Abstract: The use of unshaped refractory mixtures designed to prepare monolithic lining represents a progressive trend that often replaces traditional brick linings. Their advantage lies in the fact that a part of production operations, such as shaping and firing, is performed on the consumer's premises, which reduces production costs, increases productivity and saves energy. Moreover, the repairs of damaged linings using unshaped materials are performed more effectively and, most importantly, faster. Due to the fact that the monolithic lining is continuous, no degradation of material caused by corrosive environments occurs on three of its sides. It is only the contact surface that is affected. The production program of RMS Košice s.r.o. includes a wide range of castables based on various raw materials with different cement contents. The paper deals with the practical applications of castables in heating units used to produce iron and steel. © 2019, Springer Fachmedien Wiesbaden GmbH.