1. Introduction For some years, lower alloyed austenitic-ferritic stainless steel grades have been developed, which are summarised in the „lean duplex" - family of alloys. So far, lean duplex materials have been mainly used as plate material for construction of containers and vessels in the pulp and paper business as well as in architecture and construction. As they are lower alloyed in nickel and molybdenum compared to standard duplex grades, lean duplex grades can offer economically interesting advantages combined with a higher degree of technical reliability compared to supermartensitic stainless steels. Aim of the present study was to figure out, whether lean duplex grades can close the gap between supermartensitic steels and standard duplex stainless steels with regards to weldability, structural stability, mechanical properties as well as corrosion behaviour in typical media for the oil and gas industry. Due to the fact, that there are different grades of „lean" duplex stainless steels, which significantly differ one from the other in terms of chemical composition, the investigation covered three different commercially available grades. Plasma/TIG-, Laser- and Electron Beam-Welding have been used for the industrial production of the longitudinal welded pipes made of Uranus 35N, Al 2003 and LDX 2101. For comparison the complete characterisation of longitudinally Plasma/TIG-welded pipes has been carried out according to the Shell and PDO specifications SIEP 97–5763, SP-1095, and SP-1189. The results have proven the general suitability of longitudinally welded pipes made from lean duplex grades for linepipes for sweet and slightly sour service.