In ventilation and air-conditioning technology, so-called spiral pipes have to be joined together in a tightly sealed manner at widely differing angles, which is generally carried out by segment bends and pipe sections. An improved, durable seal of folded-seam connections is achieved by a flange-like double fold which is arranged at a first pipe end and which is surrounded on the outside at least in part with positive locking and with a continuous metal seal, by a second double fold at the second pipe end.