This paper presents the mathematical expressions for calculating the temperatures between the layers of a plan, tubular or spherical composite, by natural or forced conduction and convection or under the influence of stationary heat flow. Here there are taken into account two possibilities of contact between the layers: one is the perfect contact or the other acknowledges the existence of casual imperfections. The expressions also take into consideration the influence of added protection on the wall surface or the possible deposits of solids materials that can occur during the operation of the structure.