A refractory pipeline having ceramic pipe sections with joints therebetween located at areas where in which there are the greatest temperature differences in the pipeline. Adjacent pipe sections are connected together by shoulders at the ends of each such section, the shoulder of one pipe section being radially outside the shoulder of an adjacent section. A further pipe section is pushed over the joint so as to form a gastight seal by defining a space in communication with a borehole through the one shoulder and a peripheral groove in the other shoulder. A pressure cushion is provided in the space by applying a barrier medium under pressure to the space and thereby through the borehole to the peripheral groove.