A technique quite used in inspection of big length and principally buried pipes is the passage of a pig using the pressure differential on it to impulse itself. But, during the inspection, one of the problems that may occur is the stop of the pig because of severe incrustations or fabrication/installation defects of the pipes, doing the halt of the instrument and, due to the accumulate of pressure at back part, its posterior release with high velocities. This work purpose the use of neural networks in order to model the relation between the differential pressure on the pig and its velocity to collaborate in the velocity control of it after its release.