The connection of tubular sections (1, 2) of the lining tubes, in particular the flexible tubes for the flue ways, the sections (1, 2) of the lining tubes being alternately provided with terminal telescopic insertable inner nipples (3) with locking pins (4) and outer nipples (5) that are provided with inner circular groove (6, 7) wherein the first inner circular grooves (6) are provided with at least one guiding groove (8) for the locking pin (4), on the sides of which at least one embossed notch (9) is located in the first inner circular groove (6), said notch being arranged to be movable solely unidirectionally by the movement of the locking pin (4) in this groove (6).
