Two pipes are arranged end to end, the pipes being shaped such that a groove is defined between the ends of the pipe. A plurality of welding torches are used to weld in the groove, such that at least some of the welding torches perform a first welding pass, the welding characteristics of the torches are adjusted and at least some of the welding torches are used to perform a second welding pass. At least one torch welds in a first sector in the first welding pass and a second sector in the second welding pass, the second sector being different to the first. The sectors might overlap or might not overlap.