Method and arrangement for the optoelectronic control of the weld formation in the automated longitudinal welding of pipes

The invention relates to a method for the longitudinal welding of pipes made of steel alloys or non-ferrous metals, in which the light radiation coming from the red-hot weld deposit is measured optoelectronically for determining the weld width and for the regulation, derived from this by desired-value comparison, of the welding current, and in which the position of the welding torch(es) during the feed of the slit pipe is adapted to the position of the welding gap on the basis of measuring signals likewise recorded optoelectronically. In order to ensure uniformly high welding quality, it is proposed that both measuring signals (signal for determining the weld width and signal for determining the position of the welding gap) be recorded in a path-dependent manner by in-phase, continuous scanning transversely to the weld or the welding gap across the width of the weld or the welding gap. In this arrangement, the sensor devices for recording the signals are held in a fixed position relative to one another, the signal patterns are compared with one another in accordance with the path, and, as soon as both signal patterns do not lie concentric to one another, the position of the welding torch(es) is displaced transversely to the direction of the welding gap in such a way that the concentricity of the signal patterns is achieved again.