Folded-seam connection, method of producing it and device

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 (1) which is arranged at a first pipe end (X) 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 (2) at the second pipe end (Y). The subject of the invention also extends to an economic method of producing the flange-like double fold (1) as well as to a device suitable therefore for performing the method.