After 55 gallon drums are painted it is not possible to detect the weld seam by optical means. However, in lithographic  installations it is necessary to orientate the sharp-edged weld away from the screen containing the paint. Otherwise the weld seam may cut the screen resulting in messy cleanup problems. The Weld seam detector SND8 and the sensor NS9S finds the Weld seam for rotating the drum into a safe position.