Abstract: The present invention relates to a magneto-hydrodynamic system and method for the treatment of pipes and the fluid carried in the pipes to prevent scaling and build-up of deposits in the pipe. The magneto-hydrodynamic system comprises a pipe for carrying a fluid and at least one magnet unit abutting the exterior of the pipe to be treated. The magnet unit comprises at least four magnets, each having a magnetic-field density of about 6,700 gauss, end pole pieces on each end of the magnet units, and a top pole piece covering the surface of the magnets on a side of the magnets opposite the side in contact with the pipe to be treated.