Abstract: The invention relates to a seal means for couplings in gas conduits, particularly for the complete capture of hot exhaust gases which are conducted into a gas stack, for example the exhaust gases of coal gasification reactor. The invention provides a coupling which is gas-tight and pressure-proof, is employable in all attitudes, vertically, horizontally, obliquely, and which exhibits only slight overall height. The invention provides that the gas stack is closed relative to the reactor by means of a sealing element which is designed axially and/or radially movable, preferably as a telescope seal. The sealing element preferably includes compensator bellows for the absorption of the axially and radially effective forces.