Method for heating a metal slab

In a method for heating a metal slab (4) being transported in a longitudinal direction (L) and having a cross-direction (T) through an industrial furnace (1) in which the metal slab is heated and transported on a rail device (101;201;301) from the industrial furnace for subsequent processing (8), the improvement comprising:

• impinging a flame (103,105,205,305) from at least one direct flame impingement (DFI) burner (102,104,204,304) to contact a first portion of a first surface of the metal slab in at least one location corresponding to a second position on an under side surface of the metal slab which during transporting of the metal slab through the industrial furnace constitutes a contact point between the under side surface of the metal slab and the rail device, and counteracting a temperature gradient in the metal slab arising from local cooling of the metal slab upon contact with the rail device by heating the first portion with the DFI burner.