This paper deals with design and motion planning of a reconfigurable robot that can be used for inspection of 80-100 mm pipelines. This robot consists of two connecting modules and each module consists of three pairs of caterpillar, which is operated by micro DC motor. The robot is foldable by using an embedded four-bar mechanism and compression of a spring connected to the four-bar allows the robot to maintain contact with the wall of pipelines. Controlling the speed of each caterpillar independently provides a steering capability to go through elbow and T-branch. The robot system has been developed and the validity of this mechanism was proved by experimentation.