Degradation in bauxite refractory linings used in steel plants is localized in the slag-impregnated zone of refractories. It is proposed to estimate the contribution of the pressure of the impregnated liquid on the degradation of refractories. The study of the gradient of chemical composition allows for the evaluation of the liquid content, the oxide content in the liquid phase, and the "slag" viscosity. The thermomechanical analysis of a porous refractory impregnated by slag enables us to propose analytical expressions for a rapid estimate of the maximum "slag pressure" and its location as well as the level of thermoelastic stresses.