419 When metal moves in a continuous furnace with a lower heating zone, the screening of the billet by hearth equipment (guide pipes, riders) leads to the for� mation of lowtemperature zones (dark spots) on the billet. The associated thermal inhomogeneity of the billet leads to overloading of the mill rollers and the appearance of defects in the final product. Numerous experiments indicate that, for lowand moderatecar� bon steel, the permissible temperature variation ΔT is 50-60°C. Otherwise, defects are likely to form in the steel. The thermal heterogeneity is assessed in terms of the temperature difference in the contact zone of the lower billet surface with the guide pipes and in the plane between adjacent guide pipes. The thermal heterogeneity of the billet may be reduced by lateral displacement of the hearth pipes to a region of the furnace adjacent to the monolithic