's take young engineering graduates based on ranking in GATE and not by going to any college for placements. Best wishes to you.