In one implementation, the present invention provides a robot according to the need of a passive system which can travel for a long range. The robot travels inside a pipe by using energy of the flowing gas, hence it flows in the same direction as the gas. While moving inside a pipe it detects cracks, leaks and indents of the pipe. The robot is equipped with magnetic, optical and piezoelectric sensors to detect different types of anomalies. Piezoelectric sensors respond to the anomalies in terms of electric signals, which are stored in memory unit for further post processing. Similarly, hall sensors are used to detect the change in magnetic flux and interpret it in terms of defect/damage. LED-LDR based sensors detect the presence of surface irregularity in the pipe.